Im relatively new to using HEC-GeoHMS. I have used ArcGIS on previous projects but am now intending to use HEC-HMS to produce a hydrological model so am planning on doing my pre-processing on HEC-~GEOHMS in ArcMap.
I have read into the process and feel I have a basic understanding on how to carry it out. However when reconditioning and filling sinks on my DEM I am encountering a problem where a large black region is being identified (See attached photo with red circle) when in my original DEM this is not a low point or resevoir etc. Furthermore the entire stream network shape is not appearing on this reconditioned DEM. I am struggling to resolve this problem area so was wondering if someone could provide any advice to a new user?