I need a layer showing all the watershed or catchment of the whole world. This is very hard to find because the definition of basin watershed and catchment seems to be different each place I look. All the data that I have found have turned out to be large scale (which I would think would be basin data).
Basically I need a map of the smaller separation units of the hydrological cycle. I have attached an example of the scale that I need the info at, which is the only data that I have found at this scale and it is only for africa.
Thank you very much for your help.
Hi Ditlev, the scale that you're looking for is not really clear. For example, the US has watersheds defined at several different scales defined by HUC codes, or stream order. A problem right away, is that different countries or regions will define this differently. See this wikipedia article for more explanation: Hydrological code - Wikipedia, the free encyclopedia
I think basically I just want the smallest area units of "hydrological areas" as possible. Whether the same definition is applied everywhere is not less important.
It is therefore not a particular scale that I am looking for, just the smallest scale of watershed, catchment or basin that is possible.
If you know some links for this type of data I would be most gratefull, since my search has still been fruitless so far. Let me know if it is still to un clear what I want. Thank you!
Unrealistic expectation...I live in a defined, designated watershed with an area less than 100 Km^2...you are going to have to refine your definition or collect the data on a country-by-country basis
Yeah, I am afraid that I would need it with smaller boundaries. Ok, I guess that I will have to check it out country by country. It just seems strange that I could find the other data for the whole african continent but that it is not available for the rest of the world.
And then make a world mosaic. But you need a powerfull computer.
If You you need a detailled local Watershed, you need also a good dem like lidar or from aerial survey. I made this job for my country with a 10 metres dem with archydro and tauDEM.
Thank you for this. However I am not completely sure how to create this world mosaic and what you mean. Do you mean that I from the larger basin of Hydroshed, I can create smaller basin that I can use? And is this through the Arcmap hydrological tools? I know that there is both watershed tool and the basin tool from the spatial analysis package, is it these you mean that I should use to create delineating of the smaller watershed?
Also are you aware of any sites for good continental level DEM?
Ditlev, you wrote that you need a watershed or catchment layer of the whole world. You can do this by yourself making a mosaic of the regional/national watershed or catchment layers around the world.
And you can use ArcHydro, TauDEM, Spatial Analyst together 3D analyst or the great SAGA GIS or the marvelous QGIS. it takes time and detailled DEM, lidar or other elevation models.
For good continental level DEM you can search through the arcgis online service, or visit every national gelogical survey. In america the best is the USGS.