Summative Assessment: Topographic Maps and Surface Water

Instructions

To do your best on the assignment, it is important that you read the entire module carefully prior to coming to the lab. This lab will be completed in class (for students taking the blended course) and online for students taking the course online.

Scale:

Some maps show large areas (a map of the world, for example) and some show small areas (State College or Bellefonte, for example). These maps have different scales. For example, a map might have a scale of "one inch = one mile", which means that an inch measured on the map with a ruler corresponds to 1 mile in reality. Because 1 mile is equal to 63,360 inches (whoa!), this map would have a scale of 1:63,360. Whichever way we say it, it means that any feature on the map is 63,360 times smaller than in reality. Note that this scale reference (x distance on a map = y distance in the real world) only works for printed maps. Maps on a computer screen can be zoomed in or out, so there is no set relationship between the map and real world scales. For this reason, computer maps use graphic scale bars, as shown in Figure 13.

Measuring distances on topographic maps is relatively easy because the maps generally cover small areas-so we don't have to worry too much about the curvature of the Earth and/or the type of projection used (i.e., the way the map-makers 'projected' the curved surface onto a flat map). Topographic maps also show scale bars somewhere on the map that allow you to use a ruler to directly measure distances without having to do conversions from inches to miles, or centimeters to kilometers.

Examine the

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1. What is the scale of this map? ____________________________
2. 1 inch on the map equals ________________ inches in the real world.
3. 1 inch on the map equals ________________ miles in the real world.
4. If this map were on your computer screen and zoomed in 200% (with 100% being the 'native' scale), 1 inch on your computer screen would equal ____________ miles in the real world.
5. What direction is it from Gum Stump to Runville, as the crow flies? How far is it in miles?

Contour lines:

Topographic maps use contour lines to represent 3-dimensional land surfaces on a 2-dimensional map. (Notice that your map is covered with squiggly brown lines.) Some of these lines are labeled with altitudes, or elevations. The thing to remember is that every point on a particular contour line is at the same elevation above sea level. The elevations are usually given in feet or meters.

Another way to think of it is to imagine that somebody builds a dam across Bald Eagle Creek. The valley would gradually fill with water. As it fills, imagine that we were to go out and paint a line along the beach every time the new lake rises, say, 20 feet. If we drained the lake and rented an airplane, we could see what looks like a topographic map from the air-each painted line would represent an elevation. The elevation difference between each line, in this example 20 feet, is called the contour interval. Different maps may have different contour intervals.

1. What is the contour interval on the Bellefonte Quadrangle map? ________________
2. Find Coleville on the map. What is the elevation difference between the ridge located ~0.6 km north-northwest of the text "Coleville" on the map (hint...find the "C" in Coleville and look north, you should be looking west [left] of where a river cuts the ridge line) and Buffalo Run Creek located ~0.2 km south of the text "Coleville"? ____________________
3. What is the elevation of the highest point on the map in feet? What is it in meters?
4. How would you describe the topographic setting of Milesburg and Central City (north of Bellefonte)?

Topography, slope, and surface water flow:

Topographic maps are a critical tool for water resources planning and hydrogeology. They help us to visualize the direction water flows, the boundaries between watersheds, and the locations and sizes of floodplains, among other things. *Note: click here for help and examples on how to calculate a slope from a topo map

1. Which direction does Spring Creek flow near Bellefonte? ___________________
2. What is the average width of the floodplain for Bald Eagle Creek? _______________
3. Calculate the stream gradient (or slope) of Bald Eagle Creek from the West end of the map to the East end of the map (show your work).
4. Find the slope of the northwest flank (side) of Bald Eagle Mountain (show your work).
5. A drop of water falls at Valley View at 1140 feet elevation. To what named surface water body does it go first? __________________________
6. Where does the water ultimately end up (meaning what is its "final" destination)?
7. Describe the main differences between the morphology (map view characteristics) of Spring Creek and Bald Eagle Creek. What do you suppose controls this?

Topographic profiles or cross sections:

You can get a very good idea of the ruggedness and shape of the landscape from a topographic map by drawing a cross-section (also known as a profile). This is done by measuring the distance to various contour lines along a line from some starting point, and then plotting these points on a graph and connecting the dots. You can be as detailed as you wish. However, you really don't have to measure the distance to every contour line, especially in steep areas.

1. Using the blank graph provided, construct a topographic profile along the line drawn on the map, from A to A'
2. Label the key features on your profile – like Bald Eagle Creek, Bald Eagle Ridge, the floodplain, major roads, etc...

Submitting your Assessment

Blended course students: you will be working on this lab in class and handing it in at the end of the session.

Scoring and Rubric

Your summative assessment grade will be based on a possible 100 points using the grading rubric below. How many points you earn out of the total possible for each item will be determined by how completely the item is addressed in your submission.