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COMPREHENSIVE RESEARCH AND MANAGEMENT OF IMPERVIOUS SURFACE IMPACTS ON WATERSHED HYDROLOGY
Citation:
Shuster*, W D., Y. Zhang, H. W. Thurston*, AND A. Mayer*,A.L. COMPREHENSIVE RESEARCH AND MANAGEMENT OF IMPERVIOUS SURFACE IMPACTS ON WATERSHED HYDROLOGY. Presented at The U.S. EPA Regional/State/Tribal ORD Science Topic Workshop on Environmental Indicators, Kansas City, MO, May 17 - 20, 2004.
Impact/Purpose:
To inform the public
Description:
Impervious surface is one of the primary agents of hydrologic change in urbanizing watersheds, and its impacts on hydrologic cycles and terrestrial ecological regimes are multifold. The mechanisms through which these impacts are manifested are not well understood, hampering effective management of these impacts. Here at the USEPA National Risk Management Research Laboratory, Sustainable Environments Branch, we are concerned with promoting multidisciplinary approaches to sustainable environmental management systems through the integration of hydrologic, ecological, economic, and legal perspectives. One way that we articulate this mission is through the examination of storm water runoff regimes in urban ecosystems and how these might be better managed. We have identified two areas of focus, the first is in-situ assessment of the alteration of hydrologic cycle in response to urbanization; and secondly systemic, low-cost participatory approaches to managing storm water runoff at the watershed scale. There are few or no studies that we are aware of which determine the underlying mechanisms and extent of these impacts over the course of landscape alteration through the incremental addition of impervious surfaces over time. The USDA-ARS and USEPA-ORD-NRMRL have initiated a pilot program to study the impacts of different extents and geometries of simulated impervious surface on 1.5 ha experimental watersheds located at the North Appalachian Experimental Watershed, Coshocton OH (USA). As a complement to the experimental investigation of fundamental processes in urban hydrology, we explore distributed stormwater management practices that may mitigate the deleterious impacts of stormwater flows in a previously developed 150 hectare residential neighborhood where impervious surface impacts are typically left unmitigated. Here, we use an urban watershed as a pilot study to determine whether parcel-level Best Management Practices (BMPs; e.g., rain gardens) can be implemented throughout the residential areas, and on the basis of an economic incentive program, which itself centers on trading detention responsibility among parcel holders to achieve a preset watershed-level cap on runoff. We have implemented an before-after/control-impact experimental design and initiated hydrologic and ecological monitoring at five stations distributed across the various land uses and impacted areas to determine whether the placement of BMPs at the parcel level in the residential area have effected an improvement in hydrologic and ecological status for tributaries draining urbanized areas of the watershed. We present a basic description of experimental approach for these projects followed by a summary of field data and discussion of preliminary modeling results.