Abstract
The interaction of macrophytes, stream flow and sediments results in heterogeneity in vegetated rivers. This process is characterized by the formation of a pattern of macrophyte patches and flow gradients and defines the functionality of the river ecosystem. A one-dimensional model, describing the plant-flow interactions in a simplified way, has previously been established. For the development of a two-dimensional, depth-averaged model, the understanding of the plant-flow interactions is very important. To get more insight in those processes, the input of 2D data with a high spatial and temporal resolution is elementary. Therefore we are developing a new optical measuring technique, using aerial imagery to obtain high resolution data of the different stream characteristics needed to describe the interactions. This paper describes the setup of this optical measuring technique. An off-the-shelve digital camera (Nikon D300s) will be mounted onto a pole or an unmanned aerial vehicle. Due to the low operating altitude, a high spatial resolution can be obtained. After the necessary image geo-referencing, the pixel values captured in the imagery can be converted into physical reflectance values. The interpretation of the latter will enable the extraction of the characteristics needed for the development of the 2D model, which will support us to a better understanding of the ecosystem interactions. All measurements will be repeated regularly through the macrophytes’ growing season to capture the evolution of the growing process. Since the project only started in 2010, many issues have to be explored and further developed, while additional questions may arise. Therefore, the measurement plan and characteristics to be measured might be further adapted during the campaigns.