###### Abstract
[18] employed numerical simulations to delineate debris flow hazard zones. [PERSON] [19] integrated debris flow modeling with GIS to identify potential hazard zones. [PERSON] et al. [20] utilized GIS for three-dimensional debris flow simulations. [PERSON] et al. [21] developed a coupled model for dynamic hazard assessment, considering landslides as material sources for debris flows. Further research has focused on modeling the entire debris flow process, from initiation to deposition. [PERSON] et al. [22] proposed a two-dimensional hybrid numerical method for simulating the complete debris flow progression. [PERSON] et al. [23] investigated debris flow processes using the Arc-SCS model combined with hydraulic methods and empirical formulas to calculate runoff dynamics. [PERSON] et al. [24] presented a unified framework for addressing rainfall-induced debris flow initiation (triggered by landslides) and subsequent propagation. [PERSON] et al. [25] forecasted debris flow initiation under extremely heavy rainfall conditions. Studies have also explored debris flow risk assessment and mitigation. [PERSON] et al. [26] evaluated potential losses and damages caused by debris flows. [PERSON] et al. [27] developed an optimized fluid volume approach for simulating three-dimensional debris flows. This study employed the FLO-2D numerical simulation method to investigate the Dashiling Gully debris flow in Beijing. The objective was to simulate the movement processes under various rainfall scenarios, both before and after the implementation of mitigation measures, and to evaluate the effectiveness of the implemented gully remediation. A 1:1000 topographic map of Dashiling Gully was obtained through drone aerial photography. High-precision DEM data were acquired using GIS software (10.8), converted into ASCII format, and subsequently used to construct the computational model. Relevant parameters required for the simulation were gathered through field investigations, laboratory experiments, and calculations. The movement characteristics of the debris flow under different pre- and post-treatment conditions were simulated, and the mitigation efficacy of the implemented barrier dam was assessed through comparative analysis. The computation of pertinent kinematic features, such as flow velocity and deposition depth, provides valuable reference data for the management of similar debris flow events. Hazard zones within the Dashiling Gully were identified based on the simulated movement velocity and deposition depth, both before and after the implementation of mitigation measures. Subsequently, the effectiveness of the intervention strategies for debris flow prevention and control was evaluated. The findings of this study offer valuable insights and serve as a reference for managing similar mudslide events. This study aims to identify and assess the hazardous zones in the Dashiling Gully by examining changes in movement velocity and deposition depths before and after treatment interventions. Additionally, we evaluate the effectiveness of these interventions in mudslide prevention and control. The main innovation of this study is to combine the actual engineering projects with numerical simulation, fully consider the impact of three different rainfall frequencies, and reproduce the debris flow movement characteristics under three different rainfall frequencies. Based on the reproduced movement characteristics, a corresponding management plan is proposed, and the feasibility of the scheme is tested again by numerical simulation. The economy can be maximized while meeting the safety requirements.