Debris torrents (channelized debris flows) are a geomorphological process only relatively recently recognised in southwest British Columbia. They are of interest both because of the tremendous amount of geomorphic work they do, and because of the hazards they pose to engineering works and residential developments. Fourteen torrents on the east side of Howe Sound, near Vancouver, since October 1981, have claimed twelve lives. Debris torrents differ from water floods in that they involve large amounts of coarse organic and inorganic debris. Therefore, a major requirement for torrent occurrence in a given channel is a supply of mobilizable debris. This thesis examines debris supply mechanisms and rates of debris supply in four small watersheds along Howe Sound, near the village of Lions Bay. An inventory of major debris sources has been compiled, and selected typical sites are examined in detail. Study methods include airphoto interpretation, ground surveying and reconnaissance, field instrumentation and site monitoring, dendrochronology, and materials sampling and testing. Debris supply is controlled by natural factors such as the nature and distribution of the bedrock and surficial materials, topographic gradient, vegetation, weather, and surface and groundwater hydrology, and by human activities such as logging and road construction. A wide variety of debris supply mechanisms operate in the study area, including rockfall and rockslide, talus shift, debris slide, soil wedge failure, ravelling, and snow avalanche. In addition to delivering debris to channel systems, some of these processes are capable of triggering debris torrents. Debris redistribution in channels occurs through debris torrents which do not reach the fans, fluvial processes (bedload transport), and snow avalanches. Active debris removal from main supply points, and storage elsewhere in the channel system, can decrease the frequency but increase the magnitude of torrent events in the basin. The wide variety of debris supply, debris redistribution, and torrent triggering mechanisms acting in this relatively small area points to a need for careful study of individual basins if the torrent potential in an area is to be understood. Regionally-based climatological or hydrological models of torrent occurrence should be employed for preliminary hazard assessment only. / Arts, Faculty of / Geography, Department of / Graduate

