因應集水區水文特性之雨洪源頭管理措施政策探討-以桃園地區排洪及下水道建設為例

The Implementation Strategy of Stormwater Source Control Corresponding to Hydrological Characteristics of Watersheds: Sewer Drainage System in Taoyuan as Case Study

邱鵬豪(Peng-Hao Chiu)

指導教授 ： 游景雲

國立臺灣大學/工學院/土木工程學研究所/博士(2022年)

https://doi.org/10.6342/NTU202200125

摘要

近年來歐美等先進國家盛行以源頭管理方式管理都市逕流，我國也參考國外作法修訂相關法規，本研究嘗試以等時線理論發展出概念模式進行探討，將建築基地的水文特性簡化為概念模式的基本單元，其表現逕流的產生、蓄留與滯留等現象，按等時線理論將其劃分為不同等時區，等時區產生的逕流依等時線理論匯集，概念模式中包含雨水下水道與LID設施的經費估算系統，以比較二者經費差異。本研究發現時間面積圖（TAD圖）中，洪峰出現時間約等於面積最大的等時區集流時間加上降雨峰值出現時間，因集水區特性，部分情況洪峰時間必須微幅修正一差值，修正差值與TAD分布及降雨分布有關。此外當LID蓄留設施達滿水位時，設施失去功能，集水區施做LID的歷線會與原始歷線重合，由重合條件與原始洪峰時間相比，可以歸納出蓄留設施消減洪峰之條件；採用滯留設施時，需較蓄留的條件增加設施呈現溢流狀態的時間進行比較；短延時的降雨條件，蓄留消減的效果優於滯留，當延時增加或是降雨強度增加時，滯留的消減效果優於蓄留。在分區設置LID蓄留與滯留設施時，上游區域未施做LID的等時區，無法達到與全區施做相同結果，下游一定區域未施做時，仍可以達到與全區施做相同的效果；部分設置LID遭遇不同降雨時，全區施做與部分設置的結果相同。集流時間較長的流域，所需雨水下水道建設經費較多；對於LID設施體積相對於降雨體積較小的配置，無法達到節省經費之結果；部分區域設置LID可以減少LID的建設經費，但是是否低於未實施LID政策的結果，仍須視個案而定。在以中路重劃區為案例分析時，驗證洪峰時間的理論、以及蓄留後歷線與原始歷線在一定時間後重合的特性，而採用蓄留設施，設施體積與降雨體積比在0.45以上者，不會淹水，在0.3～0.45時，會因為不同條件有淹水及不淹水的情況，若低於0.3時，皆會淹水；案例中下游區域取消LID蓄留設施仍可以達到與全區實施LID蓄留相同的洪峰消減效果，而滯留的效果不佳。本研究藉由水文理論探討逕流在流域的物理現象，達到評估設施量體、找出關鍵配置區域目的。

關鍵字

暴雨源頭控制 ； 滯蓄洪 ； 排放量設計 ； 執行策略

並列摘要

The implementation of stormwater source control facilities has been widely accepted in Taiwan, and officially included by "Building Technical Regulations". Due to the difference in hydrological conditions, the strategy of the implementation of this kind facilities should be modified according to the local characteristics. For this concern, this study establishes a conceptual model based on watershed isochrone theory. According to the conceptual model, the occurrence time of the flood peak is related to the time-area diagram and the rainfall hyetograph. Detention and retention facilities definitely can reduce flood peaks, but finding appropriate locations to install these facilities can achieve the same effect with more cost-saving. This study also utilized Storm Water Management Model (SWMM) to analyze the Chung-Lu rezoning area, Taoyuan, Taiwan. The results indicate that the larger volume of the storage facility comes with a better effect of flood peak reduction. If the storage volume is less than 0.3 times of the total rainfall volume, the retention facilities could be evidently ineffective. This study also examines the result of the conceptual model like key allocation of stormwater source control facilities. It suggests that implementation of the exemptions in the downstream area could still have a similar effect as the application in the entire watershed. Appropriate consideration with spatial allocation in policy could make the implication more economical and effective.

並列關鍵字

stormwater source control facilities ； retention and detention ； outflow design ； implementation strategy

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