Assessing reforestation placement and benefit for erosion control: A case study on the Chi-Jia-Wan Stream, Taiwan

Improper agricultural activities accelerate soil loss and water pollution. A system for assessing reforestation placement and benefit was developed in this study. Digital elevation models, remotely sensed data extracted using fuzzy c-mean algorithm and geographic information systems coupled with sediment yield estimation and vegetated buffer strip models were used to discuss the efficiency of erosion control for land use change from the cultivated land to reforestation on the Chi-Jia-Wan stream watershed. In accordance with the concepts of high sediment delivery ratio and vegetated buffer strips, 35.98 ha of reforestation placements were suggested in the study area. The sediment delivery ratio calculations were based on the concept of the probability density function of the travel time, evaluated as a function of contributing area. From the analyzed sediment results, the suggested placement and overused farmland can reduce 15544.01 and 6339.61 t/year of sediments, respectively. Sediment retrieved ratio of the suggested placement is 2.41 times as high as that of the overused farmland. The results show that the restoration sites made in the related policy should be examined and reassessed.