Smallholder irrigation projects have identified as spring boards towards development and sustainable livelihoods in the semi-arid regions. Decreasing water resources constitutes one of the most pressing challenges facing the smallholder irrigation development. While existing research on smallholder irrigation has concentrated mostly on technical, management and socio-economic performance of the schemes, little has has been done to analyse effects of river flow variabilities on crop productivity. This book, therefore presents results of a study conducted to investigate the effects of river flow variability on performance of Nyanyadzi irrigation scheme in Zimbabwe. The research findings established that bean and wheat crop yield data for 21 years studied show significant downward trends. No crop was harvested in 1973, 1992, 1994 and 1995 as a result of poor water supply. The study recommended an improvement in water supply and crop production by switching to more drought tolerant crop varieties, use of more efficient water application methods, practice rainfall harvesting and water conservation measures.