Suspended solids concentrations and river water chemistry

Publisher Website
Google Scholar
Abstract
In some rivers concentrations of suspended solids are influenced to a large degree by the chemistry of the river water. This is particularly true for rivers with fine sediments draining areas where soils have high percentages of exchangeable sodium and where changes in the electrolyte concentrations during hydrologic events result in an alternation between conditions favouring dispersion and those favouring flocculation. This relationship is illustrated for low flow conditions by data from a small river in Eastern Australia.At high flows, variations in suspended solids concentrations independent of those resulting from changes in discharge and erosion are difficult to establish. However, in semi‐arid regions high concentrations of clay and silt may sometimes be transported. The way such concentrations reflect changes in water chemistry is illustrated by a flash flood from Morocco and by data from the Moreau River in South Dakota. A contrasting example from Northern England describes conditions where the water chemistry produces dispersion and high suspended solids concentrations.The relationship between electrolyte concentration, exchangeable sodium percentage and suspended solids concentrations is described for each drainage basin. Such relationships provide an insight into the nature of erosion processes in a catchment and help to explain why suspended solids concentrations at low flows may be so variable.