scholarly journals Evaluating snowmelt runoff generation in a discontinuous permafrost catchment using stable isotope, hydrochemical and hydrometric data

2004 ◽  
Vol 35 (4-5) ◽  
pp. 309-324 ◽  
Author(s):  
S.K. Carey ◽  
W.L. Quinton
Keyword(s):  
Stable Isotope ◽  
Specific Conductivity ◽  
Organic Layer ◽  
Snowmelt Runoff ◽  
Runoff Generation ◽  
Entire Study ◽  
Near Surface ◽  
Discontinuous Permafrost ◽  
Hydrochemical Data ◽  
Melt Water

Research on snowmelt runoff generation in discontinuous permafrost subarctic catchments has highlighted the role of: (i) permafrost in restricting deep percolation and sustaining near-surface water tables and (ii) the surface organic layer in rapidly conveying water to the stream. Conceptual models of runoff generation have largely been derived from hydrometric data, with isotope and hydrochemical data having only limited application in delineating sources and pathways of water. In a small subarctic alpine catchment within the Wolf Creek Research Basin, Yukon, Canada, snowmelt runoff generation processes were studied during 2002 using a mixed methods approach. Snowmelt timing varied between basin slopes, with south-facing exposures melting prior to permafrost-underlain north-facing slopes. The streamflow freshet period begain after 90% of snow had melted on the south-facing slope and coincided with the main melt period on the north-facing slope, indicating that contributing areas were largely defined by permafrost distribution. Stable isotope (δ18O) and hydrochemical parameters (dissolved organic carbon, specific conductivity, pH) suggest that, at the beginning of the melt period, meltwater infiltrates soil pores and resides in temporary storage. As melt progresses and bare ground appears, thawing of soils and continued meltwater delivery to the slopes allows rapid drainage of this meltwater through surface organic layers. As melt continues, soil thawing progresses and pre-event water mixes with melt water to impart streamflow with a gradually decreasing meltwater contribution. By the end of the melt period, the majority of water reaching the stream is displaced water that has resided in the catchment prior to melt. For the entire study period, approximately 21% of freshet was supplied by the snowpack, and the remaining majority was pre-melt water stored in the catchment slopes over-winter and displaced during melt. Hydrochemical data support hydrometric observations indicating the dominant flow pathway linking the slopes and the stream is through the organic horizon on permafrost-underlain slopes.

scholarly journals Exploring runoff processes using chemical, isotopic and hydrometric data in a discontinuous permafrost catchment

2010 ◽  
Vol 41 (6) ◽  
pp. 508-519 ◽  
Author(s):  
Jessica L. Boucher ◽  
Sean K. Carey
Keyword(s):  
Stable Isotope ◽  
Water Balance ◽  
Water Concentration ◽  
Yukon Territory ◽  
Hydrograph Separation ◽  
Runoff Generation ◽  
Water Balance Components ◽  
Discontinuous Permafrost ◽  
Hydrochemical Data ◽  
Mixing Diagrams

Hydrometric, isotopic and hydrochemical data were used to investigate runoff generation in a discontinuous permafrost headwater catchment. Research was undertaken between 10 April and 8 July 2008 within Granger Basin, a 7.6 km2 sub-catchment of the Wolf Creek Research Basin, Yukon Territory, Canada. The objectives of this research were to utilize hydrometric, stable isotope and hydrochemical methods to: (i) establish water balance components and (ii) couple water balance information with stable isotope and hydrochemical information to provide an enhanced understanding of runoff sources and pathways. The water balance components were snowmelt (152 mm), precipitation (68 mm), evaporation (88 mm), discharge (173 mm) and change in storage (−41 mm). The runoff ratio was high compared with previous years in this catchment. Using two-component hydrograph separation, pre-event water represented ∼73% of total discharge during freshet. End-member mixing diagrams suggested three contributing sources to streamflow in the following order: groundwater, soil water and snowmelt water. Concentration versus discharge diagrams identified the dilution of weathering ions during melt, while the ratio of potassium to calcium in streamwater suggests early contributions of pre-event water to discharge. Results from this research support previous work that pre-event water dominates freshet, yet the role of deeper groundwater is highlighted as an important contribution.

Watershed Hydrology and Chemistry in the Alaskan Boreal Forest: The Central Role of Permafrost

2006 ◽  
Author(s):  
Larry D. Hinzman ◽  
Kevin C. Petrone
Keyword(s):  
Boreal Forest ◽  
Active Layer ◽  
Hydrological Processes ◽  
Organic Layer ◽  
Freezing And Thawing ◽  
Surface Soils ◽  
Near Surface ◽  
Organic Layers ◽  
Discontinuous Permafrost ◽  
Permafrost Soils

Hydrological processes exert strong control over biological and climatic processes in every ecosystem. They are particularly important in the boreal zone, where the average annual temperatures of the air and soil are relatively near the phase-change temperature of water (Chapter 4). Boreal hydrology is strongly controlled by processes related to freezing and thawing, particularly the presence or absence of permafrost. Flow in watersheds underlain by extensive permafrost is limited to the near-surface active layer and to small springs that connect the surface with the subpermafrost groundwater. Ice-rich permafrost, near the soil surface, impedes infiltration, resulting in soils that vary in moisture content from wet to saturated. Interior Alaska has a continental climate with relatively low precipitation (Chapter 4). Soils are typically aeolian or alluvial (Chapter 3). Consequently, in the absence of permafrost, infiltration is relatively high, yielding dry surface soils. In this way, discontinuous permafrost distribution magnifies the differences in soil moisture that might normally occur along topographic gradients. Hydrological processes in the boreal forest are unique due to highly organic soils with a porous organic mat on the surface, short thaw season, and warm summer and cold winter temperatures. The surface organic layer tends to be much thicker on north-facing slopes and in valley bottoms than on south-facing slopes and ridges, reflecting primarily the distribution of permafrost. Soils are cooler and wetter above permafrost, which retards decomposition, resulting in organic matter accumulation (Chapter 15). The markedly different material properties of the soil layers also influence hydrology. The highly porous near-surface soils allow rapid infiltration and, on hillsides, downslope drainage. The organic layer also has a relatively low thermal conductivity, resulting in slow thaw below thick organic layers. The thick organic layer limits the depth of thaw each summer to about 50–100 cm above permafrost (i.e., the active layer). As the active layer thaws, the hydraulic properties change. For example, the moisture-holding capacity increases, and additional subsurface layers become available for lateral flow. The mosaic of Alaskan vegetation depends not only on disturbance history (Chapter 7) but also on hydrology (Chapter 6).

