Abstract
The characteristics of rainfall-runoff are important aspects of hydrological processes. In this study, rainfall-runoff processes and soil moisture dynamics at different soil depths and slope positions of grassland with two different row spacings (5 cm and 10 cm, respectively, referred to as R5 and R10) were analyzed, by means of a solution of rainfall simulation experiments. Bare land was also considered as a comparison. The results showed that the mechanism of runoff generation was mainly excess infiltration overland flow. The surface runoff amount of R5 plot was greater than that of R10, while the interflow amount of R10 was larger than that of R5 plot, although the differences of the subsurface runoff processes between plots R5 and R10 were little. The effects of rainfall intensity on the surface runoff were significant, but not obvious on the interflow and recession curve, which can be described as a simple exponential equation, with a fitting degree of up to 0.854–0.996. The response of soil moisture to rainfall and evapotranspiration was mainly in the 0–20 cm layer, and the response at the 40 cm layer to rainfall was slower and generally occurred after the rainfall stopped. The upper slope generally responded fastest to rainfall, and the foot of the slope was the slowest. The results presented here could provide insights into understanding the surface and subsurface runoff processes and soil moisture dynamics for grasslands in semi-arid regions.
Highlights
Rainfall-runoff is an important component of hydrological cycles, as it determines many of the characteristics of a landscape and the occurrence and size of floods; understanding and modeling the rainfall-runoff process is essential in many flood and water resources problems [1]
Yu et al investigated the slope runoff generation in a 50-m2 runoff plot in mountainous areas of northern China by means of simulated rainfall experiment, and the results showed that surface flow was the main contributor, accounting for more than 60% of the total runoff in this study area [12]
The results between the surface and subsurface flow for both grassland treatments showed that grassland spacing played an important role in the runoff generation, especially for the subsurface flow, and the soil water storage and infiltration rate were larger in the
Summary
Rainfall-runoff is an important component of hydrological cycles, as it determines many of the characteristics of a landscape and the occurrence and size of floods; understanding and modeling the rainfall-runoff process is essential in many flood and water resources problems [1]. Examples include the surface runoff generation in the Mediterranean semi-arid environment, where the soil type and rainfall characteristics exerted the runoff mechanism [3] and the hydrological response of runoff; and soil moisture and groundwater levels to rainfall events in semi-arid Zimbabwe [5]. These studies show that the hydrological responses and processes in different regions are strongly influenced by variations in soil type, vegetation and slope angle, apart from the temporal and spatial variability of rainfall, and the main factors affecting the runoff processes varied by the actual characteristics of the different study areas [5,7]
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