Effects of Mountain Resort Development on Streamwater Nitrogen Export: Importance of Spatial Location of Land Use/Land Cover Change
Abstract
Human alteration of the patterns of land use/land cover (LULC) on the earth surface is one of the most profound impacts on the functioning of natural ecosystems. At the watershed scale, we expect that not only the amount and type of landscape alteration, but also the spatial distribution and corresponding watershed characteristics will dictate changes in streamwater nitrogen (N) export. We are developing a new method to examine the impact of watershed location and spatial distribution of LULC change on the spatial, seasonal, and temporal patterns of streamwater N export and its consequent speciation. We are analyzing LULC and topography using high resolution imagery (QuickBird) and elevation data (Airborne Laser Swath Mapping - ALSM) from the West Fork watershed, a 212 km2 mountainous watershed draining the Big Sky Resort in Southwestern, Montana. This landscape level analysis is combined with high resolution spatial and temporal sampling of streamwater chemistry and isotopic signatures. To date, we have collected synoptic streamwater samples at 60 locations at 3 points in time: summer baseflow (September 2005), winter baseflow (February 2006), and peakflow (June 2005). In addition we have collected weekly samples at 9 locations since November 2004. Exploratory data analysis indicates that nitrate concentrations peaked during the winter and gradually declined with increasing discharge during spring snowmelt. A sub-set of the synoptic samples have been analyzed for 15N and 18O of nitrate. Preliminary analyses of streamwater samples collected from sub-watersheds with development indicate isotopic signatures more indicative of wastewater than samples collected in pristine sub-watersheds. Samples will be further analyzed for cations and dissolved organic nitrogen. We anticipate that LULC change will have different streamwater quality impacts depending on the location of development relative to watershed structure (e.g., local, upslope, and downslope watershed characteristics). We are investigating the relationship between spatial organization of land use/land cover, watershed structure and streamwater nitrogen export. Here, we present preliminary results of this research.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2006
- Bibcode:
- 2006AGUFM.H23B1489G
- Keywords:
-
- 1041 Stable isotope geochemistry (0454;
- 4870);
- 1803 Anthropogenic effects (4802;
- 4902);
- 1847 Modeling;
- 1871 Surface water quality;
- 1879 Watershed