topic Re: Comparing Similar Cross Sections from separate DEMs in Water Resources Questions

Comparing Similar Cross Sections from separate DEMs

RileyMcFarland — Mon, 25 Nov 2019 18:58:24 GMT

Hi all,

I am currently working on analyzing topographic data collected over a span of 3 years on the same stream reach. The analyses require I develop a cross-sectional profile at the same exact location for each year to compare the geomorphic change of the stream channel. I am using the 3D Analyst extension and the "Interpolate Line" function to complete this task. I have built a separate DEM layer for each year from the associated survey data.

After selecting a DEM layer in the 3D Analyst drop-down menu, I draw the line where the cross section is to be developed and export the profile graph data to Excel. I want to be able to use the same exact line for a different DEM layer that I select in the drop-down menu, but the "new" profile graph is still created from the DEM I had previously selected.

Is there a way to produce two separate cross-sectional profile graphs, each from a different DEM, using the same 3D Analyst line at one specific location? I am hoping to avoid redrawing the line each time in order to keep the analyses consistent.

It should also be noted that I am basing the cross-sections on an existing polyline feature class layer that represents the location of the cross sections. Is there a method of extracting cross-sectional points from a DEM layer using these polylines?

Thank you for any and all feedback!

Re: Comparing Similar Cross Sections from separate DEMs

JohnRefolo — Thu, 23 Jan 2020 15:58:11 GMT

When using the "Interpolate Line" tool, I don't believe there is a way to generate the graph from 2 different elevation sources without having to draw that line more than once.

If you already have the cross section as a feature, you might want to try using the geoprocessing tool "Interpolate Shape"...I think that's what it is called. This will convert your feature to a 3D features based on the input elevation source. I suppose you could do this multiple times (one for each year) and then combine the 3 separate outputs into 1 feature class (so 3 records; one per year). From there I think you can select the 3D line(s) and use the Graph tool on the 3D Analyst toolbar to plot the 3D features in one plot.

Let me know if you have any questions or would like to chat further.

Hope this helps even as a late response!

Re: Comparing Similar Cross Sections from separate DEMs

KurtisBaron — Tue, 28 Jan 2020 00:12:16 GMT

HEC-GeoRAS still does this very well. Alternatively, you could extract your line feature to points, and use Extract Multiple values to points, export the XYZ values to Excel, and do multiple scatter plots.