1. Indo-UK Programme on Climate Change Impacts in India : Delhi Workshop, Sep. 5-6, 2002 Impacts of Climate Change on Water Resources G.B. Pant INDIAN INSTITUTE OF TROPICAL METEOROLOGY Pune

2. Indo-UK Programme on Climate Change Impacts in India : Delhi Workshop, Sep. 5-6, 2002 OUTLINE Objectives Objectives Research Tasks Research Tasks Indian rainfall variability Indian rainfall variability Baseline precipitation analysis Baseline precipitation analysis Precipitation climatology of major river basins Precipitation climatology of major river basins Spatio-temporal variability of precipitation over major river basins Spatio-temporal variability of precipitation over major river basins Evaluation of HadRM2 simulations of precipitation over major river basins Evaluation of HadRM2 simulations of precipitation over major river basins

3. Indo-UK Programme on Climate Change Impacts in India : Delhi Workshop, Sep. 5-6, 2002 Objectives Analysis of spatio-temporal variability of precipitation over major river basins of India Analysis of spatio-temporal variability of precipitation over major river basins of India Study of past changes in water availability and their sensitivity to climate variability and land-use/land- cover changes Study of past changes in water availability and their sensitivity to climate variability and land-use/land- cover changes Evaluation of regional climate model simulations of precipitation Evaluation of regional climate model simulations of precipitation Study of past changes in water quality Study of past changes in water quality Development of future scenarios for water availability and quality under different climate change scenarios Development of future scenarios for water availability and quality under different climate change scenarios

4. Indo-UK Programme on Climate Change Impacts in India : Delhi Workshop, Sep. 5-6, 2002 Research Tasks Identification of target river basins Identification of target river basins Baseline precipitation analysis: Precipitation climatology of major river basins; Spatio-temporal variability of precipitation Baseline precipitation analysis: Precipitation climatology of major river basins; Spatio-temporal variability of precipitation Evaluation of HadRM2 simulations of monthly/daily precipitation over major river basins Evaluation of HadRM2 simulations of monthly/daily precipitation over major river basins Case studies of past changes in water availability and quality in relation to climate and land-use/land-cover changes Case studies of past changes in water availability and quality in relation to climate and land-use/land-cover changes Hydrometeorological analysis of HadRM2 simulations for major river basins Hydrometeorological analysis of HadRM2 simulations for major river basins Water availability scenarios for major river basins including the scenarios for the impacts of land use and cover Water availability scenarios for major river basins including the scenarios for the impacts of land use and cover Identification of critical areas and frequency/impacts of extreme events Identification of critical areas and frequency/impacts of extreme events

5. Indo-UK Programme on Climate Change Impacts in India : Delhi Workshop, Sep. 5-6, 2002 Mean Rainfall Patterns Data Source: CMAP (1979-2000) Summer Monsoon (mm/season) Annual (mm/year)

6. Indo-UK Programme on Climate Change Impacts in India : Delhi Workshop, Sep. 5-6, 2002 Indian Summer Monsoon Contribution to Annual Rainfall and its Variability Data Source : CMAP (1979-2000) Monsoon/Annual (%) Coefficient of Variation (%)

7. Indo-UK Programme on Climate Change Impacts in India : Delhi Workshop, Sep. 5-6, 2002 The Stability of the Indian Summer Monsoon

8. Indo-UK Programme on Climate Change Impacts in India : Delhi Workshop, Sep. 5-6, 2002 Temporal scales of monsoon variability IntraseasonalInterannualDecadal/CenturyMillennia & longer Onset/withdrawal; Active and break- monsoon phases; 30-50 day oscillations; severe rainstorms Droughts and floods Changes in the frequency of droughts and floods Changes in the areal extents of monsoons Atmospheric variability; tropical- midlatitude interactions; Soil moisture; Sea surface temperatures Atmospheric interactions; El Niño/ Southern Oscillation; Top layers of tropical oceans; Snow cover; Land surface characteristics Monsoon circulation variations; Deep ocean involvement; Greenhouse gases increase; Human activities; Biospheric changes; Volcanic dust Global climate excursions; Ice ages; Warm epochs; Sun-earth geometry Factors Features

9. Indo-UK Programme on Climate Change Impacts in India : Delhi Workshop, Sep. 5-6, 2002 Rainfall Data Homogeneous monthly rainfall data set for 306 stations (1871-2001) Homogeneous monthly rainfall data set for 306 stations (1871-2001) Daily rainfall data at 500-1000 raingauge stations during 1901-90 (variable network) Daily rainfall data at 500-1000 raingauge stations during 1901-90 (variable network)

10. Indo-UK Programme on Climate Change Impacts in India : Delhi Workshop, Sep. 5-6, 2002 Change in Raingauge Network Density (1871-1992)

11. Indo-UK Programme on Climate Change Impacts in India : Delhi Workshop, Sep. 5-6, 2002 Raingauge Network for Daily Rainfall Data

12. Indo-UK Programme on Climate Change Impacts in India : Delhi Workshop, Sep. 5-6, 2002 All-India Summer Monsoon Rainfall (1871-2001) (Based on IITM Homogeneous Monthly Rainfall Data Set)

