| Summary: | 碩士 === 國立中央大學 === 土木工程研究所 === 91 === The weather in Taiwan, being located at the subtropical zone in western Pacific Ocean, is the typical island climate. The damage of typhoon events happened to Taiwan can be related to its characteristics such as the temporal-spatial disproportionate distribution in precipitation. This study not only focuses to identify the precipitation in typhoon events but also provides in sights to Shih-Men Watershed for engineering design。
The precipitation record of typhoon events form 1986 to 2001, based on the Central Weather Bureau and 15 rain-gages in Shih-Men Watershed is used for analysis on this study. Firstly, the time-variant model and non-variant model are employed to discuss the spatial variability of different rainfall duration, and the typhoon of HEB(1996)、TORAJI(2001) and NARI(2001) is taken for case study. Secondly, the difference of regional precipitation have been compared by applying Arithmetical averaging method、Thiessen polygons method and Kriging method. Finally, this study estimates the rainfall of the Shih-Men Watershed by using different sets of rain-gage record and to detect the effective of statistical accuracy.
From the results, it is not suggesting to describe precipitation properties by applying Kriging method in the case of short duration, because there exists obviously error of counting value. But the errors are becoming less with increasing of rainfall duration. Therefore, applying traditions precipitation methods to estimate original area mean rainfall should be considered carefully. For short rainfall duration cases, the results show obviously difference among Arithmetical averaging、Thiessen polygons and Kriging method. However, as the increasing of rainfall duration, the difference decreases. To obtain a acceptable accuracy, the method of Arithmetical averaging can be used with more than one-third rain-gages on this watershed, while Thiessen polygons method should be with more than half of total gauges to estimating area mean rainfall.
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