Assessment of Soil Erosion in the Pan-Third Pole Region

Abstract: Climate change and human activities are seriously affecting the intensity and extent of soil erosion in the Pan-Third Pole region (PTP), which covers an area of approximately 5.14 × 10⁷ km². Accurate assessment of soil wind and water erosion is crucial for controlling soil degradation. In this study, soil water erosion in the PTP was estimated for 2018 using sampling units and the China Soil Loss Equation (CSLE), and soil wind erosion in the PTP from 1982 to 2020 was simulated using the Revised Soil Wind Erosion Equation (RWEQ), based on meteorological, soils, topographic, and remote sensing data. The results showed that: (1) Soil water erosion in the PTP mainly occurs in East Asia, South Asia, and the Black Sea coastal region, and the average soil wind erosion rate of the whole region is 263.4 t•km^-2•a^-1, and the average water erosion rate of the key erosion areas with water erosion rates exceeding 2,500 t•km^-2•a^-1 is 22.6 times higher than the average water erosion rate of the study area, and annual erosion amounted to 57.1×10⁸t, accounting for 38.6% of total erosion amount. The soil water erosion rates of cropland, grassland, and forest were 525.7 t•km^-2•a^-1, 362.6 t•km^-2•a^-1, and 185.6 t•km^-2•a^-1, respectively. (2) Soil wind erosion in the PTP mainly occurs in cropland and grassland in semi-arid areas, and aeolian sand activity primarily occurring in extremely arid and arid areas (deserts), and the average multi-year soil wind erosion rate in regions other than deserts is 633.65 t•km^-2•a^-1, of which the mean soil wind erosion rate in the area where soil wind erosion rate is greater than 50 t•km^-2•a^-1 was 4,316.94 t•km^-2•a^-1, for cropland, grassland, and scrubland were 1,981.14 t•km^-2•a^-1, 3,815.05 t•km^-2•a^-1, and 4,010.95 t•km^-2•a^-1, respectively. (3) From 1982 to 2020, the soil wind erosion rate in the PTP decreased by 10.61 t•km^-2•a^-1. The proportion of the area with a decreasing trend was 19.53%, while the proportion of the area with an increasing trend was 28.35%. (4) Soil wind and water combined erosion mainly occur in cross-border regions of northern Syria, the Indus River Plain, the northern border of Iran and Afghanistan, the southwestern part of the Qinghai-Tibet Plateau, central Mongolia, the central part of the Loess Plateau, Inner Mongolia, and the bordering areas of the three eastern provinces, the average soil erosion rate of is 4,534.77 t•km^-2•a^-1, with the average soil erosion rates for grassland and cropland being 4,752.41 t•km^-2•a^-1 and 1,495.68 t•km^-2•a^-1, respectively. This study provided a comprehensive understanding of soil erosion (both soil wind and water erosion) in the PTP, and offered valuable data and decision-making support for current and future soil erosion prevention and ecological restoration projects.