An assessment of sediment-transport processes in the Lower Mekong River based on deposit grain sizes, the CM technique and flow-energy data

摘要: Abstract The Lower Mekong River has been an important research topic for at least 15 years, notably in the fields of hydrology, fluvial geomorphology, and impact dams. Recent papers refer mostly to Lancang chain hydroelectric dams constructed on Chinese section river. Among pending scientific questions are (1) upstream–downstream variations concentration yield suspended sediment (2) relative importance sand total yield. general consensus among community is that load not main concern despite its extensive presence channel, as noted by geomorphologists, extreme stability delta shoreline Viet Nam. This paper contradicts consensus. Its objective present new information processes transport channel. Imagery, field observations, sampling river banks, grain size analysis deposits have carried out between Chiang Sean (downstream border) delta. C–M image technique served discriminate various (bedload different types suspension). helps understanding changing responsible downstream transfer channels. results this study following. Discrepancies values annual suspended-sediment detected gauging stations yet satisfactorily explained. CM indicates quantity transiting suspension vs. bedload vary from upstream downstream. These differences may be related energy floods. Energy explain longitudinal modes serves distinguish bedload, graded uniform suspension, wash load. (3) seen a carrying silt clay; however, suggest plays major role during result line with large amounts must reassessed, suggested Walling (2005, 2008). As expected, prime importance.