Professor Kevin Hall

The processes involved in wave/breakwater interaction, especially the external and internal pressure fields, were studied experimentally. Wave runup and rundown and the movement of the internal phreatic surface were measured. The effectiveness of a mass armoured breakwater using a thicker layer of smaller sized stones than usual was assessed. The performance of a numerical model of internal flow in breakwaters was tested using the experimental findings.

In this paper prototype experience with natural armoured breakwaters of both the mass armoured and berm types is presented. In addition the results of experimental studies in which a test breakwater is instrumented with pressure transducers on both the external face and within the core of the breakwater are presented and provide further substantiation of the benefits of this type of breakwater.

A rational design procedure for rubble-mound breakwater protection which will ensure both the structural integrity and hydraulic stability of individual concrete armour units and the overall armour system is presented. The procedure involves new experimental techniques for measuring strains in model concrete armour units in a hydraulic model of a breakwater subjected to simulated prototype loads on units. Selected design loads are used to define the resultant stress distribution to allow the designer to take the necessary measures to ensure the structural performance of the unit in a breakwater environment. (A)

In discussion of armour units for breakwaters this paper consideres the forces that act on an armour unit. The response of this armour unit in a hydraulic environment was studied and a number of instrumentation systems and hydraulic model materials were reviewed. The armour unit chosen was the dolos unit. (from paper)

Wave protection for an offshore rockfill structure was developed using two and three dimensional hydraulic model studies. The wave protection scheme, designed to survive a design storm having a peak significant wave height of 33 feet, consists of a 75 foot wide outer berm of 3.9 to 19 ton angular quarry stone placed between elevations of -55 and +10 feet (MSL) and a conventional two stone armour layer between +10 and +30 feet (MSL). The stability of the structure is developed during early periods of wave action as stones are moved and the outer berm is reshaped into a stable profile. Test results indicate that if design wave conditions are exceeded, rapid disintegration of the armour layer would not occur. The armour system is designed so that essentially 100 per cent of the quarry is utilized and so that it can be built using land based equipment that primarily consists of a truck dumping operation. (A)

Studies the history of armour system design and examines the performance of these systems in protecting rubble mound breakwaters. Quarried stone systems include random placement, regular placement, and on alternative scheme. Considers design formulae for these systems and some design limitations. Randomly placed concrete armour units are often of complex shape for better interlocking. Occasionally the units are reinforced. Regularly placed concrete units can show high stability but construction may be difficult. Examines formulae for estimating the weight of an armour unit, noting limitations of the Hudson formula. Notes the differences among various model studies to determine stability of the armour layer. Discusses the causes of recent rubble mound failures, and hence develops recommended design procedures. Discussion is on pages 121- 132. (C.J.U.)

A series of laboratory experiments were undertaken to investigate the initiation of motion of consolidated cohesive sediments. The study was primarily designed to investigate the influence of clay content and consolidation pressure on the erodibility of cohesive sediments obtained from the Norman Wells area located along the MacKenzie River, Northwest Territories. (from author's abstract)

The appropriateness of any development technology depends on its suitability to meet the needs, circumstances and capacities of the people in a unique and challenging environment. This paper focuses on the importance of collaborative innovation that harmonizes technical ingenuity with user satisfaction while working within social and environmental constraints. The people of Mylai Balaji Nagar (MBN), a low-income, peri-urban community on the fringe of Chennai, India, were recruited to participate in the design of an alternative safe water system with researchers from the University of Guelph and the Indian Institute of Technology Madras. The community obtains its drinking water from a nearby lake known to contain dangerously high concentrations of faecal indicator bacteria, implicated in diarrhoeal disease. This study employed a participatory design framework for the development of a safe water system capable of removing or rendering inactive bacterial pathogens and making the water safe for human consumption. Researchers undertook a five stage participatory design process modeled after participatory action research, to develop a household water filtration system. Following laboratory assessment to assess bacteriological and organics control efficacy, four treatment prototypes were presented to, and critiqued by, community representatives for their appropriateness to context. Copyright © 2013, Common Ground.

