topic Re: Archydro preprocessing for contours only in Water Resources Questions

Archydro preprocessing for contours only

Anonymous User — Sun, 27 Oct 2013 18:57:12 GMT

Original User: BRAVE

Greetings everyone,
I'm extracting contours from a 20m DEM for use in a topographic map.
I used the 'Level DEM' and 'DEM Reconditioning' tools in Archydro on d DEM.
I then took the 'Agree DEM' to Globalmapper for contour extraction.
I was really impressed with the improved conformity of the contours with the streams and lakes from d resulting 'AgreeDEM'.
Questions:
Since I'm only interested in generating contours and not watersheds:
1) Are other functions like the Assign/Burn stream slope, flow direction, accumulation, depression evaluation. etc necessary
2) Will d elimination of sinks on d DEM have any profound effect on the resultant contours.

Ur responses are welcome.

Re: Archydro preprocessing for contours only

Anonymous User — Wed, 30 Oct 2013 14:14:31 GMT

Original User: MBoucher21

If all you are doing is creating contours, my first thought is that none of the functions in Arc Hydro would improve the accuracy or quality of the contours.

However, the LevelDEM function might help if you were trying to force the lake level contours and geometry of the lake. The fill sinks function might eliminate minor dips for you and produce cleaner contour lines. If using the fill sinks function, I would limit how much fill is allowed so that you don't fill in all the features such as stock ponds that you might want to show up in the contours if you have some flat valleys. Otherwise, the other functions "artificially" modify the DEM to where you would get erroneous contours.

Re: Archydro preprocessing for contours only

Anonymous User — Wed, 30 Oct 2013 20:16:19 GMT

Original User: BRAVE

If all you are doing is creating contours, my first thought is that none of the functions in Arc Hydro would improve the accuracy or quality of the contours.

However, the LevelDEM function might help if you were trying to force the lake level contours and geometry of the lake. The fill sinks function might eliminate minor dips for you and produce cleaner contour lines. If using the fill sinks function, I would limit how much fill is allowed so that you don't fill in all the features such as stock ponds that you might want to show up in the contours if you have some flat valleys. Otherwise, the other functions "artificially" modify the DEM to where you would get erroneous contours.

Thanks, this will help

Re: Archydro preprocessing for contours only

Anonymous User — Sun, 15 Jun 2014 19:30:57 GMT

Original User: BRAVE

Hello,
I'm having some issues with the leveldem
The contours generated from the leveldem appear to be unnatural along the sides of the lake polygons.
They are very steep and closely spaced and gives the notion of a cliffs along the river banks.
Any help?