Publication Summary: Erosion characteristics of fine-grained cohesive sediments

Krishnappan BG, Stone M, Granger SJ, Upadhayay HR, Tang Q, Zhang Y, Collins AL. Experimental Investigation of Erosion Characteristics of Fine-Grained Cohesive Sediments. Water 2020, 12(5): 1511.

Micheal Stone, Theme 2 Leader, University of Waterloo

Adrian Collins, Partner, Rothamsted Research

Bommanna Krishnappan, Partner, Emeritus Research Scientist at National Water Research Institute

Brief summary
Cohesive sediment plays an important role in the transport and fate of pollutants and is a key driver of water quality degradation in aquatic systems such as rivers and reservoirs. Knowledge of cohesive sediment transport processes (erosion, deposition and flocculation) is critical for the development of reliable numerical models designed to simulate cohesive sediment and associated contaminant transport dynamics. 

​In this study, the erosion behavior of cohesive sediment collected from the upper River Taw in South West England was studied in a rotating annular flume located in the National Water Research Institute in Burlington, Ontario, Canada in order to model the transport of fine sediment and the associated nutrients in the River Taw. The results show that eroded sediment is transported in a flocculated form due to the presence of microorganisms and organic matter. The experimental data and the fitting coefficients were established as a function of bed shear stress and depositional history of sediment and applied to a fine sediment transport model (FLUME) which accurately simulated the erosion experiments in a rotating circular flume deposit.

Figure 1: Comparison of measured and modelled sediment concentrations predicted by the FLUME model.

Key messages

• Cohesive sediment is the primary vector for the majority of contaminants of concern in aquatic systems and is a potential driver of algal growth in downstream water bodies such as reservoirs.
• Quantification of key transport processes in an annular flume provide data required to calibrate cohesive sediment transport models (RIVFLOC) that can be coupled with USGS reservoir hydrodynamic (RMA2) and water quality (RMA4) models to simulate nutrient and algal dynamics in reservoirs. These models have implications for water treatability because they provide a simulation tool to quantify potential impacts of landscape disturbance on water quality in reservoirs. 
• The present study is an example of technology transfer and tool development with forWater international research partner in the UK (Dr. Adrian Collins, Rothamsted Research).

Research Photos