Objective The shallow mountain area on the edge of city is the buffer zone where human production and living meet the natural habitat. It is also an area where the human settlement environment is more vulnerable to natural disaster risks such as debris flows. Compared with reducing the threat of natural disasters in shallow mountain areas through engineering methods, disaster prevention forest site planning as an ecosystem-based approach, can restore healthy ecosystem, provide diverse ecosystem services, and effectively reduce the risk of natural disasters, so as to improve the resistance and adaptability of human settlements to natural disasters.
Method This study proposed a site selection system of debris flow disaster prevention forest from the perspective of human settlement safety, and evaluated the effectiveness of planned disaster prevention forest to reduce the risk of debris flow in human settlements. Based on analytic hierarchy process (AHP), the susceptibility prediction of debris flow based on maximum entropy model (MaxEnt) was taken as debris flow risk factor, and suitability of afforestation locations in the debris flow basin that reduce the probability of debris flow disasters was taken as environmental factor for afforestation, and combined with afforestation feasibility factor, three kinds of factors were superimposed to analyze the areas with high debris flow risk and suitable for afforestation. The susceptibility of debris flow and the risk of human settlements before and after afforestation were evaluated to assess the disaster reduction benefits of afforestation, and to guide the afforestation site selection of debris flow disaster prevention forest in shallow mountain area of Beijing.
Result The study selected 118.50 km2 of afforestation area, mainly distributed in the surrounding areas of Miyun Reservoir and the mountainous areas of Huairou District, Changping District and Fangshan District of Beijing, showing the characteristics of scattered patches distributed in the upstream of human settlements. The area of debris flow high-prone area decreased by 117.45 km2, and the number of settlements in the debris flow high-prone area decreased by 51.
Conclusion The purpose of this study is to build a framework for afforestation site selection that enhances resistance to debris flows in human settlements, in order to reduce the risk of natural disasters in mountainous areas through ecosystem-based approach, improve the quality and safety of human settlements, protect the health of ecosystem, and provide a theoretical basis for the Beijing a-Million-Mu Afforestation and Greening Action Plan.