Effects of increasing urban impervious surface on hydrology of coastal Rhode island watersheds

Abstract

Increasing the impervious surface area (ISA) from urban and suburban development is a particularly important component of human-induced land-use and land-cover change (LULCC). ISA is a critical factor affecting the cycling of terrestrial runoff and associated materials to and within ocean margin waters. Increasing the ISA causes a series of environmental problems for freshwater and estuarine ecosystems through the alteration of the frequency and magnitude of runoff. It impacts watershed hydrology in terms of infl uencing the runoff and base fl ow and causes problems such as soil erosion and nonpoint source pollution (Arnold and Gibbons, 1996). Runoff from urbanized watersheds frequently contains high concentrations of nutrients and pollutants, which can be harmful to freshwater and marine organisms, and therefore, it has signifi cant impacts on sensitive tidal creeks and estuaries systems (Paul and Meyer, 2001; Schiff et al., 2002). The coastal state of Rhode Island experiences urban runoff problems resulting from urban development. The understanding of how increasing the ISA infl uences the environment, especially the rainfall-runoff relationship, can provide valuable information on land management activities. Wegehenkel et al. (2006) found that a precise estimation of settlement areas in a catchment together with an improved estimation of the degree of the actual imperviousness is required for precise calculations of surface runoff and the fl ood peaks even in a rural catchment with a relatively low amount of settlement areas.