A Systems Reliability Approach to Flow Control in Dam Safety Risk Analysis

Most contemporary risk assessment techniques, such as failure modes and effect analysis (FMEA), fault tree analysis (FTA), and probabilistic risk analysis (PRA) rely on a chain-of-event paradigm of accident causation. Event-based techniques have some limitations for the study of modern engineering systems; specifically hydropower dams. They are not suited to handle complex computer-intensive systems, complex human-machine interactions, and systems-of-systems with distributed decision-making that cut across both physical and organizational boundaries. The emerging paradigm today, however, is not to analyze dam systems separately by breaking the major disciplines into stand-alone vertical analyses; but to explore the possibilities inherent in taking a systems approach to modeling the reliability of flow-control functions within the entire system. This dissertation reports on the development and application of systems reliability models to operational aspects of a hydropower cascade in Northern Ontario: The Lower Mattagami River (LMR) Project operated by Ontario Power Generation (OPG). The reliable performance of a spillway system depends on the many environmental and operational demand functions placed upon it by basin hydrology, the hydraulic conditions at reservoirs and dams, operating rules for the cascade of reservoirs in the basin, and the vagaries of human and natural factors such as operator interventions or natural disturbances such as ice and floating debris (Regan, 2010). These systems interact to control floods, condition flows, and filter high frequencies in the river discharge. Their function is to retain water volumes and to pass flows in a controlled way. The reliability of flow-control systems is a broad topic that covers structural, mechanical, electrical, control systems and subsystems reliability, as well as human interactions, organization issues, policies and procedures. All 3 of these occur in a broad spectrum of environmental conditions. A systems simulation approach is presented for grappling with these varied influences on flow-control systems in hydropower installations. The Mattagami River cascade operated by Ontario Power Generation is a series of four power stations along the Mattagami River and the Adams Creek bypass channel from Little Long GS at the top to the cascade to the Mattagami River below Kipling GS at the bottom. The number of riparians in the river flood plain is few and there is no commercial riverine navigation, so potential loss of life is small or negligible and operational safety dominates. Upstream of Little Long dam is a seasonally-varying inflow and a reservoir. The remaining three dams downstream (Smokey Falls, Harmon, and Kipling) have little storage capacity. Each dam has two vertical lift gates and all four structures have approximately the same spillway capacity. Far downstream, the river discharges into Hudson's Bay. Hydrological and climate frequency data are available for a period of 50 years. The problem facing the project was to conceptualize a systems engineering model for the operation of the dams, spillways, and other components; then to employ the model through stochastic simulation to investigate protocols for the safe operation of the spillway and flow control system. Details of the modeling, analysis, and results for safe operation of the cascade are presented

A SYSTEMS RELIABILITY APPROACH TO MODELING OPERATIONAL RISKS IN COMPLEX ENGINEERED SYSTEMS

Since the beginning of the industrial revolution in the late 18th century, the cause of many serious accidents in hydrosystems engineering has shifted from natural causes to human and technology related causes as these systems get more complex. While natural disasters still account for a significant amount of human and material losses, man-made disasters are responsible for an increasingly large portion of the toll, especially in the safety critical domain such as Dam and Levee systems. The reliable performance of hydraulic flow-control systems such as dams, reservoirs, levees etc. depends on the time-varying demands placed upon it by hydrology, operating rules, the interactions among subsystem components, the vagaries of operator interventions and natural disturbances. In the past, engineers have concerned themselves with understanding how the component parts of dam systems operate individually and not how the components interact with one another. Contemporary engineering practices do not address many common causes of accidents and failures, which are unforeseen combinations of usual conditions. In recent decades, the most likely causes of failures associated with dams have more often had to do with sensor and control systems, human agency, and inadequate maintenance than with extreme loads such as floods and earthquakes. This thesis presents a new approach, which combines simulation, engineering reliability modeling, and systems engineering. The new approach seeks to explore the possibilities inherent in taking a systems perspective to modeling the reliability of flow-control functions in hydrosystems engineering. Thus, taking into account the interconnections and dependencies between different components of the system, changes over time in their state as well as the influence upon the system of organizational limitations, human errors and external disturbances. The proposed framework attempts to consider all the physical and functional interrelationships between the parts of the dam and reservoir, and to combine the analysis of the parts in their functional and spatial interrelationships in a unified structure. The method attempts to bring together the systems aspects of engineering and operational concerns in a way that emphasizes their interactions. The argument made in this thesis is that systems reliability approach to analyzing operational risks—precisely because it treats systems interactions—cannot be based on the decomposition, linear methods of contemporary practice. These methods cannot logically capture the interactions and feedback of complex systems. The proposed systems approach relies on understanding and accurately characterizing the complex interrelationships among different elements within an engineered system. The modeling framework allows for analysis of how structural changes in one part of a system might affect the behavior of the system as a whole, or how the system responds to emergent geophysical processes. The implementation of the proposed approach is presented in the context of two case studies of US and Canadian water projects: Wolf Creek Dam in Kentucky and the Lower Mattagami River Project in Northern Ontario

