Characterization of runoff and sediment associated with rill erosion in sloping farmland during the maize-growing season based on rescaled range and wavelet analyses

Abstract

Rill erosion is one of the most serious problems in sloping farmland of purple soil. The formation and evolution of runoff and sediment associated with rill erosion are complex processes that are influenced by many factors. The aim of the present study was to investigate the temporal variation characteristics of runoff and sediment associated with rill erosion during the maize-growing season. Simulated rainfall experiments (1.0, 1.5 and 2.0 mm min−1) were carried out in three experimental croplands on a typical slope gradient of 15°. Multi-scale temporal variation characteristics of runoff and sediment associated with rill erosion were identified by rescaled range (R/S) and wavelet analyses. The results showed that the Hurst index of the runoff ranged between 0.572 and 0.875 during the maize-growing season, while those of the sediment ranged between 0.575 and 0.855, indicating a long-range positive correlation. Therefore, the time series of runoff and sediment were persistent time series, and the future trends of runoff and sediment would be consistent with the present. The principal cycles of runoff and sediment presented an initial increasing and then a decreasing trend with maize growth, and the runoff and sediment yield varied periodically every 8–15 minutes. The changes in the primary cycles of runoff and sediment were basically consistent with the changes in vegetation coverage. The results provided a new insight for describing multi-time scale characteristics of runoff and sediment associated with rill erosion.