60 years in the Senegalese Groundnut basin : Modeling wind erosion in a changing social and climatic context

In semi-arid zones, wind erosion is both a consequence and a cause of soil degradation, as it particularly affects unprotected soils and can deplete them of nutrients and organic matter. Thus it represents a major concern for rural populations who depend on soil productivity for income and subsistence. During the last 60 years in the Sahel, an intense drought affected the region between the 1970s and 1980s while major socio-economic changes were (and still are) underway, leading to a profound alteration of agropastoral systems and a decline in soil fertility in some places. In this context, estimating aeolian sediment fluxes generated from cultivated plots and disentangling climate effects from anthropic ones would allow for a better understanding of the role of wind erosion in the perceived land degradation, as well as paving the way for trajectories simulation with future climate projections. 
In this study, we aim to understand and model how the combined effect of climatic and agropastoral changes affected wind erosion in Sahelian conditions for the 1960-2020 period, using the Senegalese groundnut basin as a case study. The Senegalese groundnut basin is the agricultural heartland of Senegal and home to different sociolinguistic groups whose approach to agriculture led to varying responses to the region’s conditions. Using a modeling approach relying on an extensive dataset, we simulated vegetation growth (STICS and STEP models) and estimated the horizontal flux of aeolian sediment (DPM model) resulting from several land uses and managements at the plot scale. We used ERA5 meteorological time series (ECMWF) combined with an extensive review of the literature on the dynamics of land use in the groundnut basin to develop several realistic trajectories for horizontal flux generation in 3 different parts of the groundnut basin (North, Center, South) over the last 60 years (1960-2020). On top of integrating climate variability, these trajectories take into account the use and management of different crops, as well as crop rotation systems, fallow periods, the use of mineral and organic fertilizers, trees and livestock. Average biomass production and yield found in the literature were used to verify the model's reliability.
We found that aeolian flux generation has increased overall since 1960, especially in the northern part of the groundnut basin. The most erosive period took place after 1980 when the Senegalese groundnut basin suffered from drought and the end of government subsidies for agriculture.