Hydrological Analysis for Simanggo-2 HEPP

Part 15 Hydrological Analysis for Simanggo-2 HEPP

PART 15 HYDROLOGICAL ANALYSIS FOR SIMANGGO-2 HEPP 15.1 METEOROLOGY AND HYDROLOGY Meteorological Records and Hydrological Records are collected from Meteorological Climatological and Geophysical Agency (Badan Meteorologi Klimatologi dan Geofisika: BMKG), Research Institute for Water Resources Development under Ministry of Public Works (Pusat Penelitian dan Pengembangan Sumber Daya Air: PUSAIR, formerly DPMA), and engineering reports on various hydropower development projects. The location map of the stations is shown in Figure 1. The availability of data is summarized in Figure 2. The catchment area of Simanggo-2 HEPP intake weir site is shown in Figure 3. 15.1.1 METEOROLOGICAL DATA Climatic data such as air temperature, relative humidity, wind velocity, sunshine duration have been observed at the Sibolga station, which is collected from BMKG. Pan-evaporation has been observed at the Parapat and the Gube Hutaraja stations. Pan-evaporation data is collected from Asahan -3 HEPP report. The variation of principal climatic data at the Sibolga station, the Parapat station and the Gube Hutaraja station is shown in Figure 4. (1) Air Temperature Table 1 shows the monthly mean air temperature at the Sibolga station. The average monthly mean air temperature at the Sibolga station in the period of 1984 to 22 is summarized below. Station Name: Sibolga (1984-22) Unit: Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Mean 25.8 23.9 26.2 25.5 26.7 25.8 25.7 25.7 24.7 25.6 24.7 25.8 25.5 As seen, the mean annual air temperature at the Sibolga station is 25.5ºC on an average. There is a slight seasonal change ranging 23.9ºC in February to 26.7ºC in May. (2) Relative Humidity Table 2 shows the monthly mean relative humidity at the Sibolga station. The average monthly relative humidity at the Sibolga station in the period of 1984 to 22 is summarized below. JICA Project for the Master Plan Study of 15-1 August, 211

Station Name: Sibolga (1984-22) Unit: % Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Mean 84.4 76. 85.7 83. 83.8 79.7 83.6 85. 82.8 85.8 84.6 88.1 83.5 As well as the monthly pattern of mean air temperature, there is no significant change of relative humidity throughout the year. The annual mean relative humidity in the period of 1984-22 at the Sibolga station is 83.5 % and there is a slight seasonal change ranging from 76.% in February to 88.1 % in December. (3) Sunshine Duration Table 3 shows the monthly mean sunshine duration at the Sibolga station. The average monthly mean sunshine duration at the Sibolga station in the period of 1984 to 22 is summarized below. Station Name: Sibolga (1984-22) Unit: % Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Mean 56.9 61.9 54.9 58.3 62.4 61.2 58.9 52.3 46.6 44.8 46.9 54.3 55. As seen, the mean annual sunshine duration at the Sibolga station is 55. % on an average. The maximum duration of 62.4% and the minimum one of 44.8% occur in May and October, respectively. Sunshine duration generally decreases with an increase of rainfall. The highest sunshine duration therefore occurs in May in the dry season. (4) Wind Velocity Table 4 shows the monthly mean wind velocity at the Sibolga station. The average monthly mean wind velocity at the Sibolga station in the period of 1984 to 22 is summarized below. Station Name: Sibolga (1984-22) Unit: m/sec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Mean 5.2 5.8 6.5 5.5 4.8 5. 5.3 5.3 5.2 5.4 5.1 5.1 5.3 Mean annual wind velocity at the Sibolga station is 5.3 m/sec ranging from 4.8m/sec in May and 6.5m/sec in March. (5) Evaporation Pan evaporation records are available at the Parapat station and the Gube Hutaraja station. The pan evaporation records at both stations are summarized on monthly basis as shown in Table 5. The average monthly mean pan evaporation at the Parapat and the Gube Hutaraja stations is summarized below. JICA Project for the Master Plan Study of 15-2 August, 211

Station Name: Parapat (1997-26) Unit: mm/day Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Mean 3.6 4. 4. 3.9 4.3 4.2 4.3 4.4 4. 3.8 3.4 3.3 3.9 Station Name: Gabe Hutaraja (1996-25) Unit: mm/day Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Mean 2. 1.7 2. 1.8 2.4 2.2 2.2 2. 1.8 1.4 1.5 4.7 2.1 The ruling factors of pan evaporation may be air temperature and relative humidity, namely evaporation rate varies season to season following to mainly the variation of humidity. As seen in the above table, the seasonal variation of pan evaporation is generally small throughout the year, because there is no great seasonal variation of relative humidity. 15.1.2 RAINFALL DATA There are 12 rainfall gauging stations in and around the Simanggo river basin. The location map of these stations is shown in Figure 1. Also the data availability at these stations is shown in Figure 2. The rainfall gauging stations are operated and maintained under BMKG. Daily rainfall records are collected from BMKG in this study. PLN formerly had own hydrological observation network (PLN-LMK Observation Network). Currently most of these stations have broken down, after regional office of PLN took responsibility for maintenance which the central office of PLN had taken. (1) Monthly Rainfall Data The monthly mean rainfall records are collected at 12 stations as presented in Table 6 to Table 17. The monthly distributions of mean annual rainfall are illustrated below. Rainfall(mm) Segala(Sigala-gala): 3,816 mm (1969-28) 6 5 4 3 2 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec JICA Project for the Master Plan Study of 15-3 August, 211

Rainfall(mm) 6 5 4 3 2 Tarutung: 1,962 mm (1969-28) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Rainfall(mm) Hutaraya(Gabe Hutaraja): 2,18 mm (1969-28) 6 5 4 3 2 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Rainfall(mm) 6 5 4 3 2 Barus(Baros): 3,475 mm (1969-28) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Rainfall(mm) Siborong-borong: 2,768 mm (1969-28) 6 5 4 3 2 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec JICA Project for the Master Plan Study of 15-4 August, 211

Rainfall(mm) 6 5 4 3 2 Dolok Sanggul: 2,32 mm (1969-28) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Rainfall(mm) Gugur Balige(Pintu-Pintu): 1,975 mm (1969-28) 6 5 4 3 2 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Rainfall(mm) Rainfall(mm) 6 5 4 3 2 6 5 4 3 2 Baligi-1(Baligi): 2,432 mm (1969-28) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Paguruan: 1,865 mm (1969-28) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec JICA Project for the Master Plan Study of 15-5 August, 211

Rainfall(mm) Rainfall(mm) Rainfall(mm) 6 5 4 3 2 6 5 4 3 2 6 5 4 3 2 Salak: 3,89 mm (1969-28) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Sidikalang: 2,387 mm (1969-28) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Tiga Lingga: 1,571 mm (1969-28) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec As seen above, the annual mean rainfall at these stations ranges from 1,5 mm to 3,8 mm per year. It might be said that there exists some seasonality in the Simanggo River basin. (2) Hourly Rainfall Records Hourly rainfall records are available at the Sibolga station, which is located at 7km south of Lake Toba. Hourly rainfall records are collected to determine the rainfall pattern for the flood analysis. Hourly rainfall records of more than mm in a day were selected for estimating the characteristics of relatively heavy rainfall. The list of selected hourly rainfall records are enumerated in Table 18. JICA Project for the Master Plan Study of 15-6 August, 211

15.1.3 RUNOFF RECORDS (1) Water Level Gauging Station(AWLR Station) No water level gauging station exists in the Simanggo River. Around the Simanggo River basin there are three stations, the Pasar Sironggit station, the Dolog Sanggul station and the Marade station. AWLR stations are opereated by the River Bureau under the Ministry of Public Works (Balai Wilayah Sungai: BWS). The station around the Simanggo River is under the jurisdiction of BWS Sumatera Ⅱ in Medan. The organization chart is shown in Figure 5. BWS collects water level and discharge measurement records in twice a year, and sends those to PUSAIR Bandung. Data processing is carried out by PUSAIR presently. BWS is planning to carry out data processing in no distant future. (2) Runoff Records The daily runoff records are collected from PUSAIR in Bandung. The monthly mean runoff deriving from the daily runoff records is presented in Table 19 to Table 21. The daily hydrographs are illustrated in Figure 6 to Figure 19. The average monthly mean runoff is summarized below. Station Name: Pasar Sironggit (1982-28) Unit: m3/s Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Mean 12.3 11.5 12.5 16.9 16.4 1.4 1.1 12.7 11.3 14.8 2. 17.9 13.9 Station Name: Dolog Sanggul (1991-28) Unit: m3/s Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Mean 5. 4.4 4.2 5.1 4.7 3.2 3.1 3.1 4.2 4.2 5.7 4.8 4.3 Station Name: Marade (1983-28) Unit: m3/s Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Mean 7.4 6.6 7.2 8.4 8.1 5.6 5.1 5.8 6. 7.5 8.8 7.1 7. As seen, the annual mean runoff is 13.9m 3 /s at the Pasar Sironggit station, and 4.3m 3 /s at the Dolog Sanggul station, and 7.m 3 /s at the Marade station. The catchment area and the annual runoff are tabulated as follows. The annual runoff depth is computed by dividing the annual accumulated runoff volume by the catchment area of the gauging station. Catchment Area (km 2 ) Annual Average Runoff (m 3 /s) Annual Average Runoff Depth (mm) Pasar Sironggit 35.6 13.9 125.3 Dolog Sanggul 58. 4.3 2338. Marade 163.8 7. 1347.7 JICA Project for the Master Plan Study of 15-7 August, 211

15.1.4 LOWFLOW ANALYSIS (1) General Approach The continuous long-term runoff data for a time period of more than 2 years at the proposed intake weir site is normally required for evaluating an optimum development scale of the project through power output computation. Further, it is highly expected that the runoff data should be of high accuracy because measurement on economic viability of project is highly dependent on the reliability of available runoff records. On the Simanggo-2 HEPP, daily runoff records are required because the type of hydropower development scheme is runoff type. As described in the previous chapter, no water level gauging station exists in the Simanggo River. Around the Simanggo River basin there is the Pasar Sironggit station. The daily runoff records are available from 1982 to 28 except in 1988 to 199, 1999, 2, and 22 to 26. Furthermore, the remaining observation years still include data-missing periods. Therefore, it is necessary to supplement the runoff records at the Pasar Sironggit station by infilling of missing data. On the other hand, the daily basin mean rainfall at the Pasar Sironggit station can be estimated for the period between 1977 and 1998. Thus the runoff data at the Pasar Sironggit station can be supplemented and expanded for the period of 1977 to 1998 by constructing a rainfall-runoff simulation model. Along this line, the Tank Model Method is applied in this study as a rainfall-runoff model, the model parameters of which are calibrated by using rainfall and runoff records available in the period of 1991 to 1993. Firstly, the reliability of the available runoff records at the Pasar Sironggit station for using calibration is evaluated by means of runoff coefficient and annual rainfall loss. Then lowflow analysis by the Tank Model Method is carried out to simulate 22-year long-term daily runoff data at the Pasar Sironggit station. Finally the 22-year daily runoff data at the Simanggo-2 intake weir site is estimated. The outline of lowflow analysis is described below. JICA Project for the Master Plan Study of 15-8 August, 211

Test of Consintency of Rainfall Records Daily Runoff Records at Pasar Sironggit Estimation of Daily Basin Mean Rainfall Scrutiny of Runoff Records : ( Reliability Check ) - Runoff Coefficient - Annual Rainfall Loss - Consistency of Records ( 1991-1993 ) Establishment of Rainfall - Runoff Simulation Model ( Tank Model Method ) Calibration of Model Parameters ( 1991-1993 ) Supplementation & Expansion of Runoff Records by Tank Model ( 1977-1998 ) Estimation of Long-Term Runoff at Simanggo-2 Intake Weir Site ( 1977-1998 ) (2) Estimation of Missing Data The observed rainfall records at all of the selected stations include several data interruptions. For the purpose of supplementing the missing rainfall records, the simple regression analysis on the monthly basis are carried out among the selected stations. Missing monthly data at a station is supplemented by data at another station with linear regression equation which has the highest correlation coefficient. The number of data and correlation coefficient and slopes of linear regression equation is tabulated in Table 22. Missing daily data is also supplemented by daily data at another station with monthly linear regression equation. (3) Test of Consistency of Rainfall Records The method of testing rainfall records for consistency is the double-mass curve technique. JICA Project for the Master Plan Study of 15-9 August, 211

Double-mass analysis tests the consistency of the record at a station by comparing its accumulated annual or seasonal precipitation with the concurrent accumulated values of mean precipitation for a group of surrounding stations. The corrected rainfall is determined by the following equation. P CX = PX ( M C / M a ) where, P CX : Corrected rainfall at any time period at station x (mm) P X : Original recorded rainfall at any time period at station x (mm) M C : Corrected slope of the double-mass curve M : Original slope of the double-mass curve a The double-mass curves are presented in Figure 2. As seen, the rainfall records at the Siborong-borong station and the Gugur Balige station have different characteristic, then these stations are eliminated for following analysis. (4) Basin Mean Rainfall The basin mean rainfall at the Pasar Sironggit station is estimated by applying the arithmetic mean method. The records of selected rainfall gauging stations are divided in two periods considering data availability. Case1 (1977 to 199): Tarutung, Dolok Sanggul Case2 (1987 to 1998): Hutaraya, Dolok Sanggul The estimated monthly basin mean rainfall at the Pasar Sironggit AWLR station is presented in Table 23. The estimated annual basin mean rainfall is 1,82mm. (5) Evaluation of Runoff Records at the Pasar Sironggit AWLR station No water level gauging station exists in the Simanggo River. Around the Simanggo River basin there are three stations, the Pasar Sironggit station, the Dolog Sanggul station and the Marade station. The Pasar Sironggit AWLR station is selected as a key stream gauge station for predicting the long-term runoff at the proposed Simanggo-2 intake weir site, because the catchment area is 35.6km 2 as large as the Simanggo River basin. The evaluated period of runoff records is determined to be 3 years from 1991 to 1993, because both rainfall and runoff records are available in this period for calibration of Tank Model parameters. 1) Relationship between Annual Basin Mean Rainfall and Annual Runoff Depth at the Pasar Sironggit AWLR Station The annual basin mean rainfall at the Pasar Sironggit AWLR station is estimated for the JICA Project for the Master Plan Study of 15-1 August, 211

period of 1985 to 1987, and 1991 to 1998. On the other hand, the annual runoff depth at the Pasar Sironggit station is computed by dividing the annual runoff volume by its drainage area of 35.6km 2 for the same period as above. The established relationship between annual basin mean rainfall and annual runoff depth at the Pasar Sironggit station is as follows. Besides, the relationship is plotted in Figure 21. Year Annual Rainfall (mm) Annual Runoff Depth (mm) Annual Rainfall Loss (mm) Runoff Coefficient 1985 1,83 776 1,27.43 1986 1,533 915 618.6 1987 1,96 97 1,53.46 1991 2,714 1,929 785.71 1992 1,873 1,26 668.64 1993 2,132 1,425 77.67 1994 1,438 1,587 (15) 1.1 1995 1,869 1,38 561.7 1996 1,7 1,726 (26) 1.2 1997 1,25 1,691 (441) 1.35 1998 1,592 1,579 13.99 Average 1,86 1,368 438.79 The difference between the annual basin mean rainfall and annual runoff depth is the so-called evapotranspiration loss or annual rainfall loss. The annual rainfall loss is analyzed for major rivers in Sumatra in HPPS2 as presented in Table 24 and illustrated in Figure 22. It is therefore found that the annual rainfall loss normally falls in a range of 7 to 1,5 mm a year which varies according to altitude, natural vegetation, seasonal distribution of rainfall, etc. As seen above, the rainfall loss at the Pasar Sironggit station varies from -4mm to 1,mm. From the hydrological point of view, the rainfall loss usually varies in a small range. Generally the rainfall loss cannot be smaller than zero, and then the runoff data from 1994 to 1998 is eliminated. 2) Double Mass Curve Analysis Based on the adjusted annual basin mean rainfall and annual runoff depth at the Pasar Sironggit station, the double mass curve is constructed as given below. JICA Project for the Master Plan Study of 15-11 August, 211

1, Accumulated Runoff Depth (mm) 8, 6, 4, 2, - 1993 1985-2, 4, 6, 8, 1, 12, 14, Accumulated Basin Mean Rainfall (mm) As shown above, the annual basin mean rainfall and annual runoff depth are plotted on a straight line, satisfactorily showing the hydrological consistency ready for Tank model analysis to be discussed in the next section. (6) Tank Model 1) Concept of Tank Model Method The Tank Model simulation method is widely applied for estimating river runoff from rainfall data. The Tank Model Method has been successfully applied for low-flow analysis in various water resources development projects in Indonesia. Basic concept of Tank Model The basic idea of Tank Model is very simple. Consider a tank having a hole at the bottom and another hole at the side as illustrated below. JICA Project for the Master Plan Study of 15-12 August, 211

When the tank is filled with water, the water will be released from the holes as shown in the above. In the tank model simulation, it is considered that the water released from the side hole corresponds to runoff from a stream, and the water from the bottom hole goes into the ground water zone. The depth of water released from a hole is given by the following tank equation. Q = α H where, Q : Runoff depth of released water (mm) α : Coefficient of hole H : Water depth above the hole (mm) Applied Tank Model For the purpose of natural runoff simulation, four by four (4 4) tanks combined in series are used as shown in Figure 23. The top tank receives the rainfall as inflow to the tank, while the tanks below get the supply from the bottom holes of the tank directory above. The aggregated outflow from all the side holes of the tanks constitutes the inflow in the river course. To effectively trace dry conditions in the basin, several modifications are made on the basic model. The model is firstly facilitated with a structure to simulate the moisture content in the top tank. This sub-model is composed of two moisture-bearing zones, which contain moisture up to the capacities of saturation. Between the two zones, the water transfers as expressed below. T 2 = TC( XP / PS XS / SS) where, T 2 : Transfer of moisture between primary and secondary zones (if positive, transfer occurs from primary to secondary, and vice versa) TC : Constant XP : Primary soil moisture depth PS : Primary soil moisture capacity XS : Secondary soil moisture depth SS : Secondary soil moisture capacity When the primary soil moisture is not saturated and there is free water in lower tanks, the water goes up by capillary action so as to fill the primary soil moisture with the transfer speed T1 as given below. T1 = TB(1 XP / PS) JICA Project for the Master Plan Study of 15-13 August, 211

where, T 1 : Transfer of the water from lower tank with capillary action TB : Constant There are many tank model parameters such as hole coefficients of each tank, and height of side holes of each tank. These parameters cannot be determined mathematically. Therefore, these parameters are subject to determination through trial-and-error calculations comparing the calculated runoff with the actually observed runoff. 2) Input Data for Calibration Model The applied model and simulation condition for calibration are given below. The period for calibration set from 1991 to 1993 because there are continuously rainfall records and runoff records and the rainfall loss during the period is relatively stable. Number of Tanks 4 4 Calculation Time Interval 1 day Calculation Period 1991 to 1993 Observed Runoff at Pasar Sironggit 1991 to 1993 Basin Mean Rainfall at Pasar Sironggit 1991 to 1993 Monthly Average Evaporation at Gabe Hutaraja 1996 to 25 The pan evaporation record at the Gabe Hutaraja station is applied. The pan coefficient of.8 is applied for estimating evapotranspiration in the basin. The average monthly pan evaporation is given below. Station Name: Gabe Hutaraja (1996-25) Unit: mm/day Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Mean 2. 1.7 2. 1.8 2.4 2.2 2.2 2. 1.8 1.4 1.5 4.7 2.1 3) Calibration Results Through several trial-and-error calculations, the best coincidence between the simulated and observed runoff at the Pasar Sironggit station is obtained under the tank parameters as follows. Hole Coefficient Height of Hole (mm) β α1 α2 H1 H2 Tank-1.5.3.65 5. 6. Tank-2.3.4. 1.. Tank-3.3.3. 3.. Tank-4.1.1... The rainfall-runoff relationship of the simulated runoff is examined compared with the observed runoff as summarized below. JICA Project for the Master Plan Study of 15-14 August, 211

