Bäche, die das DEM nicht verlassen

Question

<\/HEAD>Hallo,<\/P> <\/P> Ich bin ziemlich neu in der hydrologischen Analyse und mit Arc Hydro und versuche, mich damit vertraut zu machen, wie man mit Bächen (eher künstlichen Gräben) umgeht, die mein DEM nicht verlassen. Ich möchte diese Gräben gerne mit "DEM-Rekonditionierung" in mein DEM "einbrennen", aber ich frage mich: Muss ich eine Art Senkenstruktur anwenden, da meine Gräben das DEM nicht verlassen? Ich glaube, das Problem (also der Grund, warum die Gräben das DEM nicht verlassen) ist, dass ich in einem halb-urbanen Gebiet arbeite und die Gräben tatsächlich in Regenwassersysteme münden könnten. Könnten diese irgendwie als Senken betrachtet werden? <\/P> <\/P> Entschuldigung, falls die Frage dumm ist... Ich bin einfach wirklich verwirrt und jede Hilfe wäre sehr willkommen.<\/P> <\/P> Danke,<\/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