Roger Wheate

Glacier mapping of the Illecillewaet icefield, British Columbia, Canada, using Landsat TM and digital elevation data

Glacier inventory is important to provide estimates of freshwater storage and as an indicator of climate variability. The methodology for glacier inventory in Canada has been based on manual interpretation of aerial photographs. Digital methods using Landsat Thematic Mapper (TM) satellite imagery and terrain models offer improved efficiency and repeatability, while retaining sufficient accuracy and precision. Supervised maximium likelihood classification trials using different input bands were assessed for accuracy of mapping glacier extent and discriminating glacier zones at Illecillewaet Icefield, Glacier National Park, British Columbia. Results were compared with visual image interpretation, with the best results obtained using the combination of principal components two, three and four of the masked glacier area, the ratio TM-4/TM-5, and the Normalized Difference Snow Index (NDSI). This method avoids problems with sensor saturation, shadowed areas, and discriminates debris mantled ice and icemarginal ...

Glacier Water Resources on the Eastern Slopes of the Canadian Rocky Mountains

Maps of glacier area in western Canada have recently been generated for 1985 and 2005 (Bolch et al., 2010), providing the first complete inventory of glacier cover in Alberta and British Columbia. Western Canada lost about 11% of its glacier area over this period, with area loss exceeding 20% on the eastern slopes of the Canadian Rockies. Glacier area is difficult to relate to glacier volume, which is the attribute of relevance to water resources and global sea level rise. We apply several possible volume-area scaling relations and glacier slope-thickness relations to estimate the volume of glacier ice in the headwater regions of rivers that spring from the eastern slopes of the Canadian Rocky Mountains, arriving at an estimate of 55 ± 15 km3. We cannot preclude higher values, because the available data indicate that large valley glaciers in the Rocky Mountains may be anomalously thick relative to what is typical in the global database that forms the basis for empirical volume-area scaling relations. Incorporating multivariate statistical analysis using observed mass balance data from Peyto Glacier, Alberta and synoptic meteorological conditions in the Canadian Rockies (1966–2007), we model future glacier mass balance scenarios on the eastern slopes of the Rockies. We simulate future volume changes for the glaciers of the Rockies by using these mass balance scenarios in conjunction with a regional ice dynamics model. These projections indicate that glaciers on the eastern slopes will lose 80–90% of their volume by 2100. Glacier contributions to streamflow in Alberta decline from 1.1 km3 a−1 in the early 2000s to 0.1 km3 a−1 by the end of this century.

Radiometric correction techniques and accuracy assessment for Landsat TM data in remote forested regions

Subtle change detection analysis in remote sensing relies on some form of radiometric consistency. Radiometric correction techniques developed in previous studies often require ancillary information such as climate data, illumination geometry, ground reference data of pseudo-invariant features (PIFs), and satellite calibration data. Most studies do not have the luxury of all these data. A relative radiometric correction technique of consistent quality applicable to study areas that lack urban development has not been generally accepted by the remote sensing community. A series of Landsat-5 thematic mapper (TM) and Landsat-7 enhanced thematic mapper plus (ETM+) images spanning 18 years was obtained for a primarily forested area in central British Columbia, Canada. Different techniques of radiometric correction that do not rely on ground reference data, climate data, or the subjective selection of PIFs were assessed for these images. They included an atmospheric transfer model that requires no ancillary climate data, a simple scaling function, and two scatterplot-based regression functions. Assessment of radiometric consistency was performed qualitatively by using edge detection and quantitatively using analysis of old-growth forests in equilibrium and measures of biomass accumulation in clearcuts. For these three methods of assessment, the two scatterplot-based regression functions yielded the best radiometric fidelity. These two techniques can be completely automated and are equally applicable in any Landsat TM- or ETM-based change detection studies.