Year Annual Rainfall (mm) Annual Runoff Depth (mm) Annual Rainfall Loss (mm) Runoff Coefficient Observed Simulated Observed Simulated Observed Simulated 1991 2,711 1,929 1,759 783 952.71.65 1992 1,873 1,21 1,318 672 555.64.7 1993 2,131 1,424 1,421 77 71.67.67 Average 2,238 1,518 1,499 721 739.67.67 As seen above, the average runoff coefficient and rainfall loss of the simulated runoff are derived to be.67 and 739mm, respectively. On the other hand, hydrological indices of the observed runoff at the Pasar Sironggit station are.67 and 721mm. These derived hydrological indices are judged to be in the hydrologically reasonable range. (6) Prediction of the Long-Term Runoff at the Pasar Sironggit station The tank model with the calibrated parameters in the above is applied to generate the daily runoff at the Pasar Sironggit station dating back to the period of 1977 to 1998 by use of the estimated daily basin mean rainfall. The simulation results are summarized in Figure 24. The rainfall-runoff relationship of simulated runoff is summarized below. Year Annual Rainfall (mm) Annual Runoff Depth (mm) Annual Rainfall Loss (mm) Runoff Coefficient Observed Simulated Observed Simulated Observed Simulated 1977 1,647-826 - 822 -.5 1978 2,248-1,555-693 -.69 1979 2,355-1,643-713 -.7 198 1,925-1,254-67 -.65 1981 1,223-873 - 35 -.71 1982 1,472-783 - 689 -.53 1983 1,438-748 - 69 -.52 1984 2,431-1,59-841 -.65 1985 1,83 776 1,233 1,27 57.43.68 1986 1,472 915 875 557 597.62.59 1987 1,959 97 1,251 1,52 79.46.64 1988 1,638-1,126-512 -.69 1989 1,361-638 - 723 -.47 199 2,22-1,399-623 -.69 1991 2,711 1,929 1,838 783 873.71.68 1992 1,873 1,22 1,326 671 547.64.71 1993 2,131 1,425 1,42 76 711.67.67 1994 1,438-958 - 479 -.67 1995 1,869-1,176-693 -.63 1996 1,7-989 - 71 -.58 1997 1,25-698 - 552 -.56 1998 1,592-821 - 771 -.52 Average 1,798-1,137-661 -.62 As seen in the table, the average runoff coefficient and rainfall loss of the simulated runoff are derived to be.62 and 661mm, respectively. These hydrological indices are judged to be within the hydrological reasonable range. JICA Project for the Master Plan Study of 15-15 August, 211

The daily runoff data for the flow duration curve is consisted of 6-year observed daily runoff in 1985 to 1987, and 1991 to 1993, and of 16-year simulated daily runoff in remaining period from 1977 to 1996. The flow duration curve for the 22-year runoff is drawn by arranging the discharges in descending order and assigning probabilities to each discharge. The flow duration curve of the observed and simulated runoff is shown in Figure 25. (8) Long-Term Runoff at the Simanggo-2 Intake Weir Site The long-term daily runoff at Simanggo-2 intake weir site for 22 years in the period of 1977 to 1998 is estimated from the predicted long-term daily runoff at the Pasar Sironggit station by using the following equation. The annual basin rainfall at Simanggo-2 basin is estimated from the isohyetal map, illustrated in Figure 26. The flow duration curve as shown in Figure 27, is drawn by arranging the discharges in descending order and assigning probabilities to each discharge. A D Q D = QW AW R R D W where, Q D : Runoff at Simanggo-2 intake weir site (m 3 /sec) Q W : Runoff at Pasar Sironggit AWLR station (m 3 /sec) A D : Catchment area at Simanggo -2 intake weir site (=478.3km 2 ) A W : Catchment area at Pasar Sironggit AWLR station (=35.6km 2 ) R : Annual basin mean rainfall at Simanggo-2 intake weir site D (=2,79mm) R : Annual basin mean rainfall at Pasar Sironggit AWLR station W (=1,82mm) (9) Water Level Observation and Discharge Measurement The field investigation of 3 month water level observation and 3 times discharge measurement was carried out from 21 September 28 th to 21 December 31 st by the sub-contractor. Location of the observation is at 2km upstream of the Simanggo-2 intake weir site (St.1). The location map of observation is shown in Figure 28. H-Q rating curve is established on the basis of observed water level and discharge, and hydrograph is established on the basis of observed water level and H-Q rating curve. Hydrograph is illustrated in Figure 29 and H-Q plot is shown in Figure 3. Consequently, the average water level is.58m and the average runoff is 26.69 m 3 /s calculated with H-Q rating curve. The Equation of H-Q rating curve is given below. Q = 35.1 ( H +.29) 2 where, Q : Runoff (m 3 /sec) H : Water level (m) JICA Project for the Master Plan Study of 15-16 August, 211

Runoff at the Simanggo-2 intake weir site is estimated using the following equation. Q D = QW ( AD / AW ) where, Q D : Runoff at Simanggo-2 intake weir site (m 3 /sec) Q : Runoff at the water level gauge (m 3 /sec) W A D : Catchment area at Simanggo-2 intake weir site (=478.3km 2 ) A : Catchment area at water level gauge (=29.6km 2 ) W The estimated average runoff at the Simanggo-2 intake weir site is 43.93m 3 /s. The observed average runoff is about 1% of probability on the duration curve shown in Figure 27. (1) PLTM Palilitan There is an existing intake weir of PLTM Palilitan at upstream of Simanggo-2 intake weir site. In the project report of PLTM Palilitan, the average runoff is estimated to be 22.865 m 3 /s with low-flow analysis from 1984 to 1994. Runoff at the Simanggo-2 intake weir site can be estimated with the following equation. Q D = QW ( AD / AW ) where, Q D : Runoff at Simanggo-2 intake weir site (m 3 /sec) Q : Runoff at PLTM Palilitan intake weir site (m 3 /sec) W A D : Catchment area at Simanggo-2 intake weir site (=478.3km 2 ) A : Catchment area at PLTM Palilitan intake weir site (=436km 2 ) W Consequently, the average runoff at the Simanggo-2 intake weir site is 25.8m 3 /s. The catchment area of PLTM Palilitan is measured in HPPS2 as Simanggo-1 HEPP. 15.1.5 FLOOD ANALYSIS (1) General Approach Flood analysis is carried out to estimate the probable floods with various return periods as well as the probable maximum flood (PMF) at the Simanggo-2 intake weir site which are basically required for design of spillway and diversion facilities, and determination of dam height. For estimating the probable floods, the unit hydrograph method is applied, which synthesizes the various probable runoff hydrographs from the probable basin mean rainfalls based on the relationship between unit of basin mean rainfall and its runoff, that is the so-called unit hydrograph. It is generally agreed that the unit hydrograph method is applied for catchment JICA Project for the Master Plan Study of 15-17 August, 211

areas less than 3, km 2. In this study, the Soil Conservation Service (SCS) unit hydrograph, which is empirically developed in USA Department of the Interior is used, because no hourly flood hydrograph is available in the Simanggo River basin to construct the unit hydrograph. The general approach of flood analysis is outlined below. (2) Rainfall Analysis 1) Depth-Area-Duration (DAD) Analysis DAD analysis is carried out to examine the following relationships. Relationship between rainfall depth and duration (DD Analysis) Relationship between rainfall depth and area (DA Analysis) a) Depth-Duration (DD) Analysis Generally, heavy rainfall occurs intensively in a short duration and sporadically in a limited area. The hourly rainfall records around the Simanggo River basin are shown in Table 18. The design rainfall curve is derived from collected 31 hourly rainfall curves. The accumulated hourly rainfall curves and the design rainfall curve are presented in Figure 32. JICA Project for the Master Plan Study of 15-18 August, 211

b) Depth-Area (DA) Analysis Generally, heavy rainfall occurs intensively in a short duration and sporadically in a limited area. Therefore the average depth of storm rainfall (basin mean rainfall) is likely to be smaller than the point depth of storm rainfall. In general, relation between point rainfall depth and average area is expressed by an exponential equation given by the following equation. P b n = P exp[ ka ] where, P b : Average rainfall depth over an area A (mm) P : Maximum point rainfall at the storm center (mm) A : Area in question (km 2 ) k, n : Constants for a given area The above equation is the so-called Horton s Equation. Constants k and n usually vary according to the given rainfall duration such as 1 hour, 6 hours, 12 hours, 1 day, etc. These constants are to be obtained through rainfall analysis based on the isohyetal maps of various major rain storms occurred in the river basin in question. However, the exact determination of P is practically impossible, because it is very unlikely that the rain storm center coincides with a rainfall gauging station. To estimate the basin mean rainfall from the point rainfall, the area reduction factor showing the ratio of basin mean rainfall to point rainfall is introduced as expressed below. P b = f a P where, P b : Basin mean rainfall (mm) P : Point rainfall (mm) f : Area reduction factor a If the Horton s equation is applied, the area reduction factor under the given rainfall duration is given by the following equation. f a = exp[ ka n ] However the available rain storm records in the Simanggo River basin are insufficient for reliable determination of the area reduction factor. The preliminary estimation of the design area reduction factor is carried out based on the following three approaches. Firstly, the area reduction factor is estimated as.63 under the catchment area of 478.3 km 2 for the Simanggo-2 intake weir site by applying the Horton s equation assuming that constants of k and n are.1 and.25, respectively. These constants have been widely and JICA Project for the Master Plan Study of 15-19 August, 211

empirically applied in tropical rain forest area. A 478.3 (km2) k.1 n.25 fa.63 Secondly, the estimated design area reduction factors are examined in several other projects. The following design area reduction factors are based on the rainfall analysis using the observed rain storm records. Project Name Catchment Area Area Reduction (km2) Factor Besai HEPP (D/D in 199) 415.5 Malea HEPP (F/S in 1984) 1,463.45 Tampur-1 HEPP (F/S in 1984) 2,.4 Musi HEPP (F/S in 1984) 586.5 Cibuni-3 (F/S in 1984) 1,.41 Masang-3 HEPP (Pre F/S in 1999) 993.5 Thirdly, the relation between the daily point rainfall and the daily basin mean rainfall around the Simanggo River basin is analyzed to estimate the area reduction factor of the river basin. The selected rainfall stations are the Hutaraya, the Gugur Balige, the Balige-1, and the Paguruan stations. A basin mean rainfall derives from an arithmetic average of an annual maximum daily rainfall of a target station and daily rainfalls of other stations at the same day. The average of ratios between basin mean rainfalls and annual maximum daily rainfalls of target stations is decided as the area reduction factor. The list of rainfall is presented in Table 25 and plotted on Figure 33. Usually, it is considered that the rainfall intensity in hyetal areas increases with the depth of point rainfall. However, the area reduction factor showing the ratio of area rainfall to the maximum point rainfall varies from.3 to.8 for the area rainfall amount, and the average is.52. Further, the area reduction factor does not always increase with the enlargement of the point rainfall. On the other hand, the design area reduction factors examined in several hydropower projects varies from.4 to.5. In due consideration above, the design area reduction factor is conservatively determined to be.5. 2) Probable Point Rainfall Out of the available rainfall records around the Simanggo River basin, the annual maximum 1-day rainfall records are available at the Hutaraya rainfall gauging station, the Gugur Balige, and the Paguruan as presented in Table 26. As seen in this table, the rainfall records at the Paguruan station is 2 recording periods, which is the greatest numbers among three stations. Then the Paguruan station is selected for probable point rainfall analysis. JICA Project for the Master Plan Study of 15-2 August, 211

The probable point rainfalls at the station with several return periods are estimated through frequency analysis using the Gumbel and Log Normal distributions as summarized below. The estimated frequency curves of probable daily rainfall at these stations are also presented in Figure 34. Return Period Probable Point Rainfall (mm) (years) Gumbel LN Average 4 181 161 171 2 167 151 159 15 161 147 154 153 141 147 8 149 137 143 5 139 13 135 3 129 122 126 2 12 115 118 1 16 14 15 5 91 91 91 3 79 8 8 2 68 7 69 The probable point rainfall is estimated as the average of the probable rainfalls by the Gumbel and Log Normal distributions, because the estimated frequency curves by the Gumbel and Log Normal distributions have similar shapes. 3) Probable Maximum Precipitation (PMP) Generally three (3) approaches are used for estimating the probable maximum precipitation (PMP) as follows. Meteorological (theoretical) approach in consideration of the upper physical limit of moisture source Statistical approach which is empirically developed by Dr. Hershfield from the rainfall records in the United States of America Historical approach by examining the historical maximum one over occurred in the area of interest The available basic climatological data such as dew point, humidity, wind velocity in Simanggo-2 catchment area for the first meteorological approach are insufficient for the time being. Further, no historical rain storm records are also so far available. Therefore, PMP is estimated by the simple statistical Hershfield method using a series of the annual maximum daily rainfall records. This method is widely applied in the basin where rainfall records are available but other basic climatological records are hardly obtainable. The Hershfield s equation is expressed as follows. JICA Project for the Master Plan Study of 15-21 August, 211

X = X + K S m n m n where, X m : Extreme value of 24-hour rainfall (PMP) (mm) X : Adjusted mean annual maximum rainfall (mm) n K : Statistical coefficient n m S : Adjusted standard deviation of a series of annual maximum rainfall As seen in the above equation, PMP in question is assumed to be given as the adjusted mean annual maximum rainfall in question plus the K m times the standard deviation of a series of annual maximum rainfall in question. The PMP is estimated by applying a series of annual maximum rainfall in the Simanggo river basin. The calculation process is as follows. Computation of Statistical Parameters The mean annual maximum rainfall (X n ) and its standard deviation (S n ) are calculated to be 72.5 mm and 23.7 mm, respectively. Concurrently with the above, X n-m and S n-m are estimated at 7.3 mm and 22.1 mm, which are computed after excluding the maximum rainfall in the series of rainfall data. These statistical parameters are used for several adjustment necessary computing X n and S n. Adjustment of X n and S n for Maximum Observed Event The adjustment factors of X n (f x1 ) and S n (f s1 ) for the maximum observed rainfall shall be obtained from the Hershfield s adjustment curves as shown in Figure 35 and Figure 36. Applying the values of X n, X n-m, S n and S n-m, adjustment factors are obtained 11 % for f x1 and 12 % for f s1, respectively. Adjustment of X n and S n for Sample Size The adjustment factors of X n (f x2 ) and S n (f s2 ) for the length of record shall be obtained from the adjustment curves as presented in Figure 37. The obtained factors of f x2 and f s2 are 12 % and 18 %, respectively. Statistical Coefficient K m The statistical coefficient K m shall be obtained from the empirical K m curves as presented in Figure 38. Applying the mean annual maximum rainfall at the Paguruan station (X n ) is 72.5 mm, the K m value is obtained to be 16.5. Adjustment for Fixed Observational Time Intervals JICA Project for the Master Plan Study of 15-22 August, 211

Rainfall observation has been carried out on the daily basis at the Paguruan station. Since the recorded daily rainfall is computed based on the single fixed observation time interval (say 8 a.m to 8 p.m), the PMP value yielded by the statistical procedure should be increased multiplying by the adjustment factor (f o ). The adjustment factor curve is presented by Dr. Hersfield as shown in Figure 39. Applying that the number of observation units is equal to 1, the f o value is obtained to be 113 %. Computation of PMP at the Paguruan Station The adjustment mean annual maximum rainfall (X n ) is finally given as follows. X X n = f X 1 f X 2 n In addition, the adjusted standard deviation of a series of annual maximum rainfall (S n ) is given as follows. S S n = f S1 fs 2 n The unadjusted point PMP (X m ) is computed as follows. X = X + K S m n m n Finally, the point PMP is adjusted using the adjustment factor f o as follows. PMP = f O X m The computation process of the point PMP is summarized in Table 27. As seen, the point PMP at the Paguruan station is estimated to be 571.7 mm. 4) Basin Mean Rainfall Applying the design area reduction factor of.5, the probable basin mean 1-day rainfalls with various return periods as well as PMP at the Simanggo-2 intake weir site are estimated as follows. JICA Project for the Master Plan Study of 15-23 August, 211

