CLIMATE CHANGE IMPACT AND VULNERABILITY OF SURFACE WATER. Prof. A. K. Gosian Indian Institute of Technology, Delhi

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1 CLIMATE CHANGE IMPACT AND VULNERABILITY OF SURFACE WATER Prof. A. K. Gosian Indian Institute of Technology, Delhi

NATCOM MoEF (IIT Delhi) Climate Change and its Impact on Water Resources of India Tools used Modelling: SWAT (Soil and Water Assessment Tool) GIS framework: acts as a pre-processor for the

2 NATCOM MoEF (IIT Delhi) Climate Change and its Impact on Water Resources of India Tools used Modelling: SWAT (Soil and Water Assessment Tool) GIS framework: acts as a pre-processor for the distributed modelling and for visualization of the outputs/results in terms of V & A Data used Digital Elevation Model: SRTM 90 m Land use: Global data, 1:2M USGS Soil: Global data, 1:5M FAO Drainage: 1:250,000 Weather: IPCC SRES A1B, Hadley Centre U.K. at a resolution of 0.44 X 0.44 latitude by longitude grid points obtained from IITM, Pune A1B IPCC SRES Climate Change scenario Q14 QUMP Baseline ( ), Near term ( ), End term ( ) Impacts Studied Impact on annual water availability Impact on seasonal water availability Impact on inter annual water availability Regional Variability of Water availability Extreme events Floods and Droughts

3 Hydrological model SWAT (Soil and Water Assessment Tool) Features Physically based Distributed model Continuous time model (long term yield model) Uses readily available data Used for long term impact studies

4 Hydrological Modelling Base layers

Percent change in mean annual water balance all the river systems exhibit increase in precipitation there is an associated increase in water yield for all the river systems under EC

Pennar show marginal decrease in precipitation under MC basins with reduction in precipitation show associated decrease in water yield decrease in water yield in Pennar basin is

5 Percent change in mean annual water balance all the river systems exhibit increase in precipitation there is an associated increase in water yield for all the river systems under EC majority of the river systems the ET has increased by more than 40% Majority of the river systems show increase in the precipitation at the basin level Only Brahmaputra, Cauvery and Pennar show marginal decrease in precipitation under MC basins with reduction in precipitation show associated decrease in water yield decrease in water yield in Pennar basin is more pronounced which may be on account of changes in the distribution of precipitation under MC appreciable increase (close to 10 %) in ET for Brahmputra, Indus and Luni river basins

6 Spatial and Temporal variation of mean annual Precipitation Mid Century increase (~10%) in Godavari, Indus, Krishna, Luni, Mahanadi, Mahi, Meghna, Narmada, Pennar, Sabarmati, Brahmani, Tapi marginal increase < 5%) in Baitarni, Ganga, Krishna, Subernrekha Marginal Decrease in Brahmaputra, Pennar, Cauvery End Century in Godavari, Indus, Mahanadi, Mahi, Meghna, Narmada, Pennar, Sabarmati, Brahmani, Tapi marginal increase < 5-10%) in Brahmaputra, Cauvery, Krishna, Luni, Pennar

7 Spatial and Temporal variation of mean annual Water Yield (availability) Mid Century increase (>10%) in Brahmani, Brahmaputra, Cauvery, Ganga, Godavari, Indus, Krishna, Luni, Mahanadi, Mahi, Meghna, Narmada, Pennar, Sabarmati, Subernrekha, Tapi marginal increase < 5%) in Baitarni, Krishna, Subernrekha Marginal Decrease in Brahmaputra, Cauvery, Pennar End Century Substantial increase in most basins (>20%) including Pennar Decrease Cauvery, Krishna

8 Spatial and Temporal variation of mean annual Evapo-transpiration Mid Century increase in most basins Marginal Decrease in Pennar, Cauvery, Sabarmati, Mahi, Godavari End Century Substantial increase in most basins (5 to10%

9 Change in Long-term annual Sediment Load

10 Vulnerability Assessment Drought & Flood Soil Moisture Index to monitor drought severity focuses on the agricultural drought where severity implies cumulative water deficiency weekly information has been derived using daily SWAT outputs to incorporate the spatial variability Daily outflow discharge taken from the SWAT output Maximum daily peak discharge has been identified for each year and for each sub-basin analysis performed to identify those basins where flooding conditions may deteriorate in the GHG scenario

