Elementary Schools in Pierce County
A school ground and impervious surface analysis
Impervious surfaces are typically built structures that can not absorb water (parking lots, basketball courts, rooftops, etc.). Increasing amounts of impervious surfaces can have a detrimental impact on both environmental and human health. Rain washes pollutants such as fertilizers and oil into water sources, and displaces pervious green space that promotes ecological functionality and mental well-being.
Elementary schools are symbolized within feeder zones, created by Thiessan polygons. Students would, theoretically, attend the schools within the polygon in which they live. Every school ground has a percentage that is impervious, and those with the lowest amount of impervious surfaces are ranked 1, and the highest are ranked 3. The amount of impervious surfaces on school grounds was calculated using raster data from USGS National Land Cover.
Notice how schools in urban areas have a higher percentage of impervious surfaces. Urban elementary schools grounds are approximately 50% impervious on average, while non-urban schools are approximately 30% impervious on average.
Another way to visualize how land cover changes as areas move from urban to non-urban, is with a choropleth map. The lowest percentage of impervious surface is colored dark green, to the highest percentage colored dark yellow.
The zonal statistics conducted for this analysis helped establish patterns, yet some anomalies exist. School grounds with a relatively high percentage of impervious surface, that are surrounded by other school grounds with low percentages of impervious surface, may be good candidates for further research to better the area's ecological function.
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