How does topography affect erosion?

Erosion has long been considered a significant problem in agriculture. This is because the nutrient-rich topsoil is most easily displaced by rainfall, snowmelt, and wind.

"Nutrient-rich topsoil runoff can reduce the water quality in freshwater bodies and degrade yield levels, soil quality, and soil structure," says Dr Robert Barneveld.

He has explored the relationship between topography, which refers to the terrain conditions of a land area, and the erosion process. Using digital elevation models, laser scanners, and drones, he has examined how erosion affects the morphology of the soil surface, i.e., the external shape of the terrain, both before winter and after spring snowmelt.

The researcher's analyses show, among other things, that none of the most used methods for representing topography in erosion models work well enough.

"Most of the methods used today to measure the effect of topography on erosion stem from an equation developed in the 1960s, called the Universal Soil Loss Equation (USLE). Compared to a process-based model, none of them work particularly well, partly because most are limited to slope lengths of a maximum of 50 meters," he explains.

With better methods it will be easier to assess where it will be effective to implement erosion control measures.

"This is important, especially considering that warmer and wetter weather is expected in the future, along with more frequent episodes of extreme weather. All of this brings increased erosion risk," says Barneveld.