| Summary: | 碩士 === 國立中興大學 === 水土保持學系 === 90 === Xangsane typhoon brought heavy rainfall when she was invading Keelong River watershed and caused serious flood in some areas include Keelong city and Taipei city and Taipei country, and brought hundreds of people to be dead in 2000 late autumn. Compared to the water level and the extent of the flood drown area with Lynn typhoon in 1987, Zeb and Babs typhoons in 1998, the drown area was much larger. During this period, there were quite many reports indicated that the rainfall on the upper Keelong River was too heavy, when combined with the raising tide. The flood level of the lower Keelong River area was too high. Eventually, the three cities along Keelong River was drown seriously that caused people lived poorly and the life and property was forced to danger.
This research began with the natural and manmade factors, and then compared with the four mentioned typhoon events (Lynn, Zeb, Babs, Xangsane) which caused serious flood disasters recently around Keelong River. This research used the GIS software (Arc/info, Arcview), RS software (Imagine) and Wingrid system to analyze and integrate all the data of the watershed, finally to investigate the relationship between the tide and typhoons, besides the effect on Keelong River which is caused by manmade reason. Finally, we show the most important factors those caused the flood disasters and debris disaster in Keelong River, and then mention the improvement methods to review and discuss the experience that human beings make mistakes accidentally; and can be referred by government on trying to achieve the goal of reducing the disaster caused by typhoon storms.
The results of this research indicate that the reason of flood disaster around Keelong River is that the slope of downstream is too mild. After the construction of cutting the curve river to get straight, the length of river got shorter, the slope of riverbed got steeper, and the capacity of water storage also got lower. In case the typhoon happened on October accompanied with northeast trades and the tides, the probability of causing flood disaster would get raising absolutely. Otherwise, owing to the destruction of natural environment and get land from river causing by human beings continuously and purposely. It induces the runoff volume, the discharge of flood peak and the ratio of waterproof from ground to get larger year by year. So it’s one more important point which is unable to be ignored and must pay much attention to.
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