Quantifying errors in discontinuous permafrost plateau change from optical data, Northwest Territories, Canada: 1947–2008

Chasmer, L.; Hopkinson, C.; Quinton, William L.

doi:10.5589/m10-058

Cited by 28 publications

(32 citation statements)

References 24 publications

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“…Two bog cascades (east and west) and their sub‐catchments were initially identified from remotely sensed imagery (WorldView2) and a digital elevation model (DEM) derived from LiDAR imagery (Chasmer et al ., ). The catchments were then ground‐truthed by inserting a steel rod into the ground until refusal along the perimeter of each bog cascade to ensure the presence of permafrost.…”

Section: Methodsmentioning

confidence: 99%

The hydrology of interconnected bog complexes in discontinuous permafrost terrains

Connon

Quinton

Craig

et al. 2015

Hydrological Processes

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In the zone of discontinuous permafrost, the cycling and storage of water within and between wetlands is poorly understood. The presence of intermittent permafrost bodies tends to impede and re‐direct the flow of water. In this region, the landscape is characterized by forested peat plateaus that are underlain by permafrost and are interspersed by permafrost‐free wetlands. These include channel fens which convey water to the basin outlet through wide, hydraulically rough channels and flat bogs which are typically thought to retain moisture inputs as storage. Field studies conducted at a peatland‐dominated landscape near Fort Simpson, Northwest Territories, Canada, indicate the presence of ephemeral drainage channels that form a cascade of connected bogs that ultimately discharges into a channel fen. Consequently, understanding bogs as dynamic transmitters of surface and subsurface flows, rather than simple storage regions, calls for further examination. Whether bogs act as either storage features or flow through features has a direct impact on the runoff contributing area in a basin. Here, two adjacent series of bog cascades were gauged over two consecutive years to determine spatial and temporal changes in effective runoff contributing areas. It was found that runoff varies significantly between two adjacent bog cascades with one cascade producing 125 mm of runoff over the 2‐year period, while the other yielded only 25 mm. The bog cascades are primarily active during the snowmelt season when moisture conditions are high; however flows can also be generated in response to large rain events. It is proposed that bog cascades operate under an ‘element threshold concept’ whereby in order for water to be transmitted through a bog, the depression storage capacity of that bog must first be satisfied. Our work indicates that whether bogs act as storage features or flow‐through features has a direct impact on the runoff contributing area in a basin. Neglecting to represent connected bogs as dynamic transmission features in the landscape is shown to underestimate water available for streamflow by between 5 and 15%, and these systems are therefore a key component of the water balance in discontinuous permafrost regions. Copyright © 2015 John Wiley & Sons, Ltd.

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Section: Methodsmentioning

confidence: 99%

The hydrology of interconnected bog complexes in discontinuous permafrost terrains

Connon

Quinton

Craig

et al. 2015

Hydrological Processes

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“…The most dramatic change has been observed at Scotty Creek in the Taiga Plains near Fort Simpson, NT, where degradation in permafrost has resulted in decreasing and fragmented forest cover (Baltzer et al, 2014) and increasing wetland coverage and connectivity and drainage efficiency (Quinton et al, 2011;Connon et al, 2014). From 1947 to 2008, permafrost coverage declined at the site from 70 to 43 % (Chasmer et al, 2010) and wetland permafrost-free areas expanded and coalesced. Connon et al (2014) showed that increases in flows observed in the region were not a result of reactivation of subsurface flow pathways from permafrost thaw but from an increased connectivity of surface pathways and, to a lesser extent, from increases in overall precipitation.…”

Section: Insights On Change From the Wecc Observatoriesmentioning

confidence: 98%

Recent climatic, cryospheric, and hydrological changes over the interior of western Canada: a review and synthesis

DeBeer

Wheater

Carey

et al. 2016

Hydrol. Earth Syst. Sci.

