Temporal and Spatial Variations of Rainfall and Rainfall Erosivity in Eastern Taiwan

• Main Authors: Wei-Ze, Liou, 劉維則
• Other Authors: Ming-Hsi, Lee
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/28389074657954001090

碩士 === 國立屏東科技大學 === 水土保持系所 === 102 === In recently years, frequency of high intensity rainfall, long rainfall duration and heavy rainfall are found to increase in Taiwan (Chen, 2008). Rainfall erosivity index R is a key input parameter to the USLE. R describes the soil loss potential caused by precipitation, which can be understood to change in correspondence to changes in extreme rainfall events. R is calculated from the total kinetic energy and the maximum 30-min rainfall intensity of a storm. Therefore, a lack of short duration rainfall intensity data in some countries makes applying the rainfall erosivity index more difficult. For those areas without the data and resources required to calculate rainfall erosivity index, an alternative approach has typically been used to estimate rainfall erosivity index. The purpose of the present study is estimating the rainfall erosivity based on event, monthly, seasonal, dry and wet seasonal and annual precipitation data, respectively. Temporal and spatial of rainfall and rainfall erosivity variations are investigated using 19,106 effective rainfall events by 51 rainfall stations of the Central Weather Bureau (from 1993 to 2012) in eastern Taiwan (Yilan, Hualien, Taitung). The result shows that maximum annual rainfall erosivity varied from 12,217 to 173,529 MJ-mm/ha-hr-yr. Rainfall and rainfall erosivity have a strong positive relationship. Temporal variation of rainfall erosivity shows that the average monthly, seasonal and yearly rainfall and rainfall erosivity increase year by year. The spatial analysis shows average annual rainfall erosivity increases from plain to mountain region, and from southern to northern (from Taitung to Yilan). Average annual rainfall erosivity is highly related with the latitude. In addition, rainfall erosivity index is affected by the typhoon and the northeast monsoon in eastern Taiwan.