Conjunctive use as potential solution for stressed aquifers: social constraints

Aquifers can provide water resources storage, distribution and treatment that can be combined with surface water resources and hydraulic structures to augment water availability more economically and in a more functional manner. The paper describes the two major types of conjunctive use in existence. These are alternative conjunctive use systems and comprehensive systems. They differ in the use of subsurface storage. The simplest system is alternative conjunctive use in which target yield is obtained in dry years through increased pumping. When more than average water is available in streams or surface storage, more surface water is used allowing more groundwater to remain in storage. This strategy allows water supply to be increased without the need to augment surface storage. The other system is termed comprehensive conjunctive use. In this system surface water is closely related to artificial groundwater recharge and a more complex infrastructure is required for its successful operation. The economic implications of conjunctive use advantages and the need for integrating groundwater into water resources planning and management are discussed. The chapter also discusses the existing laws defining water rights, in addition to rules and institutions, which are critical to permitting or hampering the application of conjunctive use. Conjunctive use potential in the developing world is analyzed. Lately the need for integrating groundwater resources in water resources planning is advocated plus the need for more advanced methods of analysis of the most complex water systems involved.