SS4.13 Water Quality of Lakes, Rivers and Coastal Zones
Date: Thursday, June 13, 2002
Time: 11:30:00 AM
Location: Carson B
StanelySE, University of Washington, Seattle, USA,
Arhonditsis, G, , University of Washington, Seattle, USA,
Brett, M, T, University of Washington, Seattle, USA,
A daily time series analysis of urbanization effects on stream phosphorus transport
Phosphorus (P) availability often limits primary productivity in natural freshwater ecosystems, and past research suggests urbanized watersheds may be important sources of this nutrient. The objective of this project was to develop a times series models of phosphorus transport in a range of urbanized watersheds. Four creeks were selected to fulfill these objectives: highly urbanized Thornton Creek, moderately urbanized-Swamp and North Creeks, and low-density residential Issaquah Creek. Total phosphorus (TP) and total suspended solids (TSS) samples were collected daily for one year, and soluble reactive P (SRP) was sampled weekly. Time series models (employing seasonal, antecedent and instantaneous wash off and transport terms) were moderate to strong for SRP (r2 0.53-0.80) and weak to moderate for TP (r2 0.39-0.59). Because of the dynamic behavior of TP concentrations in response to storm events this parameter was difficult to model. There were weak to moderate correlations between TP and TSS concentrations for log-transformed data (r2 0.20-0.47). These data will give us greater insight into how future increases of urban areas will impact surface water quality in the Lake Washington/Sammamish watershed.