Chapter 3.2.3 - Water Storage and Conjunctive Water Use

Abstract

The different and complementary characteristics of surface water and groundwater make it possible to solve specific needs of water quantity and quality more adequately and economically than if both resources are used separately. Aquifers can provide water storage, distribution, and treatment that can be combined with surface water and hydraulic structures to augment water availability more economically and in a more functional and environmental way. Likewise, groundwater possesses other advantages such as its adaptability to a progressive increase in water demand, the possibility of temporary overexploitation as a means of deferring costly construction projects, for mitigating the effects of droughts, and alleviating drainage problems. Another virtue of groundwater in conjunctive use schemes is the insurance role it plays in offsetting the uncertainty surrounding surface flow, hydrological parameters, or water demand. The chapter describes the current types of conjunctive use. Aquifer storage can be used through artificial recharge and alternate conjunctive use. Groundwater is used more during dry periods, while surface water is used more extensively in wet periods in alternate conjunctive use. This strategy enables an increase in water availability through an increase in subsurface storage. The chapter discusses information needs, uncertainty aspects, and the economic implications regarding conjunctive water use. It briefly examines the existing methods for analysis of complex conjunctive use schemes including aquifers and the environmental and water quality aspects. Rules and institutions allow or hamper use of water resources, but water rights and institutional and social aspects implicate incentives or issues that need to be considered for a sustainable conjunctive water use system.