Abstract
Rainfall patterns and land cover are two important factors that affect the runoff generation process. To determine the surface and subsurface flows associated with different rainfall patterns on sloping Ferralsols under different land cover types, observational data related to surface and subsurface flows from 5 m × 15 m plots were collected from 2010 to 2012. The experiment was conducted to assess three land cover types (grass, litter cover and bare land) in the Jiangxi Provincial Soil and Water Conservation Ecological Park. During the study period, 114 natural rainfall events produced subsurface flow and were divided into four groups using k-means clustering according to rainfall duration, rainfall depth and maximum 30-min rainfall intensity. The results showed that the total runoff and surface flow values were highest for bare land under all four rainfall patterns and lowest for the covered plots. However, covered plots generated higher subsurface flow values than bare land. Moreover, the surface and subsurface flows associated with the three land cover types differed significantly under different rainfall patterns. Rainfall patterns with low intensities and long durations created more subsurface flow in the grass and litter cover types, whereas rainfall patterns with high intensities and short durations resulted in greater surface flow over bare land. Rainfall pattern I had the highest surface and subsurface flow values for the grass cover and litter cover types. The highest surface flow value and lowest subsurface flow value for bare land occurred under rainfall pattern IV. Rainfall pattern II generated the highest subsurface flow value for bare land. Therefore, grass or litter cover are able to convert more surface flow into subsurface flow under different rainfall patterns. The rainfall patterns studied had greater effects on subsurface flow than on total runoff and surface flow for covered surfaces, as well as a greater effect on surface flows associated with bare land.
Highlights
Water is the primary cause of soil erosion in southern China, a region known for the production of tropical crops and grains [1]
The main objectives of this study are as follows: (1) to analyze the effects of different land cover types on surface and subsurface flows under natural rainfall conditions using in situ field observations, (2) to determine the responses of surface and subsurface flows to different rainfall patterns, and (3) to understand the roles of different land cover types in the proportions of surface and subsurface flows for different rainfall patterns
Rainfall pattern II accounted for 5.26% of the rainfall events analyzed
Summary
Water is the primary cause of soil erosion in southern China, a region known for the production of tropical crops and grains [1]. Land cover and rainfall patterns are the two main factors that affect the intensity and frequency of runoff generation [6,7,8,9,10]. Understanding the effects of rainfall patterns and surface cover on runoff production will support soil and water conservation [11]. Rainfall patterns have an important effect on the rainfall-surface runoff process on the Loess Plateau [8], and research in the Ferralsol region has produced similar results [9, 10]. Less attention has been paid to determining the effects of rainfall patterns and surface cover on subsurface flow generation. Fu et al [17] and Xie et al [18] concluded that rainfall intensity and quantity were the primary factors affecting subsurface flow generation based on rainfall simulations and simple, natural rainfall events
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