Spatio-Temporal variability of Water resources in the Ganga basin By Subashisa Dutta Associate Professor DEPARTMENT OF CIVIL ENGINEERING INDIAN INSTITUTE OF TECHNOLOGY GUWAHATI GUWAHATI, ASSAM For National Students’ Conference On River Basin Planning IIT Kanpur, 4 to 5 th November 2011 Sattriya dance-Assam, gspot.com/

Overview of the lecture 2 1.Spatio-temporal variation of surface water resources in the basin ( annual water yield, monsoon flow, non-monsoon flow, lean month flow, dependable flow) 2.Current Ground water utilization : crop statistics and GIS analysis 3.Spatio-temporal variability of Ground water Resources in the Basin 4.Fertilizer application and crop productivity : an indicator for non-point source pollution 5.Resilience in the Water Resources system: How long ?

Hydrological Storage, release function and interdependency 3 Surface water storage M J S D J Q Q Q Monsoon recharge Ground water storage Flood recharge Irrigation ET P SM ET : Evapo-transpiration, P: Precipitation, SM: Snow Melting Run-off, Q: Discharge Note for Ganga Basin: Ground water Irrigation controlled by the farmers and Agricultural Economy, Flood recharge depending upon the frequency of wet-Monsoon ET depending upon the distribution of Landuse/landcovers remains fairly constant Hydrological links between groundwater and surface water storage defined by Hydro-geological characteristics

Study Area: Ganga River basin in Bihar 4 Data used: 1.Hydrological data (1960 to 1992) 2.Satellite Altimetry data (1993 to 2003) 3.Ground water level data (2001 to 2009) 4.Agricultural statistics (Crop water requirement, productivity, Area, Crop type etc.) 5.Other ancillary information (Bhuvan satellite imagery,)

Hydrological Trends of the Ganga river flow* at the downstream of Farakka * Webster, J. P., Jian, J., Hopson, M. T., Paula, A. A., Chuang, H., Curry, J. A., Grossman, R. L., Palmer, T. N., Subiah, A. R., (2010) “Extended-range probabilistic forecasts of Ganges and Brahmaputra floods in Bangladesh.” Bulletin of the Am. Met. Society., Pre-Surface water development Project Ground water development Project

Hydrological trends of Major tributary flows * Report of the 2 nd Bihar State Irrigation Commission Monsoon season Water yield: MCM Hydrological trend : Variable Non-Monsoonal Season Water yield: 9491 MCM Hydrological trend : Fairly Constant Annual variation of water yield of the Kosi river at Saptakosi station Monsoon season Water yield: MCM Hydrological trend : Variable Non-Monsoonal Season Water yield: MCM Hydrological trend : Variable

Flow duration curve and dependable annual water yield 7

Long term Average February month flow in Ganga river Main Ganga Bay of Bengal Tons-Karmnasa Chambal Yamuna Sone Bhagirathi Indo-Bangladesh Border Azamabad Farakka Barrage RamgangaGomti Ghaghra Gandak-Burhi Gandak Ground water(Buxar to Azamabad) Mahananda Kosi Buxar Mahananda (1487) All data are 75% dependable flow (Million Cubic Meter) Findings: Indo-Bangladesh Ganga water sharing treaty: 3888 MCM at Farakka Ground water contribution: 1487 MCM * Report of the 2 nd Bihar State Irrigation Commission 1994

Long term Average March month flow in Ganga river Main Ganga Bay of Bengal Tons-Karmnasa Chambal Yamuna Sone Bhagirathi Indo-Bangladesh Border Azamabad Farakka Barrage RamgangaGomti Ghaghra Gandak-Burhi Gandak Ground water(Buxar to Azamabad) Mahanandaa Kosi Buxar Mahananda (1236) All data are 75% dependable flow (Million Cubic Meter) Findings: Indo-Bangladesh Ganga water share treaty: 3888 MCM at Farakka Ground water contribution: 1236 MCM * Report of the 2 nd Bihar State Irrigation Commission 1994

Long term Average April month flow in Ganga river Main Ganga Bay of Bengal Tons-Karmnasa Chambal Yamuna Sone Bhagirathi Indo-Bangladesh Border Azamabad Farakka Barrage RamgangaGomti Ghaghra Gandak-Burhi Gandak Ground water(Buxar to Azamabad) Mahanandaa Kosi Buxar Mahananda (502) Findings: Indo-Bangladesh Ganga water share treaty: 3888 MCM at Farakka Ground water contribution in April Month : 502 MCM Total three lean month flow GW = 3225 MCM ( 27%), Kosi and Gandak River flow = 4552 MCM ( 40%), U/S catchments at Buxer : 3386 MCM ( 29%) * Report of the 2 nd Bihar State Irrigation Commission 1994

Satellite Altimetry measurement* for water level 11 Main River Tributary Wet land Performance of Satellite altimetry for water level prediction in Brahmaputra Minimum water level variation from altimetry measurement *

Spatio-temporal variation of ground water depth 12

Analysis of Groundwater variation: Depletion, Recharge and withdrawal 13 * Report of the 2 nd Bihar State Irrigation Commission 1994

Water requirement for Agriculture system 14 Multiple cropping during Non-Monsoon season Estimated Ground water irrigation = 9800 MCM

Total crop water requirement and Annual variation of recharge : Flood year

Temporal variability of Groundwater and Potential recharge MSS (1970’s) TM (1990)ETM (2000) 16 Temporal trend of annual recharge/depletion zones in three districts Flood Area Flood inundation in Bihar in 2007 showing potential recharge zones Field photograph of a wetland

District-wise variation of fertilizer Application 17

Agriculture productivity and Fertilizer Application 18

Conclusion 19 Ground water irrigation, controlled by the farmers, is expected to be the major water resources user ( 10,000 MCM to 15,000 MCM) Conflict between Ground water irrigation and lean period flow in the river Wet monsoon year produces large-scale flood inundation based recharge system Availability of monsoon water yield is high and efficient management of the surface water projects Now, the water resources system is at resilience stage. How Long ?

ACADEMIC Building, IIT Guwahati Research Group Thank You 1.Dr Subashisa Dutta 2.Dr. Bimlesh Kumar 3.Dr Suresh A. Kartha 4.Amit Kr Dubey 5.Ikram Ali 6.Pritam Biswas 7.Sangita Devi 8.Titas Ganguly Farmer in a wheat fieldcrop harvesting at Bihar