11 Change in Drought Weeks Mid Century increase in the moderate drought development (Scale 1) for Krishna, Narmada, Pennar, Cauvery and Brahmini basins which have either predicted decrease in precipitation or have enhanced level of evapotranspiration moderate to extreme drought severity (Scale2) increase in (5-20%) Baitarni, Sabarmati, Mahi and Ganga for many areas despite the overall increase in precipitation. End Century The situation of moderate drought (Scale 1) is expected to improve for almost all the river systems but for Tapi river system which show about 5% increase in drought weeks for moderate to extreme droughts (Scale 2) does not appreciably improve much under EC scenario despite the increase in precipitation

12 Change in Extreme Flows majority of river basins show an increase in the flooding varying between 10 to over 50% of the existing magnitudes. There are very few sub-basins of Ganga, Brhmaputra, Krishna, Cauvery and Pennar that show some decrease in the peak flow magnitudes

13 Uncertainties Uncertainties in Climate Simulation Assumptions and Coarseness of the Data Landuse has been coarse detailed data on the agricultural land use and the cropping pattern has not been used Soil type and profile has also been scanty Water bodies including reservoirs were not incorporated due to lack of data on their capacities and the operation rules

14 HighNoon EU project to assess the impact of Himalayan glaciers retreat possible changes of the Indian summer monsoon on the spatial and temporal distribution of water resources in Northern India to provide recommendations for appropriate and efficient response strategies that strengthen the cause for adaptation to hydrological extreme events.

15 jan-69 mei-70 sep-71 jan-73 mei-74 sep-75 jan-77 mei-78 sep-79 jan-81 mei-82 sep-83 jan-85 mei-86 sep-87 jan-89 mei-90 sep-91 jan-93 Stream Discharge (cumecs) Month-Year Chisapani - Nepal DevGhat - Nepal BeniGhat/Chisapani 104 FLOW_OUTcms jan-89 mei-90 sep-91 jan-93 jan-69 mei-70 sep-71 jan-73 mei-74 sep-75 jan-77 mei-78 sep-79 jan-81 mei-82 sep-83 jan-85 mei-86 sep-87 Stream Discharge (cumecs) 2500 Month-Year Devghat 140 FLOW_OUTcms Observed Vs. Simulated Time Series Plots jan-76 aug-76 mrt-77 okt-77 mei-78 dec-78 jul-79 feb-80 sep-80 apr-81 nov-81 jun-82 jan-83 aug-83 mrt-84 okt-84 mei-85 dec-85 jul-86 Stream Discharge (cumecs) Turkeghat - Nepal Month-Year Turkeghat 121 FLOW_OUTcms

16 Ganga Basin Hydrological Modelling SWAT Outputs

17 Average Monthly Snow Melt Runoff (mm) snowmeltrunoff= runoff * melt/(melt+rain)

18 Simulation using PRECIS

19 End Century

20 Needs and Gaps A common framework is required to provide integration across Scales (interconnections of watersheds & river basin) and Sectors Integrated water resource development and management framework is required to be adopted Shall provide mechanism to evaluate the interventions through simulation to Provide scientific backup to development User-friendly integrated models to explore consequences of alternative policy actions and of likely climate change scenarios Address the sustainability issue effectively under present and future conditions Creating a good baseline

21 Continued Data sharing of water resources for proper understanding of the hydrological systems Comprehensive water data base in public domain and assessment of climate change on Water Resources Knowledge management for coordinating information exchange among agencies and stakeholders Synthesized Information dissemination Capacity building uptake of research in sectoral departments interdisciplinary approach and collaboration among researchers in the region except in a few areas Link biophysical and socioeconomic models Capturing Land use changes High resolution RCM (space, time, number)

22 Thank You

AN INTEGRATED FRAMEWORK FOR EFFECTIVE ADAPTATION TO CLIMATE CHANGE IMPACTS ON WATER RESOURCES

AN INTEGRATED FRAMEWORK FOR EFFECTIVE ADAPTATION TO CLIMATE CHANGE IMPACTS ON WATER RESOURCES A. K. Gosain, Professor & Head Civil Engineering Department Indian Institute of Technology Delhi: gosain@civil.iitd.ac.in