Sediment dynamics and the transport of suspended matter in the upstream area of Lake St. Francis

2000 ◽  
Vol 57 (S1) ◽  
pp. 52-62 ◽  
Author(s):  
Serge Lepage ◽  
Johann Biberhofer ◽  
Stéphane Lorrain
Keyword(s):  
Suspended Matter ◽  
Sediment Resuspension ◽  
Weather Data ◽  
River Waters ◽  
Discharge Rates ◽  
Southern Side ◽  
Northern Side ◽  
South Shore ◽  
Study Sites ◽  
St Lawrence River

A long-term project was initiated in autumn 1994 to monitor the suspended matter (SM) in the upstream area of Lake St. Francis. Over a 32-month period, 190 SM samples were collected at six study sites while conductivity and current velocity measurements were made to study resuspension and transport of SM. Weather data from a nearby station and daily discharge rates for the St. Lawrence River were also utilised. Overall, the study shows that the SM load in the central portion of Lake St. Francis is not evenly distributed. On the northern side of the lake, the SM load is mainly a function of the SM load carried by the St. Lawrence River waters coming from the Great Lakes. On the southern side, an important contribution to the SM load comes from sediment resuspension and from the local tributaries. Calculations show that wave action is likely to resuspend surficial sediments in depths shallower than 2 m, a surface area estimated to be 32-35 km2 between Cornwall Island and Thompson Basin. Also, important fluctuations of the south shore tributaries' winter discharge are thought to contribute to sediment resuspension and redistribution of contaminants such as mercury and polychlorinated biphenyls.

scholarly journals A method for simulating risk profiles of wheat yield in data-sparse conditions

2021 ◽  
pp. 1-12
Author(s):  
G. Bracho-Mujica ◽  
P.T. Hayman ◽  
V.O. Sadras ◽  
B. Ostendorf
Keyword(s):  
Reference Site ◽  
Climate Impacts ◽  
Weather Data ◽  
Climate Data ◽  
High Quality ◽  
Risk Profiles ◽  
Record Length ◽  
Daily Weather Data ◽  
Study Sites

Abstract Process-based crop models are a robust approach to assess climate impacts on crop productivity and long-term viability of cropping systems. However, these models require high-quality climate data that cannot always be met. To overcome this issue, the current research tested a simple method for scaling daily data and extrapolating long-term risk profiles of modelled crop yields. An extreme situation was tested, in which high-quality weather data was only available at one single location (reference site: Snowtown, South Australia, 33.78°S, 138.21°E), and limited weather data was available for 49 study sites within the Australian grain belt (spanning from 26.67 to 38.02°S of latitude, and 115.44 to 151.85°E of longitude). Daily weather data were perturbed with a delta factor calculated as the difference between averaged climate data from the reference site and the study sites. Risk profiles were built using a step-wise combination of adjustments from the most simple (adjusted series of precipitation only) to the most detailed (adjusted series of precipitation, temperatures and solar radiation), and a variable record length (from 10 to 100 years). The simplest adjustment and shortest record length produced bias of modelled yield grain risk profiles between −10 and 10% in 41% of the sites, which increased to 86% of the study sites with the most detailed adjustment and longest record (100 years). Results indicate that the quality of the extrapolation of risk profiles was more sensitive to the number of adjustments applied rather than the record length per se.

CARACTÉRISTIQUES DES SOLS SULFATÉS ACIDES DE LA SÉRIE DE L'ANSE EN MILIEU ESTUARIEN (QUÉBEC)

1988 ◽  
Vol 68 (3) ◽  
pp. 577-592
Author(s):  
C. R. DE KIMPE ◽  
M. R. LAVERDIERE ◽  
R. W. BARIL
Keyword(s):  
Key Words ◽  
Lower Limit ◽  
Marine Sediments ◽  
Acid Sulfate Soils ◽  
Acid Sulfate ◽  
Organic C ◽  
South Shore ◽  
Sulfate Soils ◽  
Sulfate Leaching ◽  
St Lawrence River

Acid sulfate soils were sampled according to the transect method in four bays along the south shore of the St. Lawrence river to determine their properties in their area of distribution. In each bay, six profiles of cultivated soils were sampled along a transect perpendicular to the river. One non-cultivated profile was also sampled at l'Isle-Verte. The lower limit of the B horizons, between 79 and 89 cm, suggested a homogeneous development of these soils across the area. Most profiles contained jarosite in the lower Bg and, sometimes, in the C horizons; this mineral was absent in the upper part of the profiles of soils that had been limed prior to cultivation. Total S content increased with depth, but only a few horizons had a content > 0.75% presumably because of sulfate leaching once the soils were drained. Organic C content in the de l'Anse soils decreased less rapidly with depth than in other gleysolic soils, because vegetation grew while sediments were being deposited. Key words: Acid sulfate soils, total S, recent marine sediments, jarosite

