APPENDIX B: UPDATING FLOOD DATA TO PROPER UTM ZONES
A procedure for clipping the coverages into the proper UTM zones was developed by Jeffery
Lane and Shane White, ESRI, Boston, Massachusetts.
For every river that crosses UTM zone boundaries, do the following steps:
1. Under each river directory, make as many directories as UTM zones--either zone 14 and
zone 15 or zone 15 and zone 16 for the rivers in this report. These will be the workspaces in which
the clipped and reprojected coverages will be stored. Then go into ARC and set the data directory
as the workspace.
2. Generate a "fishnet" to be used as a UTM Zone template. Type the following in bold at the
appropriate prompt:
Arc: GENERATE utmtemp1*
Generate: FISHNET
Fishnet origin coordinate (x,y): -120, 0 (120 W long, 0 lat)
Y-axis coordinate (x,y): -120, 1
Cell size (width, height): 6, 90 (6 long, 90 lat)
Number of rows, columns: 1, 2
Generate: QUIT
Note: The origin values are for UTM zones 14 and 15. For zones 15 and 16, change the origin
to -96, 0 and -96, 1.
3. On this "fishnet," add a vertex at every one minute of latitude and longitude:
Arc: DENSIFYARC utmtemp1 utmtemp2 [CALC 1 / 60]
4. Change the polygon labels to represent the zone number:
Arc:
ARCEDIT
Arcedit: EDIT utmtemp2 label
Arcedit: DRAWENVIRONMENT ARCS LABELS IDS
Arcedit: DRAW
Arcedit: SELECT
Point to the feature to be selected.
Enter point (click on the label point (+ sign) of the left polygon. The + and its number should
become highlighted)
Arcedit: CALC $ID = 14 (space on either side of the = )
Arcedit: DRAW
(the left polygon should now be labeled as 14)
Arcedit: UNSELECT ALL
Arcedit: SELECT
Same routine for the right polygon, except label as 15 instead
Arcedit: SAVE
Arcedit: QUIT
5. Build the topology of this polygon:
Arc:
BUILD utmtemp2 POLY
* Bold text signifies items that the user must enter. File names are always lowercase.
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