Glacial Lake Outburst Flood (GLOF) hazards in the Upper Indus basin

Transcription

1 Glacial Lake Outburst Flood (GLOF) hazards in the Upper Indus basin International Conference on Climate and environment change impacts on the Indus basin waters February 2016 Samjwal Ratna Bajracharya, Sudan Bikash Maharjan and Finu Shrestha International Centre for Integrated Mountain Development ICIMOD Kathmandu, Nepal

2 Contents Past glacial lake outburst floods in Indus basin Status and change of glaciers in Indus basin Status and change of glacial lakes in Indus basin Potentially dangerous glacial lakes in Indus basin Conclusions

3 GLOF events in Himalaya 57 GLOF events have been reported from the Himalayas. Tibet Autonomous Region, China 30, 10 GLOF events trans-boundary to Nepal 9 GLOF events trans-boundary to Bhutan Nepal - 14 GLOF events Bhutan - 13 GLOF (including Lemthang Tso GLOF in 28 June 2015)

4 Some devastating GLOF events in UIB A total of 57 destructive outburst floods have been recorded in the Upper Indus Basin (UIB) including at least 11 surges are of exceptional scale. Thirteen GLOFs recorded from 2001 to date Forty-four GLOFs recorded from 1826 to 2000

5 Destructive outburst floods in Upper Indus basin SN Year River System Glacier/Glacial Lake Damage description Chitral Chitral At Yarkun Last village, situated at about 9000ft, GLOF killed a large number of livestock, damaged many houses, agricultural land with crops and fruit & forest trees, when a big block of glacier fell onto the lake. In the same year another GLOF even occurred in Wasum village Yarkhun, but there was no damage to the habitation. In Brep village, GLOF damaged the main irrigation channel, hydropower, demolished 32 houses, and killed a large number of livestock Chitral In Snogar village, GLOF damaged agricultural land with crops, killed a large number of livestock and damaged many houses May-08 Hunza Gulkani and Passu, May-08 Hunza Gulkani and Passu, Damaging properties and infrastructure May-08 Hunza Gulkani and Passu Potao and wheat crops May-08 Hunza Gulkani and Passu Crop fields and trees Jun-08 Hunza Gulkani and Passu Infrastructure and properties Chitral Nine people were killed and 13 household displaced in Snogar village Booni Booni about 200 acres of private land and 4 bridges, water channels Govt School, Aga Khan School and Forest Office were damage Bindo Gol Glacier Bindo Gol Glacier Two human lives, damage to 10 houses, 13 water channels many fruit and forest trees and 5 bridges 56 Jul-13 Booni Booni 28 houses, almost all irrigation channels and crops were damaged. Many springs have dried out, a 500 ft deep ditch has formed due to landslide and about half a km slopping land near glacier is likely to slip down because of bank erosion Chitral In Roi village many houses were damaged

6 SN Year Glacier/River System Glacial lake Description Upper Shyok river Khumdan Major flood wave, Serious flooding a Upper Shyok river Khumdan Not serious b? Yashkuk Yaz Glacier Yashkuk Yaz Gl on Chapursan Trib. of Hunza River, devastating flood Sultan Chhussku Glacier Chong Khumdan GL No noticeable rise Kumdang Much less extent than Upper Shyok river Khumdan Small flood Ishkoman river serious floods in Gilgit area Khumdan b? Chungphar Glacier, Astor valley Tarshing GL local devastation a Upper Shyok ri ver Gol village innundated b Upper Shyok river Khumdan? Major flood wave, originally large rise at Attock Ishkoman ri ver Ice dam brust bringing serious flooding in Gilgit ? Upper Shyok river Khumdan Major flood wave Upper Shyok river Khumdan Major flood wave Shimshall river Ice dam brurst considerable devastation at Ganesh and Altit in Hunza valley a Shimshall river Glacial dam burst Shimshall valley b Ishkoman ri ver flood reached Gilgit on 6th July, 23 ft above summer flood level ? Upper Shyok river (?) Khumdan dam burst Rise 20 ft Kichik Khumdan Glacier Kichik, Khumdan Serious damage a Kichik Khumdan Glacier Khumdan Small flood b Karambar Glacier Karambar Minor flood wave: Considerable damage at Gilgit area c Khurdopin Glacier Khurdopin-Virjerab dam Shimshall valley; flood in Hunza valley; fllod wave 30 ft Khurdopin Glacier Khurdopin-Virjerab dam Shimshall valley; Askurdas, Tushot and Chamogah bridges washed awy 50 ft above highsummer flood in Hunza gorge Khurdopin Glacier Khurdopin-Virjerab dam Maximum rise at Bunji only 7 ft /20 Bindo Gol Glacier GLOF continued for 3 years and many people migrated from their homes b Chong Khumdan Glacier Chong Khumdan dam burst Minor flood damage at Attock; devastating flood a Kaz Yaz Glacier, U Hunza Besk-i-Yeng GL Serious floods of local extent. Massive sediment movement b Khurdopin Glacier Khurdopin dam burst Kilik river (U Hunza) Glacial dam burst local damage only Aug-29 Chong Khumdan Glacier, Upper Shyok River Chong Khumdan Estimated volume released was about m3 and peak discharge of 22,650 m3/s, which is considered as the largest discharges measured for the entire Upper Indus and at Attock 1,300 Km downstream with discharge greater than 15,000 m3/s Chong Khumdan Glacier Chong Khumdam Smaller than 1929, considerable erosion Aug-33 Chong Khumdan Glacier Chong Khumdan The death toll recorded was 2, Shimshal valley Bindo Gol Glacier GLOF washed away 5 houses, 10 flourmills, 12 water channels, and 10 bridges /74 Batura Removed a section of the Karakoram Highway embankment and destroyed a major bridge Pasu Balt Bare Several houses were took away and one important bridge and a long stretch of roadway was buried. 38 0/8/ houses and a school were washed away., Lake that cause Darkot and Barandos hazard, Kyagar Glacier Bindo Gol Glacier Damaged 3 houses, 13 water channels, 3 human lives including a boy and girl 41 25/7/1997 Hushe River tributary of Shyok River Kande upstream Lake that cause Kande hazard The debris- flow crossed the Gupis to Shandur Road and blocked the Ghizer River, creating a lake about 1.5 km in 6/8/1999 Charti Glacier at Ghizer river Khalti length, now known as Khankhui Lake. The duration of blockage is not known, but the flow over the debris lobe is still

