Stream-bed Scour and Fill in Low-order Ephemeral Stream Channels

Reach scale patterns of scour and fill have been studied in three, low-order dryland ephemeral stream channels with sandy bed materials. Depths of scour within the reaches are highly variable though scour is generally matched by equal amounts of fill. As a result, there is little net change in bed elevations over the flood season. A preliminary examination of the data using serial correlation and spectral analysis reveals no systematic pattern within the reaches although interpretation of the results is constrained by the limited length of the spatial series. For many of the events studied, the exponential model provides a satisfactory approximation for the distribution of scour and fill depths and may provide a basis for predicting sediment exchange depth distributions, at least to a first approximation, in low-order sand-bed streams.