ABSTRACT
Wise use of the different and complementary characteristics of surface and subsurface components through conjunctive use of surface and ground water can achieve greater yields, economic, or functional advantages than separate management of both components. One complementary characteristic is the large volume of water stored in aquifers, from tens to hundreds of times their annual recharge. In the same way, volume of aquifer storage provided by a relatively small fluctuation of the piezometric head in unconfined aquifers considerably exceeds the available or economically feasible surface storage. That allows the use of water in storage during dry seasons as well as the use of the subsurface space for storing surface or subsurface water. The existence of aquifers over ample areas of a basin adds to the benefits of water storage those of distribution and conveyance. Moreover, long-term storage in and passage through a ground water aquifer generally improves water quality by filtering out pathogenic microbes and many, although by no means all, other contaminants.
