A method for determining the frequency of large-magnitude earthquakes using lake sediments

1986 ◽  
Vol 23 (7) ◽  
pp. 930-937 ◽  
Author(s):  
Ronald Doig
Keyword(s):  
Lake Sediments ◽  
Quebec City ◽  
Sedimentation Rates ◽  
Historical Records ◽  
Chemical Analyses ◽  
Large Magnitude ◽  
Eastern Canada ◽  
Deep Layers ◽  
Prehistoric Earthquakes ◽  
St Lawrence River

Eastern Canada has experienced at least five earthquakes of estimated Richter magnitude 6 or greater during the last 350 years. The epicentres are usually under the St. Lawrence River, some 100 km east of Quebec City. Historical records of the earthquake of 1663, possibly the largest of these events, describe high levels of silting in streams for up to several months. A silt horizon in normally organic-rich lake sediments has been found in lakes with separate drainage systems and is interpreted as the 1663 event on the basis of rough sedimentation rates obtained from observation of 137Cs fallout of the 1950's and the effects of a dam on one of the lakes. Two other silt layers correspond reasonably well to the next largest earthquakes of 1791 and 1860 + 1870 (combined). Two deep layers were found that by extrapolation of the assumed 1663 layer yield dates of about A.D. 1060 and 600 and are believed to represent prehistoric earthquakes, though possibly not as large as that in 1663. Chemical analyses of the cores show that organic material, Ti, and especially K are very useful for identifying these layers and others that are not visible in the cores.

Observational Study of Wind Channeling within the St. Lawrence River Valley

2009 ◽  
Vol 48 (11) ◽  
pp. 2341-2361 ◽  
Author(s):  
Marco L. Carrera ◽  
John R. Gyakum ◽  
Charles A. Lin
Keyword(s):  
Surface Wind ◽  
Hudson River ◽  
Geostrophic Wind ◽  
The United States ◽  
River Valley ◽  
Quebec City ◽  
Surface Winds ◽  
Eastern Canada ◽  
St Lawrence River ◽  
Pressure Driven

Abstract The presence of orography can lead to thermally and dynamically induced mesoscale wind fields. The phenomenon of channeling refers to the tendency for the winds within a valley to blow more or less parallel to the valley axis for a variety of wind directions above ridge height. Channeling of surface winds has been observed in several regions of the world, including the upper Rhine Valley of Germany, the mountainous terrain near Basel, Switzerland, and the Tennessee and Hudson River Valleys in the United States. The St. Lawrence River valley (SLRV) is a primary topographic feature of eastern Canada, extending in a southwest–northeast direction from Lake Ontario, past Montreal (YUL) and Quebec City (YQB), and terminating in the Gulf of St. Lawrence. In this study the authors examine the long-term surface wind climatology of the SLRV and Lake Champlain Valley (LCV) as represented by hourly surface winds at Montreal, Quebec City, and Burlington, Vermont (BTV). Surface wind channeling is found to be prominent at all three locations with strong bidirectionalities that vary seasonally. To assess the importance of the various channeling mechanisms the authors compared the joint frequency distributions of surface wind directions versus 925-hPa geostrophic wind directions with those obtained from conceptual models. At YUL, downward momentum transport is important for geostrophic wind directions ranging from 240° to 340°. Pressure-driven channeling is the dominant mechanism producing northeasterly surface winds at YUL. These northeasterlies are most prominent in the winter, spring, and autumn seasons. At YQB, pressure-driven channeling is the dominant physical mechanism producing channeling of surface winds throughout all seasons. Of particular importance, both YUL and YQB exhibit countercurrents whereby the velocity component of the wind within the valley is opposite to the component above the valley. Forced channeling was found to be prominent at BTV, with evidence of diurnal thermal forcing during the summer season. Reasons for the predominance of pressure-driven channeling at YUL and YQB and forced channeling at BTV are discussed.

Nanofiltration of colored surface water: Quebec's experience

2003 ◽  
Vol 3 (5-6) ◽  
pp. 15-22
Author(s):  
P. Kouadio ◽  
M. Tétrault
Keyword(s):  
Drinking Water ◽  
Surface Water ◽  
Membrane Fouling ◽  
Pilot Scale ◽  
Operating Conditions ◽  
Quebec City ◽  
Water Regulation ◽  
Eastern Canada

Three colored surface water nanofiltration pilot-scale projects were conducted in the province of Quebec (eastern Canada), between November 2000 and March 2002, by the company H2O Innovation (2000) inc., for the municipalities of Lac Bouchette, Latulipe-et-Gaboury and Charlesbourg (now part of Quebec City). Results indicated that nanofiltration permeate quality has an advance on present drinking water regulation standard in Quebec, but important membrane fouling occurred. Fouling can be controlled by pretreatment and optimization of the operating conditions.

