EXPLORE: Discover Topographic Maps

When studying water resources, people need to know the elevation of the land--the high and low spots.

A contour line is a closed-loop line that represents a specific elevation above sea level. Contour lines are usually brown. They never cross. Look at the map on this screen. You'll see that many contour lines have the elevation printed right in them.

Definition: topographic map

A map that shows the physical features of the land, such as the rise and fall. A topographic map identifies features such as rivers, buildings, hiking trails, hills, and homes in a watershed.

A road map shows travel routes and other features of the land.

A road map is useful when traveling, and may include the names of many local rivers and creeks.

But no map is more valuable to people who study the environment than a topographic map. A topographic map is a map that shows the physical features of the land, including its rise and fall.

A topographic map shows such details as creeks, rivers and the elevation of the land above sea level.

Now look at the aerial view...

And see what happens when we add contour lines for every 500 feet in elevation.

If you are already familiar with road maps, you may find this topographic map a bit confusing.

But with practice, you'll see this map reveal a world far beyond what you see on a road map.

IT'S A FACT!

Contour lines that are close together mean the land rises steeply. If the lines are far apart, the land is fairly flat.

Topographic maps also show the vegetation on the land. Special colors and symbols show forests, scrublands, swamps, and other natural areas.

In addition, topo maps - as they're called for short - indicate trails, dirt roads, and superhighways. Mom says: They are a great way to find 4 by 4 trails.

Every topographic map legend tells the vertical distance between each contour line.

In this map, 100 feet of vertical distance separate each contour line. If you find a contour line with an elevation of 1,000 feet, for example, the next smallest contour line will be 1,100 feet. With a little practice, you will be able to determine elevations on this map easily.

Look at the model of a hill. It shows part of a watershed.

Look at the lines drawn across the mountain, each line representing 500 feet in elevation.

On this map, you can tell that roads and political boundaries are less important than rivers, woods, and other natural aspects of the landscape.

On a topographic map, you can see lines or symbols for elevation , rivers, rapids, dams, wells, and even cemeteries.

There are even larger scales, like this one...

People use a 1:100,000 map to get a feel for a wide area of land.

The scale of topographic maps is important.

Scale is the size of the objects on the map compared to the real-life objects. For instance, a scale model of a truck may be 200 times smaller than the real truck, but it looks exactly like the real truck. If one inch on a map represents 50,000 real inches (about .79 miles), then the scale of that map is 1:50,000.

A good map is a very helpful tool for finding out about the environment.

Some maps can help people learn about water resources. People who want to study water resources need maps that show where watershed boundaries are located. Maps can point out the divides between watersheds, the area's creeks. Maps can also help identify collection areas.

Making good contours on a map is slow and painstaking work.

Surveyors must measure elevation throughout the land. They also use aerial photographs.

A person studying a watershed may need a map like this one as well as maps with larger scales, such as 1:250,000 (one inch = 250,000 inches, or 3.9 miles).

That map might come in handy when he plots the boundary of a large watershed.

You can compare maps of various scales on the next few cards.

The most common topographic map scales are:

1:50,000

The shows less detail but more area.

Now the contour lines look like those on a topographic map.

The smallest loops indicate the highest elevation.

1:24,000

This size gives great detail of a local area.

Any map is a tool for the person who uses it.

Topographic maps are powerful tools for anyone who wants to help the environment. A group of people can use a topographic map to chart the boundaries of a watershed. When the boundaries are clear, the people can see where the divides, the basin, and the collection areas are.

EXPLORE: Discover Topographic Maps

Understanding the characteristics of land is important to understanding water resources. Reading topographic maps is one of the best ways to do this.