IMPACT OF KARST FEATURES ON THE RELATIONSHIP BETWEEN LAND COVER AND WATER QUALITY

In agricultural environments, fertilizers, pesticides, herbicides, and manure pollute groundwater, and in urban environments, impervious surfaces provide pathways for non-point source pollution to flow into watersheds. In non-karst environments, soils filter out these pollutants, but in karst environments, water passes through springs, sinkholes, caves, and underground streams, so it is not always filtered through the ground as it would in non-karst environments, leading to more contaminants in the water. Therefore, if predicted land-use and water quality relationships are applied to karst environments, it is likely that the pollution will be underestimated.

Our study uses GIS to calculate watershed area, the upstream land cover (% forest, % agriculture, and % impervious surfaces), the number of springs, and sinkhole area in watersheds, and compares water quality at various sites in the Shenandoah River Valley. Significant negative relationships were found between forests, sinkholes, and nitrate levels (p=0 adjusted r²=0.254), and forests, sinkholes, and turbidity levels (p=0 adjusted r²=0.381). Significant positive relationships were found between impervious surface, springs, and turbidity (p=0 adjusted r²=-0.022), agriculture, sinkholes, and nitrates (p=0 adjusted r²=0.256), as well as agriculture, sinkholes, and turbidity (p=0 adjusted r²=0.416). In the significant models, the presence of karst features had a negative correlation with the water quality, suggesting that water does not filter as well as it would in non-karst environments. This information signifies that when evaluating karst environments, we need to take additional steps to minimize pollution and improve water quality, as water flows through springs, sinkholes, caves, and underground streams instead of the soils as in non-karst environments.