Ajuster la direction de l'écoulement dans les cours d'eau

Question

<\/HEAD>Bonjour,<\/P> <\/P> J'essaie de comprendre comment utiliser correctement l'outil "Adjust flow direction in streams". D'après ce que je comprends, cela devrait être utilisé lors de l'imposition d'un système de cours d'eau (burning in streams) qui contient des zones circulaires. Voici mon flux de travail :<\/P> <\/P> 1. Remplir les dépressions<\/P> 2. Reconditionnement du MNT<\/P> 3. Remplir les dépressions<\/P> 4. Direction de l'écoulement<\/P> 5. Accumulation de l'écoulement<\/P> 6. Définition des cours d'eau<\/P> <\/P> Je lance ensuite l'outil "Adjust flow direction in streams" et comme "Stream flow direction grid", j'utilise le résultat de l'étape 6 dans mon flux de travail. Est-ce la bonne approche ?<\/P> <\/P> Merci beaucoup pour votre aide et je m'excuse si la question a déjà été posée et répondue.<\/P> <\/P> Alex.<\/P><\/BODY><\/HTML>

ChristineDartiguenave · Answer

You will use if you have known Streams you want to use.

Create Drainage Line Structures will create a rasterized version of those streams.

This tool also create StrLnk which you can use as input Str raster in DEM Reconditioning (this way we use the same raster).

Christine

AlexanderVentura · Answer

Hi Christine,

Thanks a lot for your reply. OK, I was following this manual:

http://downloads.esri.com/support/datamodels/Hydro/Comprehensive_terrain_preprocessing_using_Arc_Hydro_tools_2008.zip

and as far as I had understood it the "Adjust flow direction in streams" tool is used when burning in streams into my DEM but the streams have "braids", but I guess I had gotten this wrong.

So essentially I need to "burn in" streams (ditches or drainage systems rather) to "force" the water to flow in these. I have a detailed network of drainage lines available in vector (polyline) format. So far I have been using "DEM reconditioning" for this but you mention "Create Drainage Line Structures". Is this a process that should be performed before running the "DEM reconditioning"  tool? Or is "Create Drainage Line Structures" used when a vector of drainage lines is not available and needs to be created?

Thanks again,

Alex.

ChristineDartiguenave · Answer

You do not need to run the tool "Adjust flow direction in streams" when the streams are generated using Stream Definition based on the flow accumulation raster. This tool is used when the Streams (Drainage Line) are created using Create Drainage Line Structures, i.e. you are trying to match the geometry and digitized direction of input vector streams, which may not match the direction provided by the underlying terrain. This tool ensures that once the water gets into the stream, it follows the direction of the digitized input streams. In flat area, the water may not go the right way otherwise.

Christine Dartiguenave

Esri Water Resources Team