Estimation and forecasting of soil losses from water erosion in the Polissia and Forest Steppe of Ukraine

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Global warming and changes in land use are considered the main drivers of future soil-erosion dynamics and therefore require attention. We modelled the possible impacts of climate change and land use change on soil erosion rates in the Polissia and Forest-Steppe lands of Ukraine up to 2060. The final water-erosion rate depends on the amount and rhythm of precipitation during the year, the ability of the soil to withstand the erosive effects of precipitation, and the protective effect of vegetation cover. The variability of the observed and predicted RUSLE parameters over time demonstrated a linear trend in dependence on time over the 100 years from 1960 to 2060. The slope of the linear model indicates the direction and strength of the time trend in the variability of a relevant parameter. In 52.9% of the cases, the R-factor showed a decreasing trend over time. The zone of reduced intensity of the erosive impact of precipitation has a clear geographical distribution. In the southern, central, and to a lesser extent in the eastern part of the region, the erosive impact of precipitation will decrease in 1960–2060. In the north and southwest, there will be no significant changes in the intensity of the precipitation erosion over time. In the northeast and west of the region, the intensity of precipitation-induced erosion will increase over time. The K-factor will not change over time only in 1% of the cases. In other cases, the trend of changes in this indicator will be positive, indicating a monotonous decrease in the ability of the soil cover to withstand the erosive effects of precipitation. The least negative changes will occur in the southeast. In the north and especially in the northeast, the decrease in the soil's ability to resist erosion will be the greatest. The C-factor indicates the ability of the vegetation cover to resist water erosion. In 14.6% of the cases, this indicator will decrease over time, suggesting a strengthening in the protective capacity of the vegetation cover. This increase will occur in the southwest of the region. In the north and east of the region, the C-factor will elevate monotonically over time, indicating a decrease in the protective capacity of the vegetation cover. The water erosion score is a multiplicative indicator of all these factors. The model shows that both an upward trend in water erosion and a downward trend in soil erosion will be observed within the study area. In 35% of the cases, soil erosion will decrease. The zone of reduced erosion intensity is predicted in the centre and south of the region. Accordingly, in 65% of the cases, soil erosion will increase, most notably in the east and southeast of the region. In the northwest, the increase in erosion intensity will be moderate. The regression analysis shows that the trends in factors R, K, and C together can explain 65.1% of the variability in the water erosion trend. Factor K was the largest contributor to the erosion trend and was able to explain 26.3% of the variability in the water erosion trend. The R factor was able to explain 19.9% of the variability in the water erosion trend, and the C factor explained 18.9%.