1 research outputs found
Persistent Urban Influence on Surface Water Quality via Impacted Groundwater
Growing urban environments stress
hydrologic systems and impact
downstream water quality. We examined a third-order catchment that
transitions from an undisturbed mountain environment into urban Salt
Lake City, Utah. We performed synoptic surveys during a range of seasonal
baseflow conditions and utilized multiple lines of evidence to identify
mechanisms by which urbanization impacts water quality. Surface water
chemistry did not change appreciably until several kilometers into
the urban environment, where concentrations of solutes such as chloride
and nitrate increase quickly in a gaining reach. Groundwater springs
discharging in this gaining system demonstrate the role of contaminated
baseflow from an aquifer in driving stream chemistry. Hydrometric
and hydrochemical observations were used to estimate that the aquifer
contains approximately 18% water sourced from the urban area. The
carbon and nitrogen dynamics indicated the urban aquifer also serves
as a biogeochemical reactor. The evidence of surface water–groundwater
exchange on a spatial scale of kilometers and time scale of months
to years suggests a need to evolve the hydrologic model of anthropogenic
impacts to urban water quality to include exchange with the subsurface.
This has implications on the space and time scales of water quality
mitigation efforts