Preface: Hydrogeology of cold regions

Hydrogeology Journal, Jan 2013

Larry D. Hinzman, Georgia Destouni, Ming-ko Woo

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Preface: Hydrogeology of cold regions

Hydrogeology Journal Preface: Hydrogeology of cold regions Larry D. Hinzman 0 1 2 Georgia Destouni 0 1 2 Ming-ko Woo 0 1 2 0 M.-k. Woo School of Geography and Earth Sciences, McMaster University , Hamilton, ON L8S 4K1 Canada 1 G. Destouni Department of Physical Geography and Quaternary Geology, Stockholm University , 106 91 Stockholm , Sweden 2 L. D. Hinzman ()) International Arctic Research Center, University of Alaska Fairbanks , P.O. Box 757340, Fairbanks, AK 99775-7340 USA Permafrost; Seasonally frozen ground; Climate change; Thermal conditions Introduction Almost half a century ago, Williams (1970) compiled an annotated bibliography of published materials (up to 1960) on permafrost groundwater in the former Soviet Union, United States and Canada, and Scandinavia. That comprehensive survey encompassed literature on permafrost and related temperature and hydrological phenomena, and scientific and applied aspects of groundwater in permafrost terrain. In the intervening years, there have been major advances in permafrost hydrogeology, accompanied by shifts in research emphasis driven by scientific, environmental and societal demands. The present theme issue of Hydrogeology Journal presents a collection of articles that reflect the current status of progress in research on the hydrogeology of cold regions. Several of the papers in this theme issue describe current conditions of resources and processes in different specific regions of the world. Overall, the studies address conditions across different parts of Alaska (USA), Canada, Siberia, China, Fennoscandia and other parts of Europe, and Antarctica. Although snow and seasonally or permanently frozen ground recurs as a common consideration, each paper presents a unique perspective on widely varying conditions. Greater understanding of polar and sub-polar processes may be gleaned from a comparison among these results. With the focus of this thematic issue being on the hydrogeology of cold regions, all the papers in the issue discuss important elements of subsurface hydrology, and there is particular emphasis on ground ice and permafrost interactions with groundwater. However, the studies also deal with externalities that impact the subsurface such as surface energy budget, snow hydrology or glaciers, and groundwater below ice sheets, and some contributions address subsurface controls on the surface conditions via interaction with surface water or ecology. With regard to investigation approaches, the studies deal with interpretation of field or remotely sensed data, theory of ice-impacted hydrologic processes, field techniques, and modeling of groundwater systems in cold regions. Some of the modeling papers combine in pointing at safety assessment of nuclear waste repositories under climate-cooling scenarios as an important motivation for development and application of numerical simulation approaches for the hydrogeology of cold regions. Some articles are about management of groundwater resources, and there is also some discussion on societal aspects of cold-regions hydrology, for example, impacts of climate warming in these regions. In summary, the range of investigations presented in this thematic issue constitutes a valuable compilation of the state of knowledge of cold region hydrogeology. This contribution is timely, with groundwater resources in cold regions facing immediate or impending changes as a consequence of the ongoing climate change, the intensification of the hydrologic cycle, and in response to increased demands from communities and industry. Regional studies Cheng and Jin review the occurrence, circulation and nature of groundwater in permafrost regions of China. They present a methodical summary of processes in various seasonal freeze–thaw) and involve field investigations or parts of China as a function of the predominance of make use of measured data. The scale of enquiry ranges continuous or discontinuous permafrost. Most of the from small drainage basins to water tracks or ponds. permafrost in China is located in mountainous areas and on Carey et al. use hydrometric records together with stable the Qinghai-Tibet Plateau, which also corresponds with isotope and dissolved ions data to investigate groundwater important sources of freshwater for Asia. The permafrost contributions during snowmelt in a small alpine, discongreatly limits moisture exchanges between surface and tinuous permafrost basin in Yukon, Canada. Runoff from subsurface, and thus plays an important role in water cycling snowmelt freshet is derived largely from old water that and water availability through controls on recharge, flow existed prior to the melt event. The unsaturated organic pathways and discharge. China has experienced some of the layer that overlies mineral soils provides the capacity for greatest degradation of permafrost in the last 30 years, with storing old water over-winter and the high soil porosity areal extent decreasing by nearly 20 % and markedly permits infiltration of meltwater to displace the existent affecting hydrogeology, and with consequent effects on water in the soil. There is much inter-annual variability in surface hydrology, ecology and social systems. the magnitude of the freshet, and meltwater can contribute Callegary et al. report on groundwater conditions in from 10 to over 25 % of streamflow. Alaska as related to its