| Summary: | 碩士 === 銘傳大學 === 都市規劃與防災學系碩士班 === 105 === In response to the threat of flooding, the concept of “mitigation” has been included in land use planning and management in related domestic and foreign literature. And “urban stormwater management” is the trend of strategy development for resolving the issue of urban flooding, stressing building hierarchical and systematic spaces for rainwater harvesting and infiltration, in order to hold rainwater to prevent it from going directly to sewers immediately. In Taiwan, attempts to include related strategies in urban planning, urban design, and building management phases have been made, yet these strategies are all incomplete and fragmental flood prevention strategies which cannot help to efficiently identify the overall water flow paths (the distribution of rainwater harvesting and infiltration spaces) in a region and the actual influences on runoff rates in that region. Thus, the core spirit of stormwater management cannot be put into practice.
The research subjects of this study are the urban drainage (rainwater sewer systems), public facilities, and rainwater harvesting and infiltration facilities of private buildings in a rather small-scale “downstream urbanized area”. From the perspective of urban design, this study focuses its research area on the regional drainage in the first-phase development zone of Danhai New Town. Through the SWMM5 model, this study simulates the runoff rates in three different development scenarios with short duration rainfalls in 2 to 100-year recurrence-interval and proves that urban development can indeed increase the runoff rate from 2.91 CMS (about 38%) to 3.93 CMS (about 22%). The effects of runoff reduction of five different urban stormwater management strategies in this region are compared. It is found that if the rainwater harvesting amounts of the public facility areas and private building foundations are above the minimum required amount defined by the New Taipei City Directions Governing the Application for Rainwater Harvesting and Conservation Reuse Related Facilities and low-impact development facilities / stormwater management facilities are included during the committee stage of the urban design, in the recurrence period of 2 to 5-year recurrence-interval, the runoff rate is reduced by 4.68CMS to 5.47CMS (about 44% to 42%). Thus, this study suggests to add the “stormwater management” category for the urban design review regulations, to cover the contents related to limitations on legal vacant lot and underground excavation, foundation water infiltration and conservation, and foundation drainage and to integrate them to develop a water flow system, for the purpose of putting the stormwater management strategies into practice.
|
|---|
