干旱区生态环境知识资源中心

Small scale irrigation and water harvesting, particularly for horticultural crops, can mitigate the effect of low and unreliable rains and significantly alleviate poverty in the semi arid tropics (SAT) of the developing world. This paper describes a range of new innovative technologies for rain water harvesting and for small scale irrigation aimed at increasing both water availability and water productivity in the semi arid tropics of Africa and South Asia. Bio-reclamation of Degraded Lands (BDL) is a new rainfed horticulture production system using indigenous in situ water harvesting techniques to optimize water management at the field level for vegetables and fruit trees. New water harvesting technologies operating at the watershed level in both dry Africa and South Asia result in significant storage of water in shallow water tables. This stored water is used for vegetables irrigation by poor small farmers. The Integrated Watershed Management approach significantly improves rainfed water use efficiency of field crops while at the same time stores field run off water in shallow aquifers to increase the area of irrigated crops. An indigenous integrated rice-vegetables-fruit trees system developed by small farmers in the Gaya region of Niger is described. This system guarantees year round cash flow and is highly profitable. A new low pressure drip irrigation system called the African Market Garden (AMG) developed and tested by ICRISAT-WCA is presented. This system that is geared for small producers can bring a profit of $2.4/m(2). The high cost of water pumping and delivery is a major limiting factor for irrigation by small resource-poor farmers. A critical analysis of four water delivery technologies demonstrated that solar pumping is the most cost effective and sustainable alternative when pumping water from relatively shallow water tables.