An Evaluation of Water Demand and Supply for a Small-scale Irrigation Scheme in Zimbabwe

Abstract

Previous studies have shown that most smallholder irrigation schemes in developing countries in Africa, have proved to be unsustainable beyond external assistance. The low performance of most smallholder irrigation schemes is largely attributable to unreliable and inadequate water delivery. This research assessed the on-farm water management performance for Fuve-Panganai irrigation scheme in Zaka District of Zimbabwe. The objective of this study is to assess the on-farm water management performance for the irrigation scheme in terms of water demand and supply. The irrigation water demand for 204 ha of dry beans for the winter irrigation season (April to August) was estimated using the FAO CROPWAT. The seasonal water supply was calculated using the 2012 to 2016 recorded canal water depths. The Relative Water Supply (RWS) index was calculated from the water demand and supply. 38 randomly selected farmers, members of the waters user’s association and relevant agencies were interviewed to understand the decision-making process and the overall performance of the scheme. The results showed a stable water supply for the five years with a coefficient of variation of 0.2. The water supply was greater than water demand during the winter mid-irrigation period (May to July) with an average RWS of 1.59. The results correspond with results from the interview survey in which more than 90 percent of the farmers were satisfied with the irrigation management performance. However, 37 percent reported to have experienced water shortages. This is due to the heavy distribution losses by damaged pipes and leaking water valves. The irrigation system is in dire need for rehabilitation to minimize water losses.