There is an increasing interest in the humanitarian engineering curriculum, and a service-learning placement could be an important component of such a curriculum. International placements offer some important pedagogical advantages, but also have some practical and ethical limitations. Local community-based placements have the potential to be transformative for both the student and the community, although this potential is not always seen. In order to investigate the role of local placements, qualitative research interviews were conducted. Thirty-two semi-structured research interviews were conducted and analysed, resulting in a distinct outcome space. It is concluded that local humanitarian engineering placements greatly complement international placements and are strongly recommended if international placements are conducted. More importantly it is seen that we are better suited to address the marginalised in our own community, although it is often easier to see the needs of an outside populace. © 2010 SEFI.

The size and number of coastal wetlands in the Great Lakes have been rapidly declining over the past century, but only in the past two decades have people begun to understand the complex environmental and biological benefits of these fresh water marshes. Recently, bioengineering techniques have been adapted as an integral functioning part of shore protection schemes. Constructed wetlands are prime examples of additions to shore protection schemes that provide ancillary benefits such as water quality improvements and the provision of a buffer zone and a rich biologically diverse sanctuary for terrestrial and aquatic species. The focus of most wetland studies has been related to biological aspects and, to a lesser degree, their hydrology. Little research has been conducted from a coastal science and engineering perspective, especially with regard to wave-exposed shoreline vegetation. This paper describes a recent study undertaken to examine common Great Lakes emergent shoreline aquatic plants in order to assess their applicability for use in a bio-engineered shore protection scheme. The study consisted of both field investigations and two dimensional physical hydraulic model studies. Field measurements included evaluating wave attenuation capabilities and conducting pull out strength tests. Laboratory tests were completed to evaluate the wave attenuation characteristics of several species subject to variations in plant density, plant height, wave period, wave height and water depth. A model was developed to predict the wave forces acting on the reed beds and to predict the susceptibility of the bed to erosion.

This paper summarizes the results of a three-dimensional moveable-bed, physicalhydraulic model study for proposed engineering improvements, implemented as part of an ecosystem management plan for Martindale Pond, St. Catharines, Ontario. The ecosystem management plan is being undertaken in conjunction with improvements to the Henley Rowing Course, which recently was awarded the 1999 World Rowing Championships. The ecosystem management plan consists of improving water quality, sedimentation regimes and bank stability in Martindale Pond, and bringing an existing rowing course up to current international standards for the world championships. The model study was undertaken at a distorted scale (1:100 horizontal; 1:25 vertical). The model demonstrated that improvements to the flow regime along the rowing course will provide a number of benefits including decreasing the potential for incoming sediment to be re-deposited on the floor of the course, decreasing local bank erosion (thus reducing sediment loading in Martindale Pond), providing a uniform flow distribution across the rowing lanes, and increasing the ecological quality of the pond. Enhancement of the ecosystem will improve water quality, improve environmental conditions for the wetland areas, increase the bio-diversity of the pond ecosystem, and provide recreational and aesthetic benefits.

Direct measurements of the motion of the phreatic surface within a breakwater and the pressure distribution at both the core/filter interface and the outer slope were made during a series of experimental tests. The ability of a numerical internal flow model to reproduce these measured parameters is presented in this paper. The numerical model used was a hybrid finite element - method of characteristics model for solving unsteady non-Darcy flow in a porous medium. Several modifications were made to the model to make it compatible for use with the experimental data. Nine simulations were undertaken, representative of the wide range of conditions encountered in the experimental program. Prediction of the free surface location within the armour was found to be marginal with the accuracy increasing as the armour layer thickness increased. Poor correlation between measured and predicted pressures at the core/filter interface was found.

