B.C. Frogwatch Program
Where Am I?
Mapping and UTM Coordinates
One of the most important pieces of information we need from you is the location
of your amphibian sighting, as precisely as possible. Some atlassing programs ask
you to report your location in relation to the nearest town (for example, "ten
kilometres northeast of Kamloops"), but this is not precise and can result in error.
It would be much more helpful if you could report your sighting's location using one
of these methods:
UTM Coordinates
This is the most precise coordinate and the one used by all the Geographic Information
System databases in BC. UTM stands for Universal Transverse Mercator, a system of world
coordinates that are expressed in metres (no more figuring out how many seconds in a
degree of latitude!). UTM lines are orthogonal - that is, they are always at a right
angle to each other. This is important in northern latitudes, where lines of longitude
begin to converge toward the pole, and maps may be distorted.
The MELP data system only allows entry of UTMs from the NAD83 system. If you have
a UTM in NAD27, please put it in the comments field. We will convert it to NAD83
during our review. National Topographic Maps will have an entry in the lower
right hand corner that says either "North American Datum 1927" or "North American
Datum 1983." (If you don't understand what any of this means, skip to the next
section for more information on how to send us location information!)
UTM coordinates are expressed in terms of a Zone (7 to 11 for
British Columbia) and easting (a 6 digit number) and northing
(a 7-digit number) coordinates within this zone. It will look
like this on a GPS unit:
(only without the scribbled explanations)
This can be written as "Zone 10 S 559741 mE. 4282182 mN."
You can find your UTM location in several ways:
- Read UTM coordinates off a topographic map. Record the map
number in the Wildlife Sighting form so we can check it, and
tell us whether the map is NAD27 or NAD83.
- If you have a GPS unit, or a cell phone that can function as a GPS receiver,
you can set it to display your location as a UTM coordinate. You will need to
make sure the GPS unit is set to use "NAD83" as the map datum. Click in the GPS
box in the Wildlife Sighting Form to let us know you used this rather than a map.
- Utility poles in BC often have small metal plaques with
either the UTM or latitude and longitude coordinates engraved
on them. Record the information on the pole in the comments
box. We will decipher it.
Still stuck? Try the excellent tutorial at
MapTools.
This is what BC looks like with a UTM grid overlaid on a map with National Topographic grid:
UTM Zones - click to see
a larger image (38 Kb)
Good Old-Fashioned Latitude and Longitude
You can get this information from a good map, preferably as fine a scale as
possible. GPS receivers can also display your latitude and longitude.
Show Us A Picture
Are you stuck on the UTMs and lat/longs? Don't panic! Just photocopy
your map, and mark your sighting location clearly on it. Send it in to us,
and we'll figure it out. A hand-drawn map isn't very helpful, though, so if
you can photocopy a fine-scale topographic map and make sure its scale is
showing, along with some reference points, we'll be able to do much more with
it. Don't send us your only copy of a map!
Photo © Heather Waye. No reproduction or distribution without permission.
