Quantifying wind erosion at landscape scale in a temperate grassland: Nonignorable influence of topography

Abstract

Revised wind erosion equation (RWEQ) is widely applied to determining wind erosion and achieves reliable results. However, the spatial variability of wind erosivity and wind erosion has not been sufficiently investigated in previous studies. In this paper, RWEQ was used to determine wind erosion and its spatial variation at the landscape scale in the Xilingele grassland, which is a typical temperate grassland in North China suffering from increasing wind erosion problems. Based on field investigation and laboratory measurement, land-surface parameter data were obtained. Computational fluid dynamics (CFD) wind modelling was integrated to acquire the spatial variation of wind data, which considers the influence of topography and land use. These data were used to determine the five factors of RWEQ and wind erosion modulus. Results showed that the mean wind erosion modulus was 5.33 t ha−1 yr−1, and 97.16% of the area had light or no wind erosion, which was mostly distributed in the low plains and the leeward areas. However, there were hotspots of wind erosion which were mainly distributed in the windward slopes and the summit areas. There were no significant differences among the wind erosion moduli of different land uses, but land use affected the influence of topography on wind erosion. The maximum modulus varied greatly from 0 to 259.41 t ha−1 yr−1 for different land uses, and the most severe wind erosion occurred in moderately grazed grassland (MG), followed by heavily grazed grassland (HG), arable land (AL), lightly grazed grassland (LG) and ungrazed grassland (UG). Statistical tests indicated that topography had a significant influence on wind erosion, which was not detected in previous studies due to the lack of high-resolution topography and wind data. The combination of RWEQ and CFD wind modelling suggests that future wind erosion studies should further consider the important influence of topography. To achieve sustainable development in temperate grassland, rational grazing is critical, and special attention should be paid to windward slopes and high elevation areas.