Investigation of Watershed-scale Surface Water Quality under Changing Land Use Conditions: A Case Study in Northern British Columbia

Abstract

The effects of land use change on surface water quality in an intensively used watershed in northern British Columbia were investigated. The water of the Kiskatinaw River watershed (KRW) was analyzed for its total organic carbon (TOC) concentration in 2004-2005 and 2010-2011, and the variation of water quality within sampling sites over time was examined. The results showed that TOC concentrations in 2010-2011 were lower than those in 2004-2005 due to decreased degradation of terrestrial vegetation, agricultural activities, and the loss of wetlands, as well as the strict regulation of industrial discharge from 2004-2005 to 2010- 2011 in KRW. It was found that TOC concentrations were high in the agriculturally intensive sites. In addition to land use, the data indicated that more rainfall led to higher TOC concentrations at the nearby stream/river during spring runoff and summer due to more surface runoff and erosion. The land use change effects were more dominant on TOC concentration variation than stream flow.