An Assessment of the Reliability and Adequacy of Irrigation Water in Small Holder Irrigation Schemes

Donald Nyamayevu, Wensheng Sun, Gashirayi L. Chinopfukutwa

Abstract: Zimbabwe irrigation schemes were designed with the main aim of improving the living standards and to promote sustainable development of rural communities. Years after the implementation of these irrigation schemes most of them are now operating far below their expected performance with aging and deterioration of equipment ranging among the most prominent challenges. The present study investigates the performance of the water supply systems of Exchange Irrigation Scheme of Kwekwe District Zimbabwe. The main aim is to determine the reliability and adequacy levels of water delivered by the irrigation water supply system in meeting the irrigation water needs for the scheme during the period of 2013 to 2017. Values of crop water requirements were estimated using CROPWAT model. Levels of reliability were quantified using the RWS index. The study observed that the system is continuously failing to meet the irrigation water demand with only 2013 receiving enough water to match the water demand and from the overall monthly averages irrigation water needs and irrigation water applied for the periods of 2013 ? 2017 the system only managed to deliver adequate water for only three months that is February, March and June. The RWS index indicated that the irrigation scheme water supply system was unreliable in 2016 and 2017whith reliability levels of 78% and 72% respectively which are below the RWS index threshold.

Keywords: Reliability, Adequacy, Small Scale Irrigation Schemes, Irrigation Water Management