An inventory and morphometric analysis of British Columbia glaciers, Canada

We describe an automated method to generate an inventory of glaciers and glacier morphometry from a digital topographic database containing glacier boundaries and a digital elevation model for British Columbia, Canada. The inventory contains over 12 000 glaciers with a total cumulative area that exceeds 25 000 km 2 , based on mapping from aerial photographs circa the mid-1980s. We use the inventory to examine dimensional characteristics among glaciers, namely the scaling relations between glacier length, width and area. Glacier length is a good predictor of glacier area, and its predictive ability improves when glaciers are stratified by the number of up-valley accumulation basins. The spatial pattern of glacier mid-range altitude parallels glaciation limits previously mapped for British Columbia and similarly reflects large-scale controls of orographic precipitation and continentality. The inventory is also used to refine models that relate glacier mid-range and terminus altitudes to regional position, aspect and, in the case of terminus altitudes, an index of glacier shape. Relations between glacier altitude limits and controlling spatial and topographic factors are used to make further climatic and mass-balance inferences from the glacier inventory.

Characterizing woodland caribou habitat in sub-boreal and boreal forests

Woodland caribou (Rangifer tarandus caribou) are sensitive to changes in understory vegetation resulting from forest harvesting and are, therefore, of special concern for foresters and habitat biologists. Effective management of this species requires reliable habitat inventories which, because of the large heterogeneous areas over which caribou range, can be costly. We used Landsat Thematic Mapper (TM) imagery and digital elevation data to identify 23 vegetative cover types across the 5100 km 2 range of the Wolverine caribou herd of northcentral British Columbia, Canada. The classification was augmented with available geographical information system (GIS) data for a total of 27 cover types. We achieved an overall accuracy of 76.7% based on known ground samples; however, accuracy varied according to cover type. Considering the size of the study area, the procedure we employed was relatively cost effective and efficient. We discuss the advantages of such an approach for wildlifehabitat studies reliant on large-scale vegetation maps. # 2002 Elsevier Science B.V. All rights reserved.

Glacier change in the Cariboo Mountains, British Columbia, Canada (1952–2005)

We applied photogrammetric methods with aerial photography from 11 different years between 1946 and 2005 to assess changes in area and volume of 33 glaciers in the Cariboo Mountains of British Columbia for the latter half of the 20th century. These are used to identify changes in extent and elevation primarily for the periods 1952–1985, 1985– 2005, and 1952–2005. All glaciers receded during the period 1952–2005; area retreat averaged −0.19± 0.05 % a. From 1952 to 1985, nine glaciers advanced; following 1985, retreat rates accelerated to −0.41± 0.12 % a. Thinning rates of a subset of seven glaciers likewise accelerated, from −0.14± 0.04 m w.e. a (1952–1985) to −0.50± 0.07 m w.e. a for the period 1985–2005. Temperatures increased from the earlier to the latter period for the ablation (+0.38 C) and accumulation (+0.87 C) seasons, and average precipitation decreased, particularly in the accumulation season (−32 mm, −3.2 %). Our comparison of surface area change with glacier morphometry corroborates previous studies that show primary relations between extent change and surface area. We also find that the strength and sign of these relations varied for different epochs. Our results also indicate that the 1985 glacier extent for the study area reported previously by other studies may be slightly overestimated due to errant mapping of late-lying snow cover.

Quality in the GLIMS Glacier Database

Global Land Ice Measurements from Space (GLIMS) is an international initiative to map the world’s glaciers and to build a geospatial database of glacier vector outlines that is usable via the World Wide Web. The GLIMS initiative includes glaciologists at 82 institutions, organized into 27 Regional Centers (RCs), who analyze satellite imagery to map glaciers in their regions of expertise. The results are collected at the U.S. National Snow and Ice Data Center (NSIDC) and ingested into the GLIMS Glacier Database. A concern for users of the database is data quality. The process of classifying multispectral satellite data to extract vector outlines of glaciers has been automated to some degree, but there remain stages requiring human interpretation. To quantify the repeatability and precision of data provided by different RCs, we designed a method of comparative image analysis whereby analysts at the RCs and NSIDC could derive glacier outlines from the same set of images, chosen to contain a variety of glacier types. We carried out four such experiments. The results were compiled, compared, and analyzed to quantify inter-RC analysis consistency. These comparisons have improved RC ability to produce consistent data, and in addition show that in the lower reaches of a glacier, precision of glacier outlines is typically 3 to 4 pixels. Variability in the accumulation area and over parts of the glacier that are debris covered tends to be higher. The ingest process includes quality control steps that must be passed before data are accepted into the database. These steps ensure that ingested data are well georeferenced and internally consistent. The GLACE experiments and ingest time quality control steps have led to improved quality and consistency of GLIMS data. This chapter presents the GLACE experiments and the quality control steps incorporated in the data ingest process. More recent similar studies are referenced.

