A framework of the planning of priority revegetation areas for debris flow mitigation based on microclimate processes in dry-hot watersheds

Vegetation restoration is a critical strategy for mitigating debris flow hazards by stabilizing slopes and modifying hydrological processes. Effective planning of priority restoration areas is particularly essential in dry-hot valley regions, where extreme hydrothermal conditions pose significant challenges. This study presents a novel framework that integrates microclimatic variables, such as temperature lapse rates, to enhance the spatial precision of revegetation efforts. The Reshuihe watershed in Southwest China, a representative dry-hot valley, was chosen as the study area. By analyzing hourly temperature and rainfall across an elevation gradient, a quadratic relationship between temperature lapse rates and weak rainfall events was identified, underscoring the role of microclimatic processes in influencing rainfall distribution and plant-available water. Rainfall peaks were observed when the temperature lapse rate was approximately 4.5℃/km. This relationship was incorporated into a cost-based restoration framework using the Marxan model, optimizing the spatial allocation of priority areas for revegetation. Results demonstrated that integrating microclimatic variables significantly improved the effectiveness of revegetation strategies, particularly for reducing debris flow risks. The lowest restoration costs were observed between elevations of 3200 m and 3300 m, where strong correlations between temperature lapse rates and rainfall were recorded. Priority restoration areas covered 41 km², targeting zones with high debris flow risks. These findings highlight the value of incorporating microclimatic data into revegetation planning, enabling cost-effective and ecologically sustainable hazard mitigation in regions vulnerable to hydrological hazards.