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Temporal variation in spatial sources of discharge in a large watershed
Citation:
RAIKOW, D. AND E. D'Amico. Temporal variation in spatial sources of discharge in a large watershed. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 45(10):4392-4398, (2011).
Impact/Purpose:
The goal of this research is to develop methods and indicators that are useful for evaluating the condition of aquatic communities, for assessing the restoration of aquatic communities in response to mitigation and best management practices, and for determining the exposure of aquatic communities to different classes of stressors (i.e., pesticides, sedimentation, habitat alteration).
Description:
We examined how the spatial configuration of source areas for runoff varied over time in a watershed contaminated with mercury in order to understand processes governing material loading to rivers. Source areas within the Fox River watershed (Wisconsin, USA) were mapped for individual discharge events. Spatial distribution of source areas varied between and over the duration of individual discharge events. Relative contribution to runoff by land cover types within the source areas was quantified and compared to areal abundance of land covers in the watershed. Agricultural land dominated discharge sources, consistent with known patterns of mercury loading to regional rivers. Contributions of runoff by land cover types varied over time. Moreover, the degree to which different land cover types acted as source areas differed from their abundance in the watershed. Hence, areal quantifications of land cover within a watershed may not accurately represent what land covers are source areas over given time periods. Therefore a source area-based approach may yield more accurate spatial analysis of material loading patterns than a watershed-based approach.