climate, physiography and glaciation Utting et al. study the recharge and flow of groundhistory. They discuss the groundwater and surface-water water in carbonate terrain of northwestern Canada. interactions in six different hydrologic sub-regions of Recharge is enhanced where air temperature inversion Alaska, ranging from boreal rain forests to Arctic deserts. causes permafrost to be thinner at the higher elevations They further discuss issues of groundwater contamination, than at the lower elevations. PCO2 and δ13C values point to particularly in association with mining and petroleum a recharge of groundwater through organic-rich soils that development, along with climate-change effects on perma- overlie fractured bedrock. Noble gas results show that frost and, consequently, the hydrogeology of Alaska. recharge occurs close to 0 °C, suggesting the absence of For the continuous permafrost regions of northeastern heat advection to the subsurface. As dated by 3HeAlaska, Kane et al. note the frequent occurrence of ingrowth from tritium, groundwater has a circulation time springs and formation of icing. They suggest that the on the order of two to three decades, indicating that karst groundwater comes from a source at the south side of groundwater systems have substantial flow paths and Brooks Range, on the other side of the Continental storage capacity. Divide. There, limestone beds facilitate groundwater Koch et al. studied a permafrost basin, with an organic recharge and groundwater flow can be transmitted through layer overlying silt, near Fairbanks, in interior Alaska. deep sub-permafrost paths. Groundwater can further be They find that runoff shifts from shallow throughflow in discharged through taliks along fault lines that pierce the spring and early summer to deeper preferential flow as the permafrost, and at the northern edge of the permafrost active layer thaws. Throughflow is topographically conalong the Beaufort Sea coast. trolled, while preferential flow follows steep slopes, near For more shallow groundwater in northern latitudes stream zones and newly exposed silt along thawing subject to seasonal frost, Ireson et al. provide a general margins. Tracer dilution gauging suggests occurrence of survey of literature on soil freeze–thaw and related moisture preferential flow through pipes formed at the boundary migration processes, with particular examples from the between thawed silt and impermeable ice-rich frozen soil prairies and boreal forests of western Canada. Infiltration below. Uranium isotopes provide indication that these and recharge of seasonally frozen soils are described. Their preferential flow paths are renewed seasonally and they synthesis of northern hydrogeology focuses primarily on erode the ice-rich sediments below, thus releasing ancient seasonally frozen soil and examines seasonal differences in carbon to the ecosystem. water-balance processes. They note that snow accumulation Semenova et al. present a model analysis of data for and soil freeze–thaw cycles control the timing and magni- the Kolyma basin situated in a mountainous continuous tude of infiltration, groundwater recharge, and baseflow in permafrost setting in Siberia. They use a physically based northern regions, and propose a conceptualization for hydrological model that accounts for heat and water modeling the principal processes that influence the season- transfer in soils, and apply it to three small watersheds ally frozen–thawed vadose and shallow groundwater zones. with distinctive terrains. The model satisfactorily simuThey further discuss various problems associated with lates thaw depth, infiltration, surface and subsurface flows. quantitative models of these processes, and assert that much It is found that a mainly bare watershed with coarse, talus can be gained by combining field experiments with materials has deeper seasonal thaw and larger subsurface modeling, and by integrating models of the near surface flow than a basin covered with larch and underlain by with models of deeper groundwater. peaty ice-rich soil. A third basin with tundra vegetation exhibits thaw and runoff conditions intermediate between these two. This paper provides useful information on Process studies subsurface properties and water flow in Siberia, as well as citations to many important, but relatively unknown Papers on process studies focus mainly on supra-perma- Russian research publications. Although extensive, the frost groundwater (i.e. water in the zone subject to contributions of Russian research on permafrost hydrology are not well known in English language literature. This lowering of their water level, but the changes are not watershed was the first permafrost research watershed uniform across the region. This implies local control on established, dating back to at least 1948, and in the 1960– the water balance of individual lakes. They studied 1980s, the Soviet hydrological scientists had already studied specifically one lake that has displayed substantial volume the mechanisms of runoff generation and associated varia- loss since the early 1980s. Suggested explanations include tions with land cover and topography. This paper makes an increased loss to lateral groundwater flow through those early studies and that information more accessible. gravel across the drainage divide, vertical groundwater For watersheds in northern Sweden, Sjöberg et al. flow through a sub-lacustrine talik, and substantial combine results from a numerical model with measured reduction in snow accumulation accompanied by instreamflow data to