JWSS - Journal of Water and Soil Science

Rill erosion is the first step in soil erosion process in the hillslopes, particularly in arid and semiarid regions. This study was conducted to investigate the role of rainfall intensity and raindrop impact on the physical properties of soils and particle detachment capacity (Dc) in a marl soil. Marl soil samples were filled into the flumes with 4 m long and 0.9 m wide and exposed to simulated rainfalls with different intensity varying from 10 mm h-1 to 100 mm h-1. Particle Size Distribution (PSD), aggregate size, porosity, crust thickness, and Dc were determined in each rainfall simulation. The results found that the physical soil properties i.e. PSD, aggregate size, porosity and crust thickness (P< 0.000) were significantly influenced by different rainfall intensities. Also, the rainfall intensity was also an important factor in controlling Dc in the soil. Rainfall intensity of 30 mm.h^-1 was recognized as the threshold rainfall intensity for transporting soil particles in the marl soil and rill erosion. An increase in the rainfall intensity was attributed to the increases in the raindrop impacts and in consequence aggregate breakdown, and higher production of concentrated flows in the rills. Raindrop impact is the most important characteristics of the rainfall in the rill erosion and Dc in the marl soil.