2nd UF Water Institute Symposium Abstract

Submitter's Name Daniel Dourte
Session Name Poster Session: Optimal Use of Integrated Water Supplies 2
Category Optimal use of integrated water supplies
Poster Number 406
Author(s) Daniel Dourte,  University of Florida department of Agricultural and Biological Engineering
  Todd LeVasseur,  University of Florida department of Religion
  Cropping Systems for Food and Water Security in India: Productivity and Groundwater Responses to Farm Management
  Groundwater depletion is threatening livelihood security and macro-scale economic growth in numerous regions of India. An agricultural 550 hectare subwatershed in Andhra Pradesh was selected for analysis because it is illustrative of the common regional problem of groundwater decline and increasing vulnerability of the farming systems that are dependent on irrigation from groundwater. Farmers can manage two water balance components: evapotranspiration (through choices in crop selection, irrigation management, tillage/mulching) and runoff/infiltration (through choices largely in irrigation management, tillage/mulching). This analysis estimates the groundwater balance (recharge – irrigation withdrawals) of the watershed in response to farm management consisting of various combinations of crop selection, irrigation management, and tillage. The objective is to find management options for improving groundwater supply. The Soil and Water Assessment Tool (SWAT) is being used to simulate the water balance in the watershed. Channel flows and changes in reservoir volumes are being monitored for calibration of SWAT under existing farm management. Combinations of crop selection, irrigation management, and tillage are being simulated to find options of farm management (and their extent) that show promise for improving groundwater supplies. Improvements to the infiltration description of SWAT (to include surface storage in Green-Ampt infiltration as a variable head) are being tested to reduce uncertainty in runoff in a region having highly episodic rainfall and potentially large surface storage resulting from tillage management. Participation of farmers in the study area has provided information about farm management decision making and preferred cropping systems. This has allowed for more realistic groups of farm management options to be simulated. Sensitivity analyses suggest surface storage should be included in Green-Ampt infiltration for improvement of representation of infiltration in croplands having non-negligible surface storage. Groundwater balance results for various farm management options will be presented.