Abstract
Groundwater exchange affects the ecology of surface waters by sustaining stream baseflow and stabilizing the water level of groundwater-fed lakes. It also provides stabletemperature habitats, and supplies nutrients and inorganic ions. Groundwater input of nutrients can even determine the trophic status of lakes and the distribution of macrophytes. In streams the mixing of groundwater and surface water in shallow channel and bankside sediments creates a unique environment called the hyporheic zone, an important component of the lotic ecosystem. Localized areas of high groundwater discharge in streams provide thermal refugia for fish. Groundwater also provides moisture to riparian vegetation, which in turn supplies organic matter to streams and enhances bank resistance to erosion. As hydrologists and ecologists interact to understand groundwater' s impact on aquatic ecology, a new research field called“ecohydrology”is emerging.
