Channel processes and sedimentology of a boulder-bed ephemeral stream in the western Afar margin
published: Mar 1, 2016
manuscript accepted: Sep 18, 2015
manuscript revision received: Sep 14, 2015
manuscript revision requested: Apr 15, 2015
manuscript received: Jan 11, 2015
ArtNo. ESP022006001003, Price: 29.00 €
Abstract Few papers report and very little is known about the geomorphology and sedimentology of present day very coarse-grained, ephemeral streams. This paper aims to shed some light on fluvial processes acting in this kind of drylands rivers and to provide some insight into their sedimentological characteristics as a diagnostic tool for the interpretation of ancient deposits. Such topics are investigated in a field study on the Golina River, a sandy boulder-bed ephemeral stream of the Kobo basin in northern Ethiopia, subjected to intermittent flow generated by episodic, high intensity rainfall. Though the main gemorphological characteristics of the braid bars and channels are apparently similar to those of perennial rivers, field investigations show that the channel morphology and sedimentology of the study reach result from different depositional/erosion processes. A model based on the superimposition of coarse-grained bedload sheets, with the characteristics described by Whiting et al. (1988), and subsequent dissection during the receding flood flow is considered. This model was found to explain well the morphological and sedimentological features observed in the investigated boulder-bed, ephemeral stream.