| Summary: | 碩士 === 中華科技大學 === 土木防災工程研究所 === 98 === ABSTRACT
Precipitation characteristics in Taiwan have shown differences in recent years due to the impacts of global climate change. This paper chooses the Sanhsia River basin as the study site and uses the anomaly method to analyze the trends of various precipitation characteristics with rainfall data from Tabao station, Sanhsia station and Fusan station and examine the effect of variation in precipitation characteristics on runoff and sediment discharge. According to the study findings, through the analysis on the trends of precipitation characteristics, the annual rainfall, number of annual rainy days, annual average daily rainfall intensity, annual 1-day maximum rainfall and annual 2-day maximum rainfall show an increasing trend in all stations, except Sanhsia rain gauge station where annual rainfall slightly decreases.
With respect to the examination of runoff and sediment discharge, this study analyzes historical data (1974-2008) from Sanhsia station (2) of the Water Resources Agency and finds the annual maximum daily mean discharge, annual maximum peak discharge signal a gradual rise year by year in the basin. In addition, with the year 1990 as a change year, this paper carries out an analysis of variations in runoff-sediment discharge before and after 1990, the study finding shows no significant differences in sediment discharge between before and after 1990 under the same daily mean discharge. Also, this paper takes the year 1999 (when the 921 Earthquake hit central Taiwan) as the baseline and observes changes in sediment discharge before and after 1999. According to our findings, under the same runoff, earthquake effects have no significant impacts on sediment discharge in the study site, suggesting that changes in precipitation characteristics and earthquake effects will not result in any change in sediment discharge.
Keywords: hydrological characteristics; anomaly method; temporal hydrological variations
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