Estimation de la production de jeunes plantations de pin rouge et de pin gris du sud du Québec

1976 ◽  
Vol 6 (4) ◽  
pp. 478-486 ◽  
Author(s):  
H. A. Bolghari
Keyword(s):  
Multiple Regression ◽  
Jack Pine ◽  
Red Pine ◽  
Pine Plantations ◽  
Regression Equations ◽  
Pine Plantation ◽  
South Shore ◽  
Pine Stands ◽  
Natural Stands ◽  
St Lawrence River

Multiple regression equations have been developed to predict yield from young red pine and jack pine plantations. Data from 446 sample plots representing young red pine and jack pine stands located on the south shore of the St. Lawrence River between Quebec and Montreal were analysed. The red pine plantation yielded more than the jack pine. However, in plantation both species yield more than in natural stands. Taking into account the age and spacing of the sampled plantations, the equation obtained can provide information on yield of red pine and jack pine stands the maximum spacing of which is 3 × 3 m, up to the age of 45 and 35 years respectively. The equations will allow the construction of preliminary yield tables for both species.

scholarly journals Sensitivity of a calving glacier to ice–ocean interactions under climate change: new insights from a 3-D full-Stokes model

2019 ◽  
Vol 13 (6) ◽  
pp. 1681-1694 ◽  
Author(s):  
Joe Todd ◽  
Poul Christoffersen ◽  
Thomas Zwinger ◽  
Peter Råback ◽  
Douglas I. Benn
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Greenland Ice Sheet ◽  
Environmental Sensitivity ◽  
Predictive Capacity ◽  
Outlet Glacier ◽  
Iceberg Calving ◽  
Southern Side ◽  
Northern Side ◽  
Global Sea Level

Abstract. Iceberg calving accounts for between 30 % and 60 % of net mass loss from the Greenland Ice Sheet, which has intensified and is now the single largest contributor to global sea level rise in the cryosphere. Changes to calving rates and the dynamics of calving glaciers represent a significant uncertainty in projections of future sea level rise. A growing body of observational evidence suggests that calving glaciers respond rapidly to regional environmental change, but predictive capacity is limited by the lack of suitable models capable of simulating calving mechanisms realistically. Here, we use a 3-D full-Stokes calving model to investigate the environmental sensitivity of Store Glacier, a large outlet glacier in West Greenland. We focus on two environmental processes: undercutting by submarine melting and buttressing by ice mélange, and our results indicate that Store Glacier is likely to be able to withstand moderate warming perturbations in which the former is increased by 50 % and the latter reduced by 50 %. However, severe perturbation with a doubling of submarine melt rates or a complete loss of ice mélange destabilises the calving front in our model runs. Furthermore, our analysis reveals that stress and fracture patterns at Store's terminus are complex and varied, primarily due to the influence of basal topography. Calving style and environmental sensitivity vary greatly, with propagation of surface crevasses significantly influencing iceberg production in the northern side, whereas basal crevasses dominate in the south. Any future retreat is likely to be initiated in the southern side by a combination of increased submarine melt rates in summer and reduced mélange strength in winter. The lateral variability, as well as the importance of rotational and bending forces at the terminus, underlines the importance of using the 3-D full-Stokes stress solution when modelling Greenland's calving glaciers.

Preliminary interpretation of the first refraction arrivals in Gaspé from shots in Labrador and Quebec

1969 ◽  
Vol 6 (4) ◽  
pp. 771-774 ◽  
Author(s):  
Douglas S. Rankin ◽  
Ravi Ravindra ◽  
David Zwicker
Keyword(s):  
Upper Mantle ◽  
Arrival Time ◽  
The South ◽  
North Shore ◽  
The North ◽  
A Value ◽  
South Shore ◽  
Compressional Velocity ◽  
St Lawrence River

Previous work in the Gulf of St. Lawrence has yielded an unusually high upper-mantle compressional velocity. In the Gaspé area a more recent determination has yielded a value of 8.75 ± 0.20 km/s for an unreversed profile. The arrival time at a station on the north shore of the St. Lawrence River suggests that there is no major difference in velocity and depth relative to the south shore.

