MORPHOLOGICAL ESTIMATION OF THE TIME-INTEGRATED BED-LOAD TRANSPORT RATE

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 indic ated by changes in river channel form, may be an appropriate alternati ve. Thus far, this methodology has been successfully employed to estim ate medium-term bed load transport rates at the reach scale. This pape r illustrates the potential of such a technique and extends it further through application to the within-reach scale and estimation of spati ally distributed patterns of bed load transport. It uses a data collec tion technique that allows the rapid field acquisition of digital terr ain models of river channel form. Intercomparison of digital terrain m odels from separate lime periods allows calculation of both the total volumes and the distributed volumes of erosion and deposition. The tot al volumes can be combined with upstream information on sediment suppl y to assess the contribution of a particular reach to the total bed lo ad 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.