intro story Coast / Estuary

Coast / Estuary

Coastal systems are among the most dynamic physical systems on earth and are subject to a large variety of forces. The morphodynamic changes occurring to coastlines worldwide are of great interest and importance. These changes occur as a result of the erosion of sediments, its subsequent transport as bed load or suspended load, and eventual deposition. 
Estuaries are partly enclosed water bodies that have an open connection to the coast. Estuaries generally have one or more branching channels, intertidal mudflats and/or salt marshes. Intertidal areas are of high ecological importance and trap sediments (sands, silts, clays and organic matter).
Within the Delft3D modelling package a large variation of coastal and estuarine physical and chemical processes can be simulated. These include waves, tidal propagation, wind- or wave-induced water level setup, flow induced by salinity or temperature gradients, sand and mud transport, water quality and changing bathymetry (morphology). Delft3D can also be used operationally e.g. storm, surge and algal bloom forecasting. 
On this discussion page you can post questions, research discussions or just share your experience about modelling coastal and/or estuarine systems with Delft3D FM. 




Sub groups
D-Flow Flexible Mesh
Cohesive sediments & muddy systems



Message Boards

Processes in Sediment Layer

Martin Schueder, modified 6 Years ago.

Processes in Sediment Layer

Padawan Posts: 52 Join Date: 10/8/13 Recent Posts

In the Sediment Water Interaction manual, I read the following lines on pg 5:

"SWITCH is a rather complex process routine that simulates the vertical concentrations gradients of organic matter, oxygen, nitrate and nutrients (N, P, Si) taking into account 4 sediment layers, and that generates similar fluxes as well as the denitrification flux and the phosphate adsorption and precipitation fluxes. SWITCH is fixed with respect to the substances and layers, and is therefore not generic and not very flexible. Both options are described in Delwaq’s Technical Reference Manual. An additional full description of SWITCH is available too."

It says that SWITCH is fixed with respect to the substances and layers. Does this mean that if I wanted to specify a mass flux of [H+] from the sediment layer into the water column I would be unable to do so? I can specify new processes in the DelWaq process library, can I specify new fluxes for pre-existing compounds (namely H+) in the sediment layer?

My thanks,

Michel Jeuken, modified 6 Years ago.

RE: Processes in Sediment Layer (Answer)

Jedi Knight Posts: 154 Join Date: 1/21/13 Recent Posts
Hi Martin,

SWITCH was not very flexible, and has been replaced by a new "layered bottom" implementation. The basic idea of this new approach is that you extent your model with extra segments which represent the sediment where the same (open) processes can take place as in all your other segments, albeit sometimes with different parameters. There you could also model your [H+] flux.

Although flexible, it is still a bit complicated to apply it, and not supported by any GUI. You wil have to manually edit input files, and have quite some understanding of how Delwaq works. A draft manual can be found here: