I am currently facing a problem. Over the past week, I have been initiated to hydrology within the GIS environment and have finally successfully generated water basins (using the GRASS r.water.outlet) by selecting a pixel in my Flow direction raster generated from a DEM with r.stream.extract
My problem is as follows: I would like to be able to select any pixel (with or without a geoalgorithm) and obtain the whole water basin complex leading to this lake. I know the lake retains water and it's odd because the information generated through my DEM says otherwise. Where a wall should hold the water in, the DEM and all the treatments claim that water goes out through there.
Perhaps the precision of my DEM is lacking, but I can see the wall with a generated Hillshade so I doubt it...
Is there a way to manually modify the DEM for my treatments to detect there is a wall there and the lake is all at the same level? Or is there an existing geoalgorithm that can detect such a lake in the creation of watersheds and water basins? the GRASS commands seem limited in this topic to simply giving me the basins partially through lines.
Mainly though, I would like to be able to do the water basin request from a polygon or a general area in the raster.