101

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Abstract. It is well established that the Earth's climate system has warmed significantly over the past several decades, and in association there have been widespread changes in various other Earth system components. This has been especially prevalent in the cold regions of the northern midto high latitudes. Examples of these changes can be found within the western and northern interior of Canada, a region that exemplifies the scientific and societal issues faced in many other similar parts of the world, and where impacts have global-scale consequences. This region has been the geographic focus of a large amount of previous research on changing climatic, cryospheric, and hydrological regimes in recent decades, while current initiatives such as the Changing Cold Regions Network (CCRN) introduced in this review seek to further develop the understanding and diagnosis of this change and hence improve the capacity to predict future change. This paper provides a comprehensive review of the observed changes in various Earth system components and a concise and up-to-date regional picture of some of the temporal trends over the interior of western Canada since the mid-or late 20th century. The focus is on air temperature, precipitation, seasonal snow cover, mountain glaciers, permafrost, freshwater ice cover, and river discharge. Important long-term observational networks and data sets are described, and qualitative linkages among the changing components are highlighted. Increases in air temperature are the most notable changes within the domain, rising on average 2 • C throughout the western interior since 1950. This increase in air temperature is associated with hydrologically important changes to precipitation regimes and unambiguous declines in snow cover depth, persistence, and spatial extent. Consequences of warming air temperatures have caused mountain glaciers to recede at all latitudes, permafrost to thaw at its southern limit, and active layers over permafrost to thicken. Despite these changes, integrated effects on stream flow are complex and often offsetting. Following a review of the current literature, we provide insight from a network of northern research catchments and other sites detailing how climate change confounds hydrological responses at smaller scales, and we recommend several priority research areas that will be a focus of continued work in CCRN. Given the complex interactions and process responses to climate change, it is argued that further conceptual understanding and quantitative diagnosis of the mechanisms of change over a range of scales is required before projections of future change can be made with confidence.

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“…The flux footprints were combined with a land cover classification map , as described by Helbig et al (2016b), to derive sums of half-hourly probabilities of flux contributions for individual land cover types (i.e., flux footprint contributions from forests and wetlands; Fig. Additionally, transition zones were delineated based on aerial photographs as areas of wetland expansion (and thus of forest loss) since 1977 (see Chasmer et al, 2010). Additionally, transition zones were delineated based on aerial photographs as areas of wetland expansion (and thus of forest loss) since 1977 (see Chasmer et al, 2010).…”

Section: Eddy Covariance Measurementsmentioning

confidence: 99%

Direct and indirect climate change effects on carbon dioxide fluxes in a thawing boreal forest–wetland landscape

Helbig

Chasmer

Desai

et al. 2017

Global Change Biology

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In the sporadic permafrost zone of northwestern Canada, boreal forest carbon dioxide (CO ) fluxes will be altered directly by climate change through changing meteorological forcing and indirectly through changes in landscape functioning associated with thaw-induced collapse-scar bog ('wetland') expansion. However, their combined effect on landscape-scale net ecosystem CO exchange (NEE ), resulting from changing gross primary productivity (GPP) and ecosystem respiration (ER), remains unknown. Here, we quantify indirect land cover change impacts on NEE and direct climate change impacts on modeled temperature- and light-limited NEE of a boreal forest-wetland landscape. Using nested eddy covariance flux towers, we find both GPP and ER to be larger at the landscape compared to the wetland level. However, annual NEE (-20 g C m ) and wetland NEE (-24 g C m ) were similar, suggesting negligible wetland expansion effects on NEE . In contrast, we find non-negligible direct climate change impacts when modeling NEE using projected air temperature and incoming shortwave radiation. At the end of the 21st century, modeled GPP mainly increases in spring and fall due to reduced temperature limitation, but becomes more frequently light-limited in fall. In a warmer climate, ER increases year-round in the absence of moisture stress resulting in net CO uptake increases in the shoulder seasons and decreases during the summer. Annually, landscape net CO uptake is projected to decline by 25 ± 14 g C m for a moderate and 103 ± 38 g C m for a high warming scenario, potentially reversing recently observed positive net CO uptake trends across the boreal biome. Thus, even without moisture stress, net CO uptake of boreal forest-wetland landscapes may decline, and ultimately, these landscapes may turn into net CO sources under continued anthropogenic CO emissions. We conclude that NEE changes are more likely to be driven by direct climate change rather than by indirect land cover change impacts.

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Quantifying errors in discontinuous permafrost plateau change from optical data, Northwest Territories, Canada: 1947–2008

Cited by 28 publications

References 24 publications

The hydrology of interconnected bog complexes in discontinuous permafrost terrains

The hydrology of interconnected bog complexes in discontinuous permafrost terrains

Recent climatic, cryospheric, and hydrological changes over the interior of western Canada: a review and synthesis

Direct and indirect climate change effects on carbon dioxide fluxes in a thawing boreal forest–wetland landscape

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