Relationship between soil infiltration and crust under continuous and intermittent precipitation

Northwest A F University,College of Natural Resources and Environment

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    The Loess Plateau, one of the ecologically vulnerable regions in China, experiences concentrated and intense precipitation, characterized by significant topographical variations and fragmented landscapes. With sparse vegetation cover, the area faces prominent issues of soil erosion. Soil crusts, characterized by high bulk density and low porosity, are a common soil structural feature in the Loess Plateau formed under the impact of precipitation, runoff compaction, or irrigation. The formation of soil crusts severely affects water infiltration and runoff generation, hindering efficient water resource utilization and impeding the conversion between surface water and groundwater. To investigate the relationship between soil crust and infiltration performance under continuous and intermittent precipitation conditions, three typical cultivated soils from the Loess Plateau were selected. Indoor simulated precipitation experiments were conducted, utilizing three precipitation drop diameters (2.67 mm, 3.39 mm, and 4.05 mm), continuous precipitation durations of 10, 20, and 30 minutes, and 1-2 episodes of intermittent precipitation. The study analyzed the relationship between crust strength, cohesion, and soil infiltration performance under different precipitation conditions. Furthermore, variations in the content of soil aggregates of different particle sizes in the topsoil under different precipitation conditions were examined, along with their influence on infiltration performance. Finally, using grey relational analysis, the study summarized the weights of various factors affecting infiltration performance and ranked their significance. The results revealed that infiltration performance decreased with the increase in continuous precipitation duration and the number of intermittent precipitation episodes. Under equivalent precipitation duration and intensity, intermittent precipitation exhibited a greater reduction effect on infiltration compared to continuous precipitation. Crust strength and cohesion increased with prolonged continuous precipitation duration and a higher number of intermittent precipitation episodes. Infiltration performance of chestnut soil and black loam soil exhibited a significant linear correlation with crust strength and cohesion (P<0.05). As the duration of continuous precipitation and the number of intermittent precipitation episodes increased, the generated crust strength and cohesion also increased, consequently resulting in a greater reduction in infiltration efficiency. In contrast, the infiltration performance of sandy loam soil demonstrated a nonlinear correlation with crust strength and cohesion (P<0.05). Experimental results indicated that with an increase in the number of intermittent precipitation episodes, soil aggregates became more fragmented. Moreover, as precipitation intensity increased with precipitation duration, the efficiency of degrading large aggregates (>0.25 mm) into smaller aggregates (<0.25 mm) also increased. Comparative analysis of the changes in Mean Weight Diameter (MWD) and Geometric Mean Diameter (GMD) of soil crusts under different precipitation conditions revealed that a smaller MWD and GMD corresponded to poorer infiltration performance and a greater reduction in infiltration efficiency. Grey relational analysis further emphasized the significance of MWD and GMD as the most influential factors affecting infiltration performance, with higher correlation observed for intermittent precipitation compared to continuous precipitation. This study provides valuable insights for mitigating soil erosion and promoting effective water resource management in the Loess Plateau.

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  • Received:October 09,2023
  • Revised:December 17,2023
  • Adopted:December 27,2023
  • Online: April 29,2024
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