Developing Green Roof Hydrological Model and Application in Stormwater Reduction Analysis
Date Issued
2013
Date
2013
Author(s)
Lo, Wei-Hsuan
Abstract
As impervious area increasing due to the urbanization, along with the impact of the climate change, a new strategy for the urban stormwater management is the distributed system, instead of the traditional centralized treatment and the rapid drainage system. Green roofs are one of the widely-implemented and effective measures. However, compared to other countries’ considerable research on the green roof, the associated research based on Taiwan’s climate and environment is relatively insufficient. Therefore, the purpose of this study is developing the water-balance hydrological model for the green roof, acquiring parameters and validating the model through experimental data. Also, through the observation and model application, the stormwater reduction performance of the green roof is evaluated in order to assess the service it can provide in stormwater management.
The hydrological model for the green roof, NTU-GR, is introduced in this research, providing different priority calculation methods on the infiltration versus the runoff. The parameters used in this model can be divided into two categories; one is the physical characteristics of the medium, which can be obtained through the experiments, and the other comes from the calibration procedure. Based on the rainfall event, the model validation shows the average Nash coefficient is higher than 0.7, which implies the applicability of the model. According to the analysis of the observation data, green roofs can delay the peak for 0~1 hours, and retain 50% of total volume as well as peak value under the large rainfall events, which mean the total rainfall greater than 20 mm. Applying the model to appraise the green roof performance under the historic typhoon and design rainfall cases shows that green roof is not effective in terms of the long duration and high intensity rainfall event; in other words, it is necessary to increase the medium depth or cooperate with other measures to reach the limitation of the present drainage system. This study also preliminarily explores the ability of green roofs to take over other regions’ stormwater in expression of the additional green roof area so that it can achieve the overall stormwater reduction goal, thereby used as the planning and design tool in the future. In summary, this study develops the hydrological model and quantifies the green roof performance of the stormwater reduction. In the future, it is considered to combine with other distributed measures and incorporate into a community-scale stormwater management tool to enhance the adaptation of the stormwater impact in the urban.
Subjects
綠屋頂
實驗設計
水文模式
減洪措施
模擬
Type
thesis
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