Stream Temperature Surges Under Urbanization and Climate Change: Data, Models, and Responses

• Published in: Journal of the American Water Resources Association Vol. 43; no. 2; pp. 440 - 452
• Main Authors: Nelson, K.C, Palmer, M.A
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-04-2007; American Water Resources Association
• Subjects: agricultural watersheds; air temperature; climate change; climate variability/change; critical thermal maxima; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Exact sciences and technology; flashiness; Hydrology. Hydrogeology; impervious surface; land use; Pollution, environment geology; precipitation; simulation models; storms; streams; temperature; temperature surge; urbanization; Water resources; water temperature; Maryland; United States; Washington; climate variability/change; models; biota; flashiness; atmospheric precipitation; streams; vegetation; degradation; North America; urbanization; siltation; drainage basins; precipitation; climate modification; land use; civil engineering; impervious surface; water resource management; temperature; growth; temperature surge; critical thermal maxima; communities; thermal regime
• ISSN: 1093-474X; 1752-1688
• DOI: 10.1111/j.1752-1688.2007.00034.x

Multiple anthropogenic stressors, including increased watershed imperviousness, destruction of the riparian vegetation, increased siltation, and changes in climate, will impact streams over the coming century. These stressors will alter water temperature, thus influencing ecological processes and stream biota. Quantitative tools are needed to predict the magnitude and direction of altered thermal regimes. Here, empirical relationships were derived to complement a simple model of in-stream temperature [developed by Caissie et al. Canadian Journal of Civil Engineering25 (1998) 250; Journal of Hydrology251 (2001) 14], including seasonal temperature shifts linked to land use, and temperature surges linked to localized rainstorms; surges in temperature averaged about 3.5°C and dissipated over about 3 h. These temperature surges occurred frequently at the most urbanized sites (up to 10% of summer days) and could briefly increase maximum temperature by >7°C. The combination of empirical relationships and model show that headwater streams may be more pervasively impacted by urbanization than by climate change, although the two stressors reinforce each other. A profound community shift, from common cold and coolwater species to some of the many warmwater species currently present in smaller numbers, may be expected, as shown by a count of days on which temperature exceeds the "good growth" range for coldwater species.