Return Period (years) Probable Rainfall (mm) PMP 286 4 86 2 8 15 77 74 8 72 5 68 3 63 2 59 1 53 5 46 3 4 2 35 (3) Hydrograph Analysis 1) Unit hydrograph Since no flood hydrographs are available for the present flood analysis, the unit hydrograph is developed by means of the SCS (Soil Conservation Service) synthetic hydrograph method. The SCS method was developed by analyzing a large number of basins with varying geographic locations. Unit hydrographs were evaluated for a large number of actual watersheds and then made dimensionless by dividing all discharge ordinates by the peak discharge and the time ordinates by the time to peak. An average of these dimensionless unit hydrographs was computed. a) SCS Unit Hydrograph The SCS unit hydrograph is derived from the flood concentration time and unit basin rainfall. The unit hydrograph is constructed for a unit rainfall of 1 mm. The peak discharge of the unit hydrograph is calculated as follows. q =.28AQ / p t p where, q p : Peak discharge (m 3 /sec) A : Basin area (km 2 ) Q : Total volume of the unit hydrograph (=1mm) t p : Time to peak (hours) SCS has determined that the time to peak ( t p ) and rainfall duration ( D ) are related to time of concentration ( t c ) as follows. t = p 2 tc / 3 D =. 133t c JICA Project for the Master Plan Study of 15-24 August, 211

b) Flood Concentration Time The flood concentration time is defined as the time of travel from the most remote point in the catchment to the forecast point. The flood concentration time can be estimated by the formula of Kirpich as follows. t c.77.385 = 3.97 L S where, t c : Flood concentration time (min) L : Maximum length of travel of water (km) S : Average slope (=H/L, where H is the difference in elevation between the remotest point in the basin and the outlet) c) SCS Unit Hydrograph Calculation With a maximum length of travel ( L ) of 33km, the concentration time ( t c ) was found to be about 4.7 hours. With a catchment area ( A ) of 478.3 km 2, the peak flow ( q ) is found to be 31.8 m 3 /sec/mm. The average slope of the Simaggo River is illustrated in Figure 4. The SCS unit hydrograph for the Simaggo River basin is shown in Figure 41. A 478.3 km 2 Q 1 mm L 33.348 km t c 4.7 hours q p 31.8 m 3 /s/mm 3.1 hours t p p 2) Probable Flood Hydrograph at Simanggo-2 Intake Weir Site The probable flood hydrographs including PMF at the Simanggo-2 intake weir site are derived by convolution of the probable basin mean rainfall, PMP with the design rainfall hyetograph and the unit hydrograph. The base flow is determined to be 24 (m 3 /s) from the average rainy-season discharge records at the Pasar Sironggit AWLR station, and the rainfall loss is assumed to be 36 %. The daily hydrograph is shown in Figure 42, and the rainfall loss is presented in Table 29. The computed probable flood hydrographs as well as PMF are presented in Table 3 and shown in Figure 43. The probable design flood discharges with various return periods together with PMF are collected from various hydropower projects in Sumatra as presented in Table 31. JICA Project for the Master Plan Study of 15-25 August, 211

3) Creager s Coefficient for Probable Floods at Simanggo-2 Intake Weir Site Creager s coefficient for probable flood is computed by the following equations. Q = ( 46.2832) C (.3861 A) p a a =.894(.3861 A).48 where, Q p : Peak discharge of probable flood (m 3 /sec) C : Creager s coefficient A : Catchment area (km 2 ) The Creager s coefficients corresponding to the various return periods and PMF for the Simanggo-2 HEPP are enumerated in the table below. T Q C (year) (m3/s) PMF 3894 79 4 1182 24 2 1 22 15 167 22 119 21 8 992 2 5 938 19 3 877 18 2 823 17 1 735 15 5 64 13 3 566 12 2 491 1 Figure 44 and Figure 45 shows the relationship between probable flood peak discharges with return periods of 2, 2,, 2 years as well as PMF and catchment area for the Simanggo-2 HEPP and other water resources development projects in the whole Sumatra. The Creager s curves are illustrated using the Creager s coefficients of the Simanggo-2 intake weir site calculated in above. The probable floods at the Simanggo-2 HEPP are well plotted in reasonable range of design floods in Sumatra. 4) Probable Floods at the Simaggo-2 Regulating Pond Site The time of concentration ( t c ) at the Simanggo-2 Regulating Pond is calculated as.32 hour with the same method as the Simanggo-2 intake weir site. Probable floods at the Simanggo-2 Regulating Pond are estimated with the Creager s coefficients of the Simanggo-2 intake weir site, because short time interval rainfall records like 1-minutes do not exist in Simanggo River basin. The catchment area of the Simanggo-2 intake weir site is illustrated in Figure 47. JICA Project for the Master Plan Study of 15-26 August, 211

A 3 km 2 L 2 km t c.32 hours The results of flood analysis are estimated as follows. Intake Pond T Q C Q (year) (m3/s) (m3/s) PMF 3894 79 117.4 4 1182 24 35.7 2 1 22 33.2 15 167 22 32.2 119 21 3.7 8 992 2 29.9 5 938 19 28.3 3 877 18 26.5 2 823 17 24.8 1 735 15 22.2 5 64 13 19.3 3 566 12 17.1 2 491 1 14.8 5) Probable Floods at the Simanggo-2 Power House Site The Rambe River and the Simanggo River join together at the upstream of the Simanggo-2 Power House site. At the power house site, probable floods seem to be controlled by floods from the Simanggo River, because the catchment area of the Rambe River basin is smaller than the Simanggo River basin. So, Probable floods at the Simanggo-2 power house site are estimated with the Creager s coefficients of the Simanggo-2 intake weir site as same as the regulating pond. The catchment area of the power house site is 936.1km 2, illustrated in Figure 48. The results of flood analysis are estimated as follows. Intake Pond T Q C Q (year) (m3/s) (m3/s) PMF 3894 79 5456. 4 1182 24 1656.1 2 1 22 1541.2 15 167 22 1495. 119 21 1427.8 8 992 2 1389.9 5 938 19 1314.3 3 877 18 1228.8 2 823 17 1153.1 1 735 15 129.8 5 64 13 896.7 3 566 12 793. 2 491 1 688. JICA Project for the Master Plan Study of 15-27 August, 211

(4) Water Level Observation and Discharge Measurement As mentioned in the chapter of lowflow analysis, the field investigation of 3 month water level observation and 3 times discharge measurement was carried out from 21 September 28 th to 21 December 31 st by the sub-contractor. Consequently, the maximum water level is 3.35m and the maximum runoff is 463.87 m 3 /s calculated with H-Q rating curve in extrapolation. The Equation of H-Q rating curve is given below. Q = 35.1 ( H +.29) 2 where, Q : Runoff (m 3 /sec) H : Water level (m) Runoff at the Simanggo-2 intake weir site is estimated using the following equation. Q D = QW ( AD / AW ) where, Q D : Runoff at Simanggo-2 intake weir site (m 3 /sec) Q W : Runoff at the water level gauge (m 3 /sec) A D : Catchment area at Simanggo-2 intake weir site (=478.3km 2 ) A : Catchment area at water level gauge (=29.6km 2 ) W The estimated maximum runoff at the Simanggo-2 intake weir site is 763.49m 3 /s. (5) PLTM Palilitan There is an existing intake weir of PLTM Palilitan at upstream of Simanggo-2 intake weir site. In the project report of PLTM Palilitan, the 2-year flood is estimated to be 73.571 m 3 /s, and the -year flood to be 288.379 m 3 /s with flood analysis using annual maximum daily rainfall from 1963 to 1975. Flood at the Simanggo-2 intake weir site can be estimated with the following equation. Q D = QW ( AD / AW ) where, Q D : Runoff at Simanggo-2 intake weir site (m 3 /sec) Q W : Runoff at PLTM Palilitan intake weir site (m 3 /sec) A D : Catchment area at Simanggo-2 intake weir site (=478.3km 2 ) A : Catchment area at PLTM Palilitan intake weir site (=436km 2 ) W Consequently, the 2-year flood at the Simanggo-2 intake weir site is estimated to be 8.71 m 3 /s, and the -year flood to be 316.36 m 3 /s. The catchment area of PLTM Palilitan is measured in HPPS2 as Simanggo-1 HEPP. JICA Project for the Master Plan Study of 15-28 August, 211

15.1.6 SEDIMENT ANALYSIS (1) General Sedimentation analysis is preliminarily carried out to estimate the denudation rate in the Simaggo River basin. The sedimentation load is herein predicted based on the estimated runoff and the sediment discharge rating curve at the intake weir site. The rating curve is established based on the in-situ sampling records obtained through the field investigation conducted in the course of the study. The sediment transport in the Simaggo River is judged to be higher than other rivers in the Sumatra. The denudation rate showing the expected average annual erosion rate in a river basin is generally influenced by the topography (soil condition, river gradient), deforestation of the land in the basin, rainfall intensity, etc. In addition, the design denudation rates adopted in other water resources or hydropower development projects in Sumatra are collected for comparison purposes. (2) Suspended Load Sampling A total of thirty (3) suspended load samplings were carried out at the intake weir site where discharge measurements were taken. The samples were taken to a laboratory for further analysis. The sieve analysis results of samples are shown in Figure 49. (3) Suspended Load Rating Curve The laboratory analysis results of the samples show the total suspended sediment concentration which is the combination of both dissolved and undissolved sediment. The total suspended load is found from the following formula. Q =. 864 C S Q W where, Q S : Suspended load (ton/day) C : Total suspended sediment concentration (mg/l) Q : Flow discharge (m 3 /s) W The suspended load calculations using the above formula are presented in Table 32. Several results are considered unreliable because they show very low concentration or very high concentration. Therefore these unreliable results will not be used in the determination of the suspended load rating curve. The values of Qs are plotted against their respective Qw values to determine the suspended load rating curve. On the basis of the estimated sediment discharge at the intake weir site, the suspended load rating curve is established as shown in Figure 5. The rating curve equation is given below. S 1.7812 5.4615 QW Q = JICA Project for the Master Plan Study of 15-29 August, 211

If the flow discharge Qw is known, the suspended load sediment Qs can be estimated. (4) Total Sediment Load The annual suspended load sediment yield is simulated by applying the above rating curve to the simulated daily runoff at the intake weir site. The catchment area of the Simaggo-2 intake weir site is 478.3km 2. Substituting runoff data, the average annual suspended load sediment at the intake weir site is estimated at 662,847 ton. The density of sediment in appearance can be calculated by the following equation. γ = ( 1 V ) γ where, γ : Density of sediment (ton/m 3 ) V : Void ratio of sediment γ : Unit weight of sediment (=2.65ton/m 3 ) Assuming a void ratio of 6 % in sedimentation, the density of sediment is found to be 1.6 ton/m 3. Hence, the annual suspended load sediment is estimated at 625,327 m 3. The sediment load transport into an intake weir generally consists of suspended load and bed load. It is generally accepted that it might be difficult to accurately measure the bed load in a natural river. Usually, the rate of bed load transport is empirically estimated at 1 to 3 % of the total suspended load. The rate of bed load transport is estimated as 1% of the total suspended load, because 1% is usually applied in Indonesia. Consequently, the mean annual sediment inflow volume into the Simaggo-2 intake weir is estimated to be 687,86 m 3 which is equivalent to a denudation rate of 1.44 mm per year. For comparison purpose, design denudation rates of various schemes around the project site are presented in the following table. JICA Project for the Master Plan Study of 15-3 August, 211

Project Name Project Stage Province Catchment Area Denudation Rate Source (km2) (mm/year) S. Ular Pre-F/S N. Sumatra 1,81.77 S1 Buaya Pre-F/S N. Sumatra 428.5 S1 Karai Pre-F/S N. Sumatra 5.5 S1 Lausimeme Pre-F/S N. Sumatra 15.1 S1 Namobatang Pre-F/S N. Sumatra 93.1 S1 Tembengan Pre-F/S N. Sumatra 76.3 S1 Beranti Pre-F/S N. Sumatra 159.5 S1 Sampanan Pre-F/S N. Sumatra 37.5 S1 Sibakudu Pre-F/S N. Sumatra 64.2 S1 Asahan D/D N. Sumatra 3,674.25 S1 Renun F/S N. Sumatra 139.3 S1 Jambuaye N. Sumatra 4,56.1 S1 Wampu F/S N. Sumatra 959.44 S1 Sipan Sihaporas F/S N. Sumatra 196.1 S1 PLTM Palilitan Constructed N. Sumatra.17 S2 Legend S1: HPPS2, 1999. S2: PLN As seen in the above table, the design denudation rates vary from.1 to.77 mm/year. The assumed denudation rate of 1.44mm/year at the Simaggo-2 intake weir site might not be in the appropriate range. The suspended load sampling was carried out at the 2 km upstream of the Simanggo-2 intake weir site. There is existing intake weir of PLTM Palilitan between the Simanggo-2 intake weir site and the suspended load sampling site. Most of the suspended load might be trapped by the PLTM Palilitan intake weir and might not reach to the Simanggo-2 intake weir site. Consequently, the design denudation rate of the Simanggo-2 intake weir should be estimated to be relatively small value. The design denudation rate of the Simaggo-2 intake weir is estimated as.5mm/year which is the middle of design denudation rates in other projects. The design annual sediment inflow volume into the Simaggo-2 intake weir is estimated to be 239,15m 3 /year. 15.1.7 WATER QUALITY ANALYSIS Water quality is important because it is linked to the availability of water for various uses. Specifically, for the Simaggo-2 HEPP it is important for the well being of hydraulic machinery, other equipment and hydraulic structures used in the project. The laboratory test for water quality was carried out through the field investigation under the current study to identify the content of various chemical elements contained in the water in the Simaggo River. Water sampling is carried out three (3) times in total at 2 km upstream of the Simaggo-2 intake weir site. The samples were taken to a laboratory for further analysis. The laboratory test results are presented in Table 33. The table shows that the ph of the water in the Simaggo River is between 5 and 8. It is therefore judged that the water in the JICA Project for the Master Plan Study of 15-31 August, 211

Simaggo River will have no adverse effect on turbine and metal for hydropower use, because adverse effect is expected to occur under the ph value smaller than 4.5. JICA Project for the Master Plan Study of 15-32 August, 211

Table 1 Monthly Mean Air Temperature Station Name: Sibolga Unit: Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Average 1984 25. 26.2 26. 26.6 25. 25.1 25.1 24.3 25.3 25.5 25.4 1985 25.9 23.8 25.8 25.2 26.4 24.9 25.8 24.3 25.8 24.6 25.8 25.3 1986 25.5 23.5 25.3 25.4 26.5 25.4 25.3 25.7 24.5 25.6 24.6 25.8 25.3 1987 25.6 23.6 26.6 25.4 28.5 26. 25.9 26. 24.9 25.9 25. 26.1 25.8 1988 26. 24.8 26.2 25. 26.7 31.8 26.1 25.7 24.4 25.3 24.4 25.9 26. 1989 25.8 23.1 25.7 25. 26.2 24.7 25. 25.6 24.5 25.5 24.5 25.8 25.1 199 25.8 24. 26.3 25.5 26.7 25.5 25.6 25.7 24.8 25.6 25.1 25.8 25.5 1991 26.1 23.6 26.6 25.4 26.6 25.7 26. 25.8 25. 24.1 25.4 25.5 1992 26.4 24.6 26.7 25.8 26.6 25.5 25.9 25.6 25.9 1993 25.6 25.6 24.8 25.7 25.4 1994-1995 - 1996 25.6 24.6 26.6 27. 25.7 26. 25.3 25.8 1997-1998 - 1999 25.8 23.6 26.1 25.3 25.6 25.6 24.9 25.6 24.8 25.6 25.3 2 25.7 26.2 26.8 25.2 25.8 25.6 24.8 25.8 25.1 26.2 25.7 21-22 26.8 25.6 26.2 Min 25. 23.1 25.3 25. 26.1 24.7 25. 25.1 24.3 25.3 24.1 25.4 Max 26.4 24.8 26.7 26.2 28.5 31.8 26.1 26. 25. 25.9 25.1 26.2 Ave 25.8 23.9 26.2 25.5 26.7 25.8 25.7 25.7 24.7 25.6 24.7 25.8 25.5 Source: (1984-22) BMKG JICA Project for the Master Plan Study of T-1 August, 211

Table 2 Monthly Mean Relative Humidity Station Name: Sibolga Unit: % Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Average 1984 85.6 79.8 86.9 82.8 81.5 85.1 85.4 82. 86.4 83.9 1985 81.7 73.7 85.7 82.2 85. 76.7 92.3 82.6 83.6 84.8 87.3 83.2 1986 87.1 73.2 88. 85.3 85.2 79.1 85.3 83.3 82. 84.3 82.5 87. 83.5 1987 87.4 77.8 85.8 85.3 86.9 8.3 84.3 85.5 84.8 88.7 84.5 88.9 85. 1988 89.9 81. 89.9 83.9 83.1 8.1 81. 86.2 85.1 87.1 86. 83. 84.7 1989 84.8 76. 84.3 82.8 84. 78.9 84.4 85.4 83.6 85.7 85.3 85.6 83.4 199 83.6 74.8 85.7 83.6 83.6 8.4 85.4 81.2 82.8 88.2 83.9 86.5 83.3 1991 85.3 75.6 85.5 83.7 87. 81.5 84.4 84.6 82.8 88. 97.6 85.1 1992 78.4 75.5 83.2 8.9 84.8 8.2 82.4 84.4 81.2 1993 79.7 85.6 81.1 96.7 85.8 1994-1995 - 1996 81. 74.4 82.2 8.4 79.7 8.9 84.7 8.5 1997-1998 - 1999 84.5 74.5 83.2 79. 83.9 84.1 81. 85.2 82.8 83.9 82.2 2 83. 79.1 81.1 79.1 8.4 83.2 82.8 83.8 83.4 84.2 82. 21-22 83. 79.3 81.1 Min 78.4 73.2 82.2 79.1 8.4 76.7 8.4 81.2 81. 83.6 82.5 83. Max 89.9 81. 89.9 85.3 87. 81.5 85.6 92.3 85.1 88.7 88. 97.6 Ave 84.4 76. 85.7 83. 83.8 79.7 83.6 85. 82.8 85.8 84.6 88.1 83.5 Source: (1984-22) BMKG JICA Project for the Master Plan Study of T-2 August, 211

Table 3 Monthly Mean Sunshine Duration Station Name: Sibolga Unit: % Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Average 1984 6.6 52.8 52.9 57.2 67.5 53.9 57.5 51.7 46.4 28.7 52.9 1985 48.6 54.1 57.4 66.4 57.9 67.6 61.8 48.6 55.1 49.6 56.3 56.7 1986 64.7 72. 52.1 51.5 64.3 66.1 63.6 52.8 5.3 46.8 59.3 66.9 59.2 1987 48.8 71.9 68.4 57.4 64.9 69.2 61.2 46.1 4.6 5.8 45.1 56.1 56.7 1988 58.3 67.9 54.7 56.4 6.1 71.2 66.2 53.1 33.8 46.5 31.6 62.1 55.2 1989 62. 61.3 64.7 52.5 68.4 71.5 6.7 48.6 48.3 51. 53.2 65.7 59. 199 59.7 69.1 58.2 72.6 56.5 59.5 67.9 45.6 5.3 48.8 62.9 59.2 1991 68.8 59.5 61.9 61.9 51. 69.7 65.3 47.9 49.6 33.7 29.6 54.4 1992 82.9 56.2 6.2 63.2 63.8 53.8 62.9 43. 6.8 1993 57.1 47.9 48.5 37.2 47.7 1994-1995 - 1996 63.1 7.5 64.6 48.7 54. 29.7 44.6 1997-1998 - 1999 17.9 62.2 54.6 53.9 49.1 5.1 54.5 44.3 53.5 52.1 49.2 2 55.9 55.9 21-22 59.8 56.9 58.4 Min 17.9 52.8 7.5 51.5 51. 48.7 47.9 43. 33.8 28.7 31.6 29.6 Max 82.9 72. 69.1 66.4 72.6 71.5 66.2 67.9 54.5 55.1 59.3 66.9 Ave 56.9 61.9 54.9 58.3 62.4 61.2 58.9 52.3 46.6 44.8 46.9 54.3 55. Source: (1984-22) BMKG JICA Project for the Master Plan Study of T-3 August, 211