Evaluation of nutritional quality of tropical and temperate forages

Background: Grasses (Poaceae) and herbaceous legumes (Fabaceae) are the usual forages used in animal production. They can be categorised into temperate (C3/cool-season) and tropical (C4/warm-season). Forage crops with C3 photosynthetic pathways (temperate forages) are more nutritious than those with C4 (tropical forages). Aim: To evaluate the nutritional quality of tropical and temperate forages. Design and methods: Data were gathered for four (4) tropical forage crops (legumes; Stylosanthes guianensis and Centosema pascuorum versus grasses; Biachiara decumbens and Pennisetum purpureum) from 11 scientific publications. To be added, the publication had to contain at least data on crude protein, neutral detergent fibre, acid detergent fibre and dry matter. Forage samples were analysed using methods proposed by AOAC (1990 and 2011), Goering and Van Soes (1970), Silva and Queiroz (2002), Van-Soest et al. (1991). For temperate forage, the method was as follow: The study was done at the Research Station of Fodder Crops in Vatin (49o31'N, 15o58'E, 560 m.a.s.1) located in the Czech Republic. Medicago sativa (alfalfa) and Trifolium pratense (meadow /red clover) were the legume forages used. The grass species were Lolium perenne (perennial ryegrass) and Dactylis glomerata (cock's foot). The legumes were harvested before flowering (butonization), and the grasses were harvested at the boot stage. Samples of each forage species were analysed for crude protein (CP), neutral detergent fibre (NDF), acid detergent fibre (ADF) and dry matter (DM). SPSS (version 20) was used to analyze the data gathered, as well as analysis of variance (ANOVA). The differences in the nutritive values between crop types within the same group (tropical grass/legume and temperate grass/legume) were analysed using independent sample t-tests (SPSS). The differences in nutrients between temperate and tropical forages were analysed using ANOVA and Tukey's pairwise comparison test. For all analyses, the statistical significance threshold was fixed at P 0.05. Results: There were significant differences observed in the nutrients among the forage legumes. The CP content for Centro (C.pascuorum) was significantly more than that of stylo (S.guianensis); 14.83a ± 0.84 vs 11.32b±0.84 respectively (P-value= 0.02 from Tukey's pairwise comparison). Also, significant differences were observed among the forage grasses. The ADF content for signal grass was significantly more (40.68a ± 1.06) compared to cock's foot grass (32.39b ± 2.25) (P-value=0.011 from Tukey's pairwise comparison). Conclusion: The study resulted in temperature forages having better nutritional quality than tropical forages

3-4 Identity, Protest, and Social Media

Chair: Hannah Ascough, Queens University Hannah Ascough, Queens University ([email protected]). Ubuntu, Twitter, and a Just Transition: Exploring South African environmental charity responses to the COVID-19 and climate crises Nii Ayitey Komey, University of Ghana ([email protected]). Hashtag Pan-Afrikanism: A new Afrikan identity is being created on Twitter Felix Oyosoro, Obong University ([email protected]). “Clicks for Clacks”: Malwares as Tools of Asymmetric Warfare and a Source of Digital Power; Is Africa offside? Esther Ekong, University of Ottawa ([email protected]). A Frugally innovated Africa: Ubuntu vs. the protection of intellectual property rights. Meeting ID: 912 7895 766

Systems reliability of flow control in dam safety

The reliable performance of a spillway system depends on the many environmental and operational demand functions placed upon it by basin hydrology, the hydraulic conditions at reservoirs and dams, operating rules for the cascade of reservoirs in the basin, and the vagaries of human and natural factors such as operator interventions or natural disturbances such as ice and floating debris. These systems interact to control floods, condition flows, and filter high frequencies in the river discharge. Their function is to retain water volumes and to pass flows in a controlled way. A systems simulation approach is presented for grappling with these varied influences on flow-control systems in hydropower installations. The river system studied is a series of four power stations in northern Ontario. At the head of the cascade is a seasonally-varying inflow. The remaining three dams downstream have little storage capacity. Each has two vertical lift gates and all four structures have approximately the same spillway capacity. The problem is to conceptualize a systems engineering model for the operation of the dams, spillways, and other components; then to employ the model through stochastic simulation to investigate protocols for the safe operation of the spillway and flow control system.Non UBCUnreviewedThis collection contains the proceedings of ICASP12, the 12th International Conference on Applications of Statistics and Probability in Civil Engineering held in Vancouver, Canada on July 12-15, 2015. Abstracts were peer-reviewed and authors of accepted abstracts were invited to submit full papers. Also full papers were peer reviewed. The editor for this collection is Professor Terje Haukaas, Department of Civil Engineering, UBC Vancouver.FacultyOthe