Trends in stream and river temperature

Abstract

Information on past and likely future trends in water temperature from different parts of the world is collated. The potential causes of trends in the thermal regimes of streams and rivers are many, but the existing database of water temperature information is inadequate to provide a global perspective on changes during the recent, let alone the more remote, past. Data from Europe suggest that warming of up to ca. 1°C in mean river temperatures has occurred during the 20th century, but that this trend has not been continuous, is distorted by extreme hydrological events, is not correlated with simple hydrometeorological factors and has been influenced by a variety of human activities. Predictive studies indicate that an accelerated rise in stream and river temperatures will occur during the next century as a consequence of global warming. However, forecasts must be tentative because future climatic conditions are uncertain and interactions between climate, hydrological and vegetation changes are complex.

Recent advances in stream and river temperature research

“…Attention in recent years has also been increasingly focussed on how stream and river temperatures have changed in the past and might do so again in the future, and the main factors responsible (Webb, 1996b). The accumulation of data from routine surveillance and monitoring (e.g.…”

“…Mackey and Berrie, 1991;Stefan and Sinokrot, 1993;Sinokrot et al, 1995;Kyle and Brabets, 2001;Morrill et al, 2005). Potential increases in water temperatures between 1 and 9°C, as a consequence of global warming because of a projected doubling of atmospheric CO 2 levels by 2050, have been predicted for a range of water courses in the USA and UK (Webb, 1996b). However, caution is needed in making future estimates because the magnitude and nature of projected future temperatures may vary considerably depending on the Global Circulation Model used, as Cooter and Cooter (1990) demonstrated in a study of future July water equilibrium temperatures in the south-eastern United States.…”

Temperature in lowland Danish streams: contemporary patterns, empirical models and future scenarios

“…During the 1980s and 1990s the focus on stream temperatures increased because of the observed rise of temperatures in many regions following deforestation, removal of riparian vegetation and water abstraction resulting in undesirable reductions of cold-water and oxygen sensitive species among salmonids and ephemeropteran and plecopteran insects (Beschta and Taylor, 1988;Li et al, 1994). More recently, the documented increase of global air temperatures and water temperatures in European streams (Webb, 1996) and the forecasted future warming between 1Ð5 and 5Ð0°C for the coming 70-100 years (Table VIII in Webb, 1996;Christensen et al, 2002) have further stimulated the interest in stream temperatures and the attempts to model both contemporary and possible future temperature regimes (Sinokrot et al, 1995;Webb, 1996;Mohseni et al, , 2002.…”

“…Stream temperatures are influenced by many factors whose roles are difficult to quantify (Sinokrot and Stefan, 1994). The obvious challenge is that in-stream temperatures, on the one hand, are determined by temperature and discharge of the incoming water from different sources such as groundwater, drainage water, surface flow and point sources in the surrounding catchments and, on the other hand, are determined by the heat balance of the upstream reaches (Webb andZhang, 1997, 1999). Heat inputs along stream reaches include solar radiation and, among others, convection from air, conduction from soil and net long wave radiation from the local environment 349 to colder stream waters.…”

Impact of long‐term water and energy consumption in Tokyo on wastewater effluent: implications for the thermal degradation of urban streams

“…Most previous studies of artificial heat input to streams have focused on the effluents from electric power generating stations and industrial facilities (e.g. Webb, 1996;Erickson and Stefan, 2000). Numerous studies have been * Correspondence to: Tsuyoshi Kinouchi, Department of Environment System Management, Fukushima University, 1 Kanayagawa, Fukushima-Shi, Fukushima, Japan.…”