Table 4 Monthly Mean Wind Velocity Station Name: Sibolga Unit: m/sec Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Average 1984 5.8 5.6 5.6 6. 5.4 5.6 5.5 5.7 5.8 6.7 5.6 5.8 1985 6.1 5.8 5.8 5.9 5.7 6.6 6.2 6.3 6.1 5.6 5.8 6. 1986 5.9 6.1 6.1 6. 5.9 6. 6.4 6.5 5.9 5.8 5.8 6. 6. 1987 5.5 5.7 5.4 5.7 5.5 5.8 5.9 5.8 5.7 6.1 6.2 5.8 5.8 1988 6. 6.3 6.2 6. 5.7 5.7 5.5 5.8 6. 6.1 7. 5.8 6. 1989 5.6 7. 6.3 5.7 5.7 6.1 6. 6.1 6.4 6.4 6.2 6.5 6.2 199 6.6 7.3 6.8 6.1 6.1 6.6 6.2 6.5 6.2 6.6 6.3 5.9 6.4 1991 6.3 6.3 6.3 6. 8.8 6.1 6.3 6.7 6.4 6.4 6. 6.5 1992 6.6 6.1 6. 6.3 6.3 6.4 6.2 6.9 6.4 1993 7.1 6.7 6.6 6.8 1994-1995 - 1996 5.9 6.9 11. 6.5 6.3 7.2 7.3 1997-1998 - 1999.5.6.8 1. 1..8.7 1..9.8.8 2 1.1 1..9 1.3 1.3 1. 1.1 1.7 1.1 1. 1.1 21-22 1. 1. 1. Min.5.6 5.4 1..8 1. 1..8.7 1..9.8 Max 6.6 7.3 11. 6.3 8.8 6.6 7.1 6.9 6.7 7.2 7. 6.6 Ave 5.2 5.8 6.5 5.5 4.8 5. 5.3 5.3 5.2 5.4 5.1 5.1 5.3 Source: (1984-22) BMKG JICA Project for the Master Plan Study of T-4 August, 211

Table 5 Monthly Mean Pan Evaporation Station : Parapat Unit: mm/day Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Average 1997 3.1 5.7 4.4 5.1 4.7 4.8 4.8 4. 4.6 4.2 2.7 3. 4.3 1998 3.5 3.8 3.7 3.8 4.4 4.3 4.5 4.3 4.5 4.3 4. 3.5 4.1 1999 3.7 4.4 3.4 4.8 4. 3.8 4.1 4.5 4.4 3.3 3.3 3.1 3.9 2 3.9 3.8 4.5 3.6 4.2 4. 4.9 4. 2.9 4.1 3.5 3.8 3.9 21 3.8 3.8 4.3 3.4 4.2 3.6 4. 4.6 3.2 3.9 3.7 3.4 3.8 22 2.3 3.5 4. 3.4 3.9 4. 4.9 4. 3.4 3.4 3.2 3.2 3.6 23 3.8 2.9 4. 3.1 5. 3.6 3.8 4. 4.6 4.2 2.7 3.1 3.7 24 3.4 3.3 2.7 3.2 4.4 4.7 3.8 4.9 4.6 3.8 3.8 3.4 3.8 25 5.1 4.4 4.7 4.2 4. 4.9 4.1 4.5 4.4 3.3 3.3 3.1 4.2 26 3.5 4.1 4.1 4.2 4.2 4.2 4.3 5.6 3.3 - - - 4.2 Min 2.3 2.9 2.7 3.1 3.9 3.6 3.8 4. 2.9 3.3 2.7 3. Max 5.1 5.7 4.7 5.1 5. 4.9 4.9 5.6 4.6 4.3 4. 3.8 Ave 3.6 4. 4. 3.9 4.3 4.2 4.3 4.4 4. 3.8 3.4 3.3 3.9 Source: Asahan 3 HEPP Construction Report, 27 Station : Gabe Hutaraja Unit: mm/day Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Average 1996 2.5 1.7 2.3 1.6 2.4 2.1 2.3 2. 1.9 1.4 2. 1.5 2. 1997 2.3 2. 2.2 2. 2.3 1.9 1.8 2.1 1.5 1.2 1.7 17. 3.2 1998 2.1-1.9 2.3 2.7 2.3 2.9 1.2 - - - - 2.2 1999 - -.8 2.3 1.8 1.9 1.6 1.7 1.6 1.3 1.3 1.8 1.6 2 2.3 1.9 2.3 1.8 2.8 2.6 2.5 2.4 2.7 - - - 2.4 21 1.9 1.6 2.4 1.2 2.5 1.7 2.5 2.1 1.4 1.6 1.3-1.8 22 1.9 2. 2.2 1.8 2. - - - - - - - 2. 23 1.6 1.4 2. 1.5 2.5 1.9 1.8 1.7 1.8 1.3 1.3 1.7 1.7 24 1.6 1.5 1.8 1.6 2.8 3. 2. 2.7 1.5 1.6 1.5 1.4 1.9 25 - - - - - - - - - - - - - Min 1.6 1.4.8 1.2 1.8 1.7 1.6 1.2 1.4 1.2 1.3 1.4 Max 2.5 2. 2.4 2.3 2.8 3. 2.9 2.7 2.7 1.6 2. 17. Ave 2. 1.7 2. 1.8 2.4 2.2 2.2 2. 1.8 1.4 1.5 4.7 2.1 Source: Asahan 3 HEPP Construction Report, 27 JICA Project for the Master Plan Study of T-5 August, 211

Table 6 Monthly Rainfall Records (1/12) Station Name: Segala(Sigala-gala) Station ID: 78 Unit: mm Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual 1969 - - - 375 487 157-42 252 648-359 - 197 275 278 319 381 193 226 256 21 391 629 55 238 3,91 1971 232 184 343-174 - - 391 422 218 374-1972 19 238 299 - - 183 34-687 - - - - 1973 - - - - - - - - - - - - - 1974 - - - - - - - - - - - - - 1975 - - - - - - - - - - - - - 1976 - - - - - - - - - - - - - 1977 - - - - - - - - - - - - - 1978 237 327 - - - - - - - - - - - 1979 - - - - - - - - - - - - - 198 - - - - - - - - - - - - - 1981 - - - - - - - - - - - - - 1982 - - - - - - - - - - - - - 1983 - - - - - - - - - - - - - 1984 - - - - - - - - - - - - - 1985 - - - - - - - - - - - - - 1986 - - - - - - - - - - - - - 1987 - - - - - - - - - - - - - 1988 - - - - - - - - - - - - - 1989 - - - - - - - - - - - - - 199 - - - - - - - - - - - - - 1991 - - - - - - - - - - - - - 1992 - - - - - - - - - - - - - 1993 - - - - - - - - - - - - - 1994 - - - - - - - - - - - - - 1995 - - - - - - - - - - - - - 1996 - - - - - - - - - - - - - 1997 - - - - - - - - - - - - - 1998 - - - - - - - - - - - - - 1999 - - - - - - - - - - - - - 2 - - - - - - - - - - - - - 21 - - - - - - - - - - - - - 22 - - - - - - - - - - - - - 23 - - - - - - - - - - - - - 24 - - - - - - - - - - - - - 25 - - - - - - - - - - - - - 26 - - - - - - - - - - - - - 27 - - - - - - - - - - - - - 28 - - - - - - - - - - - - - Min 19 184 299 375 174 157 21 252 422 218 238 Max 275 327 343 381 487 226 34 42 687 648 55 374 Ave 213 257 32 378 285 189 187 36 43 566 362 324 3,816 Source: BMKG JICA Project for the Master Plan Study of T-6 August, 211

Table 7 Monthly Rainfall Records (2/12) Station Name: Tarutung Station ID: 84 Unit: mm Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual 1969 - - - - - - - - - - - - - 197 - - - - - - - - - - - - - 1971 - - - - - - - - - - - - - 1972 - - - - - - - - - - - - - 1973 - - - - - - - - - - - - - 1974 - - - - - - - - - - - - - 1975 - - - - - - - - - - - - - 1976 - - - - - - - - - - - - - 1977 95 81 73 62 128 118 44 7 2 152 131 28 1,362 1978 154 322-319 188 79 88 45 31 274 328 224-1979 319 233 114 - - 14 119 72 257 246 375 226-198 274 163 196-175 - 55 11 129 125 222 191-1981 62 272 99 295 212 4 4 - - - - - - 1982 - - - - - - - - - - - - - 1983-46 - 195-48 6 62 11 - - - - 1984 277 227-27 115-116 - 19 173 582 251-1985 26 214 346 171 148 - - - - 17 - - - 1986 - - - 34 - - - 36-169 185 68-1987 65 284 193-45 49 73 93-22 85 156-1988 - 42 - - 392 3 16 - - - - - - 1989 - - - - - 38-78 - - - - - 199 - - 254 - - - - - - - - - - 1991 - - - - - 112-24 - - - - - 1992-69 191 - - - - - - - 239 - - 1993 193 287 - - - - - - - - - - - 1994 166 - - - - - - - - - - 162-1995 - - - - - - - 183 - - - - - 1996 - - - - - 7 - - - - - 175-1997 - - - - - - - - - - - - - 1998 - - 126 65 142 45 9 237 144-149 234-1999 - 192 17 271 - - - - - - - - - 2-57 - - - - - - - - 275 - - 21 - - - - - - - - - - - - - 22 - - - - - - - - - - - - - 23 - - - - - - - - - - - - - 24 - - - - - - - - - - - - - 25 - - - - - - - - - - - - - 26 - - - - - - - - - - - - - 27 - - - - - - - - - - - - - 28 - - - - - - - - - - - - - Min 62 46 73 62 45 3 4 24 31 17 85 68 Max 319 42 346 319 392 118 16 237 257 274 582 251 Ave 187 25 17 21 172 64 85 92 152 181 257 19 1,962 Source: BMKG JICA Project for the Master Plan Study of T-7 August, 211

Table 8 Monthly Rainfall Records (3/12) Station Name: Hutaraya(Gabe Hutaraja) Station ID: 84C Unit: mm Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual 1969 245 143 326 329 323 42 - - - - - - - 197 129 14 294 174-5 156 124 23 178 - - - 1971 396 193 249 213 52 52 18 221 322 14 223 244 2,287 1972 44 154 161 447 194 84 25 138 259 26 261 - - 1973 18 16 251 315 144 73 119 118 144 168 13 232 1,98 1974 18 153 21 2-17 - 7 - - 162 - - 1975 15 162 145 244 56 49 151 4 146 64 19 237 1,589 1976 - - - - - - - - - - - - - 1977 277 139 115 229 19 245 118 93 128 23 365 292 2,34 1978 15 341 276 34 177 82 46-148 332 223 279-1979 127 129 133 25 42 143 112 63 235 2 31 226 1,97 198 177 164 351 186 12 118 96 129 95 183 31 18 2,91 1981 132 271 126-433 25 - - - - - - - 1982 - - - - - - - - - - - - - 1983 - - - - - - - - - - - - - 1984 - - - - - - - - - - - - - 1985 - - - - - - - - - - - - - 1986 - - - - - - - - - - - - - 1987 - - - - - - - - - - - - - 1988 - - - - - - - - - - - - - 1989 - - - - - 5 - - - 176 - - - 199 - - - - - - - - - - - - - 1991 - - 119 323 283 62 6 56 131 562 348-1992 84 177 131 266-34 159 17 195 - - 226-1993 131 27 162 168 28-269 154 16 355 514 38-1994 297 - - - - - - - - - - - - 1995 181 - - - - - 146 29-234 272 - - 1996 - - 238 229 12-155 153 63 24 135 - - 1997 82 178-151 - 121 - - 85 198 128 13-1998 163-163 - 167 16 12 36 148 - - - - 1999 188 12 26 - - - - - - - - - - 2 - - - - - - - - - - - - - 21 - - - - - - - - - - - - - 22 - - - - - - - - - - - - - 23 - - - - - - - - - - - - - 24 - - - - - - - - - - - - - 25 - - - - - - - - - - - - - 26 - - - - - - - - - - - - - 27 - - - - - - - - - - - - - 28 - - - - - - - - - - - - - Min 44 16 115 151 42 25 18 7 63 64 128 13 Max 396 341 351 447 433 245 269 36 322 355 562 348 Ave 162 174 26 254 172 85 117 128 164 24 27 246 2,18 Source: BMKG JICA Project for the Master Plan Study of T-8 August, 211

Table 9 Monthly Rainfall Records (4/12) Station Name: Barus(Baros) Station ID: 85 Unit: mm Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual 1969 - - - - - - - - - - - - - 197 - - - - - - - - - - - - - 1971 - - - - - - - - - - - - - 1972 - - - - - - - - - - - - - 1973 - - - - - - - - - - - - - 1974 - - - - - - - - - - - - - 1975 - - - - - - - - - - - - - 1976 - - - - - - - - - - - - - 1977 497 416 378 236 73 344 258 - - 383 43 273-1978 449 21-27 382 12 22 75 36 228 238 452-1979 4 126 237 152 53 67-221 535 212 532 166-198 5 275 155-26 48 198 72 169 5 536 428-1981 18 451 181 529 - - - - - - - - - 1982 - - - - - - - - - - - - - 1983 - - - - - - - - 178 39 148 24-1984 357 33 451 476 129-156 19 339 292 239 196-1985 56 21 254-335 - - - - 49 - - - 1986 - - - - 36 - - 118 - - 183 - - 1987 91 112-367 288 184 155 137 3 373 186 454-1988 - - - - - - - - - 263 - - - 1989 - - - - - 156 - - - 187 - - - 199 - - 156 131 - - - - - - - - - 1991 - - 182 219 139 95 89 - - - - - - 1992 - - 189 - - - - - - - - 128-1993 47 264 482-447 191 - - - - - - - 1994 38 - - - - - - - - - - - - 1995 271 223 646 469 438 151 - - - - - - - 1996 - - - 382 - - 14 549 21-43 - - 1997-17 125 314-176 222-812 655 493 - - 1998 418 - - 294 - - 245 727 776 498 316 93-1999 - - - - - - - - - - - - - 2-14 - - - - - - - - - - - 21 - - - - - - - - - - - - - 22 - - - - - - - - - - - - - 23 - - - - - - - - - - - - - 24 - - - - - - - - - - - - - 25 - - - - - - - - - - - - - 26 237 247 478 326 158 78 314 39 236 39-461 - 27 376 252 364 336 22 21 294 319 332 473 33 286 3,774 28 186 174 54 384 5 25 16 366 269 256 - - - Min 4 112 125 131 5 67 89 72 169 49 148 128 Max 5 451 646 529 447 48 314 727 812 655 536 93 Ave 278 238 319 321 234 187 23 288 372 343 334 359 3,475 Source: BMKG JICA Project for the Master Plan Study of T-9 August, 211

Table 1 Monthly Rainfall Records (5/12) Station Name: Siborong-borong Station ID: 86 Unit: mm Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual 1969 - - - - - - - - - - - - - 197 - - - - - - - - - - - - - 1971 - - - - - - - - - - - - - 1972 - - - - - - - - - - - - - 1973 49 85 279 262 331 237 117 115 196 216 186 344 2,417 1974 11 156 143 195 272 135 99 3 461 145 156 457 2,35 1975 96-26 252 195 44 15 12 252 121 134 89-1976 - - - - - - - - - - - - - 1977 - - 123 551 49 39 143 48 148 713 735 59-1978 77 335 367 63 448 78-14 223 55 795 585-1979 16 33 4 - - 226 36 242 937 498-376 - 198 38 141 193 328 367-4 145 165 222 69 362-1981 22 261 89 228 232 52 5 - - - - - - 1982 - - - - - - - - - - - - - 1983-57 199 131 351 111 147 16 35 - - - - 1984 334 119-217 - - - - 21 86 342 147-1985 233 131 321 249 447 - - - - 215 - - - 1986 - - - - - 7 12 65-298 - 66-1987 144-21 - - - - - - 573 259 644-1988 - - - - - - - - - - - - - 1989-3 - - - - - - - - - - - 199 - - - - - - - - - - - - - 1991 - - - - - - - - - - - - - 1992-126 - - - - - - - - 352 - - 1993 - - - - - - - - - - - - - 1994 - - - - - - - - - - - - - 1995 - - - - - - - - - - - - - 1996 - - - - - - - - - - - 65-1997 6-265 69 99-182 - 85 155 244 - - 1998 - - - - - - - - - - - - - 1999 - - - - - - - - - - - - - 2 - - - - - - - - - - - - - 21 - - - - - - - - - - - - - 22 - - - - - - - - - - - - - 23 - - - - - - - - - - - - - 24 - - - - - - - - - - - - - 25 - - - - - - - - - - - - - 26 - - - - - - - - - - - - - 27 - - - - - - - - - - - - - 28 - - - - - - - - - - - - - Min 49 3 4 69 99 44 5 12 85 86 69 65 Max 38 335 367 63 49 39 36 242 937 713 795 644 Ave 169 134 27 283 323 149 135 96 32 312 327 331 2,768 Source: BMKG JICA Project for the Master Plan Study of T-1 August, 211

Table 11 Monthly Rainfall Records (6/12) Station Name: Dolok Sanggul Station ID: 86A Unit: mm Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual 1969 - - - - - - - - - - - - - 197 - - - - - - - - - - - - - 1971 - - - - - - - - - - - - - 1972 - - - - - - - - - - - - - 1973 75 126 166 35 213 68 19 17 141 176 34 366 2,21 1974 17 18 249 33 252 11 98 7 469 247 171 29 2,42 1975 121 161 218 28-9 157 18 138 4 124 263-1976 - - - - - - - - - - - - - 1977 - - 12 169 - - - 9 134 243 286 137-1978 58 124 183 368 121 26-127 55 253 238 134-1979 - 84 214 - - 146 162 14 136 279 828 183-198 89 82 144 241 147-25 65 118 187 39 455-1981 62 162 44 155 123 8 - - - - - - - 1982 - - - - - - - - - - - - - 1983 - - - - - - - - 169-141 - - 1984 157 114-263 419 - - - 179 142 345 158-1985 113 66 188 27 144 - - - - 33 - - - 1986 - - - - - - 145 65 198 255 258 217-1987 13 9 5 292 242 52 123 156 228 491 238 214 2,36 1988 - - - - - - - - - - - - - 1989 - - - - - 13 - - - 155-16 - 199 - - 299 - - - - - - - - - - 1991 269-351 357 418 17 84 84 159-591 396-1992 195 132 299 368-52 78-38 67 - - - 1993 187 13 59-329 - 44 16 65 265 151 81-1994 111 - - - - - - - - - - - - 1995 14 - - - - - - - - 19 - - - 1996-18 287 63 92 22 11 95 72 221 13 215-1997 78 38 165 142-7 38 13 54-227 8-1998 37-74 7 16-67 - - - - 35-1999 251 145 97 - - - - - - - - - - 2-16 - - - - - - - - - - - 21 - - - - - - - - - - - - - 22 - - - - - - - - - - - - - 23 - - - - - - - - - - - - - 24 - - - - - - - - - - - - - 25 - - - - - - - - - - - - - 26 - - - - - - - - - - - - - 27 - - - - - - - - - - - - - 28 - - - - - - - - - - - - - Min 37 38 44 63 16 9 25 7 54 4 124 8 Max 269 18 351 368 419 146 162 156 55 491 828 455 Ave 13 117 177 244 21 64 95 66 195 214 289 231 2,32 Source: BMKG JICA Project for the Master Plan Study of T-11 August, 211

