A lacustrine sedimentary process study was undertaken at Kluane Lake, which is a large, glacier-fed, alpine lake in the southwestern corner of Yukon Territory. Data from moored instruments, sediment traps, water column profiling, and high-resolution sub-bottom acoustic surveys were collected over the peak melt seasons of 2006 and 2007 in order to document the spatial and temporal lacustrine sedimentation patterns. A river monitoring station was also established to continuously record the inflow variations of Slims River, which drains meltwater from Kaskawulsh Glacier. Kluane Lake receives sediment-laden (up to 5 g/l) water from Slims River, which varies diurnally in terms of both discharge and suspended sediment concentration. While evidence of seasonal sediment exhaustion is present within the system, the diurnal hysteresis relationship between discharge and suspended sediment is either insignificant or more commonly counterclockwise. The high suspended sediment load delivered by Slims River produces continuous, diurnally fluctuating turbidity currents with maximum velocities in excess of 0.6 m/s at delta-proximal locations, although velocities between 0.2 and 0.4 m/s are more typical. During peak flow conditions, variations in current velocity can be traced to the deepest portion of the lake, over 4 km from the point of inflow. The longitudinal changes in the vertical concentration profiles, suspended sediment load, and mass accumulation rates suggest that the flow structure of the turbidity currents changes rapidly along the first several kilometres of flow. Sedimentation in the Kluane Lake basin is dominated by turbidity currents; overflows occur intermittently and contribute less than 2% to sediment accumulation along the lake bed. The highest rate of deposition occurs approximately 1 km from the delta and is consistent with an accumulation of approximately 0.4 m/a; closer to the delta, high current velocities appear to inhibit sediment deposition. The sediment in Kluane Lake is dominated by silt-size particles and contains virtually no sand except in small amounts very close to the delta. The diurnal pattern of turbidity current activity produces daily rhythmites in sediment traps deployed near the lake bottom, but these laminations do not occur consistently over time or space. / Thesis (Master, Geography) -- Queen's University, 2008-05-22 13:42:20.629

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Although there have been useful developments in the theory of solid-liquid separation in inclined tubes, many assumptions and concepts have not been tested. In the present study the principal objective was to gain a clearer understanding of the settling mechanism through observation of the flow fields within a particle-free fluid layer which exists at the upper face of the bulk suspension and within the bulk suspension itself. Experimental investigations were carried out using glass beads in an aqueous glycerol solution. Preliminary tests in a vertical column showed that the relationship between the settling velocity Vc, and the solids concentration C could be described by Vc=A(1-C)n when n=4.66 In the subsequent work in an inclined column the flow field in the clear fluid channel and within the suspension core was studied for suspension under the concentration conditions Co = 0.1 and Co 0.2. Characteristics features (width, velocity and average flow) of the clear-fluid layer were measured and compared with existing theory. Generally it was shown that there is a fairly good agreement between theory and experiments especially at early stages of settling and away from the top interface. Particular attention was paid to mode of infiltration from the bulk suspension into the clear-fluid channel. Measurements of the concentration distribution along the settling column were carried out using an electro-conduct ivity technique from suspension. Fluid velocity was measured by a dye-tracer. From the data, it was seen that the fluid velocities within the suspension were exceedingly high, being roughly 10 times the buck settling velocity of the suspension. All the characteristics of the flow field within the clear-fluid channel indicate a change in behaviour between the upper and lower parts of the settling column and take place as if there was a form of rotation above and below a horizontal axis at the middle of the tube. Existing theory (PNK) was modified to take account of the height of the sediment layer at the bottom of the tube. This provided goodagreement with experimental data over the range of conditions studied, apart from the final stages of settlement.

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