connect shifts in two discharge creased infiltration of meltwater into the unfrozen sedicharacteristics with permafrost thaw. Baseflow has in- ment. Their analysis examines possible ranges in creased significantly in nine basins and seven basins variability of properties and processes, which may explain display changes in recession characteristics consistent why some lakes display marked changes and neighboring with degradation of permafrost. The increase in minimum lakes show little apparent change. flow in the winter is associated with a modification of flow Quinton and Baltzer describe the hydrologic behavior connectivity in the aquifer system as permafrost thaws, of a small permafrost peat plateau in a wetland environand the change in recession flow during the summer ment of northwestern Canada and provide evidence of responds to warming of the active layer. These observed recent permafrost degradation, noting shrinkage in plateau flow tendencies are in general agreement with the out- size and increase in its active layer thickness. Field data comes of a warming scenario simulated with a non- indicate that both active layer moisture and temperature isothermal, multi-phase flow model. rose as ground thaw began progressively earlier during the Helbig et al. investigate the hydrologic role of micro- decade. Both the water-balance computation and model topography, applying water-balance studies on low-cen- study show that active-layer runoff in the spring is related tered tundra polygons in the Lena River delta in Siberia. to the snow–water equivalent, and the magnitude of During and immediately following the snowmelt period, summer runoff corresponds with the depth of summer the polygons and their adjoining troughs experience rainfall. Modeled sensitivity runs that incorporate changes flooding and large lateral outflow conditions. In the associated with permafrost degradation show that desecond part of summer, a shift in lateral flow dynamics creased hydraulic gradient and increased thaw depth have leads to reduced net outflow and even inflow conditions slight effect, but plateau shrinkage gives rise to the after rain events. Hydrologic connectivity of the tundra greatest reduction of runoff from the permafrost plateau. polygons network is a manifestation of the fill-and-spill In total, the runoff is 47 % of what it would have been mechanism in which lateral drainage is connected only without the changes in hydraulic gradient, active layer when pond levels are filled above the outflow thresholds. thickness and plateau surface area that occurred between The shallow depth of seasonal thaw maintains soil water 2002 and 2010. as a limited but important component of the water balance, playing an important role in maintaining these wetlands. In another tundra polygon terrain, near Barrow in Model studies Alaska, Hubbard et al. obtain and combine point measurements, LiDAR (light detection and ranging) and Models are used increasingly to study groundwater in geophysical datasets (surface ground penetrating radar, permafrost regions, particularly the sub-permafrost and electromagnetic and electrical resistance tomography intra-permafrost groundwater systems, which are rarely data). They perform cluster analysis on these data to amenable to direct field investigation. Models are also delineate zones, each with unique geomorphic, thermal, employed to explore the evolution of permafrost and its hydrological and geochemical properties. Such character- attendant effects on groundwater, under both climate ization of the temporal and spatial variability of land warming and climate cooling scenarios. surface and subsurface properties contributes to quantify- Painter et al. discuss challenges that confront modeling the ecosystem-climate feedbacks in permafrost terrain. ing prediction of the hydrologic response to degrading For the extreme arid permafrost environment of the permafrost. In their essay, they comment that models need Dry Valley in Antarctica, Gooseff et al. report that to consider approaches for coupling various surface and meltwater from glaciers and from snow patches is the subsurface processes, and incorporate the deformation of only source of runoff. Groundwater occurs in front of topography, including micro-topography, and drainage melting snow patches, beneath water tracks, along wetted network as the landscape evolves. These requirements margins of streams and lakes, and in hyporheic zones place demands on the computational infrastructure as the along the streams. The shallow supra-permafrost ground- models need increasingly higher spatial and temporal water zones enhance the movement of solutes in the wet resolutions. soils. The hydrologic function and the biogeochemistry of Three papers apply numerical simulation to assess the the wet zones control biological communities. safety of nuclear waste repositories under climate cooling For the discontinuous permafrost area of Yukon Flats, scenarios. For a site in Forsmark, Sweden, Bosson et al. Alaska, Jepsen et al. note that many lakes experience investigate groundwater flow and solute transport under hypothetical climate and permafrost conditions. The presence of permafrost greatly diminishes vertical groundwater flow, compared with non-permafrost situations. With permafrost, the taliks and sea bottom provide passages for recharge and discharge, and for contact between shallow and deep groundwater. Tracking of particles that reach and are carried further by deep groundwater reveals that they spend much time travelling horizontally beneath the