Table 12 Monthly Rainfall Records (7/12) Station Name: Gugur Balige(Pintu-Pintu) Station ID: 86B Unit: mm Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual 1969 - - - - - - - - - - - - - 197 - - - - - - - - - - - - - 1971 11 75-15 - - - - - - - - - 1972 17 159 115 244 324 48 61-119 198 429 274-1973 222 284 313 283 169 18 16 73 36 167 153 28 2,464 1974 149 128 113 115 134 21 12 14 418 72 219 46 2,152 1975 32 48 94 231 144 131 245 31 95 64 174 172 1,461 1976 57 117 11 133 54 174 226 114 88 295 333 221 1,913 1977 256 214 59 27 253 19 61 14 27 371 275 143 2,115 1978 15 14 133 131 182-12 16 5 17 175 122-1979 83 114 97 121 36 19 54 129 21 238 314 99 1,676 198 17 219 13 19 69 25 77 23 57 75 137 213 1,358 1981 1 21 25 - - - - - - 161 159 34-1982 9 274 249 199 239-125 85 85 27 85 91-1983 9 34 127 239 16 63 72 114 14 483 162 82 1,712 1984 - - - - - - - - - - - - - 1985 - - 33 11 26-42 17 - - - 331-1986 - - - 272 - - - 14 186 139 236 - - 1987 158 115 155 212 56 97 29 188 65 359 424 337 2,96 1988 294 147 141 138 49 4 84 76 11 168 274 44 1,565 1989 73 56 299 16 143 6 88 41 19 219 196 147 1,618 199 175 64 124 196 165 14 166 18 155 216 187 158 2,268 1991 154 132 221 292 186 92 87-18 21 466 65-1992 45 153 57 - - - 28 - - 91 33 263-1993 724 44 11 14 94 8 3 238 119 28 122 152 2,133 1994 62 118 26 212 173 54 3 149 144 143 231 55 1,55 1995 192 188 182 258 311 192 14 269 182 247 129 - - 1996 - - - - - - - - - - - - - 1997 - - - - - - - - - - - - - 1998 - - 37 15 - - - 26 12 68 127 - - 1999 239 253 211 198 25 69 53 431 84-233 - - 2 - - - - - - - - - - - - - 21 - - - - - - - - - - - - - 22 - - - - - - - - - - - - - 23 - - - - - - - - - - - - - 24 - - - - - - - - - - - - - 25 - - - - - - - - - - - - - 26 - - - - - - - - - - - - - 27 - - - - - - - - - - - - - 28 - - - - - - - - - - - - - Min 1 21 25 15 36 6 3 14 27 64 85 34 Max 724 64 33 292 324 21 245 431 84 483 466 65 Ave 152 158 15 189 157 16 126 21 199 232 24 1,975 Source: BMKG JICA Project for the Master Plan Study of T-12 August, 211

Table 13 Monthly Rainfall Records (8/12) Station Name: Baligi-1(Baligi) Station ID: 86D Unit: mm Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual 1969 296 177 141 268 195 96 12 283 148 354 218 25 2,51 197 128 47 181 85 4 26 68 18 126 182 144 221 1,356 1971 239 13 151 6 71 261 65 175 25 72 248 137 1,814 1972 2 27 22 224 519 44 118 173 184 34 431 36 2,732 1973 132 193 333 22 17 255 116 185 248 355 159 499 2,865 1974 235 233 88 257 183 269 284 2 438 127 291 64 3,47 1975 198 287 183 511 115 17 332 37 439 18 259 215 2,854 1976 - - - - - - - - - - - - - 1977 146 255 - - - - - - - - - - - 1978 - - - - - - - - - - - - - 1979 - - - - - - - - - - - - - 198 - - - - - - - - - - - - - 1981 - - - - - - - - - - - - - 1982 - - - - - - - - - - - - - 1983 - - - - - - - - - - - - - 1984 - - 271 - - - - - - - - - - 1985 - - - - - - - - - - - - - 1986 - - - - - - - - - - - - - 1987 - - - - - - - - - - - - - 1988 - - - - - - - - - - - - - 1989 - - - - - 67 - - - - - - - 199 - - - - - - - - - - - - - 1991 - - - - - - - - - - - - - 1992 - - - - - - - - - - 21 - - 1993 - - - - - - - - - - - - - 1994 - - - - - - - - - - - - - 1995 - - - - - - - - - - - - - 1996 - - - - - - - - - - - - - 1997 - - - - - - - - - - - - - 1998 - - - - - - - - - 64 - - - 1999 - - - - - - - - - - - - - 2 - - - - - - - - - - - - - 21 - - - - - - - - - - - - - 22 - - - - - - - - - - - - - 23 - - - - - - - - - - - - - 24 - - - - - - - - - - - - - 25 - - - - - - - - - - - - - 26 - - - - - - - - - - - - - 27 - - - - - - - - - - - - - 28 - - - - - - - - - - - - - Min 2 47 88 6 4 26 65 2 126 64 144 137 Max 296 287 333 511 519 269 332 283 439 355 431 64 Ave 172 191 196 232 185 149 158 138 255 196 244 318 2,432 Source: BMKG JICA Project for the Master Plan Study of T-13 August, 211

Table 14 Monthly Rainfall Records (9/12) Station Name: Paguruan Station ID: 9 Unit: mm Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual 1969 - - - - - - - - - - - - - 197 - - - - - - - - - - - - - 1971 - - - - - - - - - - - - - 1972 - - - - - - - - - - 461 - - 1973 49 119 181 125 81 118 14 126 29 26 39 55 1,142 1974 13 4 48 126 64 433 49 28 15 48 46 322 1,727 1975 148 84 248 558 3-44 1 87 5 19 7-1976 67 221 314 48 169 112 56 17 23 169 158 153 1,957 1977 45-149 191 13 27 25 2 8 287 294 28-1978 149 217 27 242 112 33 77 18 43 175 215 122 1,61 1979 13 339 219 341 85 191 13 27 342 156 515 46 2,854 198 21 198 76 377 271 136 126 352 122 223 341 115 3,177 1981 97 74 86 185 25 28 21 6 86 147 51 1,14 1982 41 264 24 243 35 85 - - - - - - - 1983 61 126 344 - - 29 51 - - 221 96 243-1984 - - 188 171 235 35-111 9 52 4-1985 76 74 134 147 145-44 15 85 342 119 332-1986 61 11 119 256 83 45 13 85 58 13 151 172 1,256 1987 13 17 62-172 66 136 167 218 316 16 193-1988 17 12 214 37-353 - - - - - - - 1989-259 - - - 17 - - - - - - - 199 - - 63 - - - - - - - - - - 1991 - - - - - - - - - - - - - 1992 - - - - - - - - 43-12 182-1993 69 99 84 12 16 65 42 122 21 165 21 254 1,591 1994 125 19 156 25 159 34 23 146 112 117 211 59 1,51 1995 128 91 116 33 178 75 61 261 74 139 73 97 1,596 1996 124 336 482 39 195 82 377 196 197 39 26 13 2,997 1997 124 21 34 381-82 - - 193 38 26 13-1998 277 143 36 15 77 82 228 277 97 68 33 25 1,628 1999 116 111 24 61 178 98 183 28 413 378 118 - - 2 - - 294 - - - - - - - 96 - - 21 138 121 23 117 - - 69-86 96 18 348-22 - - - - - - - - - - - - - 23 - - - - - - - - - - - - - 24 - - - - - - - - - - - - - 25 - - - - - - - - - - - - - 26 - - - - - - - - - - - - - 27 - - - - - - - - - - - - - 28 - - - - - - - - - - - - - Min 13 4 23 61 3 17 13 1 8 5 33 4 Max 277 339 76 558 35 433 49 352 413 378 515 46 Ave 111 155 24 245 153 14 12 128 127 185 173 181 1,865 Source: BMKG JICA Project for the Master Plan Study of T-14 August, 211

Table 15 Monthly Rainfall Records (1/12) Station Name: Salak Station ID: 9C Unit: mm Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual 1969 - - - - - - - - - - - - - 197 - - - - - - - - - - - - - 1971 - - - - - - - - - - - - - 1972 - - - - - - - - - - - - - 1973 - - - - - - - - - - - - - 1974 - - - - - - - - - - - - - 1975 - - - - - - - - - - - - - 1976 - - - - - - - - - - - - - 1977 - - - - - - - - - - - - - 1978 - - - - - - - - - - - - - 1979 - - - - - - - - - - - - - 198 - - - - - - - - - - - - - 1981 - - - - - - - - - - - - - 1982 - - - - - - - - - - - - - 1983 - - - - - - - - - - - - - 1984 447 356 454 - - - 244 - - 279 369 175-1985 248 15 36 169 - - - - 174 134 - - - 1986 - - - - - - - - - - - - - 1987 - - - - - - - - - - - - - 1988 - - - - - - - - - - - - - 1989 - - - - - - - - - - - - - 199 - - 63 - - - - - - - - - - 1991 - - - - - - - 186-448 - - - 1992 161 - - - - - 24 254 - - - - - 1993 - - - - 368 21 294 151 43 47 - - - 1994 - - - - - - - - - - - - - 1995 192 - - - - - 125 384 - - - - - 1996 - - - - - - - - - - - - - 1997-154 29 279 - - 177-66 35 357 18-1998 226-167 224 26 48 399 58 176 22 454 544-1999 272 228 - - - - - - - - - - - 2 - - - - - - - - - - - - - 21 - - - - - - - - - - - - - 22 - - - - - - - - - - - - - 23 - - - - - - - - - - - - - 24 - - - - - - - - - - - - - 25 - - - - - - - - - - - - - 26 - - - - - - - - - - - - - 27 - - - - - - - - - - - - - 28 - - - - - - - - - - - - - Min 161 15 63 169 26 48 24 151 66 134 357 175 Max 447 356 454 279 368 21 399 58 43 448 454 544 Ave 258 211 256 224 287 125 211 311 212 33 393 3 3,89 Source: BMKG JICA Project for the Master Plan Study of T-15 August, 211

Table 16 Monthly Rainfall Records (11/12) Station Name: Sidikalang Station ID: 91 Unit: mm Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual 1969 - - - - - - - - - - - - - 197 - - - - - - - - - - - - - 1971 - - - - - - - - - - - - - 1972 - - - - - - - - - - - - - 1973 - - - - - - - - - - - - - 1974 - - - - - - - - - - - - - 1975 - - - - - - - - - - - - - 1976 - - - - - - - - - - - - - 1977 - - - - - - - - - - - - - 1978 112 348 - - 154-154 51 142 - - 129-1979 142 23 - - - - - - - - - - - 198 - - - - 53 - - 156 - - - - - 1981 29 247 - - - 72 - - - - - - - 1982 - - - - - - - - - - - - - 1983 - - - - - - - - - - 17 - - 1984 - - - - - - - 149 18 169 436 - - 1985 69 73 261 - - - - - - - - - - 1986 - - - - - - - - - - - - - 1987 - - - - - - - - - - - - - 1988 - - - - - - - - - - - - - 1989 - - - - - 126 - - - - - - - 199 - - - - - - - - - - - - - 1991 - - - - - - - - 68 158 226 - - 1992 53 15 199 221 112 55-14 15 98 277 - - 1993 121 17 257 358 25-144 12 283-529 - - 1994 - - - - - - - - - - - - - 1995 - - - - - 118 - - 22 31 - - 1996-31 167 229 17 187 42 - - 336 - - - 1997 139 136 214 - - 116-128 197 358 474 46-1998 9 139 168 236-55 159 577 229 172 322 291-1999 - 7 - - - - 293 - - - - - - 2 - - - - - - - - - - - - - 21 - - - - - - - - - - - - - 22 - - - - - - - - - - - - - 23 - - - - - - - - - - - - - 24 - - - - - - - - - - - - - 25 - - - - - - - - - - - - - 26 - - - - - - - - - - - - - 27 - - - - - - - - - - - - - 28 - - - - - - - - - - - - - Min 53 7 167 221 17 55 118 51 68 98 17 46 Max 29 348 261 358 53 187 42 577 283 358 529 291 Ave 127 18 211 261 213 12 215 186 178 216 343 155 2,387 Source: BMKG JICA Project for the Master Plan Study of T-16 August, 211

Table 17 Monthly Rainfall Records (12/12) Station Name: Tiga Lingga Station ID: 91B Unit: mm Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual 1969 - - - - - - - - - - - - - 197 - - - - - - - - - - - - - 1971 - - - - - - - - - - - - - 1972 - - - - - - - - - - - - - 1973 - - - - - - - - - - - - - 1974 - - - - - - - - - - - - - 1975 - - - - - - - - - - - - - 1976 - - - - - - - - - - - - - 1977 - - - - - - - - - - - - - 1978 - - - - - - - - - - - - - 1979 - - - - - - - - - - - - - 198 - - - - - - - - - - - - - 1981 - - - - - - - - - - - - - 1982 - - - - - - - - - - - - - 1983 - - - - - - - - - - - - - 1984 277 228 37 175 141 - - 66 - - 324 13-1985 174 25 222 164 216 - - - - - - - - 1986 - - - - - - - - - - - - - 1987 - - - - - - - - - - - - - 1988 - - - - - - - - - - - - - 1989 - - - - - - - - - - - - - 199 - - - - - - - - - - - - - 1991 - - - - - - 3 - - - - - - 1992 - - - - - - - - - 11 - - - 1993 117 - - - - - - - - - - - - 1994 - - - - - - - - - - - - - 1995 - - - - - - - - - - - - - 1996 - - - - - - - - - - 187 - - 1997 - - - - - - - - - - - - - 1998 - - 7 248 - - - - - - - - - 1999 - - - - - - - - - - - - - 2 - - - - - - - - - - - - - 21 - - - - - - - - - - - - - 22 - - - - - - - - - - - - - 23 - - - - - - - - - - - - - 24 - - - - - - - - - - - - - 25 - - - - - - - - - - - - - 26 - - - - - - - - - - - - - 27 - - - - - - - - - - - - - 28 - - - - - - - - - - - - - Min 117 25 7 164 141 3 66 11 187 13 Max 277 228 37 248 216 3 66 11 324 13 Ave 189 217 2 196 179 3 66 11 256 13 1,571 Source: BMKG JICA Project for the Master Plan Study of T-17 August, 211

Table 18 Selected Hourly Rainfall Records Year Month Date hour Intensity (mm) 1 2 3 4 5 6 7 8 9 1 11 12 13 14 15 16 17 18 19 2 21 22 23 24 1h 2h 6h 12h 24h 1992 2 27 1......... 7.7 7.7. 79.1 7.7 7.7......... 79.1 79.1 11. 11. 11. 5 13 2...... 2.4 2.4 2.4 16.7 16.7. 35.8 16.7 16.7 2.4 2.4 2.4...... 35.8 35.8 12.5 116.6 116.6 12 21 3...... 1.2 1.2 1.2.1.1 15. 85.5.1.1 1.2 1.2 1.2...... 85.5.5.9 17.9 17.9 1993 3 25 4......... 7.5 7.5 1.6 7. 7.5 7.5......... 7. 71.6 11.6 11.6 11.6 1994 1 15 5.......1.1.1 6.8 6.8 18. 78. 6.8 6.8.1.1.1...... 78. 96. 123.1 123.5 123.5 3 17 6...... 2.1 2.1 2.1 6.9 6.9 8.2 69.5 6.9 6.9 2.1 2.1 2.1...... 69.5 77.7 15.2 118. 118.1 1 22 7.8.8.8.8.8.8 6.8 6.8 6.8 1.2 1.2 25.6 3. 1.2 1.2 6.8 6.8 6.8.8.8.8.8.8.8 3. 55.6 6.4 11.3 111.3 1995 3 17 8...... 2.1 2.1 2.1 6.9 6.9 8.2 69.5 6.9 6.9 2.1 2.1 2.1...... 69.5 77.7 15.2 118. 118.1 9 9.6.6.6.6.6.6 3. 3. 3. 19.6 19.6 21.9 48.3 19.6 19.6 3. 3. 3..6.6.6.6.6.6 48.3 7.2 148.4 166.1 173.5 5 23 1...... 2.2 2.2 2.2 14. 14. 23.9 39.6 14. 14. 2.2 2.2 2.2...... 39.6 63.5 119.5 132.5 132.5 7 23 11...... 1.3 1.3 1.3 8. 8. 34.9 41.7 8. 8. 1.3 1.3 1.3...... 41.7 76.6 18.5 116.1 116.4 9 29 12 1.1 1.1 1.1 1.1 1.1 1.1 2.9 2.9 2.9 12.5 12.5 27.7 48.3 12.5 12.5 2.9 2.9 2.9 1.1 1.1 1.1 1.1 1.1 1.1 48.3 76. 126. 143.5 156.1 1996 2 25 13.1.1.1.1.1.1 6.5 6.5 6.5 8.4 8.4 7.6 38.1 8.4 8.4 6.5 6.5 6.5.1.1.1.1.1.1 38.1 45.7 79.1 118. 119.7 4 1 14.1.1.1.1.1.1.7.7.7 5.3 5.3 26.6 47. 5.3 5.3.7.7.7.1.1.1.1.1.1 47. 73.6 94.9 99.1.3 15 15 4.9 4.9 4.9 4.9 4.9 4.9.9.9.9 5.9 5.9 14. 41.7 5.9 5.9.9.9.9 4.9 4.9 4.9 4.9 4.9 4.9 41.7 55.7 79.4 85. 143.4 6 7 16...... 2.5 2.5 2.5 11.3 11.3 29.6 4.3 11.3 11.3 2.5 2.5 2.5...... 4.3 69.9 114.9 129.6 129.6 7 6 17.1.1.1.1.1.1 2.1 2.1 2.1 15.6 15.6 63.7 71.1 15.6 15.6 2.1 2.1 2.1.1.1.1.1.1.1 71.1 134.8 197.2 29.6 21.5 1 5 18...... 1. 1. 1. 2.6 2.6 1.6 79.5 2.6 2.6 1. 1. 1....... 79.5 9.1.4 16.6 16.9 12 1 19...... 4.7 4.7 4.7 11.7 11.7 12.5 31.8 11.7 11.7 4.7 4.7 4.7...... 31.8 44.3 91.1 119.1 119.3 1999 8 17 2...... 4.1 4.1 4.1.4.4 19.6 8.2.4.4 4.1 4.1 4.1...... 8.2 99.8 11.2 125.8 125.8 1 21.......9.9.9 6.3 6.3 36.5 42.4 6.3 6.3.9.9.9...... 42.4 78.9 14.2 19.8 19.8 7 22.3.3.3.3.3.3 2.1 2.1 2.1 2.6 2.6 19.2 55.7 2.6 2.6 2.1 2.1 2.1.3.3.3.3.3.3 55.7 74.9 85.4 98.1 11.4 1 12 No 12 23...... 1.9 1.9 1.9 9.1 9.1 3.8 62.2 9.1 9.1 1.9 1.9 1.9...... 62.2 66. 12.3 113.6 113.6 29 24.4.4.4.4.4.4 13. 13. 13. 19.8 19.8 3. 51. 19.8 19.8 13. 13. 13..4.4.4.4.4.4 51. 81. 16.3 238.2 243.3 4 25 2.1 2.1 2.1 2.1 2.1 2.1 1.3 1.3 1.3 3.1 3.1 1.1 5.1 3.1 3.1 1.3 1.3 1.3 2.1 2.1 2.1 2.1 2.1 2.1 5.1 6.2 72.4 8.4 15.9 6 26.8.8.8.8.8.8 1.7 1.7 1.7 2.4 2.4 6.1 74.4 2.4 2.4 1.7 1.7 1.7.8.8.8.8.8.8 74.4 8.5 9.2.2 11.2 24 5 5 27...... 5.6 5.6 5.6 7.1 7.1 19.8 28.2 7.1 7.1 5.6 5.6 5.6...... 28.2 48. 76.5 11. 11. 11 4 28......... 7.7 7.7 24. 6. 7.7 7.7......... 6. 84. 114.6 114.6 114.6 26 6 23 29.3.3.3.3.3.3 7.3 7.3 7.3 6.5 6.5 16.7 27.9 6.5 6.5 7.3 7.3 7.3.3.3.3.3.3.3 27.9 44.6 7.6 114.5 118.1 8 25 3...... 2.9 2.9 2.9 9.7 9.7 27.7 28.4 9.7 9.7 2.9 2.9 2.9...... 28.4 56.1 94.9 112.4 112.4 9 13 31.......1.1.1 6.7 6.7 33.4 41.5 6.7 6.7.1.1.1...... 41.5 74.9 11.5 12. 12. Source: Asahan 3 HEPP Construction Report, 27 JICA Project for the Master Plan Study of T-18 August, 211

