Abstract
Understanding the response of preferential flow paths to water movement is an important topic in soil hydrology. However, quantification of the complicated distribution patterns of preferential flow paths remains poorly understood. Therefore, dye experiments were conducted to investigate preferential flow characteristics under three different precipitation amounts (20, 40 and 60 mm, numbered as the G20, G40 and G60, respectively) in Simian Mountain grassland, Chongqing province, China. O-ring statistics were used to analyze the spatial distribution characteristics and the spatial correlation of preferential flow paths. Results revealed that precipitation could promote dye tracer infiltration into deeper soils, reaching the maximum depth of 55 cm in G60. The number of preferential flow paths in G60 plots was 3.0 and 7.4 times greater than those of G40 and G20, respectively. Structural distribution of the preferential flow paths showed a gradually clumped pattern with the increase of precipitation, which was conducive to enhancing the correlation between preferential flow paths in each pore size range. These results could expand our understanding of the effects of precipitation on the characteristic of preferential flow paths in grassland, which is helpful to evaluate the water movement in the study area.
Highlights
Preferential flow is the fast, non-equilibrium flow of water infiltration in the soil that can reduce water and nutrient availability, threaten groundwater, and cause natural disasters such as avalanches, landslides, and mudslides [1,2]
This study revealed the responses of spatial distribution and spatial association of preferential flow paths to different water infiltration conditions in the Simian Mountain grasslands preferential flow paths to different water infiltration conditions in the Simian Mountain grasslands of Chongqing, which may be of significance in exploring the characteristics of preferential flow of Chongqing, which may be of significance in exploring the characteristics of preferential flow movement
Our results indicated the important contribution of infiltration intensity to the quantities, spatial distribution, and spatial association of preferential flow paths
Summary
Preferential flow is the fast, non-equilibrium flow of water infiltration in the soil that can reduce water and nutrient availability, threaten groundwater, and cause natural disasters such as avalanches, landslides, and mudslides [1,2]. An earlier study combined a process-based model with traditional tracer experiments to simulate and validate that the vertical and lateral flow paths play an important role in controlling infiltration and affecting surface and groundwater flows [6]. The spatial distribution of soil preferential paths directly influenced the water discharge and the process of rainfall recharging groundwater. The spatial distribution of preferential paths reflected the connectivity of preferential paths along with the soil depth, which in turn affected the formation and development of preferential flow [7]. Determining the spatial pattern of preferential flow paths is integral to an understanding of the spatial heterogeneity and formation mechanism of preferential flow paths
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