Dear all,
I was recently doing flood plain delineation using HecGeoRAS 4.3 in ArcGIS 9.3. During the process in RAS Mapping for delineating the floodplain, though it generates the inundation polygons, the polygons are broken at the several places (i.e. there are many inundation polygons and these polygons are not continuous..it seems as if water flow is stopped in between them). Is it due to poor resolution of the TIN I used or is there any other reason for this problem?
Also, while defining the extent of the flowpaths, what we have to keep in mind? Is it means the overbank (or the threshold extent upto which water may reach during flooding)?
And, while giving mannings value, what’s the difference in assigning the value in RAS Geometry of HecGeoRAS and assigning it later on HEC-RAS?