Lufthansa Kanta

Virtual Cities for Water Distribution and Infrastructure System Research

In a society concerned over the possibility of terrorism, secrecy , and security of infrastructure data is crucial. However, research on infrastructure security is difficult in this environment since experiments on real systems can not be publicized. “Virtual cities” are one potential answer to this problem, and a library of these virtual cities is now under development. “Micropolis” is a virtual city of 5000 resi dents fully described in both GIS and EPANet hydraulic model frameworks. To simulate realism of infrastructure, a developmental timeline spanning 130 years was included. This timeline is manifested in items such as pipe material, diameter, and topology. An example of using the virtual city for simulation of fire protection is presented. The data files describing Micropolis are avail able from the authors for other s’ use. A larger city, “Mesopolis,” is currently under development and will incorporate add itional critical infrastructure dependencies such as electrical power grids and communications. This will supplement the development of further models to account for risks and probability of electrical power failure due to hurricane events. It is hoped t hat Micropolis, Mesopolis , and additional virtual cities will serve as a “hub” for the development of further research models.

Complex Adaptive Systems Framework to Assess Supply-Side and Demand-Side Management for Urban Water Resources

AbstractThe availability of water resources in many urbanizing areas is the emergent property of the adaptive interactions among consumers, policy, and the hydrologic cycle. As water availability becomes more stressed, public officials often implement restrictions on water use, such as bans on outdoor watering. Consumers are influenced by policy and the choices of other consumers to select water-conservation technologies and practices, which aggregate as the demand on available water resources. Policy and behavior choices affect the availability of water for future use as reservoirs are depleted or filled. This research posited urban water supply as a complex adaptive system (CAS) by coupling a stochastic consumer demand model and a water supply model within an agent-based modeling (ABM) framework. Public officials were simulated as agents to choose water conservation strategies and interbasin transfer strategies, and consumers were simulated as agents, influenced by various conservation-based programs to...

Complex adaptive systems approach to simulate the sustainability of water resources and urbanization

AbstractUrban water resources should be managed to meet conflicting demands for environmental health, economic prosperity, and social equity for present and future generations. While the sustainability of water resources can depend on dynamic interactions among natural, social, and infrastructure systems, typical water resource planning and management approaches are based on methodologies that ignore feedbacks and adaptations among these systems. This research develops and demonstrates a new complex adaptive systems approach to model the dynamic interactions among population growth, land-use change, the hydrologic cycle, residential water use, and interbasin transfers. Agent-based and cellular automaton models, representing consumers and policymakers who make land- and water-use decisions, are coupled with hydrologic models. The framework is applied for an illustrative case study to simulate urbanization and the water supply system over a long-term planning horizon. Results indicate that interactions amon...

Vulnerability, Risk, and Mitigation Assessment of Water Distribution Systems for Insufficient Fire Flows

AbstractWater distributions systems must reliably supply water for fire-fighting needs as well as everyday demands but are vulnerable to a range of failure types that can compromise both functions. A methodology is presented integrating failure probability, risk analysis, and optimization of risk that can be used to assess system vulnerabilities and potential mitigation actions. To demonstrate multiple failure mode analysis, three failure types are included: accidental failure due to soil-pipe interaction, accidental failure due to a seismic event, and malevolent attack. A risk-optimization algorithm is implemented using dynamic programming to identify the failure scenarios having the greatest consequences and probability rather than focusing on just one aspect of vulnerability. Finally, potential mitigation strategies are assessed in a benefit-cost-risk reduction analysis. The methodology is intended as a practicable means for infrastructure managers to assess and address system vulnerabilities in a real...

An agent-based modeling approach to evaluate the impact of conservation practices on water resources sustainability.

The availability of water resources in many urbanizing areas is the emergent property of the adaptive interactions among consumers, policy, and the hydrologic cycle. As water availability becomes more stressed, public officials often implement restrictions on water use, such as bans on outdoor watering. Consumers are influenced by policy and the choices of other consumers to select water conservation technologies and practices, which aggregate as the demand on available water resources. Policy and behavior choices impact the availability of water for future use as reservoirs are depleted or filled. This research posits urban water supply as a Complex Adaptive System (CAS) by coupling a consumer end use model and a water supply model within an agent-based modeling (ABM) framework. Public officials are simulated as agents to choose water pricing structures, and consumers are simulated as agents, influenced by water prices and the choices of other consumers, to select water conservation technologies and behaviors, and correspondingly update their individual end use models. A water supply reservoir is simulated to receive rainfall from the contributing watershed and supply the demands of consumer agents. The ABM framework is applied to an illustrative urban case study. A set of water pricing structures are developed to represent risky and risk-averse policies and are simulated for a long-term precipