hi sir/mam, could u please explain about the bio physical table and its component like Curve numbers. how can i get the data for it and how to prepare it.
Thanks in advance.
Regards,
Gowtham D.
Hi @DGowtham -
Have you checked out the User Guide chapter for Urban Flood? There’s a Data Needs section that gives a description of the biophysical table, and an Appendix that points to one general source of curve number values. When you installed InVEST, you may also have installed sample data, which gives an example of how the inputs should look, so you can use that as a template for creating your own data. If you did not install sample data when you installed InVEST, you can get the sample datasets from the InVEST web page.
It’s always good to try and find data that’s more specific to your study area. For curve numbers we do a literature search and see what others recommend for a similar place or land use/land cover types. In particular, government agencies who work with roads, construction and hydrology in general might have recommendations for values to use.
You also might find recommendations by searching this forum for previous posts related to curve number.
~ Stacie
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sorry mam. i forgot to say thanks for this post. Thank you. And I got an another problem. when i am trying to attach my soil hydrological group raster file in the INVEST user interface its not supporting and not uploading.
Help me out with that. Please find the screenshot.
Regards,
Gowtham.
Hi @DGowtham -
When you click on the red X to the left of “Soils Hydrological Group Raster” what does it say? You should see a brief message explaining what’s wrong.
~ Stacie
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Thanks for ur reply mam. its shows “dataset must be projected in linear units”
Regards
Gowtham
Ok, then that’s the issue. Check the coordinate system of that raster, it is likely in a geographic coordinate system. Reproject it to be in the same projected coordinate system as your other inputs that do not get that error, and see if that fixes the problem.
~ Stacie
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Hi mam.i hav tried to change the to the coordinate system. Its not helping. Could you please share any video tutorial or anything related to the the issue.
I have tried various
Methods.
Thanks in advance.
Gowtham…
Hi @DGowtham ,
I have tried to change the to the coordinate system
Could you describe the steps you took to do this? Changing the coordinate system and projecting to a new coordinate system end up being two very different things. Changing the coordinate system will simply update the metadata but have no effect on the raster itself. Projecting or reprojecting a raster will change the raster in space and have an updated coordinated system to match.
Here’s a youtube video showing how to reproject a raster in QGIS:
Doug
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Thank you sir. It worked.
Regards,
Gowtham
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Dear @swolny,
I wanted to ask if as an alternative to the introduction of the biophysical table (for the calculation of the curve number) it was possible to directly insert a raster with the values (local) of Curve Number.
Thank you,
Antonio
Hi @antobaro,
Currently it’s not possible to pass in a raster with the Curve Number values. If there’s enough interest in allowing the curve number values to be an additional raster input we could think about adding it as an option in the future. Would you find it much more helpful to be able to do so?
Thanks for your feedback!
Doug
Hi @dcdenu4, thanks for the reply.
Personally I would definitely find it more useful: because at the moment the local data that I was able to access (province of Rome, Italy) make available only the raster with the curve numbers.
I have asked the responsible offices if it is possible to have the correspondences between curve number, hydrological groups and land cover in table format, but I’m still waiting for the answer.
In general, perhaps, having more ways of entering data in INVEST could facilitate the operativity of the software, but I do not know if this would increase its complexity too much.
I also don’t know how complicated it would be for you to add these options.
Antonio
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I’ll chime in that similar functionality has been requested over the years for one or two other biophysical table parameters, USLE C in particular comes to mind (for the SDR model), since it’s often derived from NDVI raster data. So we might want to consider this a bit more broadly (although certainly most table parameters are fine as table only). I will say that I’ve never found a CN map for any of the places I’ve worked, so it’s interesting that you have one @antobaro.
If you do happen to know that they based the CN raster on particular maps of hydrological group and land cover, you can probably calculate an average CN for the different combinations (which would be used in the model’s table) with some creative use of GIS.
~ Stacie
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