The variation law of soil infiltration characteristics and its erosion effect on loess subsidence slope in northern Shaanxi coal mining area in the middle reaches of the Yellow River

Addressing the soil erosion issues triggered by subsidence slopes in the middle reaches of the Yellow River coal mining areas is a crucial breakthrough for supporting the ecological security and high-quality development strategy in the Yellow River Basin. This study takes the soil from different depth layers (0~10, 10~20, 20~30, and 30~40 cm) surrounding the typical subsidence slope positions (slope top, middle, and foot) of the northern wing of the Ningtao Tower Coalfield in Northern Shaanxi as the research object. Soil infiltration rate, cumulative infiltration, saturated hydraulic conductivity (K_s), porosity, moisture content, organic matter, mechanical composition, and the content of water-stable aggregates larger than 0.25 mm were measured using instrumental analysis and the constant-head method. The study reveals the impact of different subsidence slope positions on soil infiltration characteristics and elucidates the soil erosion effects of subsidence slopes on a small spatial scale considering infiltration properties based on the RUSLE2 model. The results show that: ① The soil infiltration rate at different subsidence slope positions exhibits a dynamic change process with three stages: Transient (0~3 min], transitional (3~60 min], and stable (60~110 min]. ② The subsidence slope significantly enhances the soil infiltration rate, cumulative infiltration, saturated hydraulic conductivity (K_s), and erodibility K-value at the slope top, middle, and foot, with average increases ranging from 13.41% to 52.51%, 22.25% to 26.84%, 21.86% to 26.67%, and 15.78% to 21.63%, respectively. This effect intensifies with decreasing soil depth, and the order of this effect on the subsidence slope is: Slope top > slope middle > slope foot. ③ The change amplitude of the soil erodibility K-value considering infiltration characteristics around the subsidence slope is 33.42%~44.99% higher than that without consideration. ④ The soil erodibility K-values of subsidence slope surfaces are significantly correlated with silt content, porosity, and saturated hydraulic conductivity (K_s). These findings can provide theoretical and technical support for the coordinated development of ecological protection in the Yellow River basin and the green transformation of mining areas.