圖書典藏及影音數位平台

許多易淹水地區位於沿海低地平原，各排水系統之排水能力及淹水減免能力之影響因素包括：(1)集水區中豪雨逕流；(2)相鄰海域及潟湖之暴潮進出；(3)因相鄰集水區間分水嶺高度不足導致之越域水流。故自流域綜合治水之需求而言，應發展可涵蓋沿海低地及其相鄰山區丘陵與海域之淹水─排水演算模式，以比較檢討區域排水系統之排水改善功能及尚需改善地區，並推廣應用。

The objective of this project is to develop a physiographic inundation warning model for the drainage system in the areas covering coastal low-altitude plains and nearby mountain regions, by which the potential maximum inundation depth and range can be estimated after the predicted rainfall and tidal data prior to or during the typhoon period are incorporated. Our results can thus serve as a reference for government in implementing the strategy for the task of disaster prevent, rescue, mitigation, and response. The selected area ranging from the south of the south embankment of the Yanshuei River creek to the north of the south embankment of the Erren River creek was used as an illustrative example for simulation, from which the inundation phenomenon in the watershed can be analyzed. Three storm events, Typhoon Haitang in 2005, and Typhoon Kalmaegi in 2008, and Typhoon Morakot in 2009, were applied to simulate the scenario of inundation and drainage. Our numerical results showed that the inundation primarily occurs in the Yongkang City of the Tainan County, the right side of the Sanye drainage in the Rende Township, the east side of National Highway No. 1 in the Rende Township, the west side of National Highway No. 1 in the Sanye drainage in the Rende Township, the Tiancuo Village, the Sanjia Village, the north side of the estuary of the Erren River, the Dajia Village of the Rende Township near the confluence of the Gangweigou drainage and Erren River, the Erxing Village, the Baoan Village, the Zhongsheng Village, and farming lands along the middle stream of the Erren River. The inundation area is dependent on the rainfall intensity. Comparison of our simulated result with the field investigation showed a good agreement in inundation locations. Therefore, our physiographic inundation warning model is not only reasonable but also reliable to be applied to simulate inundation locations. Then, we also applied our physiographic inundation warning model to simulate the inundation phenomenon with three-hour interval for the area (2,656.65 km2) ranging from the south of the Bachan River creek to the north of the Erren River creek. It only takes 5 minutes for simulation, which represents that our physiographic inundation warning model is efficient to provide imminent results. In addition, our physiographic inundation warning model allows incorporating the real-time data of rainfall, tidal level, and the reservoir discharge so that the accuracy of simulation can be enhanced. The physiographic inundation warning model developed in this project can be used to model the rising process of the inundation depth and the time taken to attain the warning inundation depth. According to the rate of rising of the inundation depth, we can allocate the priority of disaster rescue to arrange the distribution of recourses of movable water pumper, necessary machine, and etc for population, villages, and residence of necessary protection. Under a 24-duration designed rainfall with the return period of 100 years, the greater rate of rising of the inundation depth (i.e. less time needed to be taken to attain the inundation depth of 0.5 m) can be found to occur in the areas around the right side of the Sanye drainage in the Rende Township of the Tainan County, the west side of National Highway No. 1 in the Rende Township, farming lands along the middle stream of the Erren River, the Dajia Village of the Rende Township of the Tainan County, the Erxing Village and the downstream of the Taizi drainage, the confluence of the Tukugou and Yijia drainages. However, the areas around the confluence of the Liujia and Gangweigou drainages, the confluence of the Gangweigou drainage and the Erren River, the east side of National Highway No. 1, and its intersection with Tainan County Highway No. 86 need to take more time to attain the inundation depth of 0.5 m; i.e. the recession of flood is slower. All above-indicated areas need to be more altered before storms induced by typhoons. Based on the rainfall computation for the watershed of the A-Kung-Tien Reservoir during the flood period of Typhoon Fanapi, it was demonstrated that the desiltation of the A-Kung-Tien Reservoir indeed improves its flood-prevent ability. Lastly, based on our promising result, we suggest to develop the platform for disaster prevent by incorporating the ability of imminent computation of our model to provide the hydrological information immediately during storm or typhoon period for the administration responsible for the task of disaster prevent, rescue, mitigation, and response, from which the strategy for disaster alleviation and warning alert can be made in time to enhance the effectiveness of disaster rescue.