ABSTRACT
The concept of low-impact development (LID) was evolved from the goal of minimizing the urban negative impacts on the water environment. This chapter presents a comparison between the conventional distributed drainage system and the innovative cascading flow system under the concept of LID. An LID layout applies a cascading flow system to minimize the direct connectivity between adjacent impervious areas. In an urban setting, the runoff flow (Q-problem) of stormwater is directly related to the extreme events for increased peak flow, high-flow velocity, and long inundation. Q-problems are considered more as a public safety issue that can be alleviated by flood mitigation control. There are two major types of LID devices: flow-over porous pavement, and flow-in porous basin. Applications of porous basin include bioretention basin (BRB), rain garden (RG), and porous landscaping detention basin (PLDB). The drain time is defined as the period of time to deplete the water depth in the storage basin.
