Agriculture is the largest user of the world's freshwater resources, consuming 70% of the available supply (UNW-DPAC 2011). As the world's population rises and consumes more food, and industries as well as urban developments expand, water scarcity is becoming an important issue that demands improved water management systems. Water management approaches, both within rainfed and irrigated agriculture, are applicable at different scales including (i) farm level, (ii) irrigation system or catchment level, and (iii) national or river basins at the planning level. Many of the options for water management can appear generic at any of these levels. However, when applied in different combinations in specific contexts, unique improved water use efficiency (WUE) systems will emerge that are suited to specific ecological systems.
Under rainfed agriculture, improved water management can be achieved through land management practices that result in the capture and retention of rainfall and through soil fertility and crop management innovations that enhance crop growth and yield and hence water use efficiency (Landolt 2011; Roose et al. 1999; Bationo et al. 2012) or through supplemental irrigation of dry-land crops (Oweis and Hachum 2012). In irrigated systems, improved water management for greater WUE is achievable at many stages in the total process of irrigation, from the source of the water, through conveyance and application systems, scheduling and the availability of water in the root zone of the plant. Nicol et al. (2015) describe many such examples drawn from East Africa. Water management within the livestock sector and fisheries sector also offers substantial potential to increase efficiency, productivity, and resilience.