I have flown topo lines covering a large AOI. Some of these lines stretch across the whole area and therefore aren't closed while others just cut off and also aren't closed. I want to calculate the area of the lowest 5 contour lines per each basin (polygon).
I tried extending the lines and then converting them into polygons but this didn't work because some of them did not close.
How do I find the lowest 5 lines per each basin (there are about 35)?
I am using ArcMap 10.3 and AutoCAD Civil 3D. My company does not have the spatial analyst package.