topic Re: Creating a (Vertical) Hydrologic Buffer in ModelBuilder Questions

Creating a (Vertical) Hydrologic Buffer

TylerSearls1 — Tue, 20 Jun 2017 19:17:56 GMT

Wondering if anyone has any experience in creating a vertical buffer adjacent a stream as opposed to the more typical horizontal buffer. I have a method planned but it seems awkward and less than ideal.

I'm attempting to create a (horizontal) buffer which will exist as 1 metre above a given stream's typical flow. The process will be eventually converted into a model or script but for the time being, i'm more interested in potential approaches.

Cheers.

Re: Creating a (Vertical) Hydrologic Buffer

ChrisDonohue__GISP — Tue, 20 Jun 2017 19:20:58 GMT

Just a thought - would it essentially be the same if you add 1 meter to your DEM only in the horizontal extent of the stream? If so, you could probably do this with Raster Calculator.

Chris Donohue, GISP

Re: Creating a (Vertical) Hydrologic Buffer

TylerSearls — Tue, 20 Jun 2017 19:29:30 GMT

The reason for attempting to create a vertical buffer over a horizontal is to catch those 'low-lying' areas outside of the horizontal extent of both the stream and any existing horizontal buffer, which might be susceptible to flooding.

Re: Creating a (Vertical) Hydrologic Buffer

curtvprice — Tue, 20 Jun 2017 20:42:40 GMT

There are several ways to go about this, I would think a really good method to try (assuming you have access to Spatial Analyst) would be to

1. Rasterize your stream line

2. Extract By Mask and Int to get integer cells of elevation at each location along the stream

3. Run Euclidean allocation to assign each location in your raster to the nearest stream elevation

4. Select areas where the difference between your allocated elevation and the DEM are less than your estimated flood height. The Raster Calculator is a good tool for this operation.

Since you may pick up some disconnected areas, you may want to convert the result to polygon and edit the results.