GDP Contribution with Optimal Use of Water Resources in Irrigation: A Case of Bagmati Irrigation Project, Nepal

Abstract

This article examines results of GDP contribution with optimal use of water resources in irrigation. Bagmati Irrigation Project (BIP) of Nepal is taken as a case study. This study covers water availability assessment for 122,000 hectors net command area (NCA) of Rautahat, Sarlahi, Bara and Mahottari districts that lie in central Terai of the country. The assessment of irrigation and crop water requirement for the Bagmati Irrigation Project was estimated based on the cropping pattern. The Crop Wat 8 window version software (FAO 1992), which gives solution to FAO Penman-Monteith equation, has been used to calculate reference crop evapotranspiration ETo. The values of Kc for different crops have been adopted from PDSP manual. In this study, diversion of water from Sun Koshi River to Bagmati River has been conceptualized. The study concludes that diversion of constant discharge of 67 m3/sec from Sun Koshi to Bagmati river may meet crop water requirement and provide year–round irrigation facility to the study area. It results annual net benefit of around NPR 27 billions from agriculture thus contributing significantly in GDP.