Science - February 17, 2005

Radar satellite measures jungle

Using radar to measure from space how tall trees are, whether illegal logging is taking place and how much CO2 a forest can store: Dr Dirk Hoekman of the Soil Physics, Agrohydrology and Groundwater Management group is working on this promising technology. The radar looks set to find its place in satellites all over the world in the next few years. The first tests from aeroplanes have gone well.

In the last few months a propeller aeroplane has been flying over the Indonesian island of Kalimantan, making double radar recordings of the jungle. The two images are used to make a stereoscopic three-dimensional image of a forest, enabling researchers to calculate for example how tall a tree is or how dense the jungle is.

According to Hoekman radar has advantages over current satellite photos. ‘With radar you can look through clouds,’ he tells. ‘And we can also measure the height of trees because we can see through the trees, as it were, to the ground. It is also possible to measure, for example, soil subsidence and the hydrology of peat swamp forests, such as the declining rainforest of Kalimantan, a large CO2 sink and an important orang-utan habitat. The radar can also be used to find illegal logging as well as burned or flooded areas of forest. / MW