Stormwater is a natural resource that supports water supplies for urban needs, refreshes lakes and rivers, and recharges groundwater tables. Urban development leads to more pavements and impervious surfaces on the ground. Sharply increased storm runoff volumes and flows from urban areas change the spatial and temporal distributions of surface and subsurface runoff in the hydrologic cycle. To mitigate the urbanization impacts, the first priority in developing an urban drainage system is to quickly collect and drain flooding water out of urban areas. The next is to improve the urban watershed to enhance the water quality for the purpose of preserving the water environment.
Following such a thought, this course is first to cover the conventional urban drainage methods to design street hydraulic conveyance capacity, including inlets, gutter flows, sewer drains, and channels. The second part of this course focuses on how to follow the drainage criteria to set up the allowable flow release and how to design a stormwater detention system to reduce the peak flows. The concept of LID, which offers many infiltration-based approaches to improve conventional stormwater drainage systems, is introduced as well. The first 2 weeks in this course cover the hydrologic procedures for rainfall and runoff predictions, and the next 14 weeks focus on hydraulic designs of urban channel, culvert, street inlet, sewer drain, detention basin, retention basin, infiltration basin, LID designs, and stormwater modeling techniques by various routing methods.