scholarly journals Riverine Sediment Changes and Channel Pattern of a Gravel-Bed Mountain Torrent

2020 ◽  
Vol 12 (18) ◽  
pp. 3065 ◽  
Author(s):  
Gernot Seier ◽  
Stefan Schöttl ◽  
Andreas Kellerer-Pirklbauer ◽  
Raphael Glück ◽  
Gerhard K. Lieb ◽  
...  
Keyword(s):  
High Resolution ◽  
Sediment Yield ◽  
Subsurface Water ◽  
Braided River ◽  
River Channels ◽  
Entire Study ◽  
Near Surface ◽  
Highly Active ◽  
Sediment Redistribution ◽  
Alluvial Channel

The alluvial channel of the Langgriesgraben (Austria) is a highly active geomorphic riverine subcatchment of the Johnsbach River with intermittent discharge and braided river structures. The high sediment yield entails both issues and opportunities. For decades, the riverbed was exploited as a gravel pit. Today, as part of the Gesäuse National Park and after renaturation, the sediment yield endangers a locally important bridge located at the outlet of the subcatchment. High-resolution geospatial investigations are vital for the quantification of sediment redistribution, which is relevant in terms of river management. Based on unmanned aerial system (UAS) surveys in 2015 (July, September, and October) and 2019 (August and October), high-resolution digital elevation models (DEMs) were generated, which enable us to quantify intra- and multiannual sediment changes. As surface runoff at the subcatchment occurs on only a few days per year with flash floods and debris flows that are not predictable and thus hardly observable, the subsurface water conditions were assessed based on electrical resistivity tomography (ERT) measurements, which were conducted in 2019 (November) and 2020 (May, June). Results of the UAS-based surveys showed that, considering the data quality, intra-annual sediment changes affected only small subareas, whereas multiannual changes occurred in the entire study area and amount to net sediment deposition of ≈0.3–0.4 m3m−2, depending on the channel section. In addition, the elevation differences for both intra-annual surveys revealed linear patterns that can be interpreted as braided river channels. As in both survey periods the same areas were affected by changes, it can be concluded that the channel mainly affected by reshaping persisted within the 4-year observation period. The subsurface investigations showed that although both near-surface and groundwater conditions changed, near-surface sediments are mostly dry with a thickness of several meters during the observations.

Field Observations of Cyclical Pipe-Soil Interactions in Permafrost Terrain, KP 5, Norman Wells Pipeline, Canada

2000 ◽  
Author(s):  
Margo M. Burgess ◽  
Scott Wilkie ◽  
Rick Doblanko ◽  
Ibrahim Konuk
Keyword(s):  
Small Diameter ◽  
Ground Surface ◽  
Thermal Conditions ◽  
Field Work ◽  
Low Density ◽  
Freezing And Thawing ◽  
Near Surface ◽  
Oil Pipeline ◽  
Right Of Way ◽  
Discontinuous Permafrost

The Norman Wells pipeline is an 869 km long, small diameter, buried, ambient temperature, oil pipeline operated by Enbridge Pipeline (NW) Inc. in the discontinuous permafrost zone of northwestern Canada. Since operation began in 1985, average oil temperatures entering the line have been maintained slightly below 0°C, initially through constant chilling year round and since 1993 through a seasonal cycling of temperatures through a range from −4 to +9°C. At one location, 5 km from the inlet at Norman Wells, on level terrain in an area of widespread permafrost, uplift of a 20 m segment of line was observed in the early 1990s. The uplift gradually increased and by 1997 the pipe was exposed 0.5 m above the ground surface. Detailed studies at the site have included field investigations of terrain and thermal conditions, repeated pipe and ground surface elevation surveys, and annual Geopig surveys. The field work has revealed that the section of line was buried in low density soils, thawed to depths of 4 m on-right-of-way, and not subjected to complete refreezing in winter. The thaw depths are related to surface or near-surface flows from a nearby natural spring, as well as to the development of a thaw bulb around the pipe in the cleared right-of-way. Icings indicative of perennial water flow occur commonly at this location in the winter. The pipe experienced annual cycles of heave and settlement (on the order of 0.5 m) due to seasonal freezing and thawing within the surrounding low density soils. The pipe reached its highest elevation at the end of each winter freezing season, and its lowest elevation at the end of the summer thaw period. Superimposed on this heave/settlement cycle was an additional step-like cycle of increasing pipe strain related to thermal expansion and contraction of the pipe. A remedial program was initiated in the winter of 1997–98 in order to curtail the cumulative uplift of the pipe, reduce the increasing maximum annual pipe strain and ensure pipe safety. A 0.5 m cover of sandbags and coarse rock was placed over the exposed pipe segment. Continued pipe elevation monitoring and annual Geopig surveys have indicated that both seasonal heave/settlement and strains have been reduced subsequent to the remedial loading. Introduction of a gravel berm has also altered both the surrounding hydrologic and ground thermal regimes.

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