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Evaluating Percent Imperviousness of Brookside School Property

Evaluating Percent Imperviousness of Brookside School Property. What are the effects of impervious surface in a watershed? How much is too much? How does our school property compare to other areas?. We all live in a watershed!.

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Evaluating Percent Imperviousness of Brookside School Property

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  1. Evaluating Percent Imperviousnessof Brookside School Property What are the effects of impervious surface in a watershed? How much is too much? How does our school property compare to other areas?

  2. We all live in a watershed! • A watershed is an area of land that drains into a common body of water. • Everything that happens in a watershed can affect its water quality.

  3. We live in the Passaic-Hackensack Watershed. This map shows the major rivers and streams. This map shows all the smaller tributaries as well.

  4. This watershed is comprised of two smaller watersheds: • Passaic Watershed • Hackensack Watershed Allendale is located in the Passaic Watershed, shown here in neon green. Allendale’s approximate location is marked with a red star.

  5. Inside the Passaic Watershed are even smaller subwatersheds. (sometimes called catchments). Brookside School lies in the Ramsey Brook subwatershed.

  6. IMPERMEABLE vs PERMEABLE SURFACES Parts of the school property are impermeable, like the parking lots and blacktop play area, as well as the building roof. (left) Other parts of the school property are permeable, such as the outdoor classroom, the athletic fields, and the area adjacent to the brook. (right)

  7. The amount of impervious (or impermeable) surface in a watershed greatly impacts the quality of the bodies of water there. Mostly Impermeable Land Surface Permeable Land Surface The more impervious surface, the more surface runoff and the less infiltration. Therefore, there is also less subsurface flow. Infiltration and subsurface flow are crucial for maintaining high water quality.

  8. For this project, we mapped our school property to determine the percentage of impervious land surface. Now it’s time to evaluate our results. How much is too much?????

  9. The highest quality water is found in watersheds with 100% permeable (or pervious) surfaces.

  10. Even 10 – 20% imperviousness alters the natural processes of the water cycle somewhat:

  11. When the level of impervious surface reaches 35%, water quality is negatively affected:

  12. Once the amount of impervious cover reaches 75%, the water can be severely degraded:

  13. Large amounts of impervious surface also increases the chances of both droughts and flooding. Allendale has experienced both extremes in recent years. Lawn and Garden Watering with both Automatic and Hose Sprinklers is Limited to: • Odd House Numbers: Wednesday, Friday, Sunday • Even House Numbers: Tuesday, Thursday, Saturday Water Restrictions: Summer, 2013. Hurricane Irene: September, 2011.

  14. The results of several studies suggest this relationship between percentage of impervious cover in a watershed and water quality: From Rhode Island Dept. of Env. Mgmt. And the University of Delaware.

  15. According to the table on the previous page, is the part of the Ramsey Brook Watershed on Brookside property protected, impacted, or degraded? • We need to remember that our school property represents just one part of the entire Ramsey Brook Watershed. To better evaluate the health of our brook’s watershed, what additional steps could we take? • Write down some suggestions in your Journal.

  16. Another way to look at our results is to compare them to known percentages for different types of land use: From Univ. of Delaware, Water Resources Agency, 1998. To which type of land use is our average percentage imperviousness most similar?

  17. Sources of Experimental Error Why did we get so many different answers for percentage of impervious land surface on Brookside property? List as many sources of error as you can. How does using the average of all students’ results help compensate for sources of error? What steps could we take to minimize sources of experimental error?

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