Investigation of hydraulic parameters influencing interrill erosion under simulated rainfall conditions

ABSTRACT Interrill erosion is a major cause of land degradation. This study investigates the effects of slope and rainfall intensity on soil erosion and sediment loss. Two types of slopes were examined: interrill slope and a rill slope, artificially created in the center of a 1 m² soil plot. Experiments were conducted at the LEGHYD laboratory using a fixed-bed channel with a triangular cross-section to simulate the rill. Two slope values (3% and 5%) for the plot and two interrill slopes (15% and 22.5%) were tested. Sandy soil (70% sand, 30% gravel) was subjected to six artificial rainfall intensities: 101.94 mm·h−1, 90.39 mm·h−1, 81.89 mm·h−1, 69.49 mm·h−1, 37.82 mm·h−1, and 31.40 mm·h−1. Data on hydraulic parameters of overland flow were analyzed in relation to sediment concentration. Results showed that while slope had minimal impact on rill flow velocity, it significantly influenced rainfall intensity and overland flow power. A strong positive correlation was found between rainfall intensity, flow power, and sediment concentration. The findings emphasize the combined effects of slope and rainfall intensity on erosion, underscoring the importance of integrated soil management strategies for sustainable land use.