Remote Sensing of Glaciers in the Canadian Cordillera, Western Canada

We review the use of spaceborne imagery and digital elevation models (DEMs) to evaluate glacier thinning and retreat in the Canadian Cordillera, an area that includes the provinces of British Columbia (BC), Alberta, and Yukon Territory. Glaciers in Alberta and British Columbia lost 11.1 ± 3.8 % of their area over the period 1985–2005, which represents an approximate annual shrinkage rate of 0.55 %. For the period 1985–1999 the average thinning rate of sampled glaciers was 0.78 ± 0.19 m/year water equivalent (w.e.), which equates to an annual volume loss of 22.48 ± 5.53 km3. Mean annual ice loss in the Yukon between 1977 and 2007 was 5.5 ± 1.7 km3/year, while the average mass balance for Yukon glaciers over this period was −0.45 ± 0.09 m/year. We also summarize changes in glacier extents and surface elevation from 1965 to 2005, and include examples of surging glaciers in the Yukon and glacier hazards in British Columbia.

ASTER and DEM Change Assessment of Glaciers Near Hoodoo Mountain, British Columbia, Canada

Hoodoo Mountain ice cap, Hoodoo Glacier, and Twin Glacier are located about 250 km southeast of Juneau, Alaska, in the Coast Mountains (near 56.8°N, 131.3°W, northwestern British Columbia). Several outlet valley glaciers flow towards the south from an ice cap centered approximately 16 km northeast of Hoodoo Mountain; some glaciers are relatively clean ice, while others are heavily debris covered. Hoodoo and Twin glaciers have a Pleistocene and Early Holocene record of interaction with a trachyte volcano, Hoodoo Mountain (which is still ice capped), though they have retreated far enough that future eruptions are unlikely to produce direct lava–ice interactions from anything other than long-lived lava flows. Our analysis shows retreat and accelerating thinning for valley glaciers within this study; this behavior appears to be climatically driven. However, the small ice cap on Hoodoo Mountain seems to be insensitive to climate change; rather, the ice cap’s extent is controlled mainly by the shape and elevation of the landform. The overall average mass balance of the combined set of glaciers in the study region was about −840 ± 180 kg m−2 yr−1 for the period from 1965 to 2005, though different glaciers have specific mass balances ranging from near zero (i.e., in local balance) to −2,400 kg m−2 yr−1. Furthermore, the documented increase in the rate of thinning indicates an increasing magnitude of negative balances over the four decades of the study period. Aside from the Hoodoo Mountain ice cap (which is close to a balance state, except at the very edges on the cliffs, where retreat and thinning have taken place), the prevalent glacier thinning and retreat of the Hoodoo Mountain area is similar to most other maritime parts of the Canadian Cordillera (see Chapter 14 of this book by Wheate et al.). Hoodoo Mountain is a classic flat-topped glaciovolcanic edifice (tuya), and was shaped when ice was much thicker within the massive Cordilleran Ice Sheet. Continuing glacial retreat from the flanks of Hoodoo Mountain offers new possibilities for the study of fresh exposures of materials formed by ice interactions with a rare lava type.

Long-Term Geomorphic History of Georgia

This chapter discusses the location of Georgia, its orographic units, geological and geomorphological structure, zones and zoning. The Proterozoic, Paleozoic, Mesozoic, and Cenozoic sediments; Jurassic and Cretaceous formations; Palaeogenic, Oligocene and Miocene sediments; Pliocene and Quaternary formations (Pleistocene and Holocene) are described. The three main geomorphological zones such as the Greater Caucasus, Georgia’s intermountain plain, and Southern highland of Georgia are described. Within Georgia, the Neogene and Quaternary volcanisms (Late Miocene–Early Pliocene, Late Pliocene–Early Pleistocene, Middle and Late Pleistocene, and Holocene) are characterized. We do not provide the description of the Late Pleistocene glaciation of the Georgian Caucasus in this chapter, because a separate monograph directly about the glaciers of Georgia has been published.