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Groundwater Resources Assessment and Future Irrigation Potentials in Three Districts of Nepal

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Presented by IWMI's Romulus O. Okwany at the Nepal National Water Week - 6th National Symposium, March 19, 2015.

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Groundwater Resources Assessment and Future Irrigation Potentials in Three Districts of Nepal

  1. 1. www.iwmi.org Water for a food-secure world Groundwater Resources Assessment and Future Irrigation Potentials in Three Districts of Nepal Romulus O. Okwany, PhD. Ram C. Bastakoti, PhD. Sanmungam A. Prathapar, PhD. March 19, 2015 Presented at the Nepal National water Week; 6th National Symposium: Challenges and Opportunities for Sustainable Management of Groundwater Resources of Nepal
  2. 2. www.iwmi.org Water for a food-secure world Presentation Outline • Background • Objectives • Results • General Observations Photo: IWMI Nepal Research Team
  3. 3. www.iwmi.org Water for a food-secure world Background • Agriculture dominates land use and any development initiatives • Climate change: – Extreme rainfall events, – More frequent incidences of flooding and droughts • Status of groundwater is monitored but availability is not well understood • Recharge characteristics are complex – Flooding may enhance recharge – High intensity rains may limit recharge • Discharge/withdrawals are even less understood – No monitoring or accounting of withdrawals
  4. 4. www.iwmi.org Water for a food-secure world Objective • Assess the status of groundwater resources in three districts of Nepal Terai : Dhanusha, Saptari and Sunsari • Evaluate potentials for withdrawals for current and future irrigation demands • Model future demands on groundwater resources for intensive irrigated agriculture Photo: IWMI Nepal Research Team
  5. 5. www.iwmi.org Water for a food-secure world Results - Rainfall 0 250 500 750 1000 1250 1500 1750 2000 2250 2500 2750 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 AnnualRainfall(mm) Years Annual Rainfall of Sunsari 0 250 500 750 1000 1250 1500 1750 2000 2250 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 AnnualRainfall(mm) Years Annual Rainfall of Saptari 0 250 500 750 1000 1250 1500 1750 2000 2250 2500 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 AnnualRainfall(mm) Years Annual Rainfall of Dhanusha
  6. 6. www.iwmi.org Water for a food-secure world Pre:Post Monsoon Depth Fluctuation Dhanusha District Year Recharge (km3/yr) Discharge (km3/yr) Specific Yield Net Recharge (mm/yr) Net Discharge (mm/yr) 2000 2.40 0.10 209 - 2001 -2.05 0.10 - -178 2002 0.10 - - 2003 1.21 0.10 105 - 2004 -1.62 0.10 - -141 2005 0.10 - - 2006 4.19 0.10 365 - 2007 -2.54 0.10 - -221 2008 1.29 0.10 112 - 2009 -0.85 -0.35 0.10 -74 -30 2010 -0.06 -1.34 0.10 -5 -117 Average 1.36 1.58 0.10 119 -137
