No description available.

Geophysical, geochemical and geotechnical methods were used to investigate the spatial and temporal aspects of sediment distribution, accumulation, post-depositional alterations, and seafloor response and recovery to major events in a temperate, paraglacial, turbid outwash fjord. The goals of this study are to generate a complete geological model and compare the results to the global distribution of fjords. The over arching theme of this study is that the ratio of the area of the watershed to the area of the receiving basin can provide a first order indicator of many factors including glacial mass; the timing of glacial retreat; sediment input, accumulation, and preservation; and other factors. Temporal observations reveal the change of this fjord from a glaciated basin to and estuarine environment. These observations become important when viewed in the context of global climate change and the continued loss of ice. Preserved strata provide a 2800 yr record of changing modes of sedimentation as the system evolved from a glaciated basin to a non-glaciated fjord revealing a detailed chronology of change between end-member systems which can be used to infer changes as glaciers retreat from other fjords. Short lived radio isotopes were used to investigate post-depositional alteration of modern sediments. Without an understanding of how biological and physical processes work to modify sedimentary fabric during preservation, changes seen in sediment and rock core data cannot be accurately resolved. Physical processes can cause erosion and lateral transport; winnowing and armoring; and instantaneous sedimentation, all of which may be preserved. Biological processes can modulate the preservation of strata by destroying sedimentary fabric and integrating signals. The final fundamental need is to investigate the seafloor response and recovery to these events. Massive earthquakes are frequent in the study area and cause perturbations to sediment input and preservation. By understanding how lakes and deltas modulate sediment discharge after the event; how shorelines are modified after the event; and where sediment is deposited we can determine the influence these changes have on the environment and on humans.

Diss.--Berlin, 1995. / Bibliogr. p. 399-465. Index.

The first continous set of observations made over the seasonal cycle of the vertical structure and currents in the Clyde Sea, Scotland's largest fjord, are used to show that the vertical structure is controlled by a balance between mixing and stratifying processes within the basin, and exchange with the North Channel of the Irish Sea. Stratification was observed to change from being entirely saline in the winter to being thermally dominated in the summer. Deep water renewal occurred throughout the winter. The inflow rate peaked in the early spring and also in the summer, resulting in an annual mean flushing time of -3.5 months, in satisfactory agreement with previous estimates. Within the basin, a two layered flow structure was observed throughout the year, and a residual anti-cyclonic surface circulation was seen to be persistent. A 3- dimensional modelling study supports the hypothesis that this flow is driven by currents associated with the density gradients at the basin's mouth. A positive density difference across the sill is a necessary but not sufficient condition for deep water renewal; when the difference was maximum in the winter, the rate of exchange was below average. Renewal was generally episodic, which is suggestive of wind induced exchange. The 3-dimensional model confirmed that changes in the wind direction could substantially increase or diminish exchange by enhancing or blocking the estuarine circulation. Rapid renewals in the spring time of 1993 and 1994 were initiated by storm events. In the summer of 1993, persistently high rates of exchange were observed. 3-dimensional modelling supported the hypothesis that this was due to the presence of saline water over the sill, which results from the summer time retreat of the front at the mouth of the Clyde Sea due to low freshwater inflow. An existing 1- dimensional filling-box model was developed in the light of the new observations. It showed that significant entrainment of Clyde Sea bottom water into this summer inflow was a possible mechanism to explain the deep water properties in the summer. Mixing was found to be predominantly wind driven. A positive correlation was found between the wind and the amplitude of intemal oscillations at sub-tidal frequencies, which dominated the velocity field in winter. A mode 1 internal tide at the M2 frequency was observed, and had a horizontal velocity at the mooring sites of -2 cms-l throughout the year. The mixing associated with the internal tide was -0.01 mWm-2 , which is 2 orders of magnitUde lower than the wind mixing. The residual surface anti-cyclonic circulation prevents surface fresh water from entering the Kilbrannan Sound, which reduces the potential energy anomaly by -60 Jm-) relative to than that of the Arran Deep. Consequently, the wind induces relatively deeper mixing in the Kilbrannan Sound, which in the winter resulted in the reduction of the bottom water temperature without a significant decrease in salinity, and explains how the Clyde Sea bottom water may cool more rapidly than the deeper North Channel.

