Event bed load yield measurement with load cell bed load traps and prediction of bed load yield from hydrograph shape

Abstract

One of the goals of sediment transport research is to predict the bed load yield of ungauged catchments. However, what little field data exist are characterized by temporal fluctuations in the record of event yield. Attempts to model the process of transport typically involve the derivation of empirical relationships between commonly measured variables such as stream discharge and the rate of bed load transport. Such approaches fail to account for the effect of sediment supply on the process of transport, which is known to contribute to the variability in records. This paper sets out a conceptual model of sediment transport that establishes a link between the form of the stream hydrograph and the effectiveness of an event as indexed by sediment yield. The model is then tested against a dataset of 60 bed load transport events recorded using a new type of load-cell pit trap. Total event power is shown to be capable of explaining 70% of the variance in event yields for a small woodland stream