  7. 7. www.iwmi.org Water for a food-secure world Saptari District Year Recharge (km3/yr) Discharge (km3/yr) Specific Yield Net Recharge (mm/yr) Net Discharge (mm/yr) 2000 2.56 0.10 206 - 2001 -2.49 0.10 - -199 2002 0.10 - - 2003 1.52 0.10 122 - 2004 2.54 -1.67 0.10 204 -134 2005 2.21 -2.42 0.10 177 -195 2006 1.22 -2.43 0.10 98 -195 2007 0.32 -1.92 0.10 26 -154 2008 2.62 -0.60 0.10 211 -48 2009 2.91 -1.68 0.10 234 -135 2010 2.14 -2.68 0.10 171 -215 Average 2.01 -1.99 0.10 161 -159
  8. 8. www.iwmi.org Water for a food-secure world Sunsari District Year Recharge (km3/yr) Discharge (km3/yr) Specific Yield Net Recharge (mm/yr) Net Discharge (mm/yr) 2000 0.29 0.10 25 2001 0.53 1.54 0.10 46 134 2002 2.33 -2.52 0.10 202 -218 2003 0.57 -0.19 0.10 49 -16 2004 3.95 -0.62 0.10 343 -54 2005 1.28 -2.45 0.10 111 -212 2006 1.42 -2.08 0.10 123 -181 2007 1.78 -0.99 0.10 154 -86 2008 2.77 -1.80 0.10 241 -156 2009 1.27 -2.18 0.10 110 -189 2010 1.06 -1.71 0.10 92 -148 Average 1.63 -1.41 0.10 141 -112
  9. 9. www.iwmi.org Water for a food-secure world Monthly Water Table Fluctuation SAPTARI Monthly Average Water Depth of all Stations (m) ∆h (m) Specific yield Storage (∆S) MCM Net Rech. (mm/yr) YEAR JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 2000 3.27 3.49 3.72 3.86 4.11 3.56 2.33 1.84 2.01 2.25 2.66 3.19 2.10 0.10 286.00 210 2001 3.46 3.75 3.94 4.09 4.07 3.87 2.41 1.81 2.05 2.27 2.61 3.18 2.02 0.10 274.75 202 2002 3.27 3.53 3.80 3.18 3.95 4.09 2.48 1.78 2.09 2.29 2.56 3.18 1.86 0.10 253.93 186 2003 3.29 3.49 4.30 4.21 3.84 4.30 2.63 1.71 2.16 2.34 2.47 2.73 1.67 0.10 228.02 167 2004 3.05 3.70 3.65 3.86 4.03 3.50 2.50 2.30 2.01 2.29 2.74 2.98 2.02 0.10 275.14 202 2005 3.72 4.03 3.78 4.03 4.14 4.28 4.37 2.89 2.20 2.55 3.16 4.09 1.94 0.10 264.54 194 2006 3.69 3.77 4.05 4.17 4.22 4.26 3.84 3.31 3.08 2.30 2.68 3.06 1.15 0.10 156.46 115 2007 3.25 3.40 3.59 3.83 4.01 3.91 3.67 1.67 3.67 2.08 2.44 2.81 0.34 0.10 45.83 34 2008 3.02 3.36 3.66 3.87 4.23 6.70 2.76 2.32 2.52 2.34 2.74 2.96 1.71 0.10 233.48 171 2009 3.27 3.55 3.80 4.05 4.24 4.34 3.29 2.75 2.00 2.25 2.50 2.88 2.24 0.10 305.74 224 2010 3.50 3.87 4.22 4.44 4.36 4.01 4.74 3.42 2.83 3.04 3.37 3.62 1.54 0.10 209.26 154 Average 3.34 3.63 3.86 3.96 4.11 4.26 3.18 2.34 2.42 2.36 2.72 3.15 1.69 0.10 230.29 169 DHANUSA Monthly Average Water Depth of all stations (m) ∆h Sp. yield Storage (∆S) km3 Net Recharge (mm/yr)YEAR JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 2000 2.878 2.909 3.187 3.625 3.986 3.957 3.466 2.658 2.196 2.830 3.042 2.865 1.791 0.100 0.179 179 2001 3.200 3.456 3.609 3.777 4.002 3.833 3.660 2.454 2.079 2.680 2.883 2.691 1.924 0.100 0.192 192 2002 2.765 2.739 2.717 3.345 3.320 3.694 2.845 2.250 1.962 2.530 2.725 2.694 1.359 0.100 0.136 136 2003 2.763 2.840 2.930 3.094 3.318 2.649 2.036 1.843 1.728 2.230 2.408 2.523 1.590 0.100 0.159 159 2004 2.762 2.940 3.144 3.337 3.759 3.114 2.045 1.640 1.611 2.899 2.595 3.058 2.148 0.100 0.215 215 2005 2.762 2.940 3.144 3.337 3.759 3.114 2.054 1.436 1.494 2.899 2.595 3.058 2.264 0.100 0.226 226 2006 3.226 3.086 3.547 3.472 3.566 3.363 2.071 1.029 1.261 2.725 2.422 3.680 2.305 0.100 0.231 231 2007 2.293 2.367 2.650 2.765 2.782 2.654 2.398 1.572 1.783 2.658 2.636 3.479 0.999 0.100 0.100 100 2008 2.293 2.367 2.650 2.765 2.782 2.654 2.779 2.114 2.305 2.591 2.850 3.379 0.477 0.100 0.048 48 2009 1.855 1.986 2.144 2.278 2.429 2.765 2.697 2.609 2.685 2.834 3.049 3.278 -0.256 0.100 -0.026 -26 2010 3.477 3.657 3.836 3.808 3.805 3.809 3.809 3.810 3.852 3.880 3.905 3.942 -0.047 0.100 -0.005 -5 Average 2.752 2.844 3.051 3.237 3.410 3.237 2.715 2.129 2.087 2.796 2.828 3.150 1.323 0.100 0.132 132
