Quantifying the impacts of gully erosion on farmers' land productivity: The case of Shafe catchment, southern Ethiopia

Like many areas along the Ethiopian Rift, the Shafe catchment is severely affected by gully erosion. Earlier studies hypothesized that this can lead to important crop yield losses and other socio-economic impacts. Nonetheless, these effects remain poorly investigated. This study aims to quantify and better understand the impacts of gully erosion on cropland productivity, including farmers’ perceptions, cropland and yield losses, and the key factors contributing to yield reduction near gullies in Shafe catchment. We used an integrated approach combining household surveys, crop yield measurements, UAV-based mapping, soil moisture monitoring, and soil analyses. Our UAV mapping showed that gully erosion caused an average cropland loss per affected field of 26.5%, while farmers reported 20.4%. Gully widening appears to be the dominant cause of land loss. Field measurements on 1 m 2 plots of sorghum, wheat, and haricot bean over two cropping seasons showed that yields were 72–75% lower at 1 m from the gully edge compared to 40 m away. These reductions are likely attributable to a combination of factors, including soil moisture stress and reduced plant density. Combined, land loss and reduced productivity led to an average productivity reduction of 54.3% per gully-affected field. Farmers with at least one gully-affected field face on average an annual income reduction of 4972 birr (34 euro), or 13.8% of their average household income. As most of these households are (extremely) poor, these findings highlight the far-reaching impacts of gully erosion on the livelihoods of subsistence farmers and their food security.