Acreage of runoff

Discussion created by jcbrewster on Jan 8, 2013
Latest reply on Jan 9, 2013 by MBoucher21
Hi All,

I'm trying to estimate the amount of acreage that sheds runoff onto any given parcel of land -- I'm not concerned with amounts of water, just the area that contributes the runoff. I've started with the Hydrology Toolset, in the hopes that Flow Direction and/or Flow Accumulation would show me something...or at least give me an idea of where to go from there.... But I'm not getting anything that means anything. Flow Direction gives me values from 1-255, where I thought I would get directional coding of 1-128 -- I don't get it, I must be doing something wrong.  Do I need to do further calculations beyond what gets spit out from the tools? Also, I'm starting with a hydro-enforced DEM, so not filling any sinks (which may be a mistake).

I'm seeing forums regarding ArcHydro, and have yet to download that, but it's not clear if either that or the Toolset are the direction I want to go. Has anyone tried to tackle this type of problem?

Many thanks -