Fig. 3 Wind erosion
dynamics in southern Africa from 1991 to 2015.
(a) Annual average wind erosion trend; (b) spatial distribution of the
wind erosion trend.
3.3 Impacts of climate change on wind
erosion
Soil wind erosion in southern Africa is the result of both climatic
conditions and human activities. The control variable method was used to
explore the impact of climate dynamics on soil wind erosion. The average
climatic conditions from 1991 to 2015, instead of the actual climatic
conditions, were used as the model input to obtain SL’. Therefore, there
is a difference between the actual results and the soil wind erosion
estimated in 3.1, which was only affected by climate dynamics. Wind
speed is the main driving force behind soil wind erosion. However,
temperature and precipitation also have an influence on wind erosion
because they affect soil moisture and vegetation coverage. Therefore,
this study used mean annual temperature, annual precipitation, and
annual average maximum wind speed as the main climatic factors in a
partial correlation analysis that revealed the influence of the
different climatic factors on soil wind erosion.
From 1991 to 2015, the annual average temperature and precipitation in
southern Africa did not significantly change, but temperature,
precipitation, and soil wind erosion were significantly related across
local, smaller areas. The annual average temperature in southern Africa
gradually decreased from northwest to southeast (Fig. 4c), and the
Kalahari Desert and its surrounding basins were the main
high-temperature areas. In general, temperature had a more significant
impact on soil wind erosion in areas with higher annual average
temperatures. Around 18.69% of southern Africa was affected by
temperature (Fig. 4e), and temperature and wind erosion were
significantly negatively correlated across 12.71% of the area (p
< 0.05). For example, the high temperature and precipitation
in the eastern part of the study area may promote the growth of
vegetation, which would reduce soil wind erosion to a certain extent.
The annual precipitation in southern Africa increased from west to east,
and the annual precipitation in the subtropical monsoon climate region
in the southeast was generally higher than in the rest of the study area
(Fig. 4d). There was a negative correlation between soil wind erosion
and precipitation across 23.96% of the area (Fig. 4f), particularly
near the Kalahari Basin in the central region and Eswatini in the east.
Arid and semi-arid areas with annual precipitation less than 400 mm are
prone to wind erosion. However, a rise in precipitation may increase the
vegetation coverage to a certain extent, which would reduce soil wind
erosion. There was no significant correlation between soil wind erosion,
and temperature and precipitation in 81.31% and 75.37% of southern
Africa, respectively. Therefore, temperature and precipitation are not
direct determinants of soil wind erosion, but they probably have an
indirect impact on wind erosion because they affect vegetation growth.