History Low Impact Development (LID) was developed as an alternative to conventional storm-water management. The primary purpose of LID techniques is to restore the natural hydrology of a watershed by decreasing storm-water run-off and removal of sediment and pollutants. Storm-water is usually managed through conventional methods such as gutter, inlets and storm sewers. LID introduces the use of various techniques such as green roofs, rain barrels, rain gardens and vegetated swales. The types of techniques allow of greater infiltration and treatment of rainfall whereas conventional methods simple collect, route and discharge storm-water into streams. The implementation of LID techniques was first used in 1990 in Prince George’s County, Maryland as an alternative to conventional storm-water management. The conventional method typically implemented retention techniques using ponds and basins which were expensive and did not provide a system for water quality improvement. In an effort to continue the implementation of LID the Low Impact Development Center, a non-profit organization, was founded in 1998 to provide support in the adoption of LID as a storm-water management alternative. Governmental institutions overseen urban development are now adopting and implementing LID techniques as well as retrofitting existing conventional storm water management practices. Developing countries, however, are prone to uncontrolled development where the mismanagement of storm waters can have a dire impact on underprivileged communities.
Design LID is most effective when various systems, such as green roofs, rain barrel, and sand filters, are used within the same watershed. This will provide appropriate management and treatment of rainfall and run-off prior to reaching receiving bodies of water. The first step in implementing appropriate LID management is to identify a watershed, make an assessment of its original hydrological characteristics, such as its original infiltration and run-off rates. Secondly, the urban development within the watershed will determine what the location and type of storm-water management techniques that will be most effective and feasible to implement. Focusing on LID practices within rural communities in developing countries were resources, both economic and natural, are scarce the systems implemented must be cost-effective and low-tech. The following are systems which are both cost-effective and low-tech.
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