都會區水文水理快速淹水模式

Integrated Hydrological and Hydraulic Model for Rapid Flood Assessment in Urban Area

劉昱偉(Yu-Wei Liu)

指導教授 ： 張倉榮

國立臺灣大學/生物資源暨農學院/生物環境系統工程學研究所/碩士(2021年)

https://doi.org/10.6342/NTU202100086

摘要

近幾年在氣候變遷的影響下，短延時強降雨事件的增加進而導致都會區淹水事件頻繁地發生，現行水利署制定的淹水預警簡訊通報系統可提供即時預警資訊，使政府機關與民眾盡早做好防淹準備。然而水利署現行之淹水警戒並未多加考量到現地的實際情況，且警戒範圍多以村里為主，若要得知準確且詳細的淹水情況，以往多以二維淹水模式來模擬淹水範圍，此方法雖然有精準的淹水範圍，但因計算時間過長，通常只能在非災害期間預先模擬完多種降雨情境，找出易淹水區域後再做為防災工作的參考。因此發展“都會區水文水理快速淹水模式”，利用合理化公式計算降雨逕流以作為下水道系統入流量，並考慮地表排水系統的排水能力，以及利用非線性水庫概念去模擬水體在雨水下水道系統中的流動狀況，最後將模擬結果結合淹水警戒範圍以發布淹水警報，並與暴雨經理模式進行偵測率、精確度、預兆得分、NSE值與模式演算速度進行分析與比較。
本研究以臺北市雙連次分區域作為研究區域，並以四場歷史降雨事件進行模式之模擬與結果分析。結果顯示，都會區水文水理快速淹水模式於下水道水位的模擬結果與暴雨經理模式相似，而在有積淹水紀錄的兩場降雨事件中，該模式於防災警戒上的預兆得分分別以0.71和0.83，優於暴雨經理模式的0.58與0.32，且演算速度上其模擬時間僅需暴雨經理模式的70%，顯示本研究所發展之都會區水文水理快速淹水模式在淹水預警上可提供快速且準確的預報。

關鍵字

淹水模擬 ； 都會區淹水警戒 ； 雨水下水道 ； 非線性水庫

並列摘要

In recent years, urban areas are much more prone to flooding disasters due to increased short-duration heavy rainfall events in Taiwan. Currently, the warning system of flooding disaster established by Water Resources Agency provides immediate flooding warning information to not only the government but also the public in order to increase the leading time of flooding prevention. Nevertheless, the warning system only relates total rainfall amount to flooding-vulnerable regions without considering actual situations of site. Furthermore, warning regions raised by the warning system are delineated in village level. In recent years, two-dimensional inundation models are used alternatively to get detailed and accurate predictions of potential flooding areas. However, as the computational time of the two-dimensional models still exceeds the leading time of flooding prevention, flooding-vulnerable regions could only be located during the non-disaster period.
In the present study, Rapid Hydrological and Hydraulic Flood Assessment Model in Urban Area is proposed to provide real-time warning information. The proposed model uses the Rational Formula to calculate rainfall-runoff as the inflow to storm sewer system, utilizing the non-linear reservoir concept to simulate the water flow in the storm sewer system, and applying the simulation results to the new flood warning regions to issue a flood warning. Four indicators are used to compare the accuracy of the proposed model with the Storm Water Management Model (SWMM), i.e., Probability of Detection (POD), Precision or Predictive value (PPV), and Threat Score (TS) for flooding regions, and Nash-Sutcliffe efficiency coefficient (NSE) for sewer water level. The computational time is also compared to demonstrate the efficiency of the proposed model.
In this study, the area between Datong district and Zhongshan district in Taipei City is selected as the case study area. Four historical rainfall events are simulated by the proposed model and the SWMM. The comparison of the accuracy and efficiency reveals that, simulated sewer water levels by the proposed model are in good agreement with those by the SWMM. Furthermore, by the measured records of flooding in two historical rainfall events, the Threat Score (TS) of the proposed model on flooding prevention are 0.71 and 0.83, respectively, whereas the Threat Score (TS) of the SWMM are 0.58 and 0.32, respectively. Clearly, in consideration of accuracy, the proposed model outperforms the SWMM model. As to computational time, the proposed model is 30% faster than the SWMM. In summary, the Rapid Hydrology and Hydraulic Flood Assessment Model in Urban Area efficiently gives accurate prediction of potential flooding area, thus can be used on real-time flooding warning system.

並列關鍵字

Inundation flooding simulation ； Urban flooding warning ； Storm sewer ； Non-linear reservoir

參考文獻

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