The Brazeau Lake slide, Jasper National Park, Alberta

1982 ◽  
Vol 19 (5) ◽  
pp. 975-981 ◽  
Author(s):  
D. M. Cruden

An historic major rockslide has diverted John-John Creek northwards to its present channel flowing into Brazeau Lake in the Main Ranges of the Rockies in Jasper National Park, Alberta.The slide debris moved northeastwards from cliffs on the northeastern face of "Molard Mountain," an unnamed peak northeast of Flat Ridge in the Grand Brazeau. It reached the shores of Brazeau Lake.The debris occupies a plan area of 0.9 km2 with an average width of 500 m. An estimated average debris thickness of 5 m gives a volume of the displaced mass of 4.5 × 106 m3. The angle from the slide crown to the tip of the debris is about 18°. An approximate reconstruction of the depletion and accumulation of the slide suggests 23° as a lower bound for the angle of friction of the slide debris.The exposed rupture surface of the slide, a bedding plane in the lower portion of the Middle Cambrian Pika Formation, dips at 27° to the northeast. Dolostones, limestones, and shales from the Pika Formation form the slide debris. The slide site is in a panorama photographed in 1928. The slide shows on aerial photographs taken in 1951. A secondhand account of the slide places its occurrence in early July 1933. So the Brazeau Lake slide is the second major rockslide to occur in the Canadian Rockies this century and the first that is undoubtedly a natural event.

2002 ◽  
Vol 32 (11) ◽  
pp. 2010-2021 ◽  
Author(s):  
Jeanine M Rhemtulla ◽  
Ronald J Hall ◽  
Eric S Higgs ◽  
S Ellen Macdonald

Repeat ground photographs (taken in 1915 and 1997) from a series of topographical survey stations and repeat aerial photographs (flown in 1949 and 1991) were analysed to assess changes in vegetation composition and distribution in the montane ecoregion of Jasper National Park, in the Rocky Mountains of Alberta, Canada. A quantitative approach for assessing relative vegetation change in repeat ground photographs was developed and tested. The results indicated a shift towards late-successional vegetation types and an increase in crown closure in coniferous stands. Grasslands, shrub, juvenile forest, and open forests decreased in extent, and closed-canopy forests became more prevalent. The majority of forest stands succeeded to dominance by coniferous species. Changes in vegetation patterns were likely largely attributable to shifts in the fire regime over the last century, although climatic conditions and human activity may also have been contributing factors. Implications of observed changes include decreased habitat diversity, increased possibility of insect outbreaks, and potential for future high-intensity fire events. Results of the study increase knowledge of historical reference conditions and may help to establish restoration goals for the montane ecoregion of the park.


1996 ◽  
pp. 64-67 ◽  
Author(s):  
Nguen Nghia Thin ◽  
Nguen Ba Thu ◽  
Tran Van Thuy

The tropical seasonal rainy evergreen broad-leaved forest vegetation of the Cucphoung National Park has been classified and the distribution of plant communities has been shown on the map using the relations of vegetation to geology, geomorphology and pedology. The method of vegetation mapping includes: 1) the identifying of vegetation types in the remote-sensed materials (aerial photographs and satellite images); 2) field work to compile the interpretation keys and to characterize all the communities of a study area; 3) compilation of the final vegetation map using the combined information. In the classification presented a number of different level vegetation units have been identified: formation classes (3), formation sub-classes (3), formation groups (3), formations (4), subformations (10) and communities (19). Communities have been taken as mapping units. So in the vegetation map of the National Park 19 vegetation categories has been shown altogether, among them 13 are natural primary communities, and 6 are the secondary, anthropogenic ones. The secondary succession goes through 3 main stages: grassland herbaceous xerophytic vegetation, xerophytic scrub, dense forest.


Author(s):  
Ryo Sakamoto ◽  
Ryo Sakamoto ◽  
Satoquo Seino ◽  
Satoquo Seino ◽  
Hirokazu Suzaki ◽  
...  

A construction of breakwaters and other shoreline structures on part of a coast influences drift sand transport in the bay, and causes comprehensive topographic changes on the beach. This study investigated shoreline and coastal changes, taking as an example of Shiraragahama Beach in Miiraku on the northwestern end of Fukue Island, Nagasaki Prefecture (Kyushu, Japan). Miiraku, adjacent to Saikai National Park, appears in the revered 8th century poetry collection “Manyoshu” and served as a port for a ship taken by the Japanese envoy to China during the Tang Dynasty (618-709). Because of the recent development of breakwaters for a fishing harbor, the shore environments of this beach have changed significantly. In this study, the status of silt deposits and topographic changes on this beach arising from the construction of a harbor breakwater were evaluated by comparing aerial photographs taken in different years. Next, the changes in the shoreline visible from aerial photographs from 1947 to 2014 were analyzed. Lastly, the altitude of the beaches was measured using accurate survey methods. The following results were obtained: 1) coastal erosion made rock cliffs to fall off along the shore and deposited sand on this beach; 2) the more serious advances or retreats of the shoreline took place around shoreline structures; 3) sandbars and beach cliffs were formed.