Observations of circulation and exchange processes in Jervis Bay, New South Wales

1992 ◽  
Vol 43 (6) ◽  
pp. 1487 ◽  
Author(s):  
PE Holloway ◽  
G Symonds ◽  
Vaz R Nunes
Keyword(s):  
New South ◽  
New South Wales ◽  
Additional Mechanism ◽  
Near Surface ◽  
South Wales ◽  
Circulation Current ◽  
Southern Side ◽  
Northern Side ◽  
Wind Currents ◽  
Coastally Trapped Waves

This paper discusses oceanographic observations obtained in and near Jervis Bay, a small coastal embayment of approximately 124 km2 situated on the New South Wales coast, during a series of measurement programmes spanning three years. Various mechanisms that drive water circulation within the bay and water exchange between the bay and the adjacent continental shelf are discussed. Current meter data from within the bay show surprisingly little correlation with the wind. Currents are characterized by persistent flows in one direction for periods of months, and it is suggested that influences from the shelf are responsible for driving the bay circulation. Flow through the bay entrance is weakly correlated with the wind at a period of around eight days, with near-surface inflow on the southern side of the entrance being in phase with deeper outflow on the northern side and vice versa. The shelf waters are well known for their coastally trapped waves. These have the potential to oscillate vertically the density surfaces on the shelf on a time scale of around eight days, and observations indicate that these waves are an additional mechanism driving circulation in the bay. The shelf waters are influenced by the warm East Australia Current and its eddies, and this appears to maintain a density contrast between the bay and the shelf for most of the year, with the shelf waters being less dense, which may be an additional mechanism driving bay circulation. Current-meter data from the bay entrance show a persistent northward current component in contrast to the strong southward flow of the East Australia Current on the shelf. Conductivity-temperature- depth data reveal cold, dense water flowing out of the bay during periods of strong winter cooling and the effects of warm eddies pushing warm water into the bay and displacing cold deeper water away from the bay. The heating/cooling cycle of the bay appears to be influenced by advection processes on the shelf as well as by aidsea heat and radiation exchanges.

Art. XIII.—Grammatical Sketch of the Haúsa Language

1882 ◽  
Vol 14 (2) ◽  
pp. 176-217
Author(s):  
J. F. Schön
Keyword(s):  
The North ◽  
Correct Pronunciation ◽  
Southern Side ◽  
Northern Side

The word consists of three syllables, and must not be tortured into Housa as is frequently done. Ha-ou-sa conveys the correct pronunciation. The meaning of the word itself is not quite certain. From two expressions in the writer's collection it may be inferred that it means ‘language’. The first is, “He speaks another ha-u-sa,”that is, another language; and the second, in answer to the question, “Do many people speak Haúsa?” The reply given was, “How can they be Haúsa unless they speak Ha1sa?” Barth also admits that it means ‘language,’ although it is not confined to that meaning. The word itself was probably unknown to Leo Africanus, who says that Zāria Kano and Katsena speak the language of Gober, instead of Haúsa, Gober being at Leo's time the most prominent and noble among the provinces of the North. Whether the name, Aúsa given to the northern side of “the great river” in contrast to Gurma on the southern side, has anything to do with Haúsa, is left undecided by Barth. Sultan Bello derives the Haúsa from a Bornu slave, named Bāwu. This Bāwu has a real historical existence in the traditions of the Haúsa people, though not as a slave, the Haúsa word for ‘slave’ being Bāwa not Bāwa, a fact of which Sultan Bello could not have been ignorant; and besides this, it must be argued that, if the Haúsa derived their origin from the Bornu or Kanúri, there would exist a greater similarity between these two languages than is found to be the case. Both languages have a few words in common, but the grammars are most distinct.

Effects of Planting on Different Sides of the Ridge on Emergence, Plant Growth, Yield and Quality of Potato (Solanum tuberosum) in the Sudan

1989 ◽  
Vol 25 (3) ◽  
pp. 409-415 ◽  
Author(s):  
A. M. Ali
Keyword(s):  
Solanum Tuberosum ◽  
Plant Growth ◽  
Soil Temperature ◽  
Growth Yield ◽  
Potato Tubers ◽  
Yield And Quality ◽  
Southern Side ◽  
Northern Side

SUMMARYThe effects of planting potato tubers on four different sides of two ridge orientations was investigated. Soil temperature was coolest on the northern side, followed by the western, eastern and southern sides. Fifty percent emergence took place in 24, 42 and 49 days for tubers planted on the northern, western and eastern sides, respectively. Only 22% of tubers planted on the southern side emerged. The best yield and quality was obtained by planting on the northern side, followed successively by the eastern, western and southern sides of the ridge.

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.

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