Quantitative evaluation of eco-geotechnical measures for debris flow mitigation by improved vegetation-erosion model

Eco-geotechnical measures for debris flow mitigation and control have attracted wide attention, but the mitigation effect is lack of quantitative evaluation of coordinated measures. In order to evaluate the debris flow mitigation effect in the combinations of geotechnical engineering and ecological engineering, this study investigated the different trends of debris flows behaviour based on the sediment deposition on the gully bed and the loose material on the hillslope. Besides, this research proposed a new model involving vegetation coverage, source gravity energy and debris flow volume based on vegetation-erosion model. The new model validated that the debris flow volume was proportional to the gravity energy of gravel and rock fragments on the hillslope and inversely proportional to the vegetation coverage in a dry-hot valley setting. Furthermore, a typical area in the valley of the Xiaojiang River in Yunnan Province, China was quantified with the new model. The results showed that under different gravity energy conditions, the implementation order of check dam construction and afforestation was important for debris flow mitigation.