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Climate Variability, Urbanization and Water in India


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This presentation was made at "Orientation Programme for Government officials on Urbanization, Climate
Change and Water Issues" held on the 23rd of July.

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Climate Variability, Urbanization and Water in India

  1. 1. Climate Variability, Urbanization and Water in India M. Dinesh Kumar Executive Director Institute for Resource Analysis and Policy Hyderabad-82 Email: for the Orientation Workshop organized by SaciWaters
  2. 2. Purpose• The purpose of this presentation is to add a new dimension to the debate on how climate change and urbanization could impact on India’s water resources vis-à-vis its availability and demand, in the face of the country’s climate reality
  3. 3. Plan of Presentation• Conceptual Framework on the Impacts of Climate Variability and Change and Urbanization on Water• India’s Climate Reality• India’s Urban Growth Reality• Issues with climate predictions• Potential Impacts of Climate Change on Water Resources• Potential Impacts of Urbanization on Water Resources• Areas of Future Concern
  4. 4. Conceptual Framework• Farming is the largest consumptive user of water in India• Change in temperature and CO2 can alter crop yields by affecting plant bio-physical processes: depends on plant type (C3 or C4)• Temperature change can also alter evapo-transpirative demand of water (ET) in crop production• Either way, the amount of water required for producing a unit of biomass would change, changing the aggregate water demand in agriculture• Temperature changes can alter the hydrological system, by changing infiltration rate, soil moisture storage, and thereby run-off, affecting the overall water availability within a basin
  5. 5. Conceptual Framework• Urbanization can affect hydrology and water resources in many ways• Urban centres create points of concentrated water demands, often making it difficult for the local natural water systems to sustain• Urbanization pushes the growth rate in domestic water demands as per capita water demands are much higher in urban areas• Urbanization changes land use, creating impervious catchments and increasing the runoff from precipitation, thereby increasing the chances of floods, while reducing natural recharge to groundwater• Urbanization increases the level of toxic pollutants and sediment load in storm water runoff, making it unfit for human & animal consumption
  6. 6. India’s climate reality• Spatial variability in climate is very significant: – Hot & arid to hot & humid, to cold & sub-humid to cold & humid• Within the same river basin, agro climate vary significantly• Day time and night time temperature of a day can vary from year to year; so are humidity and wind speed• Monsoon records for 104 years (1901-2003) do not show any linear trend (Kelkar, 2010)• Also data for 1813-2006 do not show any uniform trend (Sontakke et al., 2008)
  7. 7. India’s climate reality• Spatial variation in rainfall is remarkable• So is the variation in number of rainy days• Regions of low rainfall receive it in very few showers; regions of high rainfall have long wet spells• Regions of high mean annual rainfall has low inter-annual variability and vice versa• Regions experiencing fewer days of rains experience high variability in number of rainy days between years
  8. 8. India’s urban growth reality• Urban population growth in India is much higher than that of rural population growth ; large cities are growing faster• Cities in ‘naturally water scarce regions ‘ are experiencing faster growth than those in water abundant regions• Water demands in these cities are growing exponentially; while their local fresh water bodies are either drying up or getting deteriorated;- tanks and lakes and hard rock aquifers in South India• These urban areas are increasingly dependent on water resources in rural areas, often competing for water from public irrigation systems
  9. 9. Issues with climate prediction for India• GCMs predict higher rainfall for Indian sub-continent, with varying “increments”; not robust for Indian monsoon (Kelkar, 2010)• The observed trends in “global temp. rise” are not uniform. Greater warming is predicted for n. hemisphere• GCM predictions are too broad (150 km X 150 km area.), and do not have much relevance for understanding river basin hydrology• Different models predict different trends (Mujumdar, 2010). Often, errors in rainfall predictions are higher than the predicted values• Generally, temperature predictions are found to be more accurate than the rainfall predictions at the global scale
  10. 10. Climate change impacts on water resources• Even if climate change is a reality, its impacts on water resources in India would not be uniform across basins and regions; but would depend on the region• In low to medium rainfall regions, rise in temperature could lead to faster soil moisture depletion and reduced runoff and recharge• In low to medium rainfall semi arid regions, basins are water-scarce• Temp. rise could also lead to further increase in the demand for water for crop production, thereby increasing magnitude of water scarcity• The impacts of droughts due to monsoon failure in these regions would become more severe