Studies were carried out to determine the circulation of water in the northern basin of Howe Sound, a small fjord on the mainland coast of British Columbia, and to determine the extent of the influence of the winds, the tide and river runoff on the circulation. In one experiment, surface-layer drogues were tracked by radar for four periods each of approximately three days duration. Data sere recorded photographically, then digitized for computer processing. Cubic spline interpolation was used to produce positions, velocities and accelerations at one minute intervals along every drogue track. The interpolated data were averaged in a suitable manner to produce pseudo-Eulerian estimates of velocity. Near the head of the fjord, both wind and tide appeared to cause temporal fluctuations in the surface current of magnitude similar to the expected mean flow due to the river. The river was the cause of spatial inhomogeneity in the flow, but did not appear to be a significant source of temporal variations. Farther down the inlet, wind forcing was the dominant cause of temporal variations in the surface-layer flow of about five times the magnitude of the expected mean river-driven flow. At no distance along the fjord was the velocity observed to be laterally uniform. Lateral gradients of long-channel velocity were strong at the inlet head and decreased away from it, indicating that the fresh water from the river was slowly mixing across the inlet. Another experiment using drogues at three depths in the upper 6 m of the water indicated that the velocity structure was not uniform, either laterally or with depth. Analysis was done on data from six current meters moored in the northern basin of Howe Sound. The mean currents from these meters showed a surface-layer outflow and a return inflow in the waters just below. A mean down-inlet current was seen at 150 m, 80 m below sill depth. Spectra of the currents showed dominant peaks at diurnal and semi-diurnal periods. The wind was coherent with the currents at 3m for periods longer than 10 hours. Below this depth, no consistent relationship was seen. In the diurnal band, the currents were strongest at the surface, indicative of forcing from the surface by the wind. In the semi-diurnal band, the currents were strongest at 10m depth. Both bands also showed a phase variation with depth indicative of a baroclinic structure. These results were compared with some models for surface-layer behaviour. The first model assumed that the wind momentum input was distributed uniformly throughout the surface layer and that the layer was not frictionally coupled to the deeper waters. Drag coefficients calculated from the wind stress and drogue acceleration gave values of 1 to 2x10-3, similar to values measured in other ways. This model was only valid for the first few hours after the onset of the wind. Another model, developed by Farmer (1972), analysed the behaviour of the surface layer of a semi-infinite canal under the influence of a steady wind stress. It predicted correctly the length of time of wind dominance of the flow, the magnitude of the velocity change and the magnitude of the acceleration of the water. A baroclinic tidal model in a two-layer fjord, adapted from Rattray (1960), correctly predicted the phase of the surface-layer currents near the head of a fjord with respect to the height of the tide. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Gap, outflow, or Squamish wind, is the cold low level seaward flow of air through fjords which dissect the coastal mountain barrier of northwestern North America. These flows, occurring mainly during winter, can be strong, threatening safety, economic activity and comfort. Howe Sound gap winds were studied using a combination of observations and several types of models. Observations of winds in Howe Sound showed that gap wind strength varied considerably along the channel, across the channel and vertically. Generally, winds increase down the channel, are strongest along the eastern side, and are below 1000 m depth. Observations were unable to answer all questions about gap winds due to data sparseness, particularly in the vertical direction. Therefore, several modelling approaches were used. The modelling began with a complete 3-dimensional quasi-Boussinesq model (CSURAMS) and ended with the creation and testing of models which are conceptually simpler, and more easily interpreted and manipulated. A gap wind simulation made using RAMS was shown to be mostly successful by statistical evaluation compared to other mesoscale simulations, and by visual inspection of the fields. The RAMS output, which has very high temporal and spatial resolution, provided much additional information about the details of gap flow. In particular, RAMS results suggested a close analogy between gap wind and hydraulic channel flow, with hydraulic features such as supercritical flow and hydraulic jumps apparent. These findings imply gap wind flow could potentially be represented by much simpler models. The simplest possible models containing pressure gradient, advection and friction but not incorporating hydraulic effects, were created, tested, and found lacking. A hydraulic model, which in addition incorporates varying gap wind height and channel geometry, was created and shown to successfully simulate gap winds. Force balance analysis from RAMS and the hydraulic model showed that pressure gradient and advection are the most important forces, followed by friction which becomes an important force in fast supercritical flow. The sensitivity of gap wind speed to various parameters was found from sensitivity tests using the hydraulic model. Results indicated that gap wind speed increases with increasing boundary layer height and speed at the head of channel, and increasing synoptic pressure gradient. Gap wind speed decreases with increasing friction, and increasing boundary layer height at the seaward channel end. Increasing temperature dilterences between the cold gap wind air and the warmer air aloft was found to increase the variability of the flow — higher maximum but lower mean wind speeds.

Gap, outflow, or Squamish wind, is the cold low level seaward flow of air through fjords which dissect the coastal mountain barrier of northwestern North America. These flows, occurring mainly during winter, can be strong, threatening safety, economic activity and comfort. Howe Sound gap winds were studied using a combination of observations and several types of models. Observations of winds in Howe Sound showed that gap wind strength varied considerably along the channel, across the channel and vertically. Generally, winds increase down the channel, are strongest along the eastern side, and are below 1000 m depth. Observations were unable to answer all questions about gap winds due to data sparseness, particularly in the vertical direction. Therefore, several modelling approaches were used. The modelling began with a complete 3-dimensional quasi-Boussinesq model (CSURAMS) and ended with the creation and testing of models which are conceptually simpler, and more easily interpreted and manipulated. A gap wind simulation made using RAMS was shown to be mostly successful by statistical evaluation compared to other mesoscale simulations, and by visual inspection of the fields. The RAMS output, which has very high temporal and spatial resolution, provided much additional information about the details of gap flow. In particular, RAMS results suggested a close analogy between gap wind and hydraulic channel flow, with hydraulic features such as supercritical flow and hydraulic jumps apparent. These findings imply gap wind flow could potentially be represented by much simpler models. The simplest possible models containing pressure gradient, advection and friction but not incorporating hydraulic effects, were created, tested, and found lacking. A hydraulic model, which in addition incorporates varying gap wind height and channel geometry, was created and shown to successfully simulate gap winds. Force balance analysis from RAMS and the hydraulic model showed that pressure gradient and advection are the most important forces, followed by friction which becomes an important force in fast supercritical flow. The sensitivity of gap wind speed to various parameters was found from sensitivity tests using the hydraulic model. Results indicated that gap wind speed increases with increasing boundary layer height and speed at the head of channel, and increasing synoptic pressure gradient. Gap wind speed decreases with increasing friction, and increasing boundary layer height at the seaward channel end. Increasing temperature dilterences between the cold gap wind air and the warmer air aloft was found to increase the variability of the flow — higher maximum but lower mean wind speeds. / Arts, Faculty of / Geography, Department of / Graduate

