Elevation Data for the Gulf of Maine
go to: USFWS Gulf of Maine Watershed Habitat Analysis

We used elevation information for modeling habitats for certain bird species, both directly in terms of elevation zones they preferred, and indirectly from derivatives, such as slope and aspect.

Our sources were primarily 1:250,000 scale raster (Digital Elevation Model) data from USGS (http://edcwww.cr.usgs.gov/pub/data/DEM/250/) because of its availability for most of the study area. The processing is detailed below. The eastern tip of Cape Cod was not available at this scale, so we filled this gap by overlaying the relevant portions from 7.5 minute (1:24,000) DEM quads.

Slope and aspect grids were later developed directly from the elevation data in the Spatial Analyst module of ArcView.  


USGS Digital Elevation Model Data:  http://edc.usgs.gov/Webglis/glisbin/guide.pl/glis/hyper/guide/usgs_dem

7.5 Minute Digital Elevation Models (DEM):  http://edc.usgs.gov/doc/edchome/ndcdb/7_min_dem/states.html


Quads included:

8/06/97 01:03p 9,840,640 albany-e.dem

02/24/94 10:14a 9,840,640 bangor-e.dem

02/24/94 10:15a 9,840,640 bangor-w.dem

02/24/94 09:58a 9,840,640 bath-e.dem

02/24/94 09:58a 9,840,640 bath-w.dem

08/06/97 01:04p 9,840,640 boston-e.dem

08/06/97 01:04p 9,840,640 boston-w.dem

02/25/94 01:57p 9,840,640 campbellton-w.dem

02/24/94 10:14a 9,840,640 eastport-e.dem

02/24/94 10:14a 9,840,640 eastport-w.dem

02/25/94 04:03p 9,840,640 edmundston-e.dem

02/25/94 04:05p 9,840,640 edmundston-w.dem

02/14/94 01:50p 9,840,640 fredericton-w.dem

02/24/94 09:59a 9,840,640 glens_falls-e.dem

02/24/94 10:16a 9,840,640 lake_champlain-e.dem

02/24/94 10:15a 9,840,640 lewiston-e.dem

02/24/94 10:15a 9,840,640 lewiston-w.dem

02/14/94 01:50p 9,840,640 millinocket-e.dem

02/25/94 09:14a 9,840,640 millinocket-w.dem

02/24/94 09:58a 9,840,640 portland-e.dem

02/24/94 09:58a 9,840,640 portland-w.dem

02/25/94 09:48a 9,840,640 presque_isle-e.dem

02/25/94 09:49a 9,840,640 presque_isle-w.dem

02/23/94 12:59p 9,840,640 providence-e.dem

02/25/94 09:49a 9,840,640 quebec-e.dem

02/25/94 09:14a 9,840,640 sherbrooke-e.dem

02/25/94 09:15a 9,840,640 sherbrooke-w.dem

02/25/94 09:48a 9,840,640 woodstock-w.dem

These zipped/tarred files were expanded into DEMs, then converted to grids using the ArcView 3.x script Spatial.demshift, which creates grids in decimal degrees. The grids were merged then projected in ArcInfo using the following projection file:


projection geographic

units dd

datum wgs84 seven



projection utm

units meters

datum nar_d three

zone 19



Grid cell size is approximately 79 m; elevation is in meters; projection is in NAD83.