The effects of impervious surface on the health of the stream

Background/Question/Methods

This study researches the affects of impervious surface on streams within a watershed. To do this two types of data was gathered, percent of impervious surface within a watershed and diversity of macroinvertebrates found within a stream. To calculate the impervious surface, ArcGIS was used to delineate and quantify the watershed and intersect the watershed area with the percent of impervious surface raster data (National Land Cover Database) found inside the watershed boundaries. The macroinvertebrate diversity was used because macroinvertebrates have been repeatedly shown to be an excellent biological indicator of stream health.  Sites sampled had impervious surface calculated for them, and the Georgia Adopt-A-Stream biological monitoring protocol was used to standardize the sampling of each of the sites.

Results/Conclusions

The results of the experiment show a strong correlation between impervious surface and macroinvertebrate diversity, and in extension stream health, by producing a linear regression line with an R² value of 0.64886. Of the other aspects of the stream that were measured, no significant results were found in relation to impervious surface. As the percent of impervious surface within a stream’s watershed increases, the diversity of macroinvertebrates decreases. The data supports the hypothesis made that the amount of impervious surface found within the watershed will cause the health of the stream to be negatively impacted.