HR: 12:00h
AN: B31G-07    [PDF]
TI: Local and Long-Distance Effects of Land Use Change on Nutrient Levels in Streams and Rivers of the Conterminous United States
AU: * Smith, R A
EM: rsmith1@usgs.gov
AF: U.S. Geological Survey, 12201 Sunrise Valley Drive 413 National Center, Reston, VA 20192 United States
AU: Alexander, R B
EM: ralex@usgs.gov
AF: U.S. Geological Survey, 12201 Sunrise Valley Drive 413 National Center, Reston, VA 20192 United States
AU: Schwarz, G E
EM: gschwarz@usgs.gov
AF: U.S. Geological Survey, 12201 Sunrise Valley Drive 413 National Center, Reston, VA 20192 United States
AB: Determining the effects of land use change (e.g. urbanization, deforestation) on water quality at large spatial scales has been difficult because water quality measurements in large rivers with heterogeneous basins show the integrated effects of multiple factors. Moreover, the observed effects of land use changes on water quality in small homogeneous stream basins may not be indicative of downstream effects (including effects on such ecologically relevant characteristics as nutrient levels and elemental ratios) because of loss processes occurring during downstream transport in river channels. In this study we used the USGS SPARROW (Spatially-Referenced Regression on Watersheds) models of total nitrogen (TN) and total phosphorus (TP) in streams and rivers of the conterminous US to examine the effects of various aspects of land use change on nutrient concentrations and flux from the pre-development era to the present. The models were calibrated with data from 370 long-term monitoring stations representing a wide range of basin sizes, land use/cover classes, climates, and physiographies. The non-linear formulation for each model includes 20+ statistically estimated parameters relating to land use/cover characteristics and other environmental variables such as temperature, soil conditions, hill slope, and the hydraulic characteristics of 2200 large lakes and reservoirs. Model predictions are available for 62,000 river/stream channel nodes. Model predictions of pre-development water quality compare favorably with nutrient data from 63 undeveloped (reference) sites. Error statistics are available for predictions at all nodes. Model simulations were chosen to compare the effects of selected aspects of land use change on nutrient levels at large and small basin scales, lacustrine and coastal receiving waters, and among the major US geographic regions.
UR: http://water.usgs.gov/nawqa/sparrow
DE: 1803 Anthropogenic effects
DE: 1806 Chemistry of fresh water
DE: 1848 Networks
DE: 1860 Runoff and streamflow
DE: 1871 Surface water quality
SC: Biogeosciences [B]
MN: 2003 Fall Meeting