Urban stream syndrome in a small, lightly developed watershed: a statistical analysis of water chemistry parameters, land use patterns, and natural sources

摘要

The relationships among land use pat-terns, geology, soil, and major solute concentra-tions in stream water for eight tributaries of the Kayaderosseras Creek watershed in Saratoga County, NY, were investigated using Pearson correlation coef-ficients and multivariate regression analysis. Sub-watersheds corresponding to each sampling site were delineated, and land use patterns were determined for each of the eight sub-watersheds using GIS. Four land use categories (urban development, agriculture, forests, and wetlands) constituted more than 99 % of the land in the sub-watersheds. Eleven water chem-istry parameters were highly and positively correlated with each other and urban development. Multivari-ate regression models indicated urban development was the most powerful predictor for the same eleven parameters (conductivity, TN, TP, NO_3~-, Cl~-, HCO_3~-, SO_4~(2-), Na~+, K~+, Ca~(2+), and Mg~(2+)). Adjusted R~2 val-ues, ranging from 19 to 91 %, indicated that these models explained an average of 64 % of the variance in these 11 parameters across the samples and 70 % when Mg~(2+) was omitted. The more common R~2, ranging from 29 to 92 %, averaged 68 % for these 11 parame-ters and 72 % when Mg~(2+) was omitted. Water quality improved most with forest coverage in stream water-sheds. The strong associations between water quality variables and urban development indicated an urban source for these 11 water quality parameters at all eight sampling sites was likely, suggesting that urban stream syndrome can be detected even on a relatively small scale in a lightly developed area. Possible urban sources of Ca~(2+) and HCO_3~- are suggested.