7 Catastrophic GLOFs 1929 GLOF: GLOF devastation during the period of , out of which 1929 GLOF of Chong Kumdan Glacier in upper Shyok River was well monitored and recorded for over 1300 km downstream (Gunn, 1930, Mason et.al.1932). The estimated reservoir to have 1.1 million acre feet (x1233m 3 ) water drained in 48 hours indicating the water discharge of 800,000 cfs. 2008: Five GLOF events were reported during the first half of 2008 in the Gojal area of the Hunza valley and substantial damage to infrastructure and arable land was reported due to GLOF events in association with the Ghulkin and Passu glaciers. 2013: GLOF Disasters in Booni, Upper Chitral : In July 2013, 28 houses, almost all irrigation channels and crops were damaged. Moreover, many springs have dried out, a 500 ft deep ditch has formed due to landslide and about half a km slopping land near glacier is likely to slip down because of bank erosion. In past forests were sustainably managed by communities through the Gram System and rotation grazing (Sak) and control grazing (Sosari)

8 Impact of climate change Climate change, increased frequency and magnitude of associated extreme weather events, and shifts in monsoon patterns, especially at higher altitudes are playing a role in rapid glacier change, These changes impact the water availability and increased GLOF hazards It is critical to improve our understanding of the changes taking place in the Cryosphere

9 Status of Glaciers in the HKH basins Glacier Area in HKH: about 60,000Km 2 Glacier Cover in HKH: 1.43% Basins Number Area (km2) Amu Darya 3,277 2,566 Indus 18,495 21,193 Ganga 7,963 9,012 Brahmaputra 11,497 14,020 Irrawaddy Salween 2,113 1,352 Mekong Yangtze 1,661 1,660 Yellow Tarim 1,091 2,310 Interior 7,351 7,535 Total 54,252 60,054 Bajracharya et al. 2011

10 , , , , Glacier area (km2) 9, , Percentage (%) 14, ,192.7 Glacier Area percentage in HKH 25,000 20,000 Glacier area Glacier area percent , , ,

11 Elevation (masl) Area-Elevation (Hypsograph) 9,000 8,000 7,000 6,000 5,000 4,000 3,000 2,000 Indus Ganga Brahmaputra Glacier area (km 2 )

12 Debris Cover (DC) Area From the analysis of 32,000 km 2 glacier area (28,500 glaciers) Debris Cover in: Ganges % Brahmaputra % Indus - 9.3% HKH region - 9.7%

13 Glaciers in Indus basin Basins Glacier number Glacier area (sq km) Ice reserves (cu km) Kabul 1,601 1, U. Indus 11,413 15,062 2,174 Panjnad 5,481 4, Indus 18,495 21,193 2,697

14 Panjnad Upper Indus Kabul Summary of Glaciers in Indus basin SN Basin Sub Basin 1 Basin Area Highest Elev. Lowest Elev. Glacier area Ice reserves Glacier number (Km 2 ) (m) (m) (sq km) (cu km) Panjsh.-Ghorb AAN Kunar Swat Total Gilgit Hunza Shigar Shyok* Zanskar Shingo Astor Upper Indus* Total Jhelum Chenab Ravi Beas Sutlej* 1E Total

15 Glacier area loss from 1980 to 2010 (in 30 years) Nepal - 24% Bhutan - 23% Bajracharya et al., 2014 ICIMOD Bajracharya et al., 2014 AoG

16 Status of Glaciers in Jhelum Basin in 1980, 1990, 2000 and 2010 Area Loss (%) Year Glacier Number Highest Lowest Glacier Ice Elevation Elevation Diff Elv. Area Reserve (m) (m) (sq.km.) (cu.km.) to 2010 (in 30 years) Glacier number increased by 3.5% Glacier area decreased by 21.4%

17 Comparison of glacial lakes of 2005 and 2015 Upper Indus Basin 2005 Inventory 2015 Inventory Comparison of lakes Number Area (km 2 ) Number Area (km 2 ) Number Area_2005 (km 2 ) Area_2015 (km 2 ) Change Percent Per GL area change (km 2 ) Swat Chitral Gilgit Hunza Shigar Shyok Shingo Astor Jhelum Indus Total : Transverse Mercator Landsat images of 1999/ : Universal Transverse Mercator Landsat images of 2007/8

18 Potentially dangerous glacial lakes in Upper Indus basin Area change of Pot. GLOF Basin Number Max Change Min change Area changed Increase Decrease Astor Chitral Gilgit Hunza Indus Jhelum Shingo Swat Shyok Total

19 A. Valley lakes are disappearing 1 3

20 9 B. Glacier fed lakes are growing 8

21 C. Number of supraglacial lakes are increasing 2 7

22 D. Surging of glaciers may form blocked lakes

23 Conclusions Glacier area is decreasing (particularly in mountain glaciers) Number and area of Glacier fed lakes are increasing Valley and erosional lakes are decreasing Out of 51 potentially dangerous glacial lakes, area of 39 lakes are increasing Blocked lakes may form due to surging of glaciers GLOF risk may increase in addition to surging of glaciers

24 Thanks