Analysis on suspended sediment deposition rate for muddy coast of reclaimed land

A new expression for calculating suspended fine-sediment deposition rate is developed based on theoretic analysis and experiments. The resulting equation is applied to simulation of fine sediment deposition in the reclaimed land in the Hangzhou Bay, China. The hydrodynamic environment in this area is solved by use of a long wave model, which gives the 2D-velocity field and considers bathymetric changes due to fine sediment deposition. The expression is proved convenient to use in engineering practice, and the predicted deposition rate agrees with the annual data available from field measurements from the first year to the third year after the construction of the long groin as a reclaiming method.

Assessing suspended sediment dynamics in relation to ecological thresholds and sampling strategies in two Irish headwater catchments

Prediction of the impact of suspended sediment on aquatic ecosystems requires adequate knowledge of sediment dynamics in surface waters. Often, studies reporting the response of aquatic biota to suspended sediment are concerned with concentrations, while catchment erosion studies often report sediment delivery as annual loads and yields, making the comparison to documented ecological impacts difficult. Similarly, the European Union Freshwater Fish Directive (FFD) (78/659/EC) stipulates a guideline value of 25mgl which should not be exceeded, with the exception of floods and droughts. In this respect, the significance of suspended sediment in two Irish rivers was assessed using turbidity sensors calibrated for suspended sediment. Sediment yields of 0.07 tonnes (t) hayear and 0.44thayear and annual FFD exceedance frequency of 8.3% and 17.8% were estimated for the two catchments. Contrasts in the frequency of exceedance events between both catchments was observed, yet duration was typically short (