Bharat R Sharma

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Groundwater Externalities of Large Surface
Irrigation Transfers Godavari- Krishna (P-V)
Link

• Bharat R Sharma
• KVGK Rao
• Sylvain Massuel

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Godavari River and the Pump Lift Schemes
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High Value Crops under Water Scarcity
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Study Area
Polavaram
Godavari
PV-link canal
Eluru canal
Vijayawada
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Polavaram (Godavari) Vijayawada (Krishna) Link

• Right Main Canal of Indira Sagar (Polavaram)
  Project on Godavari
• Linking Polavaram Project on Godavari and
  Prakasam barrage on Krishna
• 174 Km long Irrigates about 140,000 ha in West
  Godavari and Krishna Districts
• Transfer of 2265 Mm3 (80 TMC) as per GWDT award
  from Godavari to Krishna Delta

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The Study Plan

• Collation of all available data and resources
• Primary Field Survey in the P-V Link Command
• Focused Group Discussions with the
  Stakeholders
• Groundwater Modeling Studies
• Economic Analysis and Synthesis

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Land use in P-V Link Mandals in West Godavari
and Krishna Districts 2004-05
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Irrigation Source in Krishna and West Godavari Up
land Mandals 2004-05
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Irrigation pattern under P-V link
Rabi
Kharif
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Average Paddy Yield in different seasons under
various sources of Irrigation - P-V Link
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Average Kharif Net Returns for Different Crops
High returns
Low returns
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Average Rabi Net Returns for Different Crops
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Average Net Returns with Paddy under Different
Irrigation Sources
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Projections of Benefits with P-V Link

• Assumptions
• The cropping pattern of 30 under annual crops
  and 70 under seasonal crops is likely to
  continue.
• The cropping intensity in the seasonal cropped
  area is expected to be 150
• As per the current cropping pattern rice and
  maize are the crops to be grown in rabi season.
• Ground water modeling shows 34,200 ha (16) area
  is expected to be waterlogged in rabi season and
  the same shall be put under rice crop.
• Farmers survey results on the cropping pattern,
  yields and net benefits have been used to
  estimate the current (Pre-project) agricultural
  net returns and the expected benefits after
  commissioning of the P-V link project.
• In case of fruit crops like mango gardens, it is
  expected that the net returns are likely to
  increase by 25 on adoption of micro-irrigation
  practices (APMIP estimates)

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Projected Net Returns from P-V Link Command
New area 35,953 ha
Projected Net Returns After P-V Link 37,850
lakhs (125 )
Improved Yields
Pre-Project Benefits 16,872 lakhs
Cropping intensity 150 ( 26)
Enhanced GW use
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GW Scenario Post P-V LinkGW Model studies

• MODFLOW has been conducted for predicting the
  groundwater externalities due to P-V Link
  irrigation system in its command
• Satellite images from Google Earth and Digital
  Elevation Models have been used in demarcating
  the command boundaries, land use and topography.
• The information on lithology and groundwater
  depths and quality collected by the AP State
  Groundwater Department has been used in the model
  study.

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Piezometry
Mean water-table depth 17.4m
general water-table flow
Polavaram
Vijayawada
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Model Setup Aquifer Geometry
63 drill-logs
4 layers
Alluvium
Sandstones
Deccan Traps
Khondalite
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Model setup boundary conditions
Fixed flow
River condition
4 models in steady steate
Before canal After canal
MR1 Rabi MR2 MK1 Kharif MK2
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Model Calibration and Validation
RMSE4.2m
RMSE3.8m
Calibration Rabi before canal
Validation Kharif before canal
Permeability K Storativity S Recharge R
GWrf groundwater source irrigation return
flow SWrf surface water source irrigation return
flow Rrain direct recharge from rainfall Rother
other potential recharge sources
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Model Results Recharge to Groundwater
(mm) Annual recharge R Annual leakage From canals Annual discharge
Before ISRMC 462 57 -592
After ISRMC 592 179 -771
Change 130 122 -179 73
Water-table rise 2m
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GWD Status
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Model Results Change in Stage of Development
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Model Results Waterlogging Development

• Water-table rising up to 2m below ground level

19 in Kharif
16 in Rabi
WL area
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Sustainability Issues

• Groundwater Issues
• Higher costs of Installation
• Higher operational costs
• Reduced discharges and area
• coverage

• Waterlogging in low lying
• and congested areas
• Soil salinity

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Depths of Tubewells in the P-V Link Area
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Tube well Pump set Capacity in P-V Link area
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Cost of Tube well Construction and Maintenance
Cost (per ha)
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Recommended Agriculture-Water Use Strategy

• Conjunctive use needs to be promoted for
  better irrigation, use the existing
  infrastructure and prevent waterlogging.
• Presently, 40 of area is under non-rice crops
  and 12 under horticulture. Special facilities
  for primary processing of tobacco. This scenario
  needs to be maintained and enhanced- rice should
  not be all pervasive.
• Groundnut in kharif followed by maize in rabi is
  resource efficient and remunerative. Low
  productivity of annual and plantation crops may
  be addressed on priority.

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Recommended Agriculture-Water Use Strategy-II

• P-V link will improve groundwater regime but not
  sufficiently to meet present and future needs.
  All possible demand management interventions-
  physical and institutional need to be in place to
  harness benefits of this initiative.
• About 16 of the proposed command, especially
  the Ganavaram block is most likely to witness
  waterlogging. Proper GW use and crop planning has
  potential to convert it into an opportunity.
• Since projected command is already well
  developed, introduction of canal irrigation
  should aim at improving the high value
  agriculture with major improvements in
  livelihoods.

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Thank you !