Application of surface-based bed load transport equations to a desert gravel-bed stream

Abstract

Bed load measurements during low flow in a desert gravel-bed stream, LasVegasWash, were used to evaluate fractional bed load transport equations. Since the stream is an urban perennial channel that conveys primarily treated waste effluent, bed load transport is limited by the supply of transportable bed material. The Parker, Wilcock and Crowe, and Wu et al. surface-based fractional bed load transport equations were evaluated against the field data. The ratio between the calculated and measured bed load transport rate (C/O) as well as the data correlation coefficient with respect to each formula were calculated to judge the applicability of these equations to this field data set. Comparisons showed that both the Parker and Wu et al. equations satisfactorily predicted the transport rate, while theWilcock and Crowe equation has a larger scatter. The apparent success of Parker and Wu et al. equations can be attributed to two factors: a hiding function based on physical mechanism of the particle hiding and exposure, and the empirical coefficients calibrated using field data sources. The study results indicate that these two fractional bed load transport equations derived for perennial streams in wet regions are applicable to the field data collected at this arid region channel