Page 29 - Green knowledge 2023

How does topography affect erosion?
The loss of soil particles and nutrients from agricultural areas, known as erosion, is considered one of the world’s major environmental challenges, partly because it degrades water quality. Robert Jan Barneveld has investigated the relationship between the topography of agricultural landscapes and the erosion process.
Erosion has long been considered a significant problem in agriculture. This is because the nutri- ent-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 topogra- phy, 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 Univer- sal 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.
Photo: Siri Svengård-Stokke
Purpose: Investigate how erosion affects the morphology of the soil surface before winter and after spring snowmelt in connection with a doctoral thesis completed at NIBIO and Wageningen University, Netherlands.
Contact: Research Scientist Robert Barneveld. Email: robert.barneveld@nibio.no, phone: (+47) 968 51 427. Division of Environment and Natural Resources
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