Abstract
The highest annual precipitation in Ansai during the past 60 years was observed in 2013. Studying the effects of such extreme annual precipitation on soil erosion can deepen similar research and help predict environmental damage under future extreme rainfall. We selected the runoff plots (area: 4 m × 10 m) of three land-use types: cultivated land (C), wild grassland (W) and switchgrass (S). We monitored corresponding indices in the “extreme year” (2013) and “normal year” (2010–2012). The results were as follows: (1) The rainfall parameters (rainfall amount, EI30, EI60) in the “extreme year” were all higher than those in the “normal year”, especially in July; (2) In July and August, the runoff and soil loss of cultivated land in the “extreme year” increased by 1492.5% and 538.2%, respectively, compared to those in the “normal year”. The silt content of sediment was the highest generally, but the sand content increased relatively in the “extreme year”; (3) The effect of rainfall on soil erosion was the smallest in W; (4) In the “extreme year”, the same EI30 generated more runoff and soil loss than those in the “normal year”. The high antecedent precipitation which would cause high antecedent soil moisture was one of the reasons. The threshold value (100 MJ·mm·ha−1·h−1) of EI30 related to extreme erosion risk was proposed.
Highlights
Rainfall characteristics play an important role in runoff generation and soil erosion in the LoessPlateau [1]
Meteorological Organization (WMO), i.e., when the difference between the specific rainfall variable and corresponding mean values of 30-year measurements exceeds the double variance of each variable, the specific rainfall value is defined as extreme rainfall [35]
The results revealed that the effect of rainfall on soil erosion was the smallest in wild grassland, which had the highest capability for soil conservation
Summary
Rainfall characteristics play an important role in runoff generation and soil erosion in the LoessPlateau [1]. Rainfall characteristics become more variable and stochastic in the context of climate change, which increases the uncertainties and risks of water erosion in the real world [2]. A number of theoretical modeling and empirical analyses have suggested that striking changes in the frequency and intensity of extreme events, including floods, may occur even when there are only small changes in the mean climate [8,9]. Other studies predicted that the intensity, frequency and regime of extreme precipitation events would increase further [11]. Zhang and Liu [12] declared that rainfall erosivity, which is the major driving force of water erosion, would increase 8%–35% in the Chinese Loess Plateau over the 10 decades
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