Morphological Estimation of the Time‐Integrated Bed Load Transport Rate

Abstract

Recent research has suggested that given the problems associated with more conventional methods of estimating the bed load transport rate in dynamic rivers, measurement of the transfer of bed material, as indicated by changes in river channel form, may be an appropriate alternative. Thus far, this methodology has been successfully employed to estimate medium‐term bed load transport rates at the reach scale. This paper illustrates the potential of such a technique and extends it further through application to the within‐reach scale and estimation of spatially distributed patterns of bed load transport. It uses a data collection technique that allows the rapid field acquisition of digital terrain models of river channel form. Intercomparison of digital terrain models from separate time periods allows calculation of both the total volumes and the distributed volumes of erosion and deposition. The total volumes can be combined with upstream information on sediment supply to assess the contribution of a particular reach to the total bed load transport rate. The distributed information can be combined with a likely direction of movement of material in transport to estimate the distributed pattern of the time‐averaged bed load transport rate. Both of these approaches show a good correspondence with observed patterns of the bed load transport rate.