To increase the efficiency and productivity of water use, the yield response to water of crops must be known. A set of tools was packaged in this "Irrigation and Drainage Paper" to better appraise and enhance crop yield response to water. This publication is of value to various agricultural practitioners including, but not limited to, water managers and planners; extension services; irrigation districts; consulting engineers; governmental agencies; non-governmental organizations and farmers associations; agricultural economists and research scientists."