I'm doing a 2D hydraulic flood study of rivers in a 63 km2 basin. I have a RASTER of the topography (1x1 meters) that I have passed to TIN using ARCMAP. Giving a z=0.3 meters, I get a TIN network with too many triangles in areas where I do not require so much density. I am only interested in a high density close to rivers. Is it possible to edit, collapse, decrease the density of the TIN mesh using a feature such as a polygon?