ABSTRACT
Water control is recognized as a critical variable for increasing and sustaining irrigated agricultural productivity. Water control as used in this paper is defined as the ability of farmers to plan adequately and in time for cropping decisions by having the required volumes of water available at the appropriate times and places for crop needs phis increments sufficient for leaching requirements and evaporation losses. As defined, proper water control ensures that end users will have a relatively high degree of predictability of water supplies for making cropping decisions and meeting crop needs. A high degree of water control on public gravity systems is seldom possible, especially in South Asia, because it involves a high degree of refined management processes and technologies for main, minor, and farm subsystems. Presently, ad hoc conjunctive use with tubewells, lift pumps, and open wells supplementing canal supplies typically provide the upper limits for water control in Pakistan and India. Both countries have made heavy investments in ground water since the early 1960s. Pakistan now has over 200,000 private tubewells and India about 3 million.