  10. 10. www.iwmi.org Water for a food-secure world Monthly Water Table Fluctuation SUNSARI Monthly Average Water Depth of all Stations (m) ∆h (m) Specific yield Storage (∆S) MCM Net Rech. mm/yr YEAR JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 2000 4.55 4.45 5.25 5.12 5.55 5.26 5.23 5.15 5.18 5.23 4.49 4.55 0.38 0.10 47.54 38 2001 4.93 4.78 4.82 4.87 4.92 4.90 4.71 4.50 4.60 4.84 5.01 5.09 0.32 0.10 40.09 32 2002 5.31 5.51 5.90 6.18 6.45 6.01 5.25 4.79 4.49 4.63 4.79 4.86 1.96 0.10 245.81 196 2003 4.93 4.89 4.93 4.97 4.96 4.95 4.59 4.69 4.67 4.69 4.73 4.70 0.29 0.10 36.45 29 2004 4.29 4.34 4.50 4.68 4.79 4.82 1.77 1.15 1.27 1.48 1.87 2.44 3.53 0.10 443.16 353 2005 2.77 3.00 3.12 3.23 3.29 3.33 2.01 1.63 2.36 2.32 2.43 2.79 0.93 0.10 117.06 93 2006 3.20 3.26 3.41 3.60 3.70 3.44 2.53 2.62 2.49 2.78 3.00 3.15 1.21 0.10 151.55 121 2007 3.41 3.48 3.52 3.61 3.65 3.35 2.32 2.09 2.04 2.14 2.31 2.48 1.61 0.10 202.21 161 2008 3.12 3.22 3.36 3.53 3.61 3.70 2.14 1.22 1.28 1.52 1.68 2.18 2.33 0.10 293.22 233 2009 2.38 2.51 2.83 3.08 3.29 2.06 2.12 1.80 2.11 2.30 2.54 2.86 1.19 0.10 149.16 119 2010 3.10 3.15 3.30 3.50 3.64 3.51 3.37 2.59 2.50 2.58 2.67 2.85 1.14 0.10 142.78 114 Average 3.82 3.87 4.08 4.21 4.35 4.12 3.28 2.93 3.00 3.14 3.23 3.45 1.35 0.10 169.91 135 District Groundwater Table Change (m) Avg. Monthly Fluctuation (m) Sunsari Rise – 2 0.06-1.22 (1.16) Saptari Drop – 0.65 -0.86-0.89 (1.75) Dhanusa Drop – 0.65 -0.43-0.32 (0.75)
  11. 11. www.iwmi.org Water for a food-secure world Net Irrigation Requirement (mm) Crops Paddy Wheat Pulses / Oilseeds Winter Vegetable Potato Maize Sunsari 422 200 145 121 263 28 Saptari 549 261 174 149 348 108 Dhanusha 544 253 172 148 341 76 Potential Irrigation Demands by Selected Crops Note: Available surface pumped groundwater =3000mm*0.10 ~300mm
  12. 12. www.iwmi.org Water for a food-secure world Water Resources Assessment in 3 Districts of Nepal General Observations: – Wide disparity in rainfall to storage changes – large surface runoffs – Groundwater utilization for irrigation is still at an infant stage in these districts relative to available storage – Greatest groundwater variations were observed in Saptari and lowest in Dhanusa District – Suitable monitoring at pre- and post monsoon gives comparable results to all-year-round monitoring – Groundwater table variations are highly responsive to precipitation – More work needed to assess aquifer characteristics for accurate determination of storages
  13. 13. www.iwmi.org Water for a food-secure world Thank You Photo: IWMI Nepal Research Team

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