| Summary: | 碩士 === 銘傳大學 === 都市規劃與防災學系碩士班 === 103 === The spreading in the impervious surface caused by the past rapidly land development heavily increased the runoff. Moreover, the traditional urban planner using the sewing system as major measurement to lead the water to the river rapidly which will generate the runoff in the peak time. Therefore, whenever there is severe weather or typhoon, flooding happens frequently in Taiwan. Currently the flooding adaptation measures by spatial planning in the Ellb river basin of European Union and the Making space for water policy of United Kingdom claim the changes from structural mitigation strategy- leading the water into the river quickly through sewing system, to the non-structural mitigation strategy- keeping the water in the land through spatial planning. Therefore, this study tries to use different land-use to detention water and to reduce runoff, and hopefully reduce the frequently of flooding.
This study chooses the downstream catchment of Zhuoshuei River as case studying area. This study designs different land-use planning strategies and set up various detention space in the above strategies by five rainfall recurrence interval events to calculate the decrease of the runoff through the HEC-HMS model developed by the US Army Corps of Engineers hydrology research center. This study finds that by changing the land cover form and detention in the agricultural and river areas in the non-urban area can decrease at most 14 million m3 of runoff due to non-urban land area accounts for 96% of the studying area. Among of the above results, the highest efficiency is in 2-year return period, ranging from 16% to 52%. The efficiency of 100-year return period is from 3% to 8%. Detentions in the urban area are made of agricultural paddy fields, storm water ponds and rainwater retention system in building basement. Although urban area can provided 1 million m3 of runoff to be stored, but the result is not significant due to the urban are is only 4% of the study area. By changing land cover, 2-years return period has the efficiency of 9%, and 100-year return period is 2%.
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