This paper describes the application of a new instrument to
continuously measure bedload transport, an impact sensor, to a 72 km(2)
test catchment in the Yorkshire Dales, northern England. Data from a
network of impact sensors are linked to repeat surveys of channel
morphological response, to get a better understanding of the conditions
that lead to sediment generation and transfer. Results suggest certain
areas of the catchment act as key sediment sources at the annual time
scale, with material being quickly delivered to the lower parts of the
catchment along the steep bedrock channel. Sediment transfer within the
tributaries occurs in significantly smaller magnitudes than within the
main channel; but it moves more frequently and at different times of
the year, with transfer rates being strongly conditioned by
larger-scale valley geomorphology. The lower 5.6 km reach sees a
significant reduction in gradient and a widening of the valley. This
permits significant accumulation within the channel, which has
persisted for many years. This lower reach is very sensitive to changes
in sediment supply and there is good agreement between changes in
bedload transport data and the surveyed channel response. These
observations have major implications for how river management projects
should be developed in upland environments, especially those where
large-scale geomorphological controls have a major impact upon the
sediment transfer process. Evidence suggests that where river
management restricts lateral movement of the channel and transfer of
sediment into floodplain storage, changes in sediment supply can lead
to areas of severe accumulation, acceleration of bank erosion and
exacerbated flood risk. (c) 2006 Elsevier B.V. All rights reserved.