FOR357/557 – ’07
Exercise 10
Estimating Erosion Potential
See Schedule
Letter from the Town of Martinsburg.
Town of Martinsburg, Lewis County, NY
Environmental Quality Committee
123 River Road, Lowville, NY 12345
Extraordinary GIS and Storm Door, Inc
147 Rt 28
Lowville, NY 123245
Attention: Eustis B. Nifkin
Dear Mr. Nifkin: Eustis
November 20, 2007
As you are aware we have noticed an increase in the sediment in the Town’s streams and have
concluded that this increased load is due to erosion somewhere in the town. Therefore we are
contracting with EGSD to locate possible sources of the sediment. We believe that slopes of
15% or more are the most probable sources of the sediment. Your charge then is to find
Residential and Agricultural tax parcels that have anay slopes of 15% or more and are near
the streams draining the eastern parts of the Tug Hill. Any parcel that has any part within 500
of a stream or river meters is suspect. When we have your report and map of such parcels we
will then have our inspectors visit those sites to see if any erosion is taking place.
Please provide us with a letter summarizing your findings, a map showing the possible source
parcels, and an attachment outlining the method you used to find them.
Sincerely;
Peter
Peter Moss, Chair
Martinsburg Environmental Committee
CC: Dewy, Cheatum, and How, LLP, 12 Euclid Ave, Syracuse, NY
1. Notes from Sally Forth (Your supervisor --she gets around!)
1.1. You are to write the report for the EQC for my signature.
1.2. Remember that in working with Grids you want to smooth the Grid before computing slope
(as you did in EX9). You can either smooth the DEM or the percent slope GRID.
1.3. You want to end up with set of polygons that have slopes >=15%. In the conversion from
Raster to Vector be sure to UNCHECK THE SIMPLIFY POLYGONS radio button. In
addition, when you RECLASS the Grid of areas with slopes >=15% be sure to make the
slope areas in which we have no interest “NO DATA” so that the produced polys are only
those areas with the target slopes.
1.4. Since this is our first job with the EQC make the map as professional as possible
remembering that the map user has to be able to find the parcels (meets the standard in the
course details.)
1.5. Use the GDB provided in the data for Ex9 on esf-academic5. The DEM there works!
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