景美溪集水區年際及豐枯水期水文特性變化之研究

The Jingmei stream watershed, located in the Taipei metropolitan area, has been selected as a study area for this research to understand the changes in hydrological characteristics during annual and wet-dry periods and for comparing the differences between rainfall and runoff during different return periods. The annual wet-dry periods' rainfall and annual wet-dry periods' runoff from 1970 to 2009 were analyzed using frequency analysis. Four probability distributions were compared, including extreme-value type I distribution, logarithmic normal distribution, Pearson type III distribution, and logarithmic Pearson type III distribution to study the variation trend of hydrological characteristics under climate change conditions. The results show that the extreme-value type I distribution is suitable for annual rainfall of the wet-dry period, while the logarithmic normal distribution is favorable for annual and wet period average runoff. However, the extreme-value type I distribution is comfortable for dry period average runoff. Moreover, the rainfall and runoff during the wet periods in a late stage (1987-2009) are higher than that in an early stage (1970-1986). In contrast, the rainfall and runoff during the dry period in late stages are lower than that of the early stages. Conclusively, there is a phenomenon of polarization for rainfall and runoff in the study area. The water of rainfall and runoff is more abundant during wet periods, while the water is insufficient during dry periods. This is unfavorable for water resource management in the future.