permafrost. However, taliks and unfrozen seabeds offer vertical pathways for exchange of flow and solute between the deep and shallow groundwater, which increases with decreasing permafrost. Vidstrand et al. model groundwater flow in crystalline rocks of the Fennoscandian Shield, Sweden, beneath the moving margin of an ice sheet, focusing on the changes in groundwater flow as climate changes. The very long time scale of radiological safety requires consideration of the deep-seated groundwater systems during glaciation and deglaciation because the highly dynamic drainage systems of ice sheets and glaciers will also affect these deep systems. Under glacial conditions, permafrost in front of the glacier limits groundwater flow and water is discharged in taliks. As a glacier advances, pressure exerted by the ice sheet causes the permafrost to thaw. Successive reduction of the permafrost is accompanied by recharge of fresh meltwater beneath the ice, flushing saline groundwater from fractures in the bedrock. Orders of magnitude difference in Darcy velocity of flow can be caused by local variations in geological structure and hydraulic properties. The safety of nuclear waste storage is also assessed by Grenier et al. for a sedimentary basin like that of the Paris Basin in northeastern France. They simulate transient thermal evolution in a cold dry glacial period, using generic topographic settings of a river and a plain. Under cooling scenarios, conductive heat transfer alone closes a talik within several centuries, but including advection from the river to the plain, talik closure is delayed on the millennium time scale. Depending on talik position, groundwater flow varies from a reduction of recharge to its complete cessation. Frampton et al. model the effects of surface warming on permafrost degradation and subsurface flow. Several rates of warming are applied to a hypothetical subsurface configuration comprising two adjacent soils of different properties. Over a 10-year simulation period, seasonal variability of flow diminishes gradually, but the minimum flow increases notably, primarily during winter and spring. Groundwater discharge first increases as permafrost thaws but declines later when ground ice storage undergoes depletion. Wellman et al. study the impacts of climate, lake size, and groundwater flow on the evolution of lakes in permafrost areas of Yukon Flats in Alaska. Numerical simulations of heat and water fluxes over centuries suggest that a lake that loses water downward from the active layer is relatively fast in developing a throughgoing talik that links supra- and sub-permafrost aquifers. A lake that gains water from upward movement of subpermafrost groundwater does this more slowly, whereas a lake without any water gain or loss takes the longest time to form a talik through the permafrost. Once connected, the feedback of heat convected by groundwater enhances permafrost thaw. Simulation of groundwater by McKenzie and Voss further highlights the role of heat advection by groundwater flow in permafrost thaw. Applied to a hypothetical undulating topography with a nested groundwater-flow system under climate-warming scenarios, the model shows that heat transport greatly accelerates the thaw, compared with thawing due to heat conduction alone. For patchy permafrost, thaw is quicker near zones of high permeability but low-permeability patches preserve permafrost for an extended time. Introducing seasonal temperature fluctuation gives rise to non-linear interaction of annual freeze–thaw with groundwater flow, but the effect on permafrost thaw is local rather than regional. Where taliks already exist below deep lakes, permafrost thaw proceeds faster than the no-lake situation only after the taliks break through the permafrost. In conclusion We end by referring the reader back to an earlier assessment. Williams and van Everdingen (1973 ) wrote the first review paper on groundwater investigations in permafrost regions of North America for the Second International Conference on Permafrost. They addressed many of the topics that have been included in this special issue including permafrost and movement of groundwater, availability of groundwater, icings, pingos and artesian pressures, influence of permafrost on water quality, methodology, studies of basin hydrology, investigations for pipeline projects, hydrologic model studies, and research needs. The paper did consider increasing demands on groundwater from growing communities and expanding industrial use, but not the potential consequences of a changing climate and the possible effects of degrading permafrost. In these 40 years, our instruments, our models, and even our methods of analyses have become much more sophisticated, giving us better capabilities to help our societies protect and utilize limited resources. Still, we owe much to those pioneering researchers, who began the studies that now allow us to gauge changes, and understand processes and potential impacts. Williams JR ( 1970 ) Ground water in the permafrost regions of Alaska . US Geol Surv Profl Pap 696 , 83 pp Williams JR , van Everdingen RO ( 1973 ) Groundwater investigations in permafrost regions of North America: a review . North American contribution, 2nd International Conference on Permafrost, Yakutsk , USSR , July 1973 , National Academy of Sciences, Washington, DC, pp 435 - 446


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Larry D. Hinzman, Georgia Destouni, Ming-ko Woo. Preface: Hydrogeology of cold regions, Hydrogeology Journal, 2013, 1-4, DOI: 10.1007/s10040-012-0943-2