Wind erosion susceptibility modelling along the Eastern Cape Wild Coast, South Africa

Wind erosion is a major driver of land degradation, impacting more than a third of all land areas in recent centuries. It has been estimated that approximately 19% of lands in Europe are moderately to highly susceptible to wind erosion, whilst up to 25% of East and Southern Africa are at moderate to elevated risk of soil erosion. Along the eastern seaboard of South Africa, accelerated wind erosion has led to severe, localised land degradation in parts of the Wild Coast. In data sparse regions where conventional wind erosion modelling is difficult, mitigation of the devastating impacts associated with accelerated wind erosion could be facilitated by the identification of highly susceptible areas. Therefore, the study objectives were to map the regional wind erosion susceptibility conditions and identify vulnerable areas. In this study, general concepts of the Wind Erosion Equation were adopted. Two regional susceptibility methods were implemented and compared. Model 1 employed a geostatistical approach, based on erosion factor class frequency ratio data and Analytical Hierarchy Process importance weights. Model 2 utilised the data driven Weights of Evidence modelling technique. Model 1 has classified large areas of the study area as having low susceptibility (46%) whilst Model 2 classed more than 90% of the areas as very low susceptible zones. Both models show that less than 4% of the study region has a high to very high susceptibility to wind erosion. In general, areas associated with a higher wind erosion susceptibility are poorly vegetated, wind exposed coastal zones that are characterized by unconsolidated, erodible sandy soils. Model 1 and Model 2 are associated with area under the receiver operating characteristic curve values of 0.987 and 0.946 respectively, displaying satisfactory average performances. The employed modelling approaches provide an effective means to assess regional wind erosion susceptibility in coastal environments worldwide.

Automated summary

Wind erosion is a significant factor in land degradation, affecting a considerable amount of land globally. Approximately 19% of lands in Europe and 25% of lands in East and Southern Africa are at risk of wind erosion. Regional susceptibility methods can be used to identify areas vulnerable to wind erosion.