Cours d'eau ne sortant pas du MNT

Question

<\/HEAD>Bonjour,<\/P> <\/P> Je suis assez nouveau dans les analyses hydrologiques et Arc Hydro et j'essaie de comprendre comment gérer les cours d'eau (plutôt des fossés artificiels) qui ne sortent pas de mon MNT. Je voudrais "graver" ces fossés dans mon MNT en utilisant la "reconditionnement du MNT" mais ce que je me demande est : devrai-je appliquer une sorte de structure de puits car mes fossés ne sortent pas du MNT ? Je crois que le problème (c'est-à-dire la raison pour laquelle les fossés ne sortent pas du MNT) est que je travaille dans une zone semi-urbaine et que les fossés peuvent en fait se terminer dans des systèmes d'eaux pluviales. Ceux-ci pourraient-ils être considérés comme des puits ? <\/P> <\/P> Je m'excuse si la question est stupide... Je suis vraiment confus et toute aide serait vraiment appréciée.<\/P> <\/P> Merci,<\/P> <\/P> Alex.<\/P><\/BODY><\/HTML>

AlexanderVentura · Answer

Hi Christine,

I am using the Create sink structure tool for creating my sinks as you suggested. Everything flows smoothly however it seems like the tool only creates a sink polygon and sink polygon grid but no sink point. Do you have any idea of what the problem might be?

Thanks so much.

Alex.

AlexanderVentura · Answer

Hi Christine,

Thanks so much. So I have a vector representing drainage lines on the terrain. I want to "burn" these in so the water will be forced to flow inside of them. But some of the lines (not all of them) in the polyline vector don't "exit" the DEM (as mentioned above in my previous question). Essentially some lines start and end inside the DEM. If I understand it correctly if I follow these steps (to first remove sinks from my raw DEM and then burn in streams):

- Fill sinks

- DEM reconditioning

- Fill sinks

the last steps might fill in the burnt in streams that don't exit the DEM. Is this correct (if burnt streams are not filled can I simply continue with my analysis without bothering with sinks?)? If burnt in streams are filled I need to create a sink at the end of the lines (from the polyline feature) right? I tried to follow the stormwater processing workflow but still feel a bit confused, could you help me get my head around a few steps?

- When you say "buffer by 1.5*cell size to create a draft sink polygon" do you mean a buffer around a new point that I create at the end of the stream?

- In my specific case is it important that the sink is placed at the end of the stream (most downstream location) or it doesn't matter?

- Should Create Sink Structures only generate a sink for the "buffers" that I have generated at the end of the streams that don't exit the DEM?

I tried these steps but I keep getting an error when running the last. Am I getting something wrong here?

Thanks so much again.

Alex.

ChristineDartiguenave · Answer

To avoid being filled back in, a stream must either exit the dem or end in a sink. In your case, create a sink point at the end of the streams, buffer by 1.5*cell size to create a draft sink polygon and then use the Create Sink Structures to create the SinkPolygon/SinkPoint. You can look at the Stormwater processing workflow for help.

Christine Dartiguenave

Esri Water Resources