Geomorphological Processes and Human Impacts in River Basins (Proceedings of the International Conference held at Solsona, Catalonia, Spain, May 2004). IAHS Publ. 299, 2005, 171-178.

Abstract This study describes the bed load transport regime observed under low sediment transport conditions and constant discharge in the gravel-bedded lower Ebro River (NE Spain). The data show a tendency toward size-selective transport during bed load sampling. The maximum bed load transport rate was lower (35%) than average rates previously obtained under similar discharges. This decline is related to the development of an armour layer during winter floods, which has reduced sediment availability and, consequently, influenced the bed load transport rate and grain-size during the sampling period. Bed load transport observed at individual sampling verticals varied up to 3.7 times the mean rate computed at the same vertical. The highest transport rates and highest variance around the sampling mean occurred in mid-channel, with both the variance and rate diminishing towards the channel margins.

Key words bed load; Ebro River; grain-size; gravel-bed river