近年來隨著工商業發展伴隨而來的是高度的都市化，導致人口逐漸向災害敏感地區密集，都市化造成地表不透水層面積增加，以致減少雨水之入滲機會，造成地表逕流之增加，引起都市集水區之排水問題。對於都市逕流管理之對策，過去大都強調將流域降雨逕流集中往河川下游匯集，末端排洪集中處理，近期已開始改變利用流域綜合性防洪減撈措施。雨水貯集系統依據型式不同具有增加集流時問、提供滯洪、滯留空閒及增加地表入滲的功能。因此藉由雨水貯集系統的應用，對於逕流體積之減少與尖峰流量的衰減具有顯著的功效，流量延時也可得到適當的控制，並可由各型式雨水貯集系統的特性，使得其具有自然生態環境資源改善等附加效益。雨水貯集系統具備供水、逕流消減及水資源保育的功能，本文將先對都市化水環境作一探討，並對雨水貯集系統在都市減洪應用的功能與型式上作一詳細的介紹。
As a result of recent economic development, the high level of urbanization has led to population concentration in disaster-prone areas. Urbanization often increases the impermeable surface area, reduces rainwater percolation, enhances surface runoff, and induces urban watershed drainage problems. In the past, urban stormwater management usually diverts runoff downstream and uses the end-of-pipe method to dispose of urban flood water. Nowadays, the emphasis has changed to using integrate watershed flood control method. Different rainwater catchment systems may increase runoff concentration time, provide either retention or detention space, and enhance surface infiltration. Combination use of various types of rainwater catchment systems should be extremely effective in reducing runoff volume and peak flow, and adequately controlling the flow duration. It may also provide beneficial ecological, environmental, and resources conservation side-effects. Rainwater catchment systems have the capability to supply water and reduce runoff, as well as conserving water resources. This paper briefly outlines the water environment in urban areas and discusses in great detail the urban flood reduction ability of different types of rainwater catchment systems.