Direct measurements of the motion of the phreatic surface within a breakwater and the pressure distribution at both the core-filter interface and the outer slope were made during a series of experimental tests (Hall 1987). The ability of a numerical internal flow model to reproduce these measured parameters is presented in this paper. The numerical model used, developed at the University of Windsor, Canada (Hannoura 1978) is a hybrid finite element method of characteristics model for solving unsteady non-Darcy flow in a porous medium. Several modifications were made to the model to make it compatible for use with the experimental data. The simulations were undertaken, representative of the wide range of conditions encountered in the experimental programme. (A)

A breakwater under construction in Iceland will roughly half the original estimated cost. Two breakwaters being built in Racine, Wisconsin, will cost even less than half the cost of conventionally designed structures. Both are berm breakwaters designed using a new approach dictated by the availability and the properties of local quarried rock. Costs are low because the method may use smaller rock than required by conventional breakwaters, vastly simplifies the construction process, and reduces the costs of quarry operation and stone transport. The berm approach is based on the precept that the thicker the armor layer, the smaller the stones need be to protect against wave action. With a berm design, the thickness of the armor layer for a specific breakwater can be determined by the gradation of the available stone and the incident wave climate.

Discusses a cheaper approach to breakwater construction using smaller rock than required by conventional breakwaters. The berm approach is based on the principle that the thicker the armour layer, the smaller the stones needed to protect against wave action. The relatively high porosity permits wave dissipation over a large area, increasing the stability of the breakwater. The berm approach uses locally available material, with the smaller fraction being used for the core of the structure and the larger fraction for the armour. Shape and dimension of the armour protection is determined from model studies. Compares cross sections and profiles of bermed and conventional breakwaters. (C.J.U.)

An index-based method for the evaluation of the environmental impact of water distribution systems (WDSs) is introduced. A number of environmental measures are incorporated into the index-based method to account for local, regional and global non-renewable resource consumption, greenhouse gas emissions, and emissions to air, land, and water. The index-based method is applied to designs provided in the literature for the Anytown system. Design alternatives are compared on the basis of environmental impact index and cost. For the system analyzed, results show that the four most environmentally feasible alternatives are also the four most cost-effective alternatives. System analysis also shows that substantial increases in total system cost results in an increase in the environmental impact index amongst alternatives, while the relationship between the environmental impact indexes is not well defined amongst alternatives with similar costs. © ASCE 2009.

Deep draft ships transiting through confined channels can significantly alter surrounding hydrodynamic conditions. The Burlington Shipping Channel is a confined channel on Lake Ontario which has experienced significant scour due to ship drawdown. A range of investigations including the development of an SGH model of the Burlington Channel have been undertaken to understand the processes leading to scouring near the channel walls. It is proposed the direction of ship motion is fundamental to the depth of scour observed at the entrances to the channel. The SGH model achieved a good level of hydrodynamic calibration and an assessment of modeled scour based on spatial variation in critical sediment size is consistent with observed scour patterns. The critical sediment diameter along the channel is an order of magnitude greater than the native bed material. In the mid-sections of the channel, scour potential is generally independent of direction of ship motion and consecutive ship movements in opposite directions appear to cause minimal net sediment transport. The development of design criteria curves for channel protection using the SGH model is presented. © 2007 ASCE.

It is well known that surface water waves interact with the fluid mud on the sea bed. Wave-mud interaction results to high wave energy dissipation and mud mass transport. This kind of wave energy dissipation, which generally is much more significant than wave dissipation due to bottom friction, should be considered in simulation of wave evolution and transformation in muddy coastal environments. This paper presents a numerical model of wave evolution and dissipation on fluid mud. For this purpose, the spectral decay of wave due to mud is implemented in SWAN (a third generation numerical model for Simulating WAves Nearshore) using a multilayered wave-mud interaction model. In this numerical model it is assumed that mud layer has a visco-elasic-plastic behavior.

Though there is agreement that shoreline and aquatic plants are an integral part of more environmentally compatible shore protection techniques, there is little data or design information available to ensure successful implementation. The value of shoreline wetlands has become increasingly recognized. One of the important functions of shoreline wetland vegetation is its ability to absorb wave energy; however, considerable questions regarding the magnitude and importance of this process exist. In order to address these concerns, a research study was undertaken to assess, qualitatively and quantitatively, wave attenuation by emergent wetland plants. A Lake Ontario shoreline wetland was monitored over a 3 year period and an extensive series of complementary laboratory flume tests were performed. The laboratory experiments were conducted using irregular waves and live vegetation taken from the field site. Several key parameters and trends, with respect to wave attenuation and emergent wetland vegetation, were identified. A pair of empirically based equations was developed that predicted wave attenuation through the emergent, freshwater, wetland plants.

