INTEGRATED WATER RESOURCES MANAGEMENT IN CANAL COMMAND AREA IN TERAI REGION OF NEPAL

Abstract

The study area lies within the command area of proposed Sikta irrigation System. 90% * of the study area is rainfed, therefore, has severe threat of stress to the crops. Remaining land has received irrigation facility from groundwater. An irrigation system is ongoing to convey irrigation water for rest of the land from Rapti river. This study has focused on the availability of surface water and groundwater in the area and their integrated management. Quasi three dimensional ground water flow simulation modeling was, therefore, performed by using Visual MODFLOW 4.2 to assess the change in hydraulic head due to transient pumping and application of irrigation water from ongoing irrigation system. The interpreted model was calibrated and validated satisfactorily. Sensitivity analysis of the model parameter reveals that the ground water recharge is the most sensitive parameter followed by aquifer hydraulic conductivity at almost all site of the study area whereas the specific storage and specific yield are less sensible. In existing boundary and stress condition of the groundwater system, around 64% of the area is in waterlogged situation in monsoon season whereas 6 percent of area has water table within 2 m depth from ground surface in non monsoon season. After three years continuous application of irrigation water, entire area would be water logged in monsoon season and about 85 percent of the area would be in waterlogged condition in non monsoon season. In the month of June, there would be scarcity of water for irrigation for proposed cropping pattern which would reach upto 52 MCM. Available groundwater was found in unconfined aquifer is 27.22 MCM which is not sufficient for irrigation in the driest month. A study of semi and deep aquifer exploration is essential. Hence a comprehensive optimal land and integrated water resources development plan sustainable development water resources and agriculture activity of the study area is necessary