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Lessons 5: How Does the Contour of the Land Affect Runoff?

Contour refers to changes in elevation of the land in a given area. Topographic maps present land contours through the use of various elevation lines. How do you think contour impacts the runoff of transported pollutants in a watershed?

Doing the science

  1. Study Figure 1 below, which is a portion of an island in Rhode Island. Each contour line represents an elevation change of 10 meters.
  2. Determine the elevation above sea level of the following locations: Oliphant, Aquidneck Centre, Wyatt, Green End, and Paradise. Record your results in Table 1 below.

Figure 1.

Table 1.

Location (m)

Elevation Above Sea Level (m)


Aquidneck Centre


Green End


Do You Understand?

  1. Which location had the highest elevation above sea level?

  2. Which location had the lowest elevation above sea level?

  3. Which location had the steepest slope? Please explain your response.

  4. Describe the relationship between the steepness of the slope of the land and the likelihood that pollutants would run off the land and be collected in a given water shed.