Experimental determination of erosion/deposition parameters and their application to a real case: The Sancti Petri Channel

Abstract

Material from the bottom and banks of very shallow channels can be eroded due to current effects, producing suspended sediments that are transported by water movement. The problem with sediment transport in these systems can be dealt with using the transport equation, where the particle flow is calculated as a function of the sediment characteristics and of the flow itself. However, the parameters are complicated when the channels consist of cohesive matter. In this paper, a procedure based on the experimental determination of the parameters is proposed in which the erosion and deposit terms are valid for cohesive and non-cohesive silt. This method can be applied to those systems where suspended sediments originate mainly from the erosion and deposition of spring sources. The application of this method to the Sancti Petri Channel allows us, based on simultaneous recordings of current speed and concentration of sediments in suspension, to calculate the critical velocity for this system, which is formed by cohesive matter. The Sancti Petri tidal system is an inflow-outflow channel that extends from the inner zone of Cadiz Bay to the outlet to the Atlantic Ocean. It is approximately 17 km long and has a deep central zone, fringed with ample muddy areas, where the currents associated with tides reach high intensities.