groundwater resources assessment and future irrigation potentials in three districts of nepal
TRANSCRIPT
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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
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Water for a food-secure world
Presentation Outline
• Background
• Objectives
• Results
• General Observations
Photo: IWMI Nepal Research Team
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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
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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
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Water for a food-secure world
Results - Rainfall
0250500750
10001250150017502000225025002750
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010
An
nu
al R
ain
fall
(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
An
nu
al R
ain
fall
(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
An
nu
al R
ain
fall
(mm
)
Years
Annual Rainfall of Dhanusha
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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
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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
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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
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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
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Water for a food-secure world
Monthly Water Table FluctuationSUNSARI Monthly Average Water Depth of all Stations (m) ∆h
(m)
Specific
yield
Storage
(∆S)
MCM
Net
Rech.
mm/yrYEAR 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)
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Water for a food-secure world
Net Irrigation Requirement (mm)
Crops Paddy WheatPulses / 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
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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
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Water for a food-secure world
Thank You
Photo: IWMI Nepal Research Team