First I tried to model a river basin with area 4000 sq km in HEC HMS. The GIS menu in HEC-HMS upto break-points manager works fine. Thereafter, if I click the "Delineate elements" option, it runs for long long long hours. I tried to delineate elements with several values such as 50, 100, 1000, 2000.... nothing works.
Then, again I tried to model a sub-basin with an area of about 200 sq km. The GIS menu, preprocess sink, drainage works very fast. But when it comes to "Delineate elements", again it is taking long time....what may be the issue.....any solutions? Advance thanks.
What is the size of your DEM? Lagre size DEM takes time to delineate or may not delineate at all.
The time for delineating an element depends on the DEM resolution and the area of the catchment. You are required to know how many sub-catchments you want to delineate and thereafter you can set them accordingly.
Here is a tutorial and guide that compares the processing times required to delineate elements using three different DEMs: "https://www.hec.usace.army.mil/confluence/hmsdocs/hmsguides/gis-tutorials-and-guides/comparing-gis-processing-run-times-with-different-size-terrain-models-and-computers". The modeling domain in this example is approximately 1,161,600 sq km. Depending upon the resolution of the terrain, processing times can vary from minutes to hours.
Adil Javed's suggestion is extremely important: make sure your DEM is projected to a valid coordinate reference system like UTM (do not use a geographic CRS).
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