Spatiotemporal distribution of rainfall erosivity in the Yanhe River watershed of hilly and gully region, Chinese Loess Plateau

摘要

Rainfall erosivity is considered as one of the most important factors in the universal soil loss equation (USLE) or its revised form (RUSLE); it can directly reflect the potential of soil erosion caused by rainfall. In this study, the simple algorithms of rainfall erosivity including the Wischmeier model and the half-month model are selected and used to estimate rainfall erosivity values from 1971 to 2013 in the Yanhe River watershed of the hilly and gully region, Chinese Loess Plateau. Results demonstrate that: (1) the applicability of the simple algorithms of rainfall erosivity in loess hilly and gully region is good and the half-month model is more suitable for the Yanhe River watershed; (2) the overall variations of annual rainfall erosivity values estimated by the two models are similar and show a decreased trend during the relatively steady rainfall period from 1971 to 2012; but they will have a certain degree of deviation for the extreme rainfall with high intensity and short duration in 2013; the monthly variations of rainfall erosivity within a year are highly concentrated in 5-10 months, the rainfall erosivity in other months are almost zero; (3) the spatial distributions of the rainfall erosivity have strong correlation with the erosive rainfall, precipitation and rainfall erosivity which both present an increasing trend from northwest to southeast in the Yanhe River watershed; the central and southern regions both have the highest rainfall and the most serious erosivity; and both rainfall and erosivity in southeast are more serious than that in northwest of the watershed. Results may provide scientific theoretical guidance and data support for soil loss management of the hilly and gully region, Chinese Loess Plateau.