The purpose of this research is to study the dynamic change of hydrologically sensitive areas in the Lien-Hwa-Chi watersheds during different seasons. We apply the soil moisture routing model (SMR) to estimate soil saturation degree and probability of runoff generation in the study area, and to analyze the relationship between topographic index and probability of runoff generation. Based on the relationship, we identify the hydrologically sensitive areas in March, June, September, and December. Results show that the topographic indices in Lien-Hwa-Chi watershed No. 4 and No. 5 range from 2 to 15, and have a positive linear relationship with probability of runoff generation. Through the application of SMR, the soil saturation degree is properly estimated. The highest value of soil saturation degree is in June, and the lowest value is in December. It is obvious that soil saturation degree varies with different seasons. In addition, the probabilities of runoff generation in Lien-Hwa-Chi watershed No. 4 and No. 5 are highest in the summer-wet season, and are lowest in the winter-dry season. Finally, based on the same value of topographic index, the probability of runoff generation in Lien-Hwa-Chi watershed No. 4 is higher than that in watershed No. 5.
- hydrologically sensitive areas
- saturation degree
- soil moisture routing model
- topographic index