Stormwater engineers have always been involved in capturing rainwater and transferring it offsite as fast as possible. This program led to the development of a comprehensive system of large, centralized processing facilities selling millions of gallons of stormwater annually – a very efficient, but not very environmentally-minded solution. You can click for more info about low impact development.
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There has been a shift in the way we approach this problem. After decades of development that put efficiency above ecology, short-term convenience, and long-term benefits ahead of long-term benefit, there is now a significant shift.
Green Stormwater Infrastructure (GSI), a subset of low-impact development (LID), is a method of stormwater management that mimics and/or restores the natural water cycle.
GSI aims to reduce stormwater flow to large municipal systems, and the flooding and overflow events that can be caused by their failures.
Stormwater engineers trade pipe flow rates for soil infiltration times, and design methods that keep rainwater at the site, where it lands. This allows them to return rainfall to the natural environment after it has been cleaned.
Stormwater control facilities that are "conventional" include storm drain pipes, catch basins, conveyance channels, and vault-type facilities. These structures and their pipe networks offer a "capture-and-convey" method of stormwater management.
LID offers a wider range of infiltrative and distributed flow management options, including rain gardens, cisterns, and pervious pavements.
LID techniques provide many discharge points through a variety of surface collection options and large infiltration areas. This supports natural discharge locations and mimics nature's water cycle by encouraging distributed stormwater management. This reduces the risks and impacts of single-point discharge points or facilities failing.