Table 19 Monthly Mean Runoff Records (1/3) Station Name: Pasar Sironggit Station ID: 1-178--1 Unit: m3/s Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual 1982 6.7 9.6 7.8 14.8 13.1 4.6-5.3 8.2 1. - - - 1983 - - - - 1.5 6.2 5.2 6.1 8.1 1.2 7.5 14.2-1984 11.5 9.5 12.6 18.8 13.1 11.3 12.1 6.7 1.3 8.9 - - - 1985 1.6 4.9 7. 9.1 11.7 4.5 4.3 5.8 7.3 7.9 14.9 15.5 8.6 1986 9.9 7. 8.7 19.6 14.5 8.5 6.3 5.2 7.7 12.7 1.6 11.4 1.2 1987 1.2 4.8 8.9 14. 18. 5.8 11.2 5.5 6.8 7.4 14. 14.5 1.1 1988-1989 - 199-1991 6.2 7.9 19.9 2.1 31.9 19.2 1.6 9.1 11.9 17. 58.7 44.9 21.4 1992 11.5 1.2 9.7 23.7 22.9 8.3 8.4 7.8 1.8 6.7 24.9 15.6 13.4 1993 14.1 15. 12.2 14.4 16.4 11. 1.9 14.2 11.6 18.7 29.6 22. 15.8 1994 22.5 19.5 2. 21.6 19.2 14.9 13.7 13.9 16.4 15. 17.9 17. 17.6 1995 14.1 14.2 17.7 25. 24.2 8. 4.6 14.7 4. 26. 1. 12.1 14.5 1996 19. 25.7 22.5 16.1 13. 14.1 15.1 14.6 15. 27.5 21.6 25.5 19.1 1997 18.3 18.8 2.4 22.1 2.1 18. 16.4 16.4 16.5 19.7 19.8 19.2 18.8 1998 19.3 17.4 17.6 16.5 16.7 16.4 16.6 16.4 17.9 18.5 18. 19.4 17.6 1999-2 - 21 3.8 3.8 3.1 - - - - - - - - 3.4-22 - 23-24 - 25-26 - 27 6.7 5.9 6.5 1.8 1.7 1.2 1.5 8.2 17.1 17.8 15.6 9.8 1.8 28-9.5 5.4 6.9 7. 5.6 5.6 54.1-12.8 16.6 23.1 - Min 3.8 3.8 3.1 6.9 7. 4.5 4.3 5.2 4. 6.7 7.5 3.4 Max 22.5 25.7 22.5 25. 31.9 19.2 16.6 54.1 17.9 27.5 58.7 44.9 Ave 12.3 11.5 12.5 16.9 16.4 1.4 1.1 12.7 11.3 14.8 2. 17.9 13.9 Source: Pusair JICA Project for the Master Plan Study of T-19 August, 211

Table 2 Monthly Mean Runoff Records (2/3) Station Name: Dolog Sanggul Station ID: 1-184--1 Unit: m3/s Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual 1991 2.3 2.4 3.3 5.6 - - - - - - - - - 1992 3.4 1.8 2.8 4.7 7.9 1.5 1.5 1.5 2.1 1.1 4.9 4.5 3.1 1993 2.3 2.6 1.9 4.7 8.3 2.8 1.5 2.8 3.2 6.6 8.1 5.7 4.2 1994 8. 7.5 5.5 5.7 6.4 3.5 2.9 2.9 4.1 3.3 1. 4.2 5.3 1995 4.4 3.5 4.4 6.3 6.1 2.8 3.5 5.4 3.4 5.7 8.4 4.7 4.9 1996 4.6 6.3 5.1 5.2 3.3 5. 4.3 3.7 5.7 5.7 5.4 6.6 5.1 1997 3. 3.4 5. 4.4 4.1 4.4 3.6 3.7 4.1 3.8 5. 3.7 4. 1998 5.1 3.4 4. 3.4 2.5 3. 3.9 - - - - - - 1999 5.7 4.4 3.8 4.2 4.5 4.3 3.8 4.7 4.9 4.7 4.5 4.4 4.5 2-21 - 3.6 3. 3.9 3.1 2.5 5.3 2.9 1.1 3.9 3.7 4.3-22 - 23-24 - 25-26 17. 15.3 11.2 8.7 6.7 5.5 4.7 3.8 2.9 4.1 4.5 - - 27 2.4 1.3 1.8 4.3 1.9 1.8 1.1 1. - - - - - 28 1.6 1.2 2.6 4.6 1.7 1.6 1.4 1.4 1.3 2.8 3. - - Min 1.6 1.2 1.8 3.4 1.7 1.5 1.1 1. 1.3 1.1 3. 3.7 Max 17. 15.3 11.2 8.7 8.3 5.5 5.3 5.4 1.1 6.6 1. 6.6 Ave 5. 4.4 4.2 5.1 4.7 3.2 3.1 3.1 4.2 4.2 5.7 4.8 4.3 Source: Pusair JICA Project for the Master Plan Study of T-2 August, 211

Table 21 Monthly Mean Runoff Records (3/3) Station Name: Marade Station ID: 1-186--1 Unit: m3/s Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual 1983 3.8 2.7 3.7 2.6 8.7 5.8 4.8 4.8 8.9-11.6 - - 1984 13.4-6.8 8. 11. - 6. 2.8 - - - - - 1985-4.4 6. 7.4 8.1 3.5 3.8 3.7 - - 7.2 1.8-1986 4.6 3.9 8.7 11.8 9.1 3.4 2.9 2.8 4.3 6.4 1.3 4.7 6.1 1987-4.2 5.3 6.4 9.9 4.2 5.3 6.1 7.2-9.8 - - 1988 9.5 12.8 7.7 7.3 6.7 3.2 2.9 2.2 3.6 16.2 18.3 11.5 8.5 1989 3.9 4.4 9.1 7. 4.1 2.5 3. 2.3 3.8 6.7 7.6 4.8 4.9 199 5.7 3.4 3.1 4.7 7.9 2.9 3.9 3.4 2. 4.7 3.8 5.3 4.2 1991 4.9 6.4 - - - - - - - - - - - 1992-1993 2.5 2.4 4.2 4.6 5.6 3.4 3. 3.4 4.3 5.6 6.7 5.6 4.3 1994 9.9 7.9 1.4 13.4 9.9 5.1 3.6 4.9 6.3 3.9 7.1 4.2 7.2 1995 18. 18. 19.8 26.2 24.3 18.9 17.6 24.9 2. 19.9 24.1 2.2 21. 1996 4.1 5.8 5.5 5.2 2.8 5.1 1.5 2. 2.7 3.3 6.3 4. 4. 1997 - - - - - - - - - - - - - 1998 6.1 7.5 4.8 4.2 3.8 3.2 5.1 7.3 4.3 5.2 5.9 5.6 5.3 1999-2 - 21 6.9 7.4 7.3 7.9 5.2 5.1 6.1 5.5 5.9 6.4 6.2 - - 22-23 - 24-25 7.6 7.7 7.5 8.9 8. 7.5 7.2 7.2 7.3 8. 7.4 7.9 7.7 26 15.4 14.7 13.8 12.6 11.6 1.6 9.8 8.8 7.7 7. 6.6 - - 27-2.6 3.7 - - - 1.2-2.3 3.8 2.6 1.3-28 1.6 1.7 2.6 4.2 1.7 - - - - - - - - Min 1.6 1.7 2.6 2.6 1.7 2.5 1.2 2. 2. 3.3 2.6 1.3 Max 18. 18. 19.8 26.2 24.3 18.9 17.6 24.9 2. 19.9 24.1 2.2 Ave 7.4 6.6 7.2 8.4 8.1 5.6 5.1 5.8 6. 7.5 8.8 7.1 7. Source: Pusair JICA Project for the Master Plan Study of T-21 August, 211

Table 22 Regression Analysis of Monthly Rainfall Records Number of Data 78 84 84C 85 86 86A 86B 86D 9 9C 91 91B Segala 78 36 2 29 2 2 2 1 34 2 2 Tarutung 84 2 119 64 84 76 9 92 4 15 24 36 14 Hutaraya 84C 29 64 185 75 81 125 132 72 128 28 55 4 Barus 85 2 84 75 16 64 97 93 5 11 3 44 16 Siborong-borong 86 2 76 81 64 126 18 99 36 116 16 26 1 Dolok Sanggul 86A 2 9 125 97 18 179 132 36 152 35 59 17 Gugur Balige 86B 1 92 132 93 99 132 266 55 196 23 45 8 Baligi-1 86D 34 4 72 5 36 36 55 9 41 2 3 1 Paguruan 9 2 15 128 11 116 152 196 41 266 41 65 14 Salak 9C 24 28 3 16 35 23 2 41 49 3 11 Sidikalang 91 2 36 55 44 26 59 45 3 65 3 78 9 Tiga Lingga 91B 14 4 16 1 17 8 1 14 11 9 19 Correlation Ratio 78 84 84C 85 86 86A 86B 86D 9 9C 91 91B Segala 78 1. 1..55-1. 1. 1..442.517 1. 1. Tarutung 84 1. 1..586.223.384.342.224.445.222.328.411.582 Hutaraya 84C.55.586 1..231.549.59.382.399.413.538.455.495 Barus 85-1..223.231 1..183.195.216.337.132.373.311.439 Siborong-borong 86 1..384.549.183 1..426.45.669.271.462.364.484 Dolok Sanggul 86A 1..342.59.195.426 1..415.485.226.36.242.26 Gugur Balige 86B.442.224.382.216.45.415 1..79.287.268 -.21.144 Baligi-1 86D.517.445.399.337.669.485.79 1..586 1..949 Paguruan 9 1..222.413.132.271.226.287.586 1..341.389.18 Salak 9C.328.538.373.462.36.268 1..341 1..699.76 Sidikalang 91 1..411.455.311.364.242 -.21.949.389.699 1..686 Tiga Lingga 91B.582.495.439.484.26.144.18.76.686 1. Slope of Formula (Y=aX) X 78 84 84C 85 86 86A 86B 86D 9 9C 91 91B Segala 78 1. 1.113 1.43.711 1.82 2.897 2.731 1.868 1.534 1.5 Tarutung 84.869 1..87.481.463.711.77.649.77.614.748 1.172 Hutaraya 84C.552 1.28 1..472.523.821.94.73.777.563.715.988 Barus 85 1.55 1.325 1.468 1..692 1.95 1.179 2.38 1.265 1.146 1.239 1.331 Siborong-borong 86.784 1.47 1.399.836 1. 1.226 1.435.72 1.77.717.847 1.183 Dolok Sanggul 86A.333.94.869.527.542 1..858.639.744.533.628.842 Gugur Balige 86B.291.762.758.499.475.758 1..695.798.59.511 1.264 Baligi-1 86D.432 1.148.996.383 1.173 1.168 1.217 1. 1.212.551.615 Paguruan 9.652.738.876.452.486.73.713.544 1..56.619.584 Salak 9C 1.155 1.497.633 1.173 1.295 1.393 1.754 1.376 1. 1.17 1.276 Sidikalang 91.86.936 1.21.53.819.884.813 1.534 1.98.727 1. 1.25 Tiga Lingga 91B.728.82.626.754.853.375 1.28.735.831 1. JICA Project for the Master Plan Study of T-22 August, 211

Table 23 Estimated Monthly Basin Mean Rainfall at Pasar Sironggit AWLR Station Unit: mm Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual 1977 168 11 88 116 111 165 73 8 167 198 29 173 1,647 1978 16 223 23 344 155 53 64 86 291 264 283 179 2,248 1979 215 159 164 29 35 125 141 43 197 263 62 25 2,355 198 182 123 17 196 161 99 4 88 124 156 266 323 1,925 1981 62 217 72 225 168 6 21 45 65 131 129 28 1,223 1982 73 223 23 162 195 64 12 69 69 169 69 74 1,472 1983 73 38 133 176 54 7 6 14 393 134 67 1,438 1984 217 171 266 235 267 76 123 66 185 158 464 25 2,431 1985 187 14 267 189 146 75 34 87 219 9 269 1,83 1986 46 83 9 269 118 35 96 51 169 212 222 143 1,533 1987 98 187 122 25 144 51 98 125 195 347 162 185 1,96 1988 239 273 115 112 217 19 116 62 9 137 223 36 1,638 1989 59 15 243 13 116 84 72 57 155 148 16 137 1,376 199 142 492 277 16 134 85 135 15 126 176 152 129 2,22 1991 245 116 235 34 351 85 72 7 13 122 577 372 2,714 1992 14 155 215 317 75 43 119 252 61 187 211 1,873 1993 159 155 111 157 269 91 157 85 113 31 333 195 2,132 1994 24 93 149 188 136 36 1 121 15 17 181 17 1,438 1995 143 116 123 228 23 118 136 195 17 172 254 74 1,869 1996 94 164 263 146 16 47 128 124 68 231 133 197 1,7 1997 8 18 152 147 53 96 67 12 7 185 178 15 1,25 1998 93 119 68 92 99 94 286 138 77 131 295 1,592 Min 46 15 72 68 35 19 1 12 65 61 69 28 Max 245 492 277 344 351 165 157 286 291 393 62 372 Ave 138 157 17 196 156 75 89 88 139 192 233 168 1,82 Note: There is not sufficient number of daily data for estimation in June 1985, and average rainfall in June is used instead. JICA Project for the Master Plan Study of T-23 August, 211

Table 24 Annual Rainfall Loss of Various River Basins in Sumatra No. Station River Gauge ID Catchment Basin Annual Annual Annual Runoff Observation Name Basin Area Mean Mean Runoff Rainfall Coeff. Period Rainfall Runoff Depth Loss (km 2 ) (mm) (m 3 /sec) (mm) (mm) 1 Lhok Nibong Kr. Jambu Aye 1-27-1-2 4,583 2,685 175.7 1,29 1,476.45 1972-1993 2 Stabat S. Wampu 1-4-1-1 3,87 3,99 26.8 1,685 1,414.54 1974-1993 3 Lb. Sipelanduk Bt. Pane 1-55-3-2 828 2,25 28.4 1,82 1,168.48 1973-1993 4 Lb. Bendahara S. Rokan 1-58-2-1 3,325 2,589 141.5 1,342 1,247.52 1974-1993 5 Tj. Ampalu Bt. Kuantan 1-66-4-1 2,215 2,211 77.6 1,15 1,16.5 1975-1993 6 Sungai Dareh Bt. Hari 1-71-1-1 4,452 3,239 31.2 2,197 1,42.68 1975-1993 7 Muara Inum Bt. Hari 1-71-2-1 1,455 3,346 17.6 2,332 1,14.7 1973-1987 8 Martapura A. Musi 1-74-1-1 4,26 2,821 225. 1,666 1,155.59 196-1984 9 Banjarmasin W. Tl. Bawang 1-77-2-7 64 3,125 36.8 1,921 1,24.61 1972-1993 1 Kunyir W. Sekampung 1-8-1-4 438 2,74 23.1 1,663 1,77.61 1968-1993 11 Kp. Darang Kr. Aceh 1-1-1-1 1,81 2,12 33.1 966 1,46.48 1977-1993 12 Tui Kareng Kr. Teunom 1-25-1-1 2,43 3,437 183.9 2,413 1,24.7 1982-1993 13 Hp. Baru Bt. Toru 1-178-1-1 2,773 2,843 128.9 1,466 1,377.52 1972-1993 14 Air Batu Bt. Indrapura 1-141-1-1 468 2,887 31.3 2,19 778.73 1973-1993 15 Air Gadang Bt. Pasaman 1-165-1-1 1,339 3,6 121.3 2,857 743.79 1973-1993 16 Despetah A. Musi 1-74-1-2 627 3, 45.2 2,273 827.73 1974-1991 Source : Sectoral Report Vol. 2 : Hydrology, Hydro Inventory Study, July 1997 JICA Project for the Master Plan Study of T-24 August, 211

