Digital elevation model cell size effect on erosion-deposition simulation using the unit stream power erosion and deposition model in the dry-hot valley region of Southwest China

Abstract

Gully erosion is the main source of sediment in watersheds, and the assessment of soil erosion and deposition in gully systems is very important for land utilization and watershed management. Soil erosion and sediment transport are multiscale, and the digital elevation model (DEM) is one of the most important means to study the scale effect of soil erosion and deposition. To clarify the effect of DEM cell size on soil erosion and deposition in gullies, a series of DEMs with cell sizes of 0.5, 0.7, 1, 1.5, 2, 2.5, 3, 4 and 5 m were generated based on detailed field measurements in dry-hot valley region. Meanwhile, the unit stream power erosion and deposition (USPED) model was chosen to simulate soil erosion and deposition in this study. The results showed that cell size can greatly influence the average slope and aspect of the DEMs, while the accuracy and average elevation of the DEMs were only affected intensively when the cell size exceeds 3 m. As for the spatial distribution pattern of soil erosion and deposition, the increase of the DEM cell size could cause a concentration of soil erosion and deposition in main channels while weakening the occurrence on hillslopes, and the spatial proximity of soil erosion and deposition would not change with the DEM cell size. The highly positive correlation in simulation results for soil erosion and deposition was primarily observed in DEM cell sizes range of 0.5 to 2 m and from 3 to 5 m. Meanwhile, a slight increase in DEM cell size would significantly affect the simulated results of soil erosion and deposition based on the USPED model when DEM cell size ranged from 0.5 to 0.7 m, whereas the change in DEM cell size would not affect the simulation results when DEM cell size was greater than 0.7 m.