A Study of Hydrological Characteristics of Headwaters Forested Watersheds in Ta-Chia Creek Basin in Central Taiwan

• Main Authors: Chia-Hui Chen, 陳家暉
• Other Authors: J. D. Cheng
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/01682868306695466367

碩士 === 國立中興大學 === 水土保持學系 === 90 === The forested watersheds are important for water resources in Taiwan. Past local studies dealt mainly with very small forested watersheds (<2.5km2). This study investigates the hydrological characteristics of four medium sized forested watersheds in Ta-Chia creek basin in central Taiwan by analyzing mainly rainfall and runoff data. The hydrological characteristics of forested watersheds include quantity of annual rainfall、monthly rainfall、annual runoff、monthly runoff、the relationships between rainfall and runoff、equations relating annual runoff to annual rainfall, as well as stormflow and rainfall. In addition, this study calculates the hydrologic response ratio, estimates peak flow with different frequency analyses methods, and based on Hewlett’s constant slope method for separating direct runoff and baseflow, determines the values of total runoff coefficient and baseflow ratio of watersheds. Over the 10 years (1990~1999) period, the average annual rainfall for four study watersheds is 2,390mm and average annual runoff is 1,818mm, suggesting an average annual evapotranspiration loss of 572mm. Maximum hydrologic ratio, stormflow / storm rainfall, is 72.7%, 67.8%, 71.7% and 84.6% respectively for Nan-Hu, Hohuan, Chi-Chia-Wan and Chilo watersheds, indicating flashy nature of stormflows despite with good forest cover. Specific peak flows of 4 study watersheds are all smaller than nearby small sized forested watersheds, reflecting the influence of watershed area. The results of this study should help understand the hydrologic characteristics of forested watersheds in Taiwan.