Temperature microstructure observations obtained in Howe Sound are presented and related to their oceanographic context, In some instances, two free-falling probes have been launched simultaneously with separations of 10 to 20 m at the surface in an attempt to look at the lateral extent of temperature microstructure features. Patches of temperature gradient variance were found where the gradient presented peak values of both signs at smaller scales. These patches were usually observed by one probe only and seem to extend laterally over less than 20 m. In other instances the peak gradient values took mostly the same sign within a given patch. Such patches were usually detected by both probes, indicating that their horizontal extent is significantly larger than 20 m. These types of temperature microstructure are also discussed in terms of mechanisms that could provide an explanation for their existence. In Howe Sound's Inner Basin, the Deep Water occasionally receives large influxes of water from the Strait of Georgia. Otherwise, it stays essentially trapped behind a 75 m deep sill and becomes more homogeneous with time. A model is presented which relates the rate at which temperature becomes homogeneous to temperature gradient variance and the molecular coefficient of heat diffusion. Other parts of the water column are discussed in terms of the Osborn-Cox (1972) model of vertical heat transport. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Unknown

Same of the philosophical aspects of modelling are discussed along with the importance of understanding primary marine food-web components. Howe Sound, a coastal embayment on the British Columbia coast, is examined as a base study area, and field sampling methods as well as laboratory techniques are summarized. The main body of the investigation involves the development of a mathematical description of phytoplankton population growth and distribution as a function of biological and physical circulation parameters in the sound. This is accomplished by dividing the sound into zones and modelling primary productivity as a result of certain key environmental forcing functions. Transport between zones is shown to affect spatial timing and distribution. Observed and predicted values of nutrients, temperature, extinction coefficients, zooplankton biomass, and phytoplankton productivity and biomass are compared as the model is refined. It is then used to simulate the effects of a delayed spring on productivity in Howe Sound, as well as to model growth in Indian /Arm, an adjacent embayment. Simulated annual productivity in Have Sound is 235, 316 and 384 gC‧m⁻²‧yr⁻¹ in the down inlet direction for the three model zones. With a delayed spring the values are reduced to 200, 308 and gC‧m⁻²‧yr⁻¹ and comparisons are made with observed data in Howe Sound in 1974 when poor spring weather conditions prevailed. In Indian Arm the model predicts a spatial productivity distribution of 318, 256 and 239 gC‧m⁻²‧yr⁻¹, values which agree with field observations of two workers. The general applicability of such models to complex ecosystems is discussed. / Science, Faculty of / Zoology, Department of / Graduate

The study of suspended sediment provides insights into the transport and accumulation of sediment in depositional basins. Past investigations have suffered, however, from a lack of methodology that can deal with the low concentrations of suspended sediment. The theory and method of three techniques to be used in the analysis of suspended sediment have been outlined. 1) VSA, provides a rapid, accurate and precise method of determining grain size distributions of low weight samples. The method is based on the solution to a set of equations that discretely define the increasing volume of a homogeneous sediment sample settling in an enclosed volume of water. The results are in terms of sedimentation diameters, a hydrodynamically sensitive property. 2) The Ag filter mount provides a fast technique for a low sample weight random oriented mount to be used in quantitative XRD analysis. The method has excellent precision and does not fractionate the mineral component due to their settling velocity. 3) Suspended sediment collectors have been used to measure the downward flux of sediment in the fjord environment. The traps have also provided a means to calculate the natural settling velocity of flocculated or otherwise enhanced particle settlement. Laboratory and field studies have dealt with the interaction of zooplankton with suspended sediment. Marine zooplankton ingest suspended sediment at a rate dependent on sediment concentration and mineralogy. Ingested mineral particles undergo chemical and mineral transformations which are functions of mineralogy, cation exchange capacity and residence time in the digestive tract. Zooplankton fecal pellets have a much larger settling velocity than their component particles. This increased settling rate allows clay to be deposited where the hydrodynamic nature of the environment would only allow coarse silt to fine sand deposition. Glacial flour (feldspar, quartz, trioctahedral mica, chlorite, amphibole, tourmaline, and vermiculite) enters the surface-layer of the Howe Sound fjord as a sediment plume which moves quickly down inlet while slowly mixing with the marine water. Although flocculation occurs in the lower brackish water of the surface-layer, mixing and diffusion are the dominant means for sediment to enter the lower-marine-water. Once in the lower-marine-water, zooplankton pelletization and biologic agglomeration of inorganic floccules takes place. These processes that enhance the individual particle settlement, generate a fast response time between the surface-layer and the lower-marine-layer in terms of sedimentation of particulate matter. Settling velocities of particles less than 1 μm have been enhanced over 1400 times. Size distributions of sediment deposited on the sea-bed are a function of variable multimodal and/or non log-normal size distributions from sub-laminae falling through the water column. The increase in deviation away from log-normality down inlet, for size distributions of both suspended and deposited sediment, is an artifact of the size analytical method. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