2019 ◽  
Vol 8 (1) ◽  
Author(s):  
Kiros Tsegay Deribew

AbstractThe main grassland plain of Nech Sar National Park (NSNP) is a federally managed protected area in Ethiopia designated to protect endemic and endangered species. However, like other national parks in Ethiopia, the park has experienced significant land cover change over the past few decades. Indeed, the livelihoods of local populations in such developing countries are entirely dependent upon natural resources and, as a result, both direct and indirect anthropogenic pressures have been placed on natural parks. While previous research has looked at land cover change in the region, these studies have not been spatially explicit and, as a result, knowledge gaps in identifying systematic transitions continue to exist. This study seeks to quantify the spatial extent and land cover change trends in NSNP, identify the strong signal transitions, and identify and quantify the location of determinants of change. To this end, the author classifies panchromatic aerial photographs in 1986, multispectral SPOT imagery in 2005, and Sentinel imagery in 2019. The spatial extent and trends of land cover change analysis between these time periods were conducted. The strong signal transitions were systematically identified and quantified. Then, the basic driving forces of the change were identified. The locations of these transitions were also identified and quantified using the spatially explicit statistical model. The analysis revealed that over the past three decades (1986–2019), nearly 52% of the study area experienced clear landscape change, out of which the net change and swap change attributed to 39% and 13%, respectively. The conversion of woody vegetation to grassland (~ 5%), subsequently grassland-to-open-overgrazed land (28.26%), and restoration of woody vegetation (0.76%) and grassland (0.72%) from riverine forest and open-overgrazed land, respectively, were found to be the fully systematic transitions whereas the rest transitions were recorded either partly systematic or random transitions. The location of these most systematic land cover transitions identified through the spatially explicit statistical modeling showed drivers due to biophysical conditions, accessibility, and urban/market expansions, coupled with successive government policies for biodiversity management, geo-politics, demographic, and socioeconomic factors. These findings provide important insights into biodiversity loss, land degradation, and ecosystem disruption. Therefore, the model for predicted probability generally suggests a 0.75 km and 0.72 km buffers which are likely to protect forest and grassland from conversion to grassland and open-overgrazed land, respectively.


1986 ◽  
Vol 23 (6) ◽  
pp. 804-812 ◽  
Author(s):  
A. B. Beaudoin ◽  
R. H. King

The magnetite composition from three sets of samples of Mazama, St. Helens set Y, and Bridge River tephras from Jasper and Banff national parks are used to test whether discriminant function analysis can unambiguously distinguish these tephras. The multivariate method is found to be very sensitive to the change in reference samples. St. Helens set Y tephra is clearly distinguished. However, discrimination between Mazama and Bridge River tephras is less distinct. A set of unknown tephras from the Sunwapta Pass area was used to test the classification schemes. Unknown tephras are assigned to different tephra types depending on which reference tephra set is used in the discriminant function analysis.


Koedoe ◽  
1995 ◽  
Vol 38 (2) ◽  
Author(s):  
A.J. Viljoen

All observations and data related to the impact of the 1991/92 drought on the woody vegetation, excluding the riverine vegetation of major rivers, are summarised. This includes data from a visual estimate of damage from aerial photographs, surveys on selected sites, and general observations. Despite lower rainfall, the area north of the Olifants River (excluding the far-northern part) was less affected than the area south of it, suggesting that the woody vegetation in the north is more adapted to drought. A characteristic of the drought was the localised distribution pattern and variable intensity of damage to the same species in the same general area. Information on 31 species are presented briefly. Although a large number of woody species was to some extent damaged, when the woody vegetation is considered as a whole, the influence of the drought was not very severe.


2010 ◽  
Vol 47 (3) ◽  
pp. 273-290 ◽  
Author(s):  
Sojan Mathew ◽  
Robin G.D. Davidson-Arnott ◽  
Jeff Ollerhead

Greenwich Dunes, Prince Edward Island National Park, is a sandy mainland and barrier spit beach–dune complex stretching for about 10 km along the northeast shore of Prince Edward Island, Canada. In October 1923, surge associated with an intense storm produced catastrophic overwash along the whole length of the study area. Subsequent evolution of the system was quantified from historic aerial photographs taken in 1936, 1953, 1971, 1997, and 2005. Orthophoto mosaics were generated for each photo set using PCI Geomatica OrthoEngine, a digital photogrammetric software. Linear changes in shoreline position and areal changes in geomorphic units were evaluated for each photo set. In addition, digital elevation models (DEMs) were extracted from the 1953, 1971, and 1997 aerial photos, enabling analysis of topographic and volumetric changes. The 1936 photos show complete destruction of all foredunes, with overwash and transgressive dunes extending 300 to 600 m inland. A descriptive model of the stages of evolution of the system is proposed based on the processes controlling overwash healing and dune stabilization. Detailed topographic and volumetric changes associated with the development of an extensive transgressive dunefield and subsequent stabilization as a result of reduced sand supply due to the growth of a new vegetated foredune complex and vegetation colonization are doccumented for each stage. It was nearly 40 years before a continuous foredune system was re-established and a further 30 years before the inland transgressive dunes became completely stabilized.


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