Reducing Directly Connected Impervious Areas with Green Stormwater Infrastructure

Abstract

The emerging field of urban watershed protection often lacks a unifying goal to guide the efforts of many of its multidisciplined participants—planners, engineers, landscape architects, scientists, and local officials. This lack of common goal has made it difficult to achieve a consistent result. This paper proposes to define a unifying goal based on a physically defined unit—imperviousness. Many studies have dealt with total impervious area (TIA), but oftentimes this TIA contributes minimally to the pollutants that accumulate on impervious surfaces and wash into New Jersey’s waterways during storm events. The purpose of this study is to examine and quantify mitigation strategies that are designed to reduce the impacts of directly connected impervious areas (DCIA). It is the DCIA that are directly harming local streams, rivers, lakes, and bays. By implementing green stormwater infrastructure (GSI) in a given watershed to directly intercept the runoff washing off of these DCIA, water quality, aquatic life, runoff volumes, peak discharge, and baseflow effects can be reduced, and stream quality can be improved.