The ideas of sustainability and sustainable development are attracting growing attention. Civil engineers play a vital role in the design, construction, and maintenance of society's infrastructure inside the natural infrastructure and can no longer afford to view social, economic, technological, and environmental issues as being separate. This challenge to produce viable, sustainable solutions is especially true in the field of coastal engineering. With about two thirds of the world's population living within 100 km of a coastline the strain on these desirable, highly productive, sensitive, and dynamic regions is enormous. Sustainable development along coasts, lakes, and rivers faces competing demands on resources requiring an integrated systems approach. Coastal engineers must create systems and solutions within the natural infrastructure and the coastal zone. Once projects along the coast are created their sustainability depends on long term management. Growing information technology such as geographic information systems, satellite imaging, and remote sensing play a major role in providing data for the management and monitoring of coasts and impacts of human activities. Numerical and physical models can pro-actively aid in the assessment of the stability and soundness of proposed coastal zone developments and alterations providing more effective support for regulatory decisions. This paper explores some of the challenges that face coastal engineering with respect to sustainability and examines how research at the Civil Engineering Department at Queen's University is trying to address the issue. Current research includes investigations of structures which are less intrusive and more adaptable providing for fish migration and natural flow processes to continue at controlled rates. Coastal wetlands and aquatic plants for use in integrated approaches to shore protection which enhance and create habitat are being investigated through field and laboratory studies. The ultimate goal of this work is the development of practical guidelines and models for more sustainable solutions to shoreline erosion problems.

Results of a three dimensional, moveable bed, physical hydraulic model study undertaken to provide design information for proposed engineering improvements to be implemented as part of an overall ecosystem management plan for Martindale Pond, located in the City of St. Catharines, are presented. The ecosystem management plan is being undertaken in conjunction with course improvements to the Henley rowing course, which recently was awarded the 1999 World Rowing Championships. The overall ecosystem management plan consisted of improving water quality, sedimentation regimes, bank stability throughout Martindale Pond and bringing an existing rowing course (Henley Rowing Course) up to current international standards for the world championships. The model study was undertaken at a distorted scale (1:100 horizontal; 1:25 vertical). A summary of tests undertaken in conjunction with flow manipulation are presented. The model demonstrated that improvements to the flow regime along the rowing course will provided a number of benefits including, decreasing the potential for incoming sediment to be re-deposited on the floor of the course, decreasing local bank erosion (thus reducing the sediment loading in the pond), providing a uniform flow distribution across the rowing lanes and generally increasing the ecological quality of the pond.

One of the primary concerns along shorelines is to provide protection against wave action which is the prime cause of shoreline erosion. Wave screens, floating structures, and submerged breakwaters provide numerous and significant environmental advantages over conventional breakwaters. Unlike conventional structures they are semi-transparent allowing natural interactions and water to flow through and fish to pass without disrupting their migration paths. Integration of these structures with bio-engineered shore stabilization methods, using vegetation in combination with creative habitat enhancement as a fundamental part of the protection measure, provides high environmental and aesthetic value by preserving natural appearances and ecosystems. An overview of the concept of integrated shore protection and current researches is presented in this paper. The goal of these studies is to determine wave attenuation characteristics and develop practical design guidelines so these structures can be utilized effectively for shore protection.

The interaction of an incident wave with a rubblemound breakwater results in complex flow patterns involving unsteady non-uniform flow. A reshaping or berm breakwater can be described as a mound of rock, often comprised of a wide range of stone sizes, which undergoes reshaping as a result of wave-structure interaction. As a consequence of this wave action, a stable profile is developed. Two major processes occur in the development of he stable profile. First, the overall geometry of the structure responds to the nature of the hydrodynamic loadings. Secondly, this natural sorting leads to consolidation (densification) of the armor layer as stones.

