Vecteur de cours d'eau pour le reconditionnement du MNE

Question

<\/HEAD>Bonjour,<\/P> <\/P> J'ai une classe d'entités de cours d'eau que je souhaite intégrer en utilisant le reconditionnement du MNE.<\/P> <\/P> Ce que je me demande, c'est : y a-t-il des exigences spécifiques pour la classe d'entités ? <\/P> <\/P> Je sais que tous les cours d'eau doivent soit sortir du MNE, soit se terminer dans des dépressions, mais y a-t-il autre chose à considérer qui soit vraiment essentiel ? J'ai lu que les pseudo-nœuds doivent être supprimés et la géométrie vérifiée. <\/P> <\/P> Je suis principalement intéressé par le dessin de mes bassins versants (je ne prévois pas de faire d'analyse complexe au-delà de cela).<\/P> <\/P> Toute suggestion est vraiment appréciée.<\/P> <\/P> Merci beaucoup !<\/P> <\/P> Alex<\/P><\/BODY><\/HTML>

AlexanderVentura · Answer

Hi Dan,

Thanks for your answer.

Actually I’m not getting unexpected result, just want to make sure I’m following “best practice” or at least not making serious mistakes. But if all streams get burnt in and have the values I expect it should be fine right?

My stream feature class is actually 2 separate ones that I merged into one and then use to burn in streams. The reason is I believe the 2 separate stream feature classes are for main and secondary streams. They are generated by the same national authority and in order to include all of the streams in my DEM reconditioning I merged them.

Also I am not clipping the streams to the raster extent as this way all my streams “exit” the DEM and won’t get refilled after burning in. Is that a problem and is it better to instead clip the stream feature class to raster extent and then extend the streams beyond the DEM manually (by editing streams)?

One last question if you don’t mind: my DEM raster has values (approx 0 meters) for the ocean. As many of my streams end up in the ocean I was thinking of converting the ocean polygon to raster and removing this from my DEM. This way all streams will exit the raster (and won’t get refill after burning) and I can add “coastal” catchments at the end of the terrain preprocessing to complete areas with missing catchments. This makes more sense to me than treating the ocean as a “sink”.

Does this make sense to you?

Thanks again for the help.

Alex.

DanPatterson_Retired · Answer

are you getting unexpected results?

I would convert the stream to a raster with the same extent and cell size first using the dem as the snap raster.

In that way, you have control over the result and are sure that the conversion of the stream to a raster is done overtly and not behind the scenes where you can't inspect it