Sedimentation in proglacial Sunwapta Lake, Alberta

Abstract

The hydrologic and limnologic conditions of Sunwapta Lake, a small proglacial lake in the Canadian Rocky Mountains, were investigated with special reference to the sedimentology of this lake. Discharge and suspended sediment concentrations of the inflowing streams were measured to give estimates of sediment input. Distribution of large loads of fine glacial sediment is largely by an inflow- and wind-controlled circulation, which commonly fluctuates diurnally. The spatial distribution of sedimentation was determined by use of sediment-collecting pans placed on the lake bed. Turbidity currents are rare with only one event monitored in 2 years. This event was caused by a burst of highly sediment-charged inflow water. The rarity of turbidity currents is attributed to the high sediment concentration in the lake water, which results from the small size of the lake in relation to the inflow. Wind-generated water movement at the lake floor ranges from 0.0–0.03 m/s while the maximum recorded velocity of the turbidity currents was 0.32 m/s.Sedimentation rates are calculated and six cores from the lake bed, each containing sediment deposited over several years, are described. Although bedding and lamination are found in all cores, correlation between cores was not possible. Sedimentary characteristics are related to inflow and lake conditions: laminated and massive beds of medium to fine sand and silt are related to turbidity events, graded laminae in coarse and fine silt to diurnal variations in lake currents, and massive beds in silt to periods of continuous sedimentation without diurnal variation. Deformed beds result from subaqueous slumps.

Pleistocene Stratigraphy of the Athabasca River Valley Region, Rocky Mountains, Alberta

“…Vertical faciès changes in the unit are equivalent to the distal to proximal, glaciolacustrine fades sequence described by Ashley (1988) and probably reflect the increased proximity and eventual advance of glaciers into the lakes as glaciation in the region progressed. Similar faciès associations also have been described from several modern glacial lakes in mountain regions (Gilbert and Shaw, 1981;Ashley et ai, 1982).…”

Glacilacustrine environment of part of the Oak Ridges Moraine, Southern Ontario

“…These may represent the warm, clear days that give rise to strong daily pulses of meltwater and sediment at the peak of the melt season and that distribute them by daily katabatic winds in a proximal glacilacustrine environment (cf. Sunwapta Lake - Gilbert and Shaw, 1981).…”

“…Third, avulsion in input streams related to catastrophic changes in flow patterns in the glacier (Ashley, 1988), especially when associated with the tapping of reservoirs of sediment within the ice (Gilbert and Shaw, 1981), may instantaneously increase or decrease rates of accumulation at a given site. This may have been a factor at the Vandorf site, although there are normally several varves that may be regarded as transitional between each type (Fig.…”

Effects of upstream hydropower operation on riverine particle transport and turbidity in downstream lakes

“…[7] Lake Brienz and its major tributary, River Aare, situated next to the highest Alps of Switzerland, are chosen for this study, as their setting ( Figure 1 and section 2) is representative for many lakes affected by surface turbidity in the European Alps [Lambert et al, 1976], the Rocky Mountains [Gilbert and Shaw, 1981;Weirich, 1986], and the Alps of New Zealand [Schallenberg et al, 1999].…”