Ice Bridges on the St. Lawrence River as an Index of Winter Severity from 1620 to 1910

2007 ◽  
Vol 20 (4) ◽  
pp. 757-764 ◽  
Author(s):  
Daniel Houle ◽  
Jean-David Moore ◽  
Jean Provencher
Keyword(s):  
Positive Impact ◽  
Volcanic Eruptions ◽  
Temperature Reconstruction ◽  
Winter Temperature ◽  
Climate Forcing ◽  
Quebec City ◽  
Temperature Index ◽  
Saint Lawrence River ◽  
St Lawrence River ◽  
Winter Severity

Abstract Temperature reconstruction of the last thousand years suggests that an unprecedented warming (+0.6°C) occurred over the globe in the last century. However, regional variations in climate are not resolved by Northern Hemisphere reconstructions. In northeastern North America, past climate and, particularly, past winter variations are poorly known. Here, the authors report on the variation of a winter temperature index during the 1620–1910 period, based on the ice bridge formation (IBF) rate on the Saint Lawrence River at Québec City (Canada), combined with instrumental data (1876–2000). During this 300-yr period, the IBF rate shows that winters in the seventeenth and eighteenth centuries were warmer than those in the nineteenth century. In particular, the IBF rate suggests that winter severity culminated in the 1850–1900 period, while very few ice bridges were reported between 1620 and 1740, presumably because of warmer temperatures and the relative scarcity of historical documents for the 1680–1740 period. These data suggest that winter temperature, particularly between ∼1800 and 1910, was 2.4° to 4.0°C colder than the last 30-yr average. Major volcanic eruptions had a significant positive impact on IBF rates, which is consistent with their role as important climate-forcing events.

Water at the Outlet of the St. Lawrence River Part I - Sampling and Major Cations

1993 ◽  
Vol 28 (2) ◽  
pp. 415-432
Author(s):  
C. Barbeau ◽  
J.-B. Sérodes ◽  
M. Paquet
Keyword(s):  
Treatment Plant ◽  
Drinking Water Treatment ◽  
Water Treatment Plant ◽  
Daily Basis ◽  
High Flow ◽  
Quebec City ◽  
Water Composition ◽  
Many Sources ◽  
Dissolved Phase ◽  
St Lawrence River

Abstract The St. Lawrence River exports important loads of contaminants to the estuary, but good estimates of annual loadings are presently not available. During two years (1989–91), discrete and composite samples were taken on a daily basis at the water intake of the drinking water treatment plant of Lévis in front of Québec City. Our data indicate that discrete samples are representative of the bulk of the water and that magnesium or calcium measurements provide valuable information on the species transported to the estuary in the dissolved phase. Any decrease in magnesium concentrations at Lévis is the result of relative flow increases from the tributaries of the river. Using high flow episodes in tributaries and daily magnesium measurements at Lévis, the time of transport of the dissolved phase from many sources along the river has been evaluated. At high flow, the time of transport from the Carillon Dam (on the Ottawa River) to Lévis is 11 days, while it is 8 days from Beauharnois. With these data, a predictive model using magnesium (or calcium) as the chemical parameter characterizing the dissolved phase of the St. Lawrence River at the mouth of the estuary was developed. Loadings to the estuary of any dissolved contaminant can now be estimated by combining daily calculated flow values with daily measured water composition at Levis.

