urban stormwater runoff a new class of environmental flow problem城市雨水径流环境流问题的一个新类.pdfVIP

Urban Stormwater Runoff: A New Class of Environmental Flow Problem 1 1,2 2 Christopher J. Walsh *, Tim D. Fletcher , Matthew J. Burns 1 Department of Resource Management and Geography, The University of Melbourne, Parkville, Victoria, Australia, 2 Department of Civil Engineering and Monash Water for Liveability, Monash University, Victoria, Australia Abstract Environmental flow assessment frameworks have begun to consider changes to flow regimes resulting from land-use change. Urban stormwater runoff, which degrades streams through altered volume, pattern and quality of flow, presents a problem that challenges dominant approaches to stormwater and water resource management, and to environmental flow assessment. We used evidence of ecological response to different stormwater drainage systems to develop methods for input to environmental flow assessment. We identified the nature of hydrologic change resulting from conventional urban stormwater runoff, and the mechanisms by which such hydrologic change is prevented in streams where ecological condition has been protected. We also quantified the increase in total volume resulting from urban stormwater runoff, by comparing annual streamflow volumes from undeveloped catchments with the volumes that would run off impervious surfaces under the same rainfall regimes. In catchments with as little as 5–10% total imperviousness, conventional stormwater drainage, associated with poor in-stream ecological condition, reduces contributions to baseflows and increases the frequency and magnitude of storm flows, but in similarly impervious catchments in which streams retain good ecological condition, informal drain