Estimating cohesive sediment erosion and deposition rates in wide rivers

Abstract

Sediment erosion and deposition rates are two of the most important factors that influence fluvial geomorphology. Several experimental devices have been constructed to estimate cohesive sediment erosion rate. However, estimated erosion rates may not be reliable for large rivers due to limited soil sampling and a high dependency of cohesive sediment behaviour on several physical, mechanical, and electrochemical properties of the sediment and eroding fluid. A new methodology has been developed to estimate the erosion and deposition rate of wide rivers using in situ measurements. To test this methodology, an acoustic Doppler current profiler was used to collect bathymetry and velocity profiles over a study area along the Red River in Winnipeg, Canada. Sediment concentration profiles along an 8.5 km reach of the river were measured several times under different flow conditions. Finally, an advection–dispersion equation was numerically solved using measured and calculated streamwise dispersion coefficients, flow and channel characteristics to calculate net erosion and deposition over the study area. Moreover, an exponential relationship was obtained between the river discharge and longitudinal dispersion coefficient for the Red River.

Origin of photo-enhanced hysteretic electrical conductance in nanostructured silicon-based heterojunction

“…The rate of trapping and detrapping depends on the flow rate of charge carriers as well as presence of an empty and filled trap respectively available in the path of a free carrier. This phenomenon may be compared to the deposition and erosion of river bed where the flow rate and the geological structure of the river bed controls the deposition or erosion [28,29]. A reasonable matching has been obtained between the experimentally observed hysteresis in I-V characteristics and the theoretically calculated ones using this model.…”

“…When the current is small the carriers are more likely to get trapped in a way similar to the deposition of soil and sand by a river near its estuary [28,29]. If the flow rate is high then de-trapping or erosion is more likely to occur as seen for a river in the hilly region near river-source [28,29].…”

“…When the current is small the carriers are more likely to get trapped in a way similar to the deposition of soil and sand by a river near its estuary [28,29]. If the flow rate is high then de-trapping or erosion is more likely to occur as seen for a river in the hilly region near river-source [28,29]. In the trace path when bias is just applied, as the rate of flow of carriers is low and most of the traps are available to capture the free carriers, the trapping is likely to dominate the transport.…”

Morfodinamika Jangka Pendek Pendangkalan Di Alur Pelayaran Barito, Kalimantan Selatan

“…2013). Sementara studi-studi sebelumnya yang menggunakan pendekatan permodelan numerik dengan meggunakan software Delft3D ( van Maren, et al 2015;George, et al2012;Van Leeuwen 2003), MIKE 21 (Kimiaghalam et al 2016). Sementara (Miller et al 2014 Modul morfologi pada Delft3D membagi perhitungan pada dasar permukaan (bed load) dan sedimen tersuspensi (suspended sediment), juga berdasarkan jenis sedimen menjadi kohesif dan non kohesif (Deltares 2017).…”