Groundwater and surface water are not isolated components of the hydrologic system, but instead interact in a variety of physiographic and climatic landscapes. Therefore, an understanding of the basic principles of interactions between groundwater and surface water is needed for effective management of water resources.
Despite its general abundance, water does not always occur in the place, time or in the desired form. People strive to grow crops and other water-consuming products in semi-arid regions, and they attempt to use water simultaneously, as a pure source, and deliberately or inadvertently, as a dump for waste. Consequently, the world faces a serious water management problem. The decline of groundwater levels around pumping wells near a surface-water body creates gradients that capture some of the ambient groundwater flow that would have, without pumping, discharged as baseflow to the surface water.