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

Problem Calibrating Water Levels

MS
Mihael Souza, modified 8 Years ago.

Problem Calibrating Water Levels

Padawan Posts: 65 Join Date: 10/11/12 Recent Posts
Hi all,

In the past few days, I started to learn how to use Delft 3D for coastal modelling.
I'm still very new to modelling, so I apologize if the question I have is somewhat basic.

I'm trying to model an estuarine system.
I have open boundaries in the SW-E-NE, and i'm forcing those boundaries with the harmonics extracted from Tidal Model Driver, from OSU models.
I have extracted the constituints in each boundary, and I am trying to calibrate only the water levels right now.
Although amplitude and phase appear to almost be okay, there seems to be a slight time lag between modeled and observed data.
I have tried increasing bottom roughness, to delay the tidal wave, but it made no change.
I even tried using a defined roughness for all the modeled area, using a .rgh file, and no luck.

I'm attaching an example of a comparison between modeled and observed water level.
Any thoughts?
Katherine Cronin, modified 8 Years ago.

RE: Problem Calibrating Water Levels

Padawan Posts: 42 Join Date: 2/23/11 Recent Posts
Dear Mihael,

Welcome to the forum - all questions are welcome. Over what period did you extract the tidal constituents? You should check that the time-series was long enough to resolve the constituents properly, otherwise you may mis-calculate some important components. How many tidal constituents are you applying?

best wishes,

Katherine
MS
Mihael Souza, modified 8 Years ago.

RE: Problem Calibrating Water Levels

Padawan Posts: 65 Join Date: 10/11/12 Recent Posts
Katherine, thanks for the welcome and the suggestions!

I extracted the constituints from the global model. I do not know how long is the time-series they used, gonna check into that.
I'm applying mainly 8 constituints: M2, S2, K1, O1, Q1, M4, K2 and N2, that were the ones with the highest amplitude from all constituints.
Is there any practical way to choose which constituints to consider?
My region is dominated by semi-diurnal tides.

I do tried using less and even more constituints, up to twelve, and the same time lag applies. That is why i'm unsure if its a problem with the number of constituints. Any other thoughts?
Katherine Cronin, modified 8 Years ago.

RE: Problem Calibrating Water Levels (Answer)

Padawan Posts: 42 Join Date: 2/23/11 Recent Posts
Hi Mihael,

Yes do check how long the time series was for the tidal analysis as this is important if you want to resolve the constituents properly. Also what about the phases?
You said you picked the constituents based on the largest amplitudes but the phases are also important and will influence the propagation of the tide.

best wishes,

Katherine