For the gravel bed river, the Grensmaas, plans have been made by which extraction of gravel and ecological rehabilitation of the river will be combined. One way to study the morphological changes, the time scale of these changes and the expected ecological rehabilitation is to study gravel bed rivers with approximately the same morphological characteristics as the future Grensmaas. Since scale models in nature of the future Grensmaas do not exist, selection criteria of reference rivers have to be modified. The results of the reference investigation will be different and the interpretation will be much more complicated. An important morphological parameter is the (yearly) sediment transport. A method to measure sediment transport during high discharges is described and tested.