Table 25 Area Reduction Factor for Simanggo River Basin Paguruan Baligi-1 Gugur Baligi Hutaraya Point Rainfall (mm) Area No Date Average Reduction Hutaraya Gugur Baligi Baligi-1 Paguruan Factor 1 1969/4/27 63 32.5 2 197/3/13 62 6 34.55 3 1971/3/9 91 46.5 4 1972/8/22 65 14 26.41 5 1973/11/21 45 7 6 15.32 6 1974/4/14 19 13 14 34.31 7 1975/4/9 62 2 16.26 8 1977/11/3 78 25 1 35.44 9 1978/2/21 67 7 37.55 1 1979/4/13 76 47 41.54 11 198/1/23 61 98 19 59.97 12 1981/5/6 83 4 44.52 13 1989/1/17 57 15 36.63 14 1991/11/27 63 33 48.76 15 1992/12/27 85 5 15 35.41 16 1993/11/14 77 52 1 46.6 17 1994/1/1 44 5 16.37 18 1995/7/2 57 9 33.58 19 1996/4/3 57 29 43.75 2 1997/1/9 54 2 28.52 21 1998/8/24 76 17 32 42.55 22 1999/2/2 3 1.33 23 1971/4/26 33 5 28.55 24 1972/11/14 37 79 77 28 55.7 25 1973/2/27 12 66 26.39 26 1974/7/15 72 3 14 3.41 27 1975/7/21 62 44 3 27.44 28 1976/4/3 57 18 38.66 29 1977/1/4 15 88 13 25 35.4 3 1978/5/9 6 98 23 42.43 31 1979/11/19 65 84 71 73.87 32 198/1/23 61 98 19 59.61 33 1981/11/3 54 5 3.55 34 1983/1/16 67 8 38.56 35 1985/12/4 75 11 43.57 36 1991/12/3 62 175 119.68 37 1992/7/28 58 5 54 1.8 38 1993/1/17 39 18 12 77.43 39 1995/11/15 47 84 1 47.56 4 1998/8/3 16 5 22.44 41 1999/4/5 75 18 31.41 42 197/9/14 76 38.5 43 1971/3/16 83 42.5 44 1972/1/28 57 17 55.51 45 1973/12/1 13 52 15 5 44.42 46 1974/12/25 96 51 49.51 47 1975/4/21 6 123 54 46.37 48 1977/2/28 3 18 37.34 49 1984/3/29 64 2 33.52 5 1989/6/2 13 4.33 51 1992/11/25 6 3 13 16.54 52 1998/1/31 31 31 21.67 53 1972/11/26 46 124 43.34 54 1973/2/25 28 45 18.41 55 1974/6/22 8 7 38 38.38 56 1975/3/31 115 38.33 57 1977/12/5 21 2 81 35.43 58 1978/1/17 27 3 97 42.44 59 1979/12/8 15 91 35.39 6 198/4/22 73 24.33 61 1981/1/23 8 57 33.57 62 1984/3/26 2 71 46.64 63 1985/4/1 27 45 36.8 64 1986/11/2 1 4 25.63 65 1992/12/21 12 3 14.47 66 1993/9/17 33.33 67 1994/11/2 23 47 35.74 68 1995/1/27 11 67 39.58 69 1996/3/4 4 62 33.53 7 1997/4/6 7 72 4.55 71 1998/1/14 52 26.5 72 1999/5/6 Average 39 68 54.79.52 JICA Project for the Master Plan Study of T-25 August, 211

Table 26 Annual Maximum 1-Day Rainfall around Simanggo River Basin Year Hutaraya Gugur Balige Paguruan 1969 - - - 197 - - - 1971 91 - - 1972 65 79-1973 45 66 45 1974-72 1975 62 62 115 1976-57 8 1977 78 88 81 1978 67 98 97 1979 76 84 91 198 61 98 73 1981 - - 57 1982-8 - 1983-67 - 1984 - - - 1985 - - 45 1986 - - 4 1987-46 46 1988-51 - 1989-14 - 199-2 - 1991-175 - 1992 - - - 1993 77 18 1994-74 47 1995-84 67 1996 - - 62 1997 - - 72 1998 - - 52 1999 - - 68 2 - - - 21 - - 112 Count 9 19 2 JICA Project for the Master Plan Study of T-26 August, 211

Table 27 Calculation of Probable Maximum Precipitation (PMP) Annual Maximun 1-Day Precipitation at Paguruan Station Unit: mm Year Rainfall Max = 115 mm (1975) 1969-197 - n = 2 1971 - X n = 72.5 mm 1972 - S n = 23.7 mm 1973 45 X n-m = 7.3 mm 1974 S n-m = 22.1 mm 1975 115 1976 8 X n-m / X n =.97 1977 81 S n-m / S n =.93 1978 97 1979 91 Adjustment for Maximum Observed Event 198 73 f X1 = 11% 1981 57 f S1 = 12% 1982-1983 - Adjustment for Sample Size 1984 - f X2 = 12% 1985 45 f S2 = 18% 1986 4 1987 46 Statistical Coefficient 1988 - K m = 16.5 1989-199 - Adjustment for Fixed Observational Time Intervals 1991 - f = 113% 1992-1993 Computation of PMP 1994 47 X n = f X1 * f X2 * X n 1995 67 = 74.7 mm 1996 62 S n = f S1 * f S2 * S n 1997 72 = 26.1 mm 1998 52 X m = X n + K m * S n 1999 68 = 55.9 mm 2 - PMP = f * X m 21 112 = 571.7 mm JICA Project for the Master Plan Study of T-27 August, 211

Table 28 Ratios for SCS Unit Hydrograph t/t p q/q p...1.3.2..3.19.4.31.5.47.6.66.7.82.8.93.9.99 1. 1. 1.1.99 1.2.93 1.3.86 1.4.78 1.5.68 1.6.56 1.7.46 1.8.39 1.9.33 2..28 2.2.27 2.4.147 2.6.17 2.8.77 3..55 3.2.4 3.4.29 3.6.21 3.8.15 4..11 4.5.5 5.. JICA Project for the Master Plan Study of T-28 August, 211

Table 29 Average Rainfall Loss at Pasar Sironggit AWLR Station Monthly Runoff at Pasar Sironggit Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 1991 6 8 2 2 32 19 11 9 12 17 59 45 1992 11 1 1 24 23 8 8 8 11 7 25 16 1993 14 15 12 14 16 11 11 14 12 19 3 22 Monthly Basin Mean Rainfall Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 1991 245 116 235 34 351 85 72 7 13 122 574 372 1992 14 155 215 317 75 43 119 252 61 187 211 1993 159 155 111 157 269 91 157 85 112 31 333 195 Number of Days Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 1991 31 28 31 3 31 3 31 31 3 31 3 31 1992 31 29 31 3 31 3 31 31 3 31 3 31 1993 31 28 31 3 31 3 31 31 3 31 3 31 Runoff Depth Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 1991 47 54 152 148 244 142 81 69 88 13 434 343 1992 88 73 74 175 175 61 64 6 8 51 184 119 1993 18 14 93 16 125 81 83 18 85 143 219 168 Rainfall Loss in Rainy Season 1991.34 1992.368 1993.359 Average.356 JICA Project for the Master Plan Study of T-29 August, 211

Table 3 Probable Flood Hydrographs at Simanggo-2 Intake Weir Catchment Area = 478.3 km2 Unit:m3/s Time Return Period (year) (hour) PMF 4 2 15 8 5 3 2 1 5 3 2 24 24 24 24 24 24 24 24 24 24 24 24 24 1 28 25 25 25 25 25 25 25 25 25 25 25 24 2 4 29 28 28 28 28 28 27 27 27 27 26 26 3 57 34 33 33 32 32 32 31 31 3 29 29 28 4 71 38 37 37 36 36 35 34 34 33 32 31 3 5 81 41 4 39 39 38 37 37 36 34 33 32 31 6 86 43 41 41 4 4 39 38 37 35 34 33 32 7 111 5 48 48 46 46 45 43 42 4 38 36 35 8 187 73 69 68 66 65 62 6 58 54 5 47 44 9 29 14 98 96 92 91 87 83 79 73 66 61 56 1 432 146 137 134 129 126 12 114 18 99 89 81 73 11 664 215 22 196 188 184 175 165 156 141 126 114 11 12 148 438 49 397 38 37 351 329 31 278 244 218 191 13 2874 876 817 792 757 737 697 652 612 547 478 423 368 14 3894 1182 1 167 119 992 938 877 823 735 64 566 491 15 3858 1171 19 157 11 983 929 869 815 728 634 561 487 16 318 946 882 855 817 795 752 74 661 59 515 456 396 17 2266 695 648 628 61 585 553 518 487 436 381 338 295 18 164 57 473 459 439 428 46 38 357 321 281 25 219 19 1174 368 344 334 32 312 296 277 261 235 27 185 163 2 823 263 246 239 23 224 213 2 189 171 151 136 12 21 56 184 173 168 162 158 151 142 135 122 19 99 89 22 375 129 122 118 114 112 17 11 96 88 8 73 66 23 258 94 89 87 84 83 79 76 72 67 61 57 52 24 192 74 71 69 67 66 64 61 59 55 51 47 44 25 135 57 55 54 53 52 5 48 47 44 42 4 37 26 47 45 45 44 43 42 41 4 38 36 35 33 27 73 39 38 37 37 36 36 35 34 33 32 31 3 28 52 32 32 31 31 31 31 3 3 29 28 28 27 29 4 29 28 28 28 28 28 27 27 27 27 26 26 3 33 27 26 26 26 26 26 26 26 26 25 25 25 31 29 25 25 25 25 25 25 25 25 25 25 25 25 32 27 25 25 25 25 25 25 25 25 24 24 24 24 33 25 24 24 24 24 24 24 24 24 24 24 24 24 34 25 24 24 24 24 24 24 24 24 24 24 24 24 35 24 24 24 24 24 24 24 24 24 24 24 24 24 36 24 24 24 24 24 24 24 24 24 24 24 24 24 37 24 24 24 24 24 24 24 24 24 24 24 24 24 Peak 3894 1182 1 167 119 992 938 877 823 735 64 566 491 JICA Project for the Master Plan Study of T-3 August, 211

Table 31 Probable Floods under Various Schemes in Sumatra Catchment Probable Peak Discharge (m3/sec) No Scheme River Province Area Return Period (year) (km2) 2 2 2 1, 1, PMF 1 Tampur-1 Kr. Tampur D.I. Aceh 2,25 2,87 3,59 7,47 2 Teunom-1 Kr. Teunom D.I. Aceh 9 2,3 3,12 8,39 3 Aceh-2 Kr. Aceh D.I. Aceh 323 1,3 1,47 3,51 4 Lawe Alas-4 Lawe Alas D.I. Aceh 5,75 2,5 4,25 12,5 5 Peusangan-4 Kr. Peusangan D.I. Aceh 945 1,6 6 Lake Laut Tawar Kr. Peusangan D.I. Aceh 195 5 81 94 1,67 7 Residual Basin-1 Kr. Peusangan D.I. Aceh 16 36 53 6 1,2 8 Jambu Aye Kr. Jambu Aye D.I. Aceh 3,89 1,939 2,331 3,8 4,85 9 Rubek Kr. Jambu Aye D.I. Aceh 93 142 1 Residual Basin-2 Kr. Peusangan D.I. Aceh 128 32 48 55 94 11 Lalang S. Belawan N. Sumatera 254 25 41 61 12 Tembakau S. Percut N. Sumatera 171 14 23 34 13 Lausimeme S. Percut N. Sumatera 16 18 28 3 14 Helvetia S. Deli N. Sumatera 341 28 53 69 15 Namobatang S. Deli N. Sumatera 93 25 27 16 Baru S. Serdang N. Sumatera 671 47 75 94 17 Pulau Tagor S. Ular N. Sumatera 1,13 43 82 1,7 18 Karai S. Ular N. Sumatera 5 5 56 19 Brohol S. Padang N. Sumatera 759 39 72 94 2 Rampah S. Belutu N. Sumatera 423 18 29 37 21 Renun A. Renun N. Sumatera 139 58 74 82 96 1,9 22 Wampu S. Wampu N. Sumatera 1,57 2,97 23 Limang S. Wampu N. Sumatera 959 3 94 24 Sipan Sihaporas Sipan Sihaporas N. Sumatera 196 269 1,8 25 Batang Bayang-1 Bt. Bayang W. Sumatera 84 59 26 Batang Bayang-2 Bt. Bayang W. Sumatera 36 34 27 Muko-Muko Bt. Antokan W. Sumatera 248 44 74 93 12 28 Masang-3 Bt. Masang W. Sumatera 993 1,136 2,24 2,878 3,168 3,851 4,854 1,419 29 Merangin-5 Bt. Merangin Jambi 2,597 1,97 2,46 5,3 3 Lake Kerinci Siulak Jambi 916 59 1,538 2,177 2,464 3,12 4,92 13,347 31 Batang Hari Bt. Hari Jambi 4,452 1,937 4,192 5,63 6,25 7,61 32 Batang Hari (Alt.) Bt. Hari Jambi 3,825 1,664 3,62 4,814 5,331 6,531 33 Kiri-1 Bt. Kampar Riau 1,187 2,537 7,274 34 Kiri-2 Bt. Kampar Riau 552 1,446 35 Kapoernan Bt. Kampar Riau 699 2,181 36 Kotapanjang Bt. Kampar Riau 3,337 1,183 1,624 8, 11,4 37 Upper Sinamar Bt. Indragiri Riau 3,18 3,18 8,383 38 Sukam Bt. Indragiri Riau 36 1,755 39 Lower Kuantan Bt. Indragiri Riau 7,453 1,47 4 Ombilin Bt. Ombilin Riau 1,78 118 175 211 263 41 Musi (Intake Dam) A. Musi S. Sumatera 587 24 53 72 78 1,1 1,31 42 Musi (Regulation Dam) A. Musi S. Sumatera 3 79 138 175 19 226 277 43 Martapura Way Komering S. Sumatera 4,26 1,3 1,9 2,2 2,3 2,7 6,3 44 Lematang-4 A. Lematang S. Sumatera 1,321 1,87 2,43 5,5 45 Mine Mouth Steam Plant A. Lematang S. Sumatera 3,667 6,636 46 Ketaun-1 A. Ketaun Bengkulu 449 5 8 98 1,7 7,14 Simanggo-2 A. Simanggo N. Sumatera 478.3 491 823 1,19 1, 3,894 Source: Hydro Inventory Study, Sectral Report Vol.2 Hydrology, July 1997. Masang-3 HEPP, 1999. JICA Project for the Master Plan Study of T-31 August, 211

Table 32 Calculations of Suspended Load in Simanggo River No Sampling Date Water Level Qw C Qs Remarks Site (m) (m3/s) (mg/l) (ton/day) 1 Upstream of Intake Weir 21/1/5.85 44.22 5,432. 2,753.54 U 2 Upstream of Intake Weir 21/1/8.38 16.55 26.67 38.14 3 Upstream of Intake Weir 21/1/22.31 12.5 31. 33.48 4 Upstream of Intake Weir 21/1/24.5 21.49 6,246. 11,597.17 U 5 Upstream of Intake Weir 21/11/7.55 23.26 5,912. 11,881.13 U 6 Upstream of Intake Weir 21/11/21.54 21.56 4,599.33 8,567.56 U 7 Upstream of Intake Weir 21/11/25.46 17.88 6,199.67 9,577.45 U 8 Upstream of Intake Weir 21/12/5.32 13.21 45.33 51.74 9 Upstream of Intake Weir 21/12/9.32 12.81 36.2 4.7 1 Upstream of Intake Weir 21/12/25.41 18.21 665.67 1,47.33 Legend U: The concentration value is not reliable and not considered in the determination of the suspended load rating curve. JICA Project for the Master Plan Study of T-32 August, 211

Table 33 Water Quality Analysis of Simanggo River No Water Quality Parameter Unit Sample-1 Sample-2 Sample-3 Date 21/1/24 21/11/25 21/12/25 Weather Clear Clear Cloud 1 ph 6.51 7.34 5.28 2 Temperature 25.2 25.4 24.8 3 Total Hardness mg/l 7.21 9.28 12.4 4 Temporary Hardness mg/l 1.3 7.22 6.19 5 Suspended Matter mg/lit 37.7 35.5 123 6 Total Solid mg/lit 222 44.5 126 7 Ignition Residue mg/lit.1.8.8 8 Permanganate Value as O2 mg/lit 5.51 13.71 2.93 9 Carbonates as CaCO3 mg/lit 1 Bicarbonates as CaCO3 mg/lit 1.8 26.88 24.6 11 Calcium (Ca) mg/lit 2.8 2.49 2.58 12 Magnesium (Mg) mg/lit.49.74 1.44 13 Sodium (Na) mg/lit 4.29 8.22 5.24 14 Potassium (K) mg/lit 3.56 1.31 3.67 15 Iron (Fe) mg/lit 1.9.67.5 16 Manganese (Mn) mg/lit.7 <.2 <.2 17 Copper (Cu) mg/lit <.1 <.1.21 18 Turbidity NTU 5.3 5.3 6.3 19 Color Pt-Co-Unit 25 2 2 2 Electric Conductivity µ/cm 53.5 5.6 54.5 21 Aluminum (Al) mg/lit 1.14.2.34 22 Silica (SiO2) mg/lit 18.18 53.88 69.9 23 Lead (Pb) mg/lit <.1 <.1 <.1 24 Arsenic (As) mg/lit.28.14.2 25 Ammonium (NH4) mg/lit.47.596.2 26 Albuminoid mg/lit <.1 <.1 <.1 27 Nitrites (NO2) mg/lit.4.2 <.5 28 Nitrates (NO3) mg/lit 14.8.722.863 29 Sulfities (SO3) mg/lit.72.72 <.2 3 Sulfates (SO4) mg/lit 7.9 3.7 1.15 31 Chlorides (Cl) mg/lit 11.39 3.63 3.63 32 Phosphates (PO4) mg/lit <.2.23.14 33 Oxygen (O2) mg/lit 7.15 7.31 7.26 34 Carbon Dioxide (CO2) mg/lit.87 3.3 35 P-value as CaCO3 mg/lit <.2.242.138 36 M-Value as CaCO3 mg/lit 21.6 21.8 23.2 JICA Project for the Master Plan Study of T-33 August, 211

Figure 1 Location Map of Meteo-Hydrological Stations JICA Project for the Master Plan Study of F-1 August, 21

