Dynamic simulation of debris flow waste-shoal land use based on an integrated system dynamics-geographic information systems model

Given the increased conflict between human development and land use in fragile mountainous areas, debris flow waste-shoal land (DFWSL) use has shown beneficial effects and drawn public concern in recent years. However, temporal-spatial future change trends of DFWSL are not yet clear, meanwhile widely applied singular methods, including the system dynamics (SD) model and geographic information systems (GIS), are unsatisfactory. To better assess the sustainability and challenges of DFWSL use and provide reference for future development, we propose a hybrid SD-GIS model for characterizing complex relationships and performing dynamic simulations and spatial spreading. A causality flowchart was plotted and response equation defining the changes was established to predict macro land-use demands in the SD model component. Additionally, the spatial distribution of land-use types was determined using the GIS model component. The Awang DFWSL system in the Yunnan Province, China was analyzed using the coupled method. The results revealed a steadily declining trend in cultivated land and water areas accompanied by a substantial increase in construction land. Future projections indicate that from 2018 to 2025, the total area of cultivated land will decrease by nearly half compared with that in 2018 and decrease to one-quarter of the level in 2018 by 2030. These predictions consider the reciprocal influences of social, economic, and ecological indicators, and risk factors, such as debris flow scale and frequency. This study provides a new approach for estimating future trends of DFWSL use and increases the awareness of the spatiotemporal changes encountered when using marginal land.