Estuarine Hydrodynamics - Science topic

It was a mesh problem. Thanks for your input.

Mike21 is a good choice for your interest, we used it in the simulation of Tide and tidal currents estuarine environment.

You could indeed use ANCOVA/linear regression (after checking your model assumptions, i.e. linear relationship between length and weight (in model 1), normality and homoscedasticity of residuals and independence of observations).

As observations from the same population are probably not independent, you should add population as a variable in your model.

There are two possibilities:

Since you are interested in the difference of length-weight slopes between sexes, you should add an interaction effect in your model.

The model looks something like this:

length ~ weight + sex + population + weight*sex

If the interaction effect is significant, the length/weight slope differs with sex. To identify the which of the four groups differ significantly from each other, you can carry out a post-hoc test on the interaction term (e.g. Tukey test). If the interaction is not significant, you cannot assume that the l/w ratio is significantly different between any of the four groups.

Another way would be to use the length/weight relationship directly in a model:

length/weight ~ Sex + Population

Here, we do not need an interaction term, as the relation between the l/w ratio and the four ‘Sex’-groups is implicitly part of the model. If ‘sex’ is significant, you can again perform a post-hoc test on ‘sex’.

If you are using R, this link might be helpful: https://rcompanion.org/handbook/G_09.html

One added point, installing dikes, diversions or filter silt fencing can after flow pathways. Under normal conditions, undesturbed salt marsh should hold up to small to moderate changes in flow stress. But monitoring is advisable until there is assurance of recovery, especially after major storms, winds that might alter forces.

Dear Jayachandran,

you mean all living beings? reaction is too different. But working at the lab of the Danube and Limans (Estuaries) we found several interesting facts. Even desalinated the Estuary never lose completely its marutime or brackish water fauna. Look, please, my last presented publication about the Sassyk ciliates fauna! As well  what happened with this ineresting freshened basin after desalination are gathered in our book (as well my site). If estuary is of some large river and practically fresh, so marine fauna can penitrate over the deep relict river bad and it can be the very upper part of this type Estuary. Moreover  in this relic river bad is concentrated hydrogen sulphide that is suitable for anaerobic organismes od marine origin. I wrote about the Dnieper-Bug Estuary. As about tides it can stimulate exchange of the organismes but is not comfortable for a stable fauna. Therefore in the locality of the Estuary with abruptly changing regime it will be enough poor fauna, eg especially if salinity will be changing from 1-2 over 5-7 promille diapazone and back.

Extra interesting can be redistribution of the primary production of phytoplancton that can be consumpted in the deeper layers and in benthos...

I have enough much books on the question, so if necessary, call me by RG mailing, Will send.

Andrey

Try MNDWI water index with Landsat 5-8 / SPOT 5 imagery. 

Hi, you might also find the following reference of interest:

Valle-Levinson, A. 2012. Impact of record flooding of a subtropical river on estuary/ocean exchange. Ocean Dynamics 62: 77-85.

Really thank you for the answer, I ll get a look. However I do not have isotopes. 

All the best

Fabio

Dear Heron

It is very difficult to provide a range. It all depends on many factors such as salinity, depth, height of tides etc... as you know about them. A very broad figure may vary from 0.01 to 10. The attached paper may help you in many ways. 

We have often used conductivity as a conservative. For example, suppose we have only one streamflow measurement below the confluence with a tributary, and also have measurement of conductivity above and below the confluence and in the tributary. Then, using a simple mixing equation and assuming conductivity acts as a conservative, you can calculate the flows in the upper stream and in the tributary. We also use conductivity balances to assure that our flow measurements are correct. 

This works because total dissolved solids (TDS) which is a good conservative tracer is usually proportional to conductivity. In our day-to-day work we seldom actually estimate TDS, and simply use conductivity as if it was a concentration of a conservative material. 

Thank you for the answers. Based on your suggestions I searched some articles. The link below seems to be useful for better understanding.

As the prior answers suggest, it's a compromise.  Structured grids are simpler to code, so if a significant constraint is programming time, this is the way to go.  Unstructured grids allow you to place the resolution where you need it (more easily), so if computing time is the main limit, this is the way to go.

In deciding whether you're more limited by programming time or computing time, don't underestimate the programming time.  It's awfully easy to do so.  Programming time includes not just the initial getting to the point of having meaningful answers in this particular model, but in developing all the programs and scripts for the care and feeding of the model (e.g. translating forcing fields to the model's grid -- easier with structured grids), and in maintaining all of your system's codes (again, can be more complex with unstructured grids).  The maintenance, care, and feeding of a model system is about 10x the programming time of the core model in my experience.