Examination of Terrain and Land use Control on Soil Water Chemistry in Two Suburban Watersheds

Scientific literature has advanced our understanding about controlling factors of water chemistry in forested watersheds, however the linkage between watershed characteristics and soil water chemistry in suburban watersheds is poorly understood.

A better understanding of suburban watershed characteristics that control soil water chemistry concentrations will help watershed managers in addressing water pollution issue. Soil water samples were taken biweekly from nineteen sampling clusters throughout the study areas; B28 watershed, a 558860 m² catchment, and Power Station watershed, a 446450 m² catchment, in Croton New York City water supply system, from June 2001 to August 2002. Watershed characteristics (land use and topographic) were generated from land use data and 2 meters grided digital elevation model using extensive ARC/GIS functions and analyses. Clusters have a range of development density. Relationships between annual average total phosphorous (TP), total nitrogen (TN) and dissolved organic carbon (DOC) concentration and watershed characteristics were examined and regression models for TP, TN, and DOC concentration were developed. The best predictive model for average TP concentration was based on Number of houses and Road width (R² _adj = 0.47), based predictive model for average TN concentration was based on number of houses and impervious area (R² _adj = 0.78), and best predictive model for average DOC concentration based on road width (R² _adj = 0.46).