| Summary: | 碩士 === 國立屏東科技大學 === 土木工程系所 === 101 === Reliable estimations of missing data is an important task for hydrologists, engineers and environmental researchers. This study applies the correlation analysis to assess the accuracy of the rainfall station network for Yenshui river basin. In addition, employ Thiessen polygons to compare maximum one-day precipitation variations in the basin. The objective is to study the effects on watershed rainfall estimation in case data is missing in one of the stations in the network. Then, we apply frequency analysis
for comparing maximum one-day rainfall in different return periods. From the correlation analysis, relationship among the stations is high having correlation between 0.75 and 0.96. Thiessen polygons method shows that in Heshun rainfall station (P04) the weight is highest and in Qiding rainfall station (P05) is lowest. For frequency analysis based on the results, we suggest using the Log Pearson type III method to estimate the return periods of 25, 50, 100 and 200 year in Yenshui River. When P04 is omitted in a 25 year return period the maximum one-day precipitation is 484 mm, Hutoupi rainfall station (P01) is 463 mm and Xinshi rainfall station (P07) is 445mm. In this study it revealed that using Thiessen polygons analysis alone is insufficient and unreliable. Instead, more than one form of analysis should be taken into account in the adjustment and estimation of watershed rainfall under missing records condition.
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