Fair and sustainable irrigation water management in the Babai basin, Nepal

摘要

This paper attempts to find a strategy to provide year-round irrigation for cultivating three cropsnper year in the southern plains of the country taking a case study of the Babai basin. Despitenhaving enough flows during the summer for growing rice in total 27,000 ha area, the dry seasonnflows of the Babai river can irrigate only 6,300 ha in winter and 4,000 ha in spring limiting thencropping intensity to 138.50%. It is proposed to irrigate the 7,500 ha southern dry area at thenright bank bringing water from a large snow-fed river: the Karnali. Water balance study ofnthe three irrigation regions to be irrigated from the Babai source preserving their existing waternrights showed that the year-round irrigation at the west with the proposed arrangement will fallnshort of only 13.9 million m3 water volume. At the east side, the head reach area and the tailnportion will fall short of 19.4 and 66.4 million m3 of water to insure a cropping intensity of 250%.nThe deficits can be fulfilled by means of capturing the excess river water of rainy season in localnreservoirs and by making conjunctive use of groundwater. The proposed solution is financially,nenvironmentally and socially viable being a cost effective, user friendly and should be the linchpinntowards attaining a sustainable year-round irrigation in the region.