Sediment Transport Circulation Pattern through Mesotidal Channels System

TLDR: In this article, the authors focus on the bed sediment transport pointing to the pathway migration rather than the sediment transport rate itself, and estimate the transport of non-cohesive sediments, mobilized by the channel floor.

Abstract: There are three modes of sediment in motion, which are recognized as rolling and/or sliding; jumped and suspension particles motion. These particles motion include two essential sediment transport modes, which are bedload and suspended load. The first corresponds to the part of the total load which is moving very close to the bed. On this opportunity, the sediment is transported by rolling and/or sliding along the floor or jumping immediately above the bed. The suspended load comprises the particles that are carried away at suspension in the moving fluid. Bedload transport occurs in low velocity flow and/or large grain sizes, while suspended load take place at high velocity flow and/or small grain sizes. The sediment transport theory to point out that sediment capacity flow and sediment availability in channels regulates the motion of sediments. The sediment transport capacity is the maximum load that can be transported by flow and the sediment availability is the material supply that the flow can put in motion. In general, the sediment load that moves in a rolling or saltating mode is smaller compared with the suspended load transported in a natural flow. However, the bedload sediment is important for its contribution to the morphological change of the channel. Moreover, it is the most important factor in determining the stability of natural channel, the bed topography, and therefore, the cause of the hydraulic resistance and some properties of the flow. Accordingly, on this chapter we focus on the bed sediment transport pointing to the pathway migration rather than the sediment transport rate itself. The sediments transport as bedload in estuarine environment controls the bottom morphology. Therefore, estimating the transport of non-cohesive sediments, mobilized by the channel floor, has relevance to the understanding of many pressing environmental problems including eutrophication, contaminant transport, sediment bed erosion, siltation and waste disposal, which impacts on seabed stability and at times on ecosystem distribution. Also, sediments that are moving on the bed generate different bedforms such as shoal, dunes, point bar, etc., which can be hazards to navigation and to affect the flow conditions and the flanks channel stability.