CUMULATIVE IMPACTS OF HIGHLY VARIABLE LAND-USE WITHIN A NEW YORK WATERSHED

The physical and chemical impacts of land use change within watersheds are of growing concern. In particular, urbanization has been shown to have a great influence on the physical response of stream flow to rain events as well as the chemical response, reflected in an increase of dissolved solids within surface water. This study aims to evaluate the effect of impervious surfaces on stream flow and the long term salinization impact on groundwater due to the use of de-icing salts. A small watershed (~9.2 km²) in south central New York (Fuller Hollow Creek) was chosen because it contains five sub-catchments with impervious surface ranging from ~0% to ~60%. Three tipping bucket rain gages were employed within the watershed, evenly distributed across the roughly 280m of topographic relief. Automated data loggers recorded stream stage, electrical conductivity, and temperature at each of the sub-catchments' outlets. All data were collected at five minute intervals between June 2008 and December 2008. Sub-catchments with greater impervious surface area displayed storm hydrographs that had increased peak discharges and decreased lag times. The most highly urbanized sub-catchments also display drastically increased conductivity. This observed elevation in conductivity is witnessed during both baseflow and stormflow conditions. The physical response data are broadly consistent with many of results in the literature, but also indicate the need for obtaining high resolution measurements, both spatially and temporally in urbanized areas. The chemical response indicates salt use during winter months can ultimately produce year-round, artificially saline groundwater input (baseflow). The long-term ecosystem impacts from this recent salinization merit further study.