One hundred surface sediment samples and two 30 cm cores were collected from Howe Sound, British Columbia, a deep (≈280 m) fjord with a restricted inner basin into which mine tailings had been dumped for 75 years. The abundances of major elements Si, Al, Ti, Fe, Mg, Ca, Na, K, C, N, and P, and minor elements Ba, Co, Cr, Cu, Mn, Ni, Pb, Rb, Sr, V, Y, Zn, and Zr were determined as well as nutrient and trace metal concentrations in porewater from the two cores. The solid-phase data suggest that the inner basin sediments are dominated by Squamish River-derived feldspars, while the outer basin is characterized more by quartz and Fe and Mg minerals, which enter the southernmost portion of the fjord via estuarine circulation from Georgia Strait. Although Fe, Cu, Pb, Zn, and Ba are still enriched in sediments near the tailings outfall, the lapse of 13 years since cessation of tailings deposition has apparently resulted in reduced metal levels throughout much of the rest of the inlet due to ongoing dilution by natural sedimentation. Profiles of these metals with depth show that the tailings deposit proper is buried by ≈14 cm of natural sediment in the deep central portion of the inner basin. Porewater analysis of the two cores revealed that active bacterial remobilization of organic matter is occurring at both locations; although the organic carbon content of the outer basin is greater than that in the inner basin, sulphate-reduction is more intense in the latter due to the higher sedimentation rate. Despite this, dissolved sulphides were nearly absent in porewaters, leading to the conclusion that authigenic pyrite precipitation is removing some of the dissolved Fe. Dissolved Cu and Zn are enriched in surficial porewaters of both the outer and inner basins (i.e. Cu = 215 and 132 nmol/L, respectively, and Zn = 32 µmol/L and 1.6 /µmol/L), but decrease rapidly within the top 2-3 cm, suggestive of active removal by some mechanism. Dissolved Pb concentrations were low (<3 nmol/L) in both cores, and did not show any surface enrichment. These data suggest that a strongly reducing environment such as is found at depth in natural sediments inhibits the release of some labile metals which may be contained within them. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

In 1937, Howe Sound Company built the town of Holden, Washington, to support its copper-mining operation at Copper Peak, located in the North Cascade Mountains, approximately 10 miles west of Lake Chelan. The operation produced concentrate from 1937 to 1957, during which time the town was home to a lively community featuring many families, a variety of organized recreational activities, and a public school. It was a company town, in which most property, business, organized activity, and public utilities and services were either directly or indirectly controlled by Howe Sound. After the operation shut down in 1957, the town was abandoned. Three years later, the property was donated to the Lutheran Bible Institute of Issaquah, Washington. It subsequently became Holden Village, an independent, non-profit Lutheran retreat center. Though different in purpose and character from the community that preceded it, life in Holden Village during its formative years (the 1960s and, to a lesser extent, the 1970s), and in the 2010s, was and is similar in a number of ways to life in the mining town. This thesis argues that Holden Village, too, might be considered a company town within a loose definition of the term. The many parallels between the two communities support this argument, and point to the role of the remote setting and the environment in shaping the lives of the town's residents.