I am delineating a basin in the river Nile using Arcmap (spatial analyst tool), during delineating the sub-basins and defining different outlets, the result is one watershed consisted of all the sub basins! why is this happening ? in the past i delineated the sub basins and they appeared separated right.
Attached picture with the merged sub basins in green and the blue circles is on the place where sub-watersheds are merged.
Not an expert in ArcMap. We use a separate coverage for the different size hydrologic units such as basins, subbasins, watersheds, subwatersheds, and also various stream orders for smaller hydrologic units. The merge command apparently actually merged your polygons and you lost the lines. Someone may know how to reverse this. If I get a product I am going to want to reuse, I always keep a separate file, before continue to edit and also the reverse arrow button is a good one to know when you make a critical mistake and want to go back. I don't know how to fix this, but have used GIS software long enough to know I am not an expert, just a careful user. If this happened without using the merge command, then its a problem I don't know about. But next time something happens you don't like, use the large left reverse arrow to be back one or more steps. If you are mapping hydrologic units without names, I developed a numbering scheme based on stream order that I could send. On the national forest areas I have worked on, we typically go down to third order catchments that receive unit numbers. In one analysis in the mountains, I analyzed the erosion and sediment effects on over 300 third order streams (these are perennial in our area with fish values). That 2013 EIS was uploaded in researchgate as an example of analyzing a large loblolly pine removal project at various hydrologic unit scales. My advice is to keep each hydrologic scale boundaries as separate coverages. I typically use stream ordering (Strahler) to define the various size streams and their branching pattern. The publication on stream types and management implecations discusses some of that work before we had LiDAR.
you can contact prof. Mahmoud Adel at ARCA through E-mail: [email protected]
he is professional in ArcGIS, he will help you
Hello,
You can use esri hydrology v2 dll. It's a dll file to add to Arcmap. it provides interfaces for creating watersheds, flow directions, flow accumulation, stream networks. But it also has two buttons to delineate watersheds and rain drops interactively just by clicking on the different outlets. The sub basins appear separated.
Hello Mr. Samy,
I agree with Mr. El Mehdi Saidi, I have already used this tool, the steps are described on my master's thesis: "Etude de la relation eaux de surface-eaux souterraines au contact de l'Oued Rheraya avec la Plaine du Haouz; bilan et quantification des apports".
First install ArcHydroTools in ArcGIS, then follow the steps:
1. DEM Reconditioning ou reconditionnement du Modèle digital d’élévation
2. Fill Sinks ou comblement des ‘puits’
3. Flow Direction ou direction d’écoulement
4. Flow Accumulation ou accumulation des flux
5. Stream Definition ou définition du cours d’eau
7. Catchment Grid Delineation ou délinéation du maillage du bassin
8. Catchment Polygon Processing ou traitement polygonal du bassin
9. Drainage Line Processing ou traitement des lignes de drainage
10. Adjoint Catchment Processing ou traitement des bassins adjoints
For more details please see:
https://web.ics.purdue.edu/~vmerwade/education/terrain_processing.pdf
Hello Mr.Samy
as Mr El Mekki said. follow his steps and you will get results that you wanted
recently my srudents are working on watershed delination for Duhok Reservoir's Catchemnet by using Arcmap, and results are pretty clear and good.
Regards
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