13. Indo-UK Programme on Climate Change Impacts in India : Delhi Workshop, Sep. 5-6, 2002 Long-term Trends in Indian Summer Monsoon Rainfall

14. Indo-UK Programme on Climate Change Impacts in India : Delhi Workshop, Sep. 5-6, 2002 Major River Basins of India

15. Indo-UK Programme on Climate Change Impacts in India : Delhi Workshop, Sep. 5-6, 2002 Identification of Target River Basins 66 notable river basins 66 notable river basins 3 large river basins identified : Ganga, Godavari and Krishna 3 large river basins identified : Ganga, Godavari and Krishna Summer monsoon main source of water for all the three basins Summer monsoon main source of water for all the three basins

16. Indo-UK Programme on Climate Change Impacts in India : Delhi Workshop, Sep. 5-6, 2002 Seasona Precipitation : GANGA

17. Indo-UK Programme on Climate Change Impacts in India : Delhi Workshop, Sep. 5-6, 2002 Seasonal Precipitation : GODAVARI

18. Indo-UK Programme on Climate Change Impacts in India : Delhi Workshop, Sep. 5-6, 2002 Seasonal Precipitation : KRISHNA

19. Indo-UK Programme on Climate Change Impacts in India : Delhi Workshop, Sep. 5-6, 2002 Variation of Basin-mean Precipitation: GANGA

20. Indo-UK Programme on Climate Change Impacts in India : Delhi Workshop, Sep. 5-6, 2002 Variation of Basin-mean Precipitation: GODAVARI

21. Indo-UK Programme on Climate Change Impacts in India : Delhi Workshop, Sep. 5-6, 2002 Variation of Basin-mean Precipitation: KRISHNA

22. Indo-UK Programme on Climate Change Impacts in India : Delhi Workshop, Sep. 5-6, 2002 The Hadley Centre Regional Climate Models (HadRM2/HadRM3H) High-resolution limited area model driven at its lateral and sea- surface boundaries by output from HadCM High-resolution limited area model driven at its lateral and sea- surface boundaries by output from HadCM Formulation identical to HadAM Formulation identical to HadAM Grid : 0.44° x 0.44° Grid : 0.44° x 0.44° One-way nesting One-way nesting Climate change simulations performed by the Hadley Centre using HadRM2 for the Indian region Climate change simulations performed by the Hadley Centre using HadRM2 for the Indian region HadRM3H installed at IITM; Climate change simulations and scenario development will be performed at IITM HadRM3H installed at IITM; Climate change simulations and scenario development will be performed at IITM

23. Indo-UK Programme on Climate Change Impacts in India : Delhi Workshop, Sep. 5-6, 2002 All-India Mean Monthly Rainfall

24. Indo-UK Programme on Climate Change Impacts in India : Delhi Workshop, Sep. 5-6, 2002 All-India Seasonal Rainfall

25. Indo-UK Programme on Climate Change Impacts in India : Delhi Workshop, Sep. 5-6, 2002 All-India mean Surface Air Temperature

26. Indo-UK Programme on Climate Change Impacts in India : Delhi Workshop, Sep. 5-6, 2002 HadRM2 Simulations: Seasonal Precipitation (Control)

27. Indo-UK Programme on Climate Change Impacts in India : Delhi Workshop, Sep. 5-6, 2002 HadRM2 Simulations: Seasonal Surface Air Temperature (Control)

28. Indo-UK Programme on Climate Change Impacts in India : Delhi Workshop, Sep. 5-6, 2002 HadRM2 Simulations: Seasonal Precipitation (GHG-Control)

29. Indo-UK Programme on Climate Change Impacts in India : Delhi Workshop, Sep. 5-6, 2002 HadRM2 Simulations: Seasonal Surface Air Temperature (GHG-Control)

30. Indo-UK Programme on Climate Change Impacts in India : Delhi Workshop, Sep. 5-6, 2002 State-wise mean precipitation scenarios : HadRM2

31. Indo-UK Programme on Climate Change Impacts in India : Delhi Workshop, Sep. 5-6, 2002 State-wise mean monsoon precipitation change scenarios : HadRM2

32. Indo-UK Programme on Climate Change Impacts in India : Delhi Workshop, Sep. 5-6, 2002 State-wise Mean Temperature Scenarios : HadRM2

33. Indo-UK Programme on Climate Change Impacts in India : Delhi Workshop, Sep. 5-6, 2002 State-wise Mean Annual Temperature Change Scenarios : HadRM2

34. Indo-UK Programme on Climate Change Impacts in India : Delhi Workshop, Sep. 5-6, 2002 Annual Cycles of Rainfall in Major River Basins of India Ganga Godavari Krishna

35. Indo-UK Programme on Climate Change Impacts in India : Delhi Workshop, Sep. 5-6, 2002 CONCLUSIONS  Coupled atmosphere-ocean models consistently indicate general warming over India, by about 2° to 4°C from 1990 to 2090.  The models also indicate enhanced rainfall conditions over India in a greenhouse gas increase scenario; however, there is some disagreement among the models on rainfall changes  The models consistently indicate substantial increase in monsoon precipitation over northwest India.  Significant potential for regionalization; work in progress.