Topographic Maps and Digital Elevation Models

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Chapter 6 Topographic Maps and Digital Elevaton Models 109 2. Analyze a landscape: Let's say that you're a developer with a big project in mind for an area near Averill, Vermont (Fig. 6.15). You first need to study a topographic map to understand the landscape. Show any calculations you make for the following questions. Conversion factors are listed inside the back cover. a. Determine the following basic facts about the map: Interval between index contours: Contour interval (units in feet): Fractional scale (Hint: Use the UTM grid and metric units.): Verbal scale (I inch = miles): Approximate height and width of the map. (Hint: Use the UTM grid as a bar scale.) Approximate height and width of the map in miles (Hint: Use the verbal scale and a ruler.): By what factor was this map enlarged or reduced from its original 1:24,000 scale? b. To get a feel for the landscape, find the three most prominent mountains rising above 2200 feet. List their elevations starting with the mountain near the top of the map and going clockwise. The "T" following the bench mark elevations means they were determined from air photo measurements, which have errors of a few feet relative to the more accurate method of surveying. c. Determine which way the streams flow by looking at how the contours are deflected as they cross them. Draw arrows showing the flow directions of the streams flowing into or out of the ponds and lake. Which ponds or lakes flow into each other? (You can double-check your inferences by noting water level [WL] elevations.) Use the stream drainages to help you find the lowest elevation on the map. What is this elevation? What is the total relief of the map area? Let's say that you plan to hike up Brousseau Mountain from a canoe beached on Little Averill Pond. What is the height of Brousseau Mountain relative to this starting point? d. At the top of Brousseau Mountain you plan on checking your hand-held Global Positioning System (GPS) unit to be sure it works. Note that UGSG maps show latitude and longitude divisions no finer than 2' 30" (see left map margin), so you have to switch your GPS unit to UTM coordinates. Use the map to determine the UTM grid coordinates you expect to see when you reach the peak of the mountain (marked with an elevation on the map). e. Because your development plans include golf courses, a water park, factory outlet shopping, and extreme paintball, you need quite a bit of land around the Averill ponds. Do the little black dots on the map represent anything relevant to your development plans? Explain.
( FIGURE 6.15 Portion of the Averill, Vermont, 7 ~-minute quadrangle map for use in Problem 2. Canada is just a few kIn north of the map area. Scale and contour interval are determined as part of Problem 2. 110
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Topographic Maps and Digital Elevation Models

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