Fig. 2 Spatial
distribution of the average wind erosion moduli in southern Africa for
(a) 1991–2015; (b) 1991–1995; (c) 1996–2000; (d) 2001–2005; (e)
2006–2010; and (f) 2011–2015.
3.2 Temporal-spatial trends for wind
erosion
The soil erosion modulus in southern Africa fluctuated from 1991 to
2015, but the temporal changes showed a significant downward trend (Fig.
3a) with an average annual decrease of 0.99 t/ha/a, and a maximum soil
loss of 61.01 t/ha in 1995. In general, wind erosion in southern Africa
can be divided into three phases. From 1991 to 2000, the amount of wind
erosion fluctuated around 46.40 t/ha/a; from 2001–2010, it fell
significantly at an average rate of 1.95 t/ha/a; and then it stabilized
after 2010. According to Sen’s trend test (Fig. 3b), 70.84% of the
southern Africa study area showed a downward trend in annual average
soil erosion. This decrease was significant across 66.65% of the area
(p < 0.05), but 7.1% of the area showed a significant
increase (p < 0.05). The Namib Desert along the western
coastal area only had severe soil wind erosion at certain times during
the study period (Fig. 2); In the central part of the study area, such
as Botswana and Lesotho, the soil wind erosion modulus in local areas
showed an increasing trend, but the soil wind erosion modulus showed no
significant change over 21.11% of the area.