  11. 11. Climate change impacts on water resources• In high rainfall, (above 1,000mm), hot & sub-humid to cold & humid regions), an overall rise in temperature rise could lead to higher rainfall increasing surface water availability• Water demand for crop production is quite low in these regions.• A rise in temp. won’t cause much increase in irrigation water demand, as more water would be available from soil moisture for crop growth• Further, the basins in these regions are water-abundant basins (Ganges, Brahmaputra-Meghna), with limited amount of arable land for crop production
  12. 12. Climate change impacts on water resources• On the contrary, temperature reduction can cause opposite trends in these two distinctly different hydro-climatic regimes.• The naturally water-scarce regions could receive more rainfall, and that in naturally water rich regions could decline• Accumulation of particle aerosol in the atmosphere over the Gangetic plains is reported to be leading to lower temperature, and reduction in rainfall in that region and also crop yield losses owing to decline in incident solar radiation
  13. 13. Impact of climate variability and urbanization on water resources• Low to medium rainfall regions in India experience high variability in stream flows and groundwater recharge• The variability might increase if the temperature in these regions experience rise• Fast growing urban centres in naturally water-scarce regions induce huge pressure on the limited freshwater, with excessive increase in water demands, depleting local aquifers and highly variable flows• With climate change, the occurrence of climate induced water-related disasters like droughts and urban floods are likely to be more i
  14. 14. Areas of concern for future• Water scarcity are growing in India, and challenges of managing water would be greater in years to come• There are issues associated with climate predictions for India, particularly rainfall. But, even under the best case scenario, there could be some human induced climate impacts, which are negative• But, there are priority issues in water management, which need to be addressed• Generating accurate scientific data on climate and hydrology is one among them (temp., rainfall & its intensity, stream flows, base flows, groundwater recharge & withdrawal, glaciers etc.)
  15. 15. Areas of concern for future• Addressing these fundamental issues would help plan for climate induced impacts• More importantly, India has capabilities to adapt to the changes which the current predictions on climate shows• Further strengthening these capabilities would require : – Management of aquifers in the water-scarce regions – Building multi-annual storage in reservoirs – Improving water productivity in irrigated agriculture would be key to strengthening our adaptive capacities and reducing emissions
  16. 16. Rainfall and ET0 in Nine agro climatic sub- zones in Narmada basin 2000 1800 1600millimetres 1400 1200 1000 800 600 400 200 0 CNV - Jabalpur CNV - Kymore Plateau Malwal Plateau Nimar Plains Northern Hill Satpura Plateau Satpura Plateau Vindhya Plateau Hosangabad & Satpura Hills Region of Chhattisgarh Annual ET0 (mm) Average Normal Rainfall (mm)
  17. 17. Variations in daily min. and max. temperature between years Temperature of Aurangabad (2009 and 2010) 50.0 45.0Temperature in degrees C 40.0 35.0 30.0 25.0 20.0 15.0 10.0 5.0 0.0 12 23 34 45 56 67 78 89 100 111 122 133 144 155 166 177 188 199 210 221 232 243 254 265 276 287 298 309 320 331 342 353 364 1 Daily Max Temp-2009 Daily Max Temp-2010 Daily Min Temp-2009 Daily Min Temp-2010
  18. 18. Relative humidity and wind speed 100 20.0 90 18.0 80 16.0 70 14.0Relative Humidity % Wind Speed KMPH 60 12.0 50 10.0 40 8.0 30 6.0 20 4.0 10 2.0 0 0.0 10 19 28 37 55 64 73 82 91 46 100 118 127 136 145 154 163 181 190 199 208 217 226 244 253 262 271 280 289 298 307 316 325 334 343 361 109 172 235 352 1 RH%-AM-2009 RH%-AM-2010 RH%-PM-2009 RH%-PM-2010 Wind Speed (KMPH) - 2009 Wind Speed (KMPH)-2010
  19. 19. Rainfall variability across regions
  20. 20. Variability in rainy days
  21. 21. Rainfall variability between years
  22. 22. Variability in rainy days between years
  23. 23. City Size Vs Surface water Contribution to Water Supply
  24. 24. Water-scarce basins & regions Average Reference Evapo-transpiration Against Effective Annual Water Resources in Selected River Basins in Water-Scarce RegionsSr. No Name of the Mean Annual Rainfall Average Effective Reference Basin (mm) Annual Annual Evapo-transpiration3 Water Water (mm) Resources Resource2 Upper Lower 1mm) (mm) Upper Lower Catchment Catchment1 Narmada basin 1352.00 792.00 444.70 937.60 1639.00 2127.002 Sabarmati basin 643.00 821.00 222.84 309.61 1263.00 1788.803 Cauvery basin 3283.00 1337.00 316.15 682.80 1586.90 1852.904 Pennar basin 900.00 567.00 193.90 467.80 1783.00 1888.005 Krishna basin 2100.00 1029.00 249.16 489.15 1637.00 1785.90
  25. 25. Water-abundant basins & regionsName of the Average Annual Average Average Mean Annual Reference Waterbasin Rainfall in the basin Renewable Effective Evapo-transpiration Demand (mm) Water Water (mm) for Resources Resources Agriculture (m3/capita/ (m3/capita (m3/capita annum) / annum) / Upper Lower Upper Lower annum) Catchment CatchmentGanga 1675.0 1449.0 1179.9 1399.4 710.0 1397.0 721.5Brahmaputra 2359.0 2641.0 1737.1 2052.8 1064.0 1205.0 1180.9
  26. 26. Annual Yield of three Sub-basins of Sabarmati River Basin Total Yield from Dharoi 6000 Total Yield from Watrak 5000Yield in Million Cubic Metres Total Yield from Hathmati 4000 3000 2000 1000 0 1977 1983 1989 1950 1953 1956 1959 1962 1965 1968 1971 1974 1980 1986
  27. 27. Historical Inflow series for Narmada River at Sardar Sarovar Dam Site, CWC (1891-1990)