Constructing a sediment budget from morphological channel change,
typically measured using repeat cross-sectional surveys, has proven a
useful technique for estimating mean bedload transport rates in
gravel-bed rivers. We apply and suggest improvements to the approach
using new data sources from an intensely monitored 5.6 km reach of an
upland gravel-bed river in northern England. Sediment impact sensors
were placed in the bed to record the instantaneous passage of grains
during transport events. These sensors provide valuable information for
the budget including: (1) a downstream budget limit from which the rest
of the budget can be calculated; (2) estimates of sediment input from
tributaries; and (3) a better indication of active transport time used
in the calculation of average transport rates. Further information
collected from field studies include estimates of lateral inputs from
the banks using field surveys and bank erosion pins and estimates of
the variability of sediment porosity from bed grain size distributions.
Budget calculations for different locations and time periods
demonstrate large spatial and temporal variabilities in bedload
transport rates over a short distance (<3 km). Whilst some uncertainty
in the new data sources remains, this work highlights some limitations
of the traditional budget approach and some potential solutions; in
particular the value of sediment impact sensors for sediment transport
studies. (C) 2010 Elsevier B.V. All rights reserved.