Modeling of Irrigation Water Demand for Sustaining Crop Yield in Saline Environment

Abstract

Increasing the productivity of water and making safe use of poor quality water in agriculture will play a vital role in easing competition for scarce water resources prevention of environmental degradation and provision of food security. The purpose of this study is to cover the crop water demand and supply gap with the management strategies. The comparison of actual water supplies and demand, i.e. crop water demand has been calculated and found that demand is more than supply. The daily reference evapotranspiration for Bhutana distributory is estimated using pan-Montieth method in CROPWAT model and crop-water demand has also been calculated using CROPWAT model. The supply shortfall in total Rabi seasons is 329.5 mm in 2009-10 and 162.2 in 2010-11. This gap is met by pumping ground water. Different scenario is generated after canal supply gap analysis because supply is less and demand is more and at the same, ground water quality is not so good. In some places, there is a problem of salinity or sodicity. Twelve point have been selected for soil sample from different locations of Butanadistributory. The result revealed that EC, SAR, RSC varies from 1.5 g/kg, 2.7-20 (mmoles kg-1)0.5 , 0- 8.8 mg/l. The best management strategies such as growing salt tolerant crops varieties and proper irrigation scheduling with effective conjunctive use of multiquality irrigation water, and pre-sowing water management was suggested for various scenarios of deficit canal water supply, poor soil and ground water quality, and water logging conditions for growing more food with less water of good/poor quality. This study will be helpful for engineers, researchers and farmers in taking decision on utilization of ground water, which will minimize their yield losses in scarce water supply and marginal quality of ground water.