The Compartmented Reservoir

Abstract

Introduction: The need for an efficient method of storage of water in arid zones has long been recognized. Efforts have been made everywhere to develop small storage tanks to provide water at critical periods. However, most of the existing tanks have such annual or seasonal evaporation losses that they are equal or even greater than the average depth of the tank. Thus many of these tanks are completely depleted before the end of the dry season, often with dramatic consequences for human beings, livestock or agricultural activities depending on the water supply. Reducing the heavy evaporation and seepage losses in these tanks is an important way to increase the supply of water. Several methods have been developed to reduce these losses but one of the most effective ways is to make the tanks with a smaller surface but deeper. The importance of making tanks deeper has been recognized for many years but there are several constraints for achieving depth in tanks: (a) the gradient of the water stream, (b) the unsuitability of dozers to work in deep pits, and (c) shallow soils. However, these constraints can be removed by using high rise banks and water pumps. Efficiency can also be improved by keeping the water concentrated. With this idea in mind, Mr. Cluff, FAO Consultant, has developed the concept of the compartmented tank, which is being tried out successfully in Mexico, and whose main features are summarized below.