Abstract

The development of a soil erosion prediction model applicable to Taiwan (subtropical area) is a very important issue for the sustainable development of soil and water resources. Both the Universal Soil Loss Equation (USLE) and the Revised USLE (RUSLE) are the most widely used soil erosion prediction models in the world at present. However, the regional variability of the parameters (including the rainfall erosivity factor) needs to be considered during the application of the models. The main objective of this study is to investigate the variations of rainfall erosivity (R-factor) and the rainfall characteristics in different areas of Taiwan.

Experimental results indicated that both the median raindrop diameter and the rainfall kinetic energy increased with an increase of the rainfall intensity. In general, for the western area of Taiwan (west of the Central mountains) the mean annual rainfall amount was about the same, while the mean annual rainfall erosion index increased with a decrease of the latitude due to the increasing effect of Typhoons. On the other hand, both the mean annual rainfall and the mean annual rainfall erosion index increased with an increase of the latitude due to the influence of the northeast monsoon for the northern and eastern areas of Taiwan. In addition, an isoerodent map of Taiwan was also developed for the practical application.

Keywords: Soil erosion, rainfall erosivity, rainfall kinetic energy