Visualization modeling of residual plastic film distribution in the plow layer of cotton fields and simulation verification of water movement

The "white pollution" caused by residual plastic film (RPF) in farmland soil has emerged as a prominent environmental issue, while the fine-scale spatial distribution characteristics and ecological effects of RPF in the plow layer remain unclear. In this study, based on field grid sampling and point cloud imaging technology, the point cloud data of RPF were segmented and reconstructed. Subsequently, 3D visualization models of RPF were successfully established for three plow layer soil quadrats, each with dimensions of 1 m × 1 m × 0.5 m. Statistical analysis revealed that 77%–87% of the RPF accumulated in the 0–30 cm soil layer, and the proportions of RPF fragments with areas of < 4 cm², 4–25 cm², and > 25 cm² were 40.8%, 48.3%, and 10.9%, respectively. Numerical simulations were performed using COMSOL Multiphysics software, which verified the effectiveness of the established model in assessing the impact of RPF on soil water movement. Within 0–30 minutes, the average deviations between the simulated and measured values of soil water diffusion rate and diffusion distance were 0.035 cm min⁻¹ and 1.3 cm, respectively. The 3D visualization model of RPF constructed in this study clarifies its stratified accumulation characteristics, thereby providing important theoretical and technical support for the ecological risk assessment of farmland RPF pollution.