Daily Rainfall Records No. Station Name BMG ID HPPS2 ID 1969 197 1971 1972 1973 1974 1975 1976 1977 1978 1979 198 1981 1982 1983 1984 1985 1986 Year 1987 1988 1989 199 1991 1992 1993 1994 1995 1996 1997 1998 1999 2 21 22 23 24 25 26 27 28 Remarks 1 Segala 78 24-78- 2 Tarutung 84 24-84- 1954-3 Hutaraya 84C 24-84-3 1954-4 Barus 85 24-85- 1962-5 Siborong-borong 86 24-86- 1953-6 Dolok Sanggul 86A 24-86-1 1954-7 Gugur Balige 86B 24-86-2 8 Baligi-1 86D 24-86-4 9 Paguruan 9 24-9- 1 Salak 9C 24-9-3 1951-11 Sidikalang 91 24-91- 1951-12 Tiga Lingga 91B 24-91-2 1961-1966 Source: BMKG Jakarta Daily Runoff Records Year DPMA HPPS2 No. Station Name ID ID Remarks 1 Aek Sigeon - Pasar 1-178- Sirongit -1 178-2-1 17 years 2 A. Sibundong - 1-184- Dolog Sanggul -1 13 years 3 A. Silang - Marade 1-186- -1 2 years Source: Pusair Bandung 1969 197 1971 1972 1973 1974 1975 1976 1977 1978 1979 198 1981 1982 1983 1984 1985 1986 1987 1988 1989 199 1991 1992 1993 1994 1995 1996 1997 1998 1999 2 21 22 23 24 25 26 27 28 Evapolation Year No. Station Name 1969 197 1971 1972 1973 1974 1975 1976 1977 1978 1979 198 1981 1982 1983 1984 1985 1986 1987 1988 1989 199 1991 1992 1993 1994 1995 1996 1997 1998 1999 2 21 22 23 24 25 26 27 28 Remarks 1 Parapat 2 Gabe Hutaraja Source: Asahan 3 HEPP Construction Report, 27 Air Temparature BMG No. Station Name ID 1 Sibolga 214 Source: BMKG HPPS2 ID 1969 197 1971 1972 1973 1974 1975 1976 1977 1978 1979 198 1981 1982 1983 1984 1985 1986 Year 1987 1988 1989 199 1991 1992 1993 1994 1995 1996 1997 1998 1999 2 21 22 23 24 25 26 27 28 Remarks Relative Humidity BMG No. Station Name ID 1 Sibolga 214 Source: BMKG HPPS2 ID 1969 197 1971 1972 1973 1974 1975 1976 1977 1978 1979 198 1981 1982 1983 1984 1985 1986 Year 1987 1988 1989 199 1991 1992 1993 1994 1995 1996 1997 1998 1999 2 21 22 23 24 25 26 27 28 Remarks Sunshine Duration BMG No. Station Name ID 1 Sibolga 214 Source: BMKG HPPS2 ID 1969 197 1971 1972 1973 1974 1975 1976 1977 1978 1979 198 1981 1982 1983 1984 1985 1986 Year 1987 1988 1989 199 1991 1992 1993 1994 1995 1996 1997 1998 1999 2 21 22 23 24 25 26 27 28 Remarks Wind Velocity BMG No. Station Name ID 1 Sibolga 214 Source: BMKG HPPS2 ID 1969 197 1971 1972 1973 1974 1975 1976 1977 1978 1979 198 1981 1982 1983 1984 1985 1986 Year 1987 1988 1989 199 1991 1992 1993 1994 1995 1996 1997 1998 1999 2 21 22 23 24 25 26 27 28 Remarks : Complite Data : Incomplite Data Figure 2 Availability of Climatic Records JICA Project for the Master Plan Study of F-2 August, 21

Simanggo-2 Basin 478.3 km 2 A. Simanggo Simanggo-2 Intake Weir Figure 3 Catchment Area of Simanggo-2 Intake Weir based on 1:5, map A. Rambe JICA Project for the Master Plan Study of F-3 August, 211

Monthly Mean Air Temperature St. Sibolga Monthly Mean Relative Humidity St. Sibolga Temperature ( ) 27. 26.5 26. 25.5 25. 24.5 24. 23.5 23. 22.5 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month Humidity ( % ) 9. 88. 86. 84. 82. 8. 78. 76. 74. 72. 7. Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month Monthly Mean Sunshine Duration St. Sibolga Monthly Mean Wind Velocity St. Sibolga 7. 7. 6. 6. Duration ( % ) 5. 4. 3. 2. 1. Velocity ( m/s ) 5. 4. 3. 2. 1.. Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month. Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month Monthly Mean Evaporation St. Parapat Monthly Mean Evaporation St. Gabe Hutaraja 6. 6. Evaporation ( mm/day ) 5. 4. 3. 2. 1.. Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month Evaporation ( mm/day ) 5. 4. 3. 2. 1.. Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month Figure 4 Variations of Principal Climatic Data JICA Project for the Master Plan Study of F-4 August, 211

Figure 5 Organization Cart of BWS JICA Project for the Master Plan Study of F-5 August, 211

Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1982 Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1983 Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1984 Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec Figure 6 Daily Runoff Hydrograph at Pasar Sironggit Station (1/5) 1985 JICA Project for the Master Plan Study of F-6 August, 211

Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1986 Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1987 Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1991 Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec Figure 7 Daily Runoff Hydrograph at Pasar Sironggit Station (2/5) 1992 JICA Project for the Master Plan Study of F-7 August, 211

Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1993 Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1994 Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1995 Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec Figure 8 Daily Runoff Hydrograph at Pasar Sironggit Station (3/5) 1996 JICA Project for the Master Plan Study of F-8 August, 211

Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1997 Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1998 Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 21 Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec Figure 9 Daily Runoff Hydrograph at Pasar Sironggit Station (4/5) 27 JICA Project for the Master Plan Study of F-9 August, 211

Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 28 Figure 1 Daily Runoff Hydrograph at Pasar Sironggit Station (5/5) JICA Project for the Master Plan Study of F-1 August, 211

Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1991 Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1992 Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1993 Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec Figure 11 Daily Runoff Hydrograph at Dolog Sanggul Station (1/4) 1994 JICA Project for the Master Plan Study of F-11 August, 211

Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1995 Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1996 Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1997 Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec Figure 12 Daily Runoff Hydrograph at Dolog Sanggul Station (2/4) 1998 JICA Project for the Master Plan Study of F-12 August, 211

Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1999 Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 21 Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 26 Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec Figure 13 Daily Runoff Hydrograph at Dolog Sanggul Station (3/4) 27 JICA Project for the Master Plan Study of F-13 August, 211

Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 28 Figure 14 Daily Runoff Hydrograph at Dolog Sanggul Station (4/4) JICA Project for the Master Plan Study of F-14 August, 211

Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1983 Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1984 Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1985 Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec Figure 15 Daily Runoff Hydrograph at Marade Station (1/5) 1986 JICA Project for the Master Plan Study of F-15 August, 211

Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1987 Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1988 Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1989 Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec Figure 16 Daily Runoff Hydrograph at Marade Station (2/5) 199 JICA Project for the Master Plan Study of F-16 August, 211

Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1991 Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1993 Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1994 Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec Figure 17 Daily Runoff Hydrograph at Marade Station (3/5) 1995 JICA Project for the Master Plan Study of F-17 August, 211

Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1996 Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1997 Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 1998 Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec Figure 18 Daily Runoff Hydrograph at Marade Station (4/5) 21 JICA Project for the Master Plan Study of F-18 August, 211

Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 25 Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 26 Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec 27 Discharge (m3/s) 9 8 7 6 5 4 3 2 1 1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec Figure 19 Daily Runoff Hydrograph at Marade Station (5/5) 28 JICA Project for the Master Plan Study of F-19 August, 211

Accumulation of annual rainfall at Tarutung station 5, 4, 3, 2, 1, - 1977 y =.8683x 1998-1, 2, 3, 4, 5, Accumulation of average annual rainfall at surrounding stations Accumulation of annual rainfall at Hutaraya station 5, 4, 3, 2, 1, - 1977 y =.9766x 1998-1, 2, 3, 4, 5, Accumulation of average annual rainfall at surrounding stations Accumulation of annual rainfall at Siborongborong station 5, 4, 3, 2, 1, - 1977 y = 1.5594x 1998-1, 2, 3, 4, 5, Accumulation of average annual rainfall at surrounding stations Accumulation of annual rainfall at Dolok Sanggul station 5, 4, 3, 2, 1, - 1977 y =.9199x 1998-1, 2, 3, 4, 5, Accumulation of average annual rainfall at surrounding stations 5, Accumulation of annual rainfall at Gugur Balige station 4, 3, 2, 1, - 1977 y =.8611x 1998-1, 2, 3, 4, 5, Accumulation of average annual rainfall at surrounding stations Figure 2 Double Mass Curves of Rainfall Records JICA Project for the Master Plan Study of F-2 August, 211

2,5 Annual Runoff Depth (mm) 2, 1,5 1, 5 mm 7mm 15mm - - 5 1, 1,5 2, 2,5 3, 3,5 4, Annual Basin Mean Rainfall (mm) Figure 21 Relationship between Annual Basin Mean Rainfall and Annual Runoff Depth at Pasar Sironggit AWLR Station 4,5 4, mm Annual Runoff Depth (mm) 3,5 3, 2,5 2, 1,5 7 mm 1,5 mm 1, 5 5 1, 1,5 2, 2,5 3, 3,5 4, 4,5 Annual Basin Mean Rainfall (mm) Figure 22 Relationship between Annual Basin Mean Rainfall and Annual Runoff Depth of Various River Basins in Sumatra JICA Project for the Master Plan Study of F-21 August, 211

Figure 23 Concept of Composite Tank Model JICA Project for the Master Plan Study of F-22 August, 211

1977/1 1978/1 1979/1 198/1 1981/1 1982/1 1983/1 1984/1 1985/1 1986/1 1987/1 1988/1 1989/1 199/1 1991/1 1992/1 1993/1 1994/1 1995/1 1996/1 1997/1 1998/1 9 8 7 6 5 4 3 2 1 Rain Observed Runoff Simulated Runoff 1 2 3 4 5 6 7 8 9 Figure 24 Simulated Long-term Daily Runoff at Pasar Sironggit AWLR Station JICA Project for the Master Plan Study of F-23 August, 211

% Observed and Simulated Runoff (%) % 223. 5% 27.7 1% 21.48 15% 18.9 2% 15.8 25% 14.1 3% 12.76 35% 11.65 4% 1.79 45% 1. 5% 9.26 55% 8.69 6% 8.5 65% 7.53 7% 7.2 75% 6.45 8% 5.85 85% 5.3 9% 5.1 95% 4.39 %.82 Average 12.23 5 45 4 35 3 25 2 15 1 5 Observed and Simulated Runoff (Pasar Sirongit).1.2.3.4.5.6.7.8.9 1 Discharge (m3/s) Figure 25 Flow Duration Curve of Estimated Daily Runoff at Pasar Sironggit AWLR Station JICA Project for the Master Plan Study of F-24 August, 211

Figure 26 Isohyetal Map of Annual Rainfall around Simanggo River Basin JICA Project for the Master Plan Study of F-25 August, 211

% Estimated Runoff (%) % 457.6 5% 56.77 1% 44.3 15% 37.8 2% 32.39 25% 28.9 3% 26.15 35% 23.88 4% 22.12 45% 2.5 5% 18.98 55% 17.81 6% 16.5 65% 15.43 7% 14.39 75% 13.22 8% 11.99 85% 1.86 9% 1.27 95% 9. % 1.68 Average 25.8 5 45 4 35 3 25 2 15 1 5 Simanggo-2 Intake Weir Site Estimated Runoff.1.2.3.4.5.6.7.8.9 1 Discharge (m3/s) Figure 27 Flow Duration Curve of Estimated Daily Runoff at Simanggo-2 Intake Weir JICA Project for the Master Plan Study of F-26 August, 211

Figure 28 Location Map of Water Level Observation and Discharge Measurement JICA Project for the Master Plan Study of F-27 August, 211

3.5 3. Maximum Water Level 3.35m 21/1/1 18: 2.5 Water Level (m) 2. 1.5 1. Average Water Level.58m.5 Minimum Water Level.3m 21/1/22. 21/9/15 21/9/3 21/1/15 21/1/3 21/11/14 21/11/29 21/12/14 21/12/29 5 45 Maximum Runoff 463.87 m3/s 21/1/1 18: 4 Runoff (m3/s) 35 3 25 2 Estimated Runoff with H-Q Rating Curve Discharge Measurement 15 Minimum Runoff 12.19 m3/s 21/1/22 Average Runoff 31.55 m3/s 5 21/9/15 21/9/3 21/1/15 21/1/3 21/11/14 21/11/29 21/12/14 21/12/29 Figure 29 Result of Water Level Observation and Hydrograph Calculated with H-Q Rating Curve JICA Project for the Master Plan Study of F-28 August, 211

1.4 Q=35.1(H+.29)^2 1.2 1. Water Level (m).8.6.4.2. Observation H-Q Rating Curve 2 4 6 8 Discharge (m3/s) Figure 3 H-Q Rating Curve JICA Project for the Master Plan Study of F-29 August, 211

Upstream Basin 29.6 km 2 Water Level Gauge Simanggo-2 Basin 478.3 km 2 A. Simanggo Downstream Basin 187.7 km 2 Figure 31 Catchment Area of Water Level Gauge installed by the Field Investigation JICA Project for the Master Plan Study of F-3 August, 211

Figure 32 Accumulated Hourly Rainfall Pattern around Simanggo River Basin and Design Hyetograph JICA Project for the Master Plan Study of F-31 August, 211

1..9.8 Area Reduction Factor.7.6.5.4.3.2.1. 5 15 2 Point Rainfall Depth (mm) Figure 33 Area Reduction Factor for Simanggo River Basin JICA Project for the Master Plan Study of F-32 August, 211

Figure 34 Frequency Curves of Probable Daily Rainfall at Paguruan station JICA Project for the Master Plan Study of F-33 August, 211

11 15 Length of record (years) 1 15 2 95 3 5 X n adjustment factor (%) 9 85 8 75 7.7.75.8.85.9.95 1 X n-m / X n Source : Operational Hydrology Report No. 1 Manual for Estimation of Probable Maximum Precipitation Page 97, World Meteorological Organization, 1973 Figure 35 Adjustment of Mean of Annual Series for Maximum Observed Rainfall JICA Project for the Master Plan Study of F-34 August, 211

12 11 9 Length of record (years) 1 15 3 5 S n adjustment factor (%) 8 7 6 5 4 3 2.2.3.4.5.6.7.8.9 1 1.1 S n-m / S n Source : Operational Hydrology Report No. 1 Manual for Estimation of Probable Maximum Precipitation Page 98, World Meteorological Organization, 1973 Figure 36 Adjustment of Standard Deviation of Annual Series for Maximum Observed Rainfall JICA Project for the Master Plan Study of F-35 August, 211

13 125 12 Adjustment Factor (%) 115 11 Standard Deviation 15 Mean 1 15 2 25 3 35 4 45 5 55 Length of Record (years) Source : Operational Hydrology Report No. 1 Manual for Estimation of Probable Maximum Precipitation Page 99, World Meteorological Organization, 1973 Figure 37 Adjustment of Mean and Standard Deviation of Annual Series for Length of Record JICA Project for the Master Plan Study of F-36 August, 211

2 15 K m 1 5 min 6 hours Duration 24 hours 1 hour 5 5 15 2 25 3 35 4 45 5 55 6 Mean Annual Rainfall (mm) Figure 38 Km as a Function of Rainfall Duration and Mean of Annual Series 114 112 11 Adjustment Factor 18 16 14 12 98 4 8 12 16 2 24 Number of Observational Units Source : Operational Hydrology Report No. 1 Manual for Estimation of Probable Maximum Precipitation Pages 96 &, World Meteorological Organization, 1973 Figure 39 Adjustment of Fixed Interval Precipitation Amounts for Number of Observational Units within the Interval JICA Project for the Master Plan Study of F-37 August, 211

1,8 Slope 1,6 1,4 Height (m) 1,2 1, 8 6 4 1.6hr 1.4hr 1.7hr - 5, 1, 15, 2, 25, 3, 35, 4, Distance (m) Figure 4 Slope of Simanggo River 35. 3. Discharge (m3/s) 25. 2. 15. 1. 5.. 1 2 3 4 5 6 7 8 9 1 11 12 13 14 Time (hour) Figure 41 SCS Unit Hydrograph at Simanggo-2 Intake Weir JICA Project for the Master Plan Study of F-38 August, 211

5 45 4 35 3 25 2 15 1 5 Daily Runoff Record at Pasar Sironggit Station Dischatge (m3/s) 1991/1/1 1991/3/1 1991/5/1 1991/7/1 1991/9/1 1991/11/1 1992/1/1 1992/3/1 1992/5/1 1992/7/1 1992/9/1 1992/11/1 1993/1/1 1993/3/1 1993/5/1 1993/7/1 1993/9/1 1993/11/1 Figure 42 Daily Runoff Hydrograph at Pasar Sironggit AWLR Station JICA Project for the Master Plan Study of F-39 August, 211

4 35 3 25 2 15 5 1 2 3 4 5 6 7 8 9 1 11 12 13 14 15 16 17 18 19 2 21 22 23 24 25 26 2728 29 3 31 32 33 34 35 36 37 Time (hour) PMF 4 2 15 8 5 3 2 1 5 3 2 Discharge (m3/s) Figure 43 Probable Flood Hydrographs at Simanggo-2 Intake Weir JICA Project for the Master Plan Study of F-4 August, 211

, Probable Maximum Flood Flood Peak Discharge (m3/s) 1, 1, PMF C=79 Simanggo-2 PMF 1 1 1, 1,, Catchment Area (km2) 1, Return Period = 2 year Flood Peak Discharge (m3/s) 1, 2 C=22 Simanggo-2 2 1 1 1, 1,, Catchment Area (km2) Figure 44 Relationship between Probable Peak Discharge and Catchment Area in Sumatra (1/3) JICA Project for the Master Plan Study of F-41 August, 211

1, Return Period = year Flood Peak Discharge (m3/s) 1, C=21 Simanggo-2 1 1 1, 1,, Catchment Area (km2) 1, Return Period = 2 year Flood Peak Discharge (m3/s) 1, 2 C=17 Simanggo-2 2 1 1 1, 1,, Catchment Area (km2) Figure 45 Relationship between Probable Peak Discharge and Catchment Area in Sumatra (2/3) JICA Project for the Master Plan Study of F-42 August, 211

1, Return Period = 2 year Flood Peak Discharge (m3/s) 1, 2 C=1 Simanggo-2 2 1 1 1, 1,, Catchment Area (km2) Figure 46 Relationship between Probable Peak Discharge and Catchment Area in Sumatra (3/3) JICA Project for the Master Plan Study of F-43 August, 211

Figure 47 Catchment Area of Regulating Pond based on 1:1, Map JICA Project for the Master Plan Study of F-44 August, 211

Simanggo-2 Basin 478.3 km 2 Rambe Basin 422.8 km 2 Sub Basin 25.9 km 2 A. Simanggo A. Rambe Simanggo-2 Intake Weir Simanggo-2 Power House Sub Basin 9.1 km 2 Figure 48 Catchment Area of Power House based on 1:25, Map JICA Project for the Master Plan Study of F-45 August, 211