Mémoire (M. A.)--Université du Québec à Chicoutimi, 1990. / Programme de maîtrise en arts plastiques extensionné de l'UQAM à l'UQAC. Document original en caractères symboliques, traduction française inserée. CaQCU CaQCU Document électronique également accessible en format PDF. CaQCU

Tidewater glaciers form a significant drainage catchment of glacierised areas, directly transporting meltwater from the terrestrial to the marine environment. Surface melt of glaciers in the Arctic is increasing in response to warmer atmospheric temperatures, whilst tidewater glaciers are also exposed to warmer ocean temperatures, stimulating submarine melt. Increased freshwater discharge not only freshens fjord waters, but also plays a key role in glacimarine sedimentary processes, transporting sediment to glacial fjords. Despite this, the temporal evolution of meltwater production, storage and release from tidewater glacier systems at seasonal and interannual time scales is poorly understood. This leaves large uncertainties in the predictions for future sea level rise, ocean circulation and the impacts on the marine ecosystem. This study focuses on Kronebreen, a tidewater glacier which flows into the head of Kongsfjorden, north west Svalbard. Surface melt produces freshwater runoff, which is discharged from the grounding line as a buoyant, sediment laden plume, which spreads laterally across the surface water. This supraglacial melt is the dominant freshwater source, contributing an order of magnitude more freshwater to Kongsfjorden, than direct submarine melting of the ice face. Calibration of MODIS band 1 satellite imagery with in situ measurements of Total Suspended Solids and spectral reflectance, provides a method to quantify meltwater and sediment discharge. Plume extent has been determined for each cloud free day, from June to September, 2002 - 2013. Analysis of plume extent with atmospheric temperature and modeled surface runoff, gives a source to sea insight to meltwater production, storage and discharge. The extent of the plume changes in response to meltwater; larger plumes form when discharge increases. These results reveal that meltwater discharge into Kongsfjorden lags atmospheric temperature, the primary driver of meltwater production, by over a week during June and July. This is reduced to only 1 - 2 days in August and September, indicating a decline in meltwater storage as the ablation season progresses, and the development of more efficient glacial drainage. Sediment plumes respond to meltwater production, making them a valuable tool for quantifying meltwater discharge from a tidewater glacier. Insights to glacier hydrology can also be obtained when surface processes are also considered. This furthers the understanding of tidewater glacier hydrology, which is valuable for improving the accuracy of sea level rise predictions.

No description available.

Thesis (Ph.D.)--Memorial University of Newfoundland, 2005. / Includes bibliographical references.

Simpson Bay is a turbid, outwash fjord located in northeastern Prince William Sound, Alaska. A high ratio of watershead:basin surface area combined with high precipitation and an easily erodable catchment create high sediment inputs. Fresh water from heavy precipitation and meltwater from high alpine glaciers enter Simpson Bay through bay head rivers and small shoreline creeks that drain the catchment. Side scan sonar, seismic profiling, and high resolution bathymetry were used to investigate the record of modern sedimentary processes. Four bottom types and two seismic faces were described to delineate the distribution of sediment types and sedimentary processes in Simpson Bay. Sonar images showed areas of high backscatter (coarse grain sediment, bedrock outcrops and shorelines) in shallow areas and areas of low backscatter (estuarine mud) in deeper areas. Seismic profiles showed that high backscatter areas reflected emergent glacial surfaces while low backscatter areas indicated modern estuarine mud deposition. The data show terminal morainal bank systems and grounding line deposits at the mouth of the bay and rocky promontories, relict medial moraines, that extend as terrestrial features through the subtidal and into deeper waters. Tidal currents and mass wasting are the major influences on sediment distribution. Hydrographic data showed high spatial variability in surface and bottom currents throughout the bay. Bottom currents are tide dominated, and are generally weak (5-20 cm s-1) in the open water portions of the bay while faster currents are found associated with shorelines, outcrops, and restrictive sills. Tidal currents alone are not enough to cause the lack of estuarine mud deposition in shallow areas. Bathymetric data showed steep slopes throughout the bay suggesting sediment gravity flows. Central Alaska is a seismically active area, and earthquakes are most likely the triggering mechanism of the gravity flows.

Thesis--Copenhagen. / "Reprinted from Ophelia, vol. 11, August 1973." Includes bibliographical references (p. 463-482) and index.