A series of two-dimensional hydraulic model tests was carried out to investigate the stability of rubblemound breakwater crown walls. The effect of seven design parameters on the minimum mass required for a crown wall to remain stable was studied: wave height, wave period, crown wall height, water level, front slope of the breakwater, position of the crown wall and length of stabilizing legs. Observations regarding the type of wave interaction, degree of overtopping, superstructure movement and overall hydraulic stability were studied. The coefficient of friction at the crown wall/breakwater interface was also measured. The crown wall superstructure was located on the crest of a conventional multi-layer breakwater and was subjected to both regular and irregular wave attack. Preliminary analysis of this data set is presented which shows trends established for each of the seven design parameters.

A series of experiments has been conducted at the Coastal Engineering Laboratory of Queen's University in order to investigate the characteristics of accelerating flow through porous media. The nature of the steady flow law in coarse granular material has been reasonably well-defined from a large number of previous studies. Variations on this steady flow law have been applied to the case of oscillatory flow, in numerical models of forces in breakwaters for example, with the explicit assumption that the steady law is applicable to the unsteady case. Few experimental investigations have been conducted to verify this assumption. Hence, the present study was designed specifically to test the applicability of the steady flow law to oscillatory flow. Tests were conducted in an oscillating water tunnel.

The reshaping of dynamically stable breakwaters was studied subject to variations in armour stone, (gradation and shape), wave characteristics and duration of wave attack from head on waves in a two dimensional wave flume. Tests were undertaken at the Coastal Engineering Research Laboratory of Queen's University, Kingston, Canada using irregular waves. Profiles of the structure during the various stages of reshaping were measured using a semi-automatic profiler developed for this study. The volume of stones and the initial berm width required for development of a stable profile along with the extent to which the toe of the structure progressed seaward were chosen as the characteristic parameters of the reshaped breakwater. The results indicated that the toe width formed as a result of reshaping and the area of stones required for reshaping were dependent on the wave height, gradation of the armour stone and duration of the storm. The initial berm width required for reshaping was also found to be dependent on the wave height, armour stone gradation, percentage of rounded stones in the armour and the duration of the storm.

An experimental investigation was conducted to examine the change in fluid pressure through a breakwater armour layer as a function of the incident wave characteristics, breakwater geometry, armour unit type, number of layers of armour and core permeability. Values of internal pressure were found to decrease with the number of layers of armour. The largest percentage decrease occurred within the first few layers; although this trend was somewhat influenced by armour type.

A series of hydraulic model test were carried out to investigate the mechanism by which naturally armoring breakwaters, that is breakwaters in which the initial profile is adjusted into a more stable profile as a result of wave action, gain their stability. The breakwater models were instrumented with pressure transducers placed along the outer face of the structure and at the core/filter interface. Specially designed capacitance gages were installed throughout the core to monitor the motion of the phreatic surface within the breakwater. A substantial reduction in the magnitude of the internal and external pressure field was found for a natural armoring breakwater compared with a conventional structure. In addition, this paper provides a detailed summary of research on naturally armoring breakwaters which has occurred during the past 150 years.

In this paper an alternative approach to the design of quarried stone breakwaters is discussed. The basic principal involved in this concept is the use of locally available materials. It is established that the greater the thickness of the armor layer, the smaller the stones that are required to provide stable protection against wave action. Therefore, the thickness of the armor layer for a specific breakwater is determined by the gradation of the available armor stones and the incident wave climate. The final cross-section makes allowance for the practical considerations of breakwater construction. New concepts for breakwaters that have resulted from the use of this alternative design procedure are described. Construction of these breakwaters in 1983-84 has demonstrated that significant cost savings are obtained.

A rational design procedure for rubblemound breakwater protection which will ensure both the structural integrity and hydraulic stability of individual concrete armor units and the overall armor system is presented. The procedure involves new experimental techniques for measuring strains in model concrete armor units in a hydraualic model of a breakwater subjected to simulated prototype wave attack and analytical techniques for determining equivalent prototype loads on units. Selected design loads are used to define the resultant stress distribution to allow the designer to take the necessary measures to ensure the structural performance of the unit in a breakwater environment.