Climate Change Impacts on Glacial Lakes and Glacierized Basins in Nepal and Implications for Water Resources Suresh R. Chalise 1, Madan Lall Shrestha 2, Om Ratna Bajracharya 2 & Arun Bhakta Shrestha 2 1HKH-FRIEND; 2 DHM, NEPAL
1. Introduction 2. ClimateWarmingImpactsonGlacialLakesofNepal LakesofNepal 3. HydrologicalImpactsofClimateWarming Warming 4. Implicationsfor Water Resources 5. Conclusion
1. INTRODUCTION
HKH Region Ice Reserve 3734KM 3 ; 18,115 Glaciers
WORLD ICE Source: GLIMS Global Glacier Recession files
HKH: IMPORTANT FRESH WATER RESEVE SIX MAJOR RIVER BASINS OF HKH Source: ICIMOD
Accelerated Retreat of Glaciers in Nepal, during 1990s Retreat o f Glacier AX0 10 at Shoro ng 14 12 10 8 6 4 2 0 1978-89 1989-99 1999-2004 Source: GEN & DHM Source: DHM Retreat of Glacier AX010 at Shorong Time period
Rapid Growth of Glacial Lakes in Nepal, since1960s 0. 050 0. 040 0. 030 0. 020 0. 010 0. 000 Source: DHM Development of Tsho Rolpa Glacier Lake T s ho-r olpa Gla c ie r La ke Ar e a Inc r e a s e 1959-68 1968-79 1979-90 1990- T ime P e r iod 2002
2. Climate Warming Impacts On Glacial Lakes of Nepal
Glacial Lakes: All over HKH Glacier/Glacial lakes Inventory available for Nepal and Bhutan Nepal: Glaciers 3252; Glacial Lakes 2323 of which 20 potentially dangerous
Nepal Glacial Lakes Moraine- Dammed; Unstable. August 4, 1985: Bursting of Dig Tsho Glacial Lake (Mt Everest Region). Lasted only 5 hrs. Damage up to 40 Km downstream destroying Human Life, Settlements, Bridges and a near complete Hydropower Plant 12 Km downstream. Starting Point for Scientific Investigation of Glacial Lake Outburst Floods (GLOFs) in HKH
Greater Warming Impact in the east All recent GLOF Events (21)/All Potentially Dangerous Glacial Lakes (20): East of Pokhara Location map of high altitude stations (Langtang, Tsho Rolpa and Khumbu) and potentially dangerous glacial lakes in Nepal. Data source: ICIMOD/UNEP (2001b) and DHM
Higher Warming at Higher Altitudes 30 29 28 27 Warming Trends & Evidences: 0.00 82 84 86 88 Longitude ( o E) 1971-1994: 0.06-0.12 C/yr after 1977 in the mid mountains and Himalayan regions (Shrestha et al 1999) 1976-1996: 0.1C/yr average annual temp at >1800 m (Rees & Collins,2004) -0.09-0.05 0.00 0.05 0.09 Color Coding of temperature trends ( o C year -1 ) Warming at higher elev. In Nepal ~3 times the IPCC Predictions (+0.03 C/yr)
GLOF Mitigation Measures Rapid Growth of Large Glacial Lakes in East Nepal since the 60s (e.g. Tsho Rolpa; Imja) Tsho Rolpa (4580m): Total cost including Structure, Warming System and Power Plant (15 kw) > US$4 million
Tsho Rolpa Discharge Analysis No visible diference in discharge between the two periods (before/after construction) Average Monthly Mean Dischgarge (high flow period, May-October) of Tsho Rolpa: Higher during 2000-04 than 1993-96 : Intensification in Melting & Increasing Risk of GLOF DHM 1993 1995 1997 1999 2001 2003 2005 Yea rs Fig. 2 Discharge from Tsho Rolpa Glacial Lake. 12 2000 to 2004 10 1993 to 1996 D is c h a r g e ( m 3 s -1 ) 8 6 4 2 0 May Jun Jul Aug Sep Oct Months Fig. 3 Average monthly mean discharge at Tsho Rolpa.
3. HYDROLOGICAL IMPACTS OF CLIMATE WARMING
Implications for Dry Season (March-June) Flows High Altitude Temperature and Discharge Analyses: Langtang 3, 900 m & Khumbu (Imja) 4,200m 7 Discharge 6 ) 1 s 6 4 T - emp 3 (m e ge a r a r u t re s ch 5 2 D i ( o C Temperature ) March-June Annual 4 0 1986 1988 1990 1992 1994 1996 1998 2000 Year Temperature and discharge at Langtang station
High Altitude Temperature and Discharge Analyses: Langtang 3, 900 m & Khumbu (Imja) 4,200m (contd) Discharge (m 3 s -1 ) 16 14 12 10 8 6 4 Langtang y = 2.9257 * e 0.14164x R 2 = 0.67 8 7 6 5 4 3 2 Khumbu y = 2.1671 * e 0.14527x R 2 = 0.53 2 1 0-15 -10-5 0 5 10 15 Temperature ( o C) 0-15 -10-5 0 5 10 Temperature ( o C) Relationship between temperature and dry season discharge at Langtang (left) and Khumbu (Imja Khola, right) Langtang: Distinct Trend in Warming and Increasing Discharge. Khumbu/Imja Khola: No distinct trend in Warming or Discharge Dry Period Temperature and Discharge at both basins show strong relationship
4. IMPLICATIONS FOR WATER RESOURCES: NEPAL & HKH REGION
Two Major Implications for Nepal (15% Snow Cover) Increasing Warming Trend at Higher Elevations > Increased Melting of Glacial Lakes and Glacierized Basins > Increase in GLOF and Flash Flood Events > Adverse Impact on Hydropower Development: Feasible 42,000 MW ; Exportable 22,000 MW. Shrinking Ice Reserve (Resource Base) > Sharp Decrease in Dry Season Flow > Adverse impact on Water supply for Irrigation (Food Production), Industrial Development and Human Consumption during Dry Season (Dry Season Flow 10-20 times < High Flows)
Implications for the Regional Countries Nepal 13% of Ganga Basin Area wise. All Nepalese Rivers drain into Ganga and Contribute 47% of Annual discharge (382,000 million m 3 ) of Ganga at Farakka. Decreased Flows in Nepalese Rivers > Adverse Impact on Ganga dependent Areas In Bangladesh as Nepalese Rivers contribute 75% of the dry season (March May) Flow of the Ganga. Likely Impact on India s River Linking Project (Linking Ganga and Brahmaputra with Peninsular Rivers)
5. CONCLUSION
Climate Warming and Increasing Deglaciation will further Intensify the Too Much (during short wet period) or Too Little (during long dry period) situation. Coping Strategy Needs to be developed Urgent Need: Develop a) Scientific Database for Quantitative Assessment of Climate Warming Impacts on Snow and Ice Reserve; b) Scientific Understanding of Growth Mechanism of Glacial Lakes; c) National & Regional Strategies to Cope and Mitigate GLOF Events. Contd
HKH Countries should share Scientific Data, Knowledge and Skill on Managing Potentially Dangerous Glacial Lakes. Support Collaborative Scientific Research: National, Regional and International (Past Contributions of ICSI/IAHS & HKH-FRIEND) Challenge Ahead: Meeting Increasing Water Demands during the long Dry Period. Adverse Impact on Hydropower Development, Food Production, Human Health and Economic Development.
Thank You
III. Vulnerabilities and Potential Impacts of Climate Change Climate Change additional external stress for people and ecological systems Ecological and Socio-economic Systems are successive to the magnitude and the rate of climate change Diversity in physical environment does not allow broad generalisation. Climate change impact on soil erosion and sedimentation will be significant: Effect on the life of the reservoirs. Increased severity and frequency of monsoonal storms and flooding in the Himalayas.
Transboundary Rivers Regional Cooperation : Imperatives of Nature to Save lives and Manage Floods Flood Disaster Mitigation/Early Warming Systems - Humanitarian Aspects: Reducing further miseries of the marginalised/ poor people
HKH-FRIEND: - 6 Research Groups (Database, Floods, Low Flow, Rainfall-Run-off, Water Quality, Snow & Glaciers) - Regional Hydrological Data Centre - 2 nd Steering Committee, April 2000 - WMO: HKH-HYCOS, Concept proposed
Location Map of Tsho Rolpa
Altitude: 4580 m, Area of the lake: 1.76 km2, Max. and Average depth: 142 m and 56 m, Lengh: : 3.5 km, Breadth: 0.5 km. Water volume in the Lake: 92.4 X106 m3
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Glaciers Mass-balance Rika Samba Glacier, Dhaulagiri
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