Small Storm Hydrology and BMP Modeling with SWMM5
Stormwater management practices increasingly are required to meet not only peak flowrate restrictions but also are required to include measures that can minimize the impacts on base flow, water quality in receiving waters and erosion in watercourses. The best management practices (BMPs) and low impact development (LID) techniques that are specifically designed to reduce these impacts generally consider small to moderate rainfall events and the hydrologic modeling of these events is in some respect different from the modeling for the larger storms that are typically used in control of peak flowrates.
Small storm hydrology features have been defined and studied for the past 20 y (Pitt, 1987; 1999a) to examine the specific elements that should be taken into account for the design of BMPs used for recharge, quality and erosion control. After a discussion of characteristics of rain-fall events and design criteria, this chapter reviews small storm hydrology concepts and the main findings as they are currently applied in different stormwater management guides. The chapter subsequently describes how SWMM5 (Stormwater Management Model, V5 - as implemented in PCSWMM.NET) could be used to reproduce results obtained empirically in small storm hydrology research, with a specific discussion of design storms. Finally, the use of SWMM5 for the analysis of filter strip, infiltration trench, porous pavement and bioretention is discussed.
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