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. 
 

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

 

 

Message Boards

Using DELWAQ with a single-column hydrodynamics time series (U/V/density)

SB
Sebastien Blaise, modified 4 Months ago.

Using DELWAQ with a single-column hydrodynamics time series (U/V/density)

Youngling Posts: 2 Join Date: 1/27/17 Recent Posts

Hi,

 

I have been provided a time series of horizontal velocity and density at a single location along the water column, to be used in a pollutant dispersion study. It is a relatively flat area with little spatial variability of the hydrodynamics. 

 

Can such data be used in a Delwaq simulation? Should I generate a .hyd file from it?

 

Thanks

AM
Arjen Markus, modified 4 Months ago.

RE: Using DELWAQ with a single-column hydrodynamics time series (U/V/densit

Jedi Knight Posts: 222 Join Date: 1/26/11 Recent Posts

When I first read your message, I thought it was the wrong kind of question, but reading it more carefully, I realise what it is all about. Yes, as a matter of fact, you can use such data to construct a hydrodynamic database of sorts. Depending on what kind of resolution in the horizontal you want it could actually be easy. If you want one column, then the thing to do is: set up a one-column model with Delft3D-FLOW or D-FLOW-FM - use the number of layers you want and the layer thicknesses you want (the latter is not strictly necessary though). Then run it for a short period. This gives you the hyd-file and the grid files you need, as well as several others. You will then need to replace the volumes and the flows files: the volumes file contains the volumes per segment, per time. The flows file contains the flow rate through every exchange area  - flow velocity time surface area for both the horizontal and vertical exchanges.

The actual contents of these file is described in the manuals, but for a simple flow field as you indicate it is not hard to construct a proper set of such files.

SB
Sebastien Blaise, modified 4 Months ago.

RE: Using DELWAQ with a single-column hydrodynamics time series (U/V/densit

Youngling Posts: 2 Join Date: 1/27/17 Recent Posts

Thanks. It seems like a very pragmatic and efficient solution.

 

A follow-up question (I am a new user, still waiting for the GUI): can we model in DELWAQ a buoyant tracer that will sink/rise according to its density and concentration, despite the fact there is no feedback from the tracer distribution to the hydrodynamics? In other works: can DELWAQ include buoyancy effects due to a different effluent density compared to the ambient waters? 

AM
Arjen Markus, modified 4 Months ago.

RE: Using DELWAQ with a single-column hydrodynamics time series (U/V/densit

Jedi Knight Posts: 222 Join Date: 1/26/11 Recent Posts

Well, inorganic matter (IM1, IM2, IM3) are the substances we use to model suspended solids, but there is no reason why the settling velocity should be positive only. In fact I have used a _negative_ settling velocity to model microplastics lighter than water. Consult the manual to see if the current implementation wrt the settling velocity as function of salinity and the concentration suits your requirements. Otherwise it is possible to define your own processes vai "Open PLCT".