I am currently working on constructing a countywide riparian area, which normally consists of the integration of water bodies, wetlands, wildlife corridors, flood prone areas and hydric soils. We perform such analysis before but this time around we would like to add the component of Steep slopes (15% or more) that are directly adjacent to riparian features that associated with a waterway. In other words, steep slopes that are directly adjacent to waterways or directly adjacent to any other riparian feature associated with the waterway will be included.
Figuring and extracting steep slopes is straight forward, the challenge remain on the proper methodology and tool to determine the slopes that flow directly down to other riparian components of a waterway. I cannot just extract the steep slope and merge wherever it intersect with the existing riparian area, since many of them do not facing the river. I need to figure out some steps to “draw” a line.
I am aware that some Hydrology tools from the Spatial Analysis can be used to define Watershed (such as using the function Fill, Fill Direction, Flow Accumulation, Snap Pour Point etc from the DEM file) I am not sure (a) if these procedures are applicable to what I am looking for, and (b) I wonder if is that a necessity to carry out all these procedure in order to get a particular section of the slopes that happens to flow downhill to riparian area.
Do anyone of you have any takes or suggestions on these?
Update: I have done the following so far:
Construct the Riparian based on Wetland, Wildlife Corridor, Floodplains, Alluvial Soils & Water Bodies.
Using the Spatial Analysis on the DEM to find out the slope.
Using relcass to find out the steep slopes that are more than 15%. Convert that DEM to vector format to select those steep slopes.
Then it come to the way to determine the "Cut-off" line to get the slopes going downward to the features. I assume I need perform hydrology analysis on the DEM again. Should I do the Flow Direction next from the Hydrology Tools? And then Flow Accumulation?
Am I doing that correctly? Is there any step by step procedure can be provided?