Nieuws - 8 februari 2007

Mapping erosion from satellite images

A Wageningen doctoral student has developed a method for automatically recognising erosion gullies on satellite photos. The method can help to detect erosion and therefore do something about it at an earlier stage.

Erosion is often clearly seen in the field after heavy rainfall, but it is more difficult to determine where erosion is taking place on a larger scale. Satellite remote sensing may offer a solution. In his PhD thesis, Anton Vrieling shows that it is easy to recognise erosion gullies in central Brazil on satellite images from the way they reflect light. He trained the computer to recognise gullies without needing to use the human eye. The method could be used to map large areas where erosion is occurring.

By integrating this data with other spatial data, such as vegetation coverage and geological information, it is possible to determine the cause of the erosion, and as a result, devise measures to deal with the erosion.

It is not always possible to detect erosion using satellite images, for example if the signs are too small. In this case, however, it is often possible to determine the risk of erosion, by looking at the factors that influence erosion, such as vegetation, gradient, rainfall and soil characteristics.

Usually, the data collected are integrated into existing erosion models, says Vrieling. But these models often require types of data that are not available. They are often specific to a certain area but they are applied, wrongly according to Vrieling, to other areas. The simpler, location-specific data integration methods that Vrieling has developed can make use of the remote sensing data to map erosion.

Vrieling regards his research as an important step in the fight against erosion. ‘Erosion causes land degradation all over the world. We have ways to deal with this, but first we need to know where the biggest problem areas are. Remote sensing can play a key role here.’ / Koen Moons

Anton Vrieling will receive his PhD on 14 February. His promotor is Professor Leo Stroosnijder, chair of Erosion, Soil and Water Conservation.