Climate Change Impacts on Water Resources in River Basins of India A. K. Gosain Professor & Head, Civil Engineering Department Indian Institute of Technology Delhi
Water resource development Shall always remain one of the preferred options to cater to vagaries on account of Inherent Spatial variability and Temporal variability of this resource Tuesday, June 07, 2011 2
Possible development options Surface water Interventions different scales Big projects Reservoir or runoff the river scheme Medium & Minor schemes Watershed level check dams Ground water exploitation Shallow wells Tuesday, June 07, 2011 3 Deep tubewells
Implications of interventions Every intervention big or small has associated impact Integrated Watershed philosophy was the scientific option suggested to judiciously tackle possible implications Watershed being the natural system where water balance can be resolved and thereby impacts of the manmade interferences can be quantified Integrated implies consideration of all possible usage and interest of all stake holders Tuesday, June 07, 2011 4
Extent of interventions It is true that the enhanced water requirement shall warrant enhanced level of interventions But in our country, of late there seems to be a competition of sorts between various ministries and departments for unabated, at times unwarranted development especially at the local level Tuesday, June 07, 2011 5
Conventional departments and ministries implementing interventions Irrigation/ water resources (Major, medium, minor) Hydropower (Mega to small) Rural development -Watershed programme Forestry - Watershed programme Agriculture & horticulture - Watershed programme Municipalities - Water supply and sanitation Tuesday, June 07, 2011 6
India s National Communications to UNFCCC Coordinated by MoEF The first communication was made in 2004 It was a multidisciplinary effort Work on water Resources was entrusted to IIT Delhi Second National Communication has just started and IIT Delhi is again leading the Water Resources work
SWAT Model Components Features Physically based Distributed model Continuous time model (long term yield model) Uses readily available data Suitable for long term impact studies
River Basins Modeled
Annual mean water balance for Control and GHG climate scenarios in different river basins Value (mm) Trends in Waterbalance Components (Control and GHG Climate Scenarios) 1800 1600 1400 1200 1000 800 600 400 200 0 Cauvery Brahmani Godavari Krishna Luni Mahanadi Mahi Narmada Pennar Tapi Ganga Sabarmati Rain (Control) Rain (GHG) Runoff (Control) Runoff (GHG) AET (Control) AET (GHG)
Mahanadi Brahmani Ganga Godavari Cauvery Narmada Tapi Krishna Pennar Mahi Luni Sabarmati Change from Current to GHG Scenario (% Percent change in mean annual water balance for Control and GHG climate scenarios 40 20 Rainfall Runoff ET 0-20 -40-60 -80 River Basins
1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2041 2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 2059 2060 Value (mm) Value (mm) Himalayan River Systems: Ganga Basin 1800 1600 1400 Control Scenario Precipitation ET Water Yield 1800 1600 1400 GHG Scenario Precipitation ET Water Yield 1200 1200 1000 1000 800 800 600 600 400 400 200 200 0 0 Year Year
Model Outputs Analaysed Detailed outputs include all the water balance component at spatial and temporal scales which are analysed for Changes in magnitude and frequency of flood peaks Severity of droughts Changes in flow patterns Changes in groundwater recharge
Vulnerability Assessment Procedure Palmer Drought Severity Index (PDSI) widely used index incorporates information on rainfall, land-use, and soil properties in a lumped manner PDSI value below 0.0 indicates the beginning of drought situation A value below -3.0 as sever drought condition Soil Moisture Index to monitor drought severity using SWAT output to incorporate the spatial variability
Total Drought Events (Weeks) Number of drought weeks in Sub-basins of Ganga for Current & GHG scenarios 350 300 Total Drought Event (control) Total Drought Event (GHG) 250 200 150 100 50 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 Subbasins
Flow (Cumecs) Flow Duration Curve for Ganga River for Control and GHG scenarios Ganga River - Flow Duration Curve 100000 10000 1000 100 10 1 0.1 0.01 0.001 0.0001 0.00001 Dependa ble Flow (cumecs) Control GHG 0 10 20 30 40 50 60 70 80 90 100 % of time flow equal or exceeded 25% 50% 75% 90% Control 4648 716 12.88 0.4394 GHG Scenario 3649 754.5 50.5 5.323
The major concern Evaluate the implications of climate change by incorporating the baseline Adaptation shall require enhanced level of interventions through line departments A common framework is required to provide an integrated information base Procedures for scenario generation and evaluation Tuesday, June 07, 2011 17
Conclusions Integrated water resource development and management requires a common framework Creation of NDSI complaint spatial databases is essential for sustainable use of water resources and associated development and adaptation for climate change impacts http://gisserver.civil.iitd.ac.in/natcom/ Tuesday, June 07, 2011 22
Thank you