Low-Impact-Development Practices for Stormwater: Implications for Urban Hydrology

Abstract

Since 1970, the design focus of urban stormwater systems has expanded from quick removal of stormwater to include control of peak flows (1970s) and removal of pollutants (1980s). The addition of stormwater ponds as control elements satisfied these two concerns to some extent, but further concerns arose in the 1990s related to changes in flow patterns in urban receiving waters, such as extended periods of high flow rates and reduced baseflow. These changes result from altered surface water storage, reduced evapotranspiration and infiltration, and increased runoff in urbanized areas and cause unintended damage to ecosystems dependent on surface water and groundwater. An alternative form of urban development and stormwater management, called Low Impact Development (LID), provides for urban development while maintaining hydrologic and water quality characteristics closer to those existing prior to urbanization. This study used watershed modelling to evaluate the capability of LID techniques to mitigate the impact of urbanization on hydrology using a catchment area in Kitchener, Ontario as a case study. Results are consistent with those reported in recently published papers and demonstrate that LID practices have the potential to minimize the undesirable hydrologic effects of urbanization not only in new developments but also in a retrofit application.