Water temperature dynamics in High Arctic river basins

Abstract

Despite the high sensitivity of polar regions to climate change, and the strong influence of temperature upon ecosystem processes, contemporary understanding of water temperature dynamics in Arctic river systems is limited. This research gap was addressed by exploring high-resolution water column thermal regimes for glacier-fed and non-glacial rivers at eight sites across Svalbard during the 2010 melt season. Mean water column temperatures in glacier-fed rivers (0.3 -3.2 ºC) were lowest and least variable near the glacier terminus, but increased downstream (0.7 -2.3 ºC km -1 ). Non-glacial rivers, where discharge was sourced primarily from snowmelt runoff, were warmer (mean 2.9 -5.7 ºC) and more variable, indicating increased water residence times in shallow alluvial zones and increased potential for atmospheric influence. Mean summer water temperature and the magnitude of daily thermal variation were similar to those of some Alaskan Arctic rivers but low at all sites when compared to alpine glacierized environments at lower latitudes. Thermal regimes were correlated strongly (p<0.01) with incoming shortwave radiation, air temperature, and river discharge. Principal drivers of thermal variability were inferred to be: (1) water source (i.e. glacier melt, snowmelt, groundwater); (2) exposure time to the atmosphere; (3) prevailing meteorological conditions; (4) river discharge; (5) runoff interaction with permafrost and buried ice and (6) basin-specific geomorphological features (e.g. channel morphology). These results provide insight into the potential changes in high-latitude river systems in the context of projected warming in polar regions. We hypothesise warmer and more variable temperature regimes may prevail in future as the proportion of bulk discharge sourced from glacial meltwater declines and rivers undergo a progressive shift towards snow-and groundwater sources. Importantly, such changes could have implications for aquatic species diversity and abundance and influence rates of ecosystem functioning in high-latitude river systems.

Stream temperature response to variable glacier coverage in coastal watersheds of Southeast Alaska

“…The seasonal patterns in run‐off and δ 18 O across streams are consistent with an increase in the proportion of streamflow derived from δ 18 O‐depleted snow and ice melt in the higher elevation watersheds during the summer months (Rietti‐Shati et al ., ; Mark and McKenzie, ). The increase in glacial meltwater had a strong moderating effect on stream temperature (Hood and Berner, ; Blaen et al ., ), especially during the months of July through September when the three heavily glaciated watersheds (Eagle, Herbert and Mendenhall Rivers) were at their coolest. This contrasts with low gradient, forested watersheds (e.g.…”

Comparing various artificial neural network types for water temperature prediction in rivers

“…It is governed by a number of environmental factors, including air temperature, net radiation, river runoff, groundwater inputs, river width and depth, shading and many others. Probably because of global warming the temperature increase in many natural rivers has already been observed (Webb et al, 2008;Orr et al, 2015) and is expected to continue , what may especially impact the ecosystem of rivers located in cold and temperate climate zones (Blaen et al, 2013;Ficklin et al, 2013), due to the shortening of freezing periods (e.g. Takacs and Kern, in press) and the increasing possibility of exceedance of the extreme maximum air temperatures.…”

Long‐term variability of proglacial groundwater‐fed hydrological systems in an area of glacier retreat, Skeiðarársandur, Iceland

“…However, proglacial ecology is vulnerable to glacial retreat and climate change, with projected impacts of decreasing meltwater contributions and increasing contributions from rainfall, snowmelt and groundwater (Brown et al, 2006;2007a, b;Blaen et al, 2013;. Proglacial groundwater flow, spring discharge, and groundwater contributions to runoff and storage are also projected to alter due to glacial retreat (Haldorsen et al, 2010;Rutter et al, 2011;Finger et al, 2013).…”