Isotopic investigation of runoff generation in a glacierized catchment in northern Sweden

Abstract

In this study, summer rainfall contributions to streamflow were quantified in the sub‐arctic, 30% glacierized Tarfala (21.7 km2) catchment in northern Sweden for two non‐consecutive summer sampling seasons (2004 and 2011). We used two‐component hydrograph separation along with isotope ratios (δ18O and δD) of rainwater and daily streamwater samplings to estimate relative fraction and uncertainties (because of laboratory instrumentation, temporal variability and spatial gradients) of source water contributions. We hypothesized that the glacier influence on how rainfall becomes runoff is temporally variable and largely dependent on a combination of the timing of decreasing snow cover on glaciers and the relative moisture storage condition within the catchment. The results indicate that the majority of storm runoff was dominated by pre‐event water. However, the average event water contribution during storm events differed slightly between both years with 11% reached in 2004 and 22% in 2011. Event water contributions to runoff generally increased over 2011 the sampling season in both the main stream of Tarfala catchment and in the two pro‐glacial streams that drain Storglaciären (the largest glacier in Tarfala catchment covering 2.9 km2). We credit both the inter‐annual and intra‐annual differences in event water contributions to large rainfall events late in the summer melt season, low glacier snow cover and elevated soil moisture due to large antecedent precipitation. Together amplification of these two mechanisms under a warming climate might influence the timing and magnitude of floods, the sediment budget and nutrient cycling in glacierized catchments. Copyright © 2012 John Wiley & Sons, Ltd.

Tracer-based analysis of spatial and temporal variations of water sources in a glacierized catchment

“…5. Indeed, despite the large variability of measurements in all waters (evidenced by the long horizontal and vertical error bars), the mixing plot clearly reveals the importance of snowmelt and glacier melt as endmembers in the study catchment, playing therefore a major role on the runoff regimes of the Saldur River and of its tributaries, as also observed in other glacierized catch- ments (Zhang et al, 2009;Dahlke et al, 2013;Olhanders et al, 2013). However, it must be mentioned that we normally collected samples during no-rain periods, and therefore the contribution of rain water to the isotopic and EC composition of stream water and groundwater was likely underestimated.…”

“…A powerful investigation tool useful for this purpose is represented by tracers. Particularly, the stable isotopes of water (δ 2 H and δ 18 O) have been recently used in high-elevation catchments to quantify post-snowmelt summer rainfall contributions to streamflow (Dahlke et al, 2013), estimate the regional water balance (Ohlanders et al, 2013), compute catchment residence times (Jeelani et al, 2013;Chiogna et al, 2014) and constrain model parameters (Cable et al, 2011). Moreover, water isotopes, coupled to other geochemical tracers, such as electrical conductivity (EC), have the potential to identify end-members (i.e.…”

On the variability of cold region flooding

“…Additionally, catchment properties such as the state of permafrost, which influences a catchment's water storage capacity (especially for the catchments located in the south of the study area), a catchment's elevation (both mean and maximum), and its location with respect to the Scandinavian mountain range have an influence on the exhibition of significant trends (e.g. Walvoord et al, 2012;Dahlke et al, 2014;Tetzlaff et al, 2015). Whereas other studies (e.g.…”

“…Across Canada, for example, trends toward decreasing flood magnitudes and earlier flood occurrences have been detected for snowmelt-dominated catchments (Cunderlik and Ouarda, 2009;Burn et al, 2010). An ongoing shift in flow regime from snowmelt-dominated to rainfall-dominated coupled to the development of a bi-modal flow regime with two peaks in the annual hydrograph (one in late spring due to snowmelt and one in late summer due to rainfall events) has been found both in North America and northern Europe (Cunderlik and Ouarda, 2009;Dahlke et al, 2014). With regards to the magnitude and the occurrence of floods, variable spatial and temporal patterns have been http://dx.doi.org/10.1016/j.jhydrol.2016.01.055 0022-1694/Ó 2016 Elsevier B.V. All rights reserved.…”

Comparative Assessment of Runoff and Its Components in Two Catchments of Upper Indus Basin by Using a Semi Distributed Glacio-Hydrological Model

“…To know the contribution of glaciers to runoff is an essential step to identify the impact of climate change on water resources, flooding and drought in glacier fed basins. At present there are four approaches to investigate the runoff components from rainfall, melting of snow and glaciers: the water balance analysis (Thayyen et al, 2005;Kumar et al, 2007), glacier degradation from observation or modelling as contribution to runoff (Kotliakov, 1996;Kaser et al, 2010), isotopic investigations (Dahlke et al, 2013) and hydrological modelling (Hagg et al, 2007;Naz et al, 2013) though limitations of these methods cannot be ignored, especially for climate change studies. The water balance method can roughly estimate the effects of glacier and snow in monthly or larger time scale.…”