open TELEMAC-MASCARET The mathematically superior suite of solvers

Hello,

I am a new user. I am trying to simulate urban flooding. I imported the elevation file as ASCII and also as a shapefile as mentioned in the tutorial. However, I found that that I can import also as TIF file but it didn't work when I tried it. I give me an Error (Error retrieving RGBA raster from study_dem.tif)

I would like also to ask about the following:

- In the tutorial, we convert the raster to tin then to nodes in Arcmap to import it in Blue Kenue. My question is do the generated elevation mesh will have the same resolution as the original raster as I saw that the number of generated points are small comparing to have a 1m resolution DEM.

- I would like to define the building with a different roughness coefficient in the model. How can I do this?

- I know that Telemac is including Rainfall-Runoff model and it calculates the loses based on SCS-CN method. Normally, I use the Hec-GeoHMS extension in Arcmap to create the CN map. I know that the best option is to define the CN map in the mesh to reduce the computation cost. So I have the same problem as importing the elevation as I prefer to import it as a GeoTIFF file to be more accurate. I don't know if the 2D interpolator will give the same accuracy as importing it as a GeoTIFF.

I really appreciate if someone can help me with these issues and thanks in advance

Hi

For the error, i don't have an explanation but ils potentially linked to the raster file itself. Are you sure it's a raster with 4 bands?

1 m raster is not necessarily more precise than nodes as the raster could be interpolated...

For roughness, if you have the buildings as polygons, you could give a friction value to each polygon and map these layer onto the mesh

The same for CN map. It's easier to map polygons, in my opinion, rather that using a raster...

Regards

Hi,

Thank you for your prompt response.

The raster that I have is with 1 band as in the attached image 1.

Yes, I used the 2D interpolator to interpolate the raster again (as shown in image 3) but the points which are used to generate it are few, I think they are not representing all the elevations in my study area as shown in image 2, I don't know if I am wrong or not.

For roughness, I have the buildings as polygon shapefile so I imported it as a shapefile to Blue Kenue as shown in image 4, the shapefile includes the roughness values. I would like to ask if it is possible to use the roughness value from it or I have to draw closed line manually and give them the values then use the map object tool to add them to the friction.

I will try to use the CN as polygons.

Thank you again and sorry for asking many questions.

Hi

It's more a grided value rather than a raster, that's why you probably cannot open it as a raster in BK.
Have a look to other import options...
I don't know how you manage the points but you should avoid this treatment because you miss to much elevations values.

For the buildings, the size of polygons is too small in regards to the mesh size so this will be difficult to implement the building roughness in a such large mesh.
You should at least aggregate the buildings by homogeneous area

Regards

Dear All,

Thank you for your reply.
I am still a new user and would like to know how to use Telemac first. I reduced the DEM resolution to 10 m and imported it to BlueKneue. I created the mesh, interpolated the elevation to it using the inverse distance method. Afterwards, I defined the bottom, bottom friction and CN (I used one number to all my study area for simplicity).
I checked the Pluie example and tried to create a file based on it. I defined the CN in the mesh and the rainfall as a hyetograph in a formatted data file.

I would like to ask the following questions:
- what does the ''NUMBER OF PRIVATE ARRAYS = 4'' in the Steering File means.

- What is the Fortran file in the input/output files (FORTRAN FILE ='t2d_pluie_cn_geo_hyetograph.f')?

-I created the boundary condition file but didn't define any boundary condition as I don't have any gauge or source of water ( I am working on urban area and would like to perform rainfall-runoff model). However, when I checked the files from Pluie example, I found that there is a boundary condition file. Thus, I just created the file.

When I tried to run my model with the attached files, all results are zeros.
I would be grateful if someone can check the files and explain for me my mistakes.

Best regards.
Omar