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How to Map Water Resources

The New Hampshire Method of marking sources of water located on land is done with a topographical map. By studying the map's contour lines you can figure out the slope of the ground. This is where the water is going to naturally flow and collect. Water moves perpendicular to the contours on a topographical map. The further it moves downhill, the more the water gathers together until it forms a watercourse that flows into an ocean.

Things You'll Need

Topographic map
Pencil
Ruler

Instructions

Mapping Water Resources
- 1
  Waterways on topographical maps will be drawn in blue lines. Lakes, ponds, and seas will be shapes that are filled in and colored blue. With this information in mind, locate on your topographical map a river that leads to and from a lake. Near the lake there will be a wetland area, which will look like an outline of a lake with hatch marks or diagonal lines running through it's center. Draw a small circle over the downstream outlet point of the wetland.
- 2
  Take your pencil and start to draw small X's on the topographical map's high points. The highest points of the map will be at the center of the shape that the contour lines make on the paper. They will be closed in on themselves and tend to look like oblong or distorted circles. Contour lines connect locations of similar elevation, and they are used to represent mountains and the steepness of slopes. Contour lines are usually drawn at uniform vertical distances called contour intervals, and they will have a number on every fifth line that indicates how many feet above sea level it is. The highest point on the map will be easy to see once you start following the elevation lines.
- 3
  Now take your pencil and starting at the circle you drew at the outlet of the wetland, draw a line to the first X that is located directly above it. Then draw a line from the first X to the next X that is near it and continue connecting the X's. Be sure to start connecting the X's by drawing along the right side of the wetland and it's corresponding lakes, streams, or rivers. Do not cross the lines over the waterways. The lines should be drawn over the contour lines at right angles. They should be perpendicular to each contour line when they cross it.
- 4
  Finish connecting all of the X's until you have made a rough circle around the wetland and all of the other waterways on the topographical map. Double check to make sure that you have not accidentally drawn a connecting line over a blue line. The pencil lines should not cross over any of the waterways, but should encircle the waterways on the map completely. When you are done it may look a little bit like a fence. If it does, then you have done this correctly. The encircled area on the topographical map that you drew is the watershed, or the area where the water is coming from under the ground.

Nature