Epilithic diatoms of the St. Lawrence River and their relationships to water quality

1998 ◽  
Vol 76 (2) ◽  
pp. 251-257 ◽  
Author(s):  
Euan D Reavie ◽  
John P Smol
Keyword(s):  
Water Quality ◽  
Chlorophyll A ◽  
Suspended Solids ◽  
Fecal Coliforms ◽  
Weighted Averaging ◽  
Quebec City ◽  
Diatom Assemblages ◽  
Epilithic Diatoms ◽  
Epilithic Diatom ◽  
St Lawrence River

Epilithic diatoms were sampled at 48 sites along the St. Lawrence River, from Salaberry de Valleyfield to Québec City, in an attempt to determine how diatom assemblages were related to measured water quality variables. Canonical correspondence analysis was used to explore the relationships between environmental variables and patterns in the epilithic diatom assemblages. "Distance downstream from Cornwall" was determined to be the strongest variable influencing the structure of epilithic diatom assemblages, likely due to the effect of tides (favouring aerophilic species) closer to the river outlet. Variables related to pollution (suspended solids, fecal coliforms, chlorophyll a) also explained significant (P < 0.05) amounts of variance in the diatom assemblages. The optima of common diatom species to suspended solids were explored further. Reconstructive models using weighted-averaging calibration and regression illustrated that "distance from Cornwall" and concentrations of suspended solids, fecal coliforms, and chlorophyll a, the most influential variables, could be inferred from the diatom assemblages. When compared with the inference models developed for pollution variables using epiphytic diatom assemblages (attached to macrophytes or Cladophora), the epilithon model appears to perform better.Key words: diatoms, rocks, epilithic, St. Lawrence River, water quality, calibration.

Distribution, Transport, and Composition of Suspended Matter in the St. Lawrence Estuary

1973 ◽  
Vol 10 (9) ◽  
pp. 1380-1396 ◽  
Author(s):  
Bruno F. d'Anglejan ◽  
Eric C. Smith
Keyword(s):  
Suspended Matter ◽  
Large Time ◽  
Total Suspended Matter ◽  
Quebec City ◽  
Lawrence Estuary ◽  
Tidal Circulation ◽  
Saguenay River ◽  
St Lawrence Estuary ◽  
Vertical Gradients ◽  
St Lawrence River

The distribution of total suspended matter in the estuary of the St. Lawrence River was studied by quantitative filtration through membrane filters. Tidal fluctuations in the vertical gradients of suspensoids were followed at fixed stations along the estuary. The concentrations varied from nearly 40 mg/1 below near Ile d'Orléans, to values less than 1 mg/1 at the downstream end of the upper estuary near the Saguenay River entrance. The tidal mean concentrations for the fixed stations ranged from 20 mg/1 to 2 mg/1. A turbidity maximum, which develops because of entrapments of particles by the tidal circulation, extends for 100 km below Quebec City. In this zone large vertical gradients changing in intensity with the tide by resuspension of settled material exist above the bottom. The total suspended matter is 60% to more than 90% inorganic by weight, and has a mean particle size between 5 and 7 μ. The annual rate of transport of suspended material out of the upper estuary at a section near the Saguenay River is estimated at less than 1 × 106 metric tons.Chemical and mineralogical analyses were performed on 23 suspensoid samples collected by centrifuging large volumes of water. The clay mineral composition of the less than 2 μ fraction is on the average 1.5% montmorillonite, 8% kaolinite, 31% chlorite, and 60% illite. However, large time and space variations are found both in the chemistry and mineralogy of the suspended matter.

Reducing CSOs and giving the river back to the public: innovative combined sewer overflow control and riverbanks restoration of the St Charles River in Quebec City

2011 ◽  
Vol 63 (2) ◽  
pp. 331-338 ◽  
Author(s):  
Olivier Fradet ◽  
Martin Pleau ◽  
Christiane Marcoux
Keyword(s):  
Wastewater Treatment Plants ◽  
Management Strategies ◽  
Quebec City ◽  
The Public ◽  
Combined Sewer ◽  
Water Courses ◽  
Overflow Control ◽  
The City ◽  
Two Sectors ◽  
St Lawrence River

After the construction of its wastewater treatment plants, the City of Quebec began to implement overflow control in wet weather to ultimately meet the effluent discharge objectives, i.e. no more than two overflows per summer season in the St. Lawrence River and no more than four in the St-Charles River. After several years of studies to determine which management strategies would best suit the purpose, and to propose optimum solutions, a first project to implement optimal and predictive management in real time, called « Pilot », came to life in 1999. Construction in phases soon followed and the work was completed in the fall of 2009. As a result, requirements with regard to environmental rejects were met in two sectors, namely the St-Charles River and the Jacques-Cartier Beach, and aquatic recreational activities could resume. Meanwhile, the City also worked at giving back access to the water courses to the public by developing sites at the Jacques-Cartier Beach and in the Bay of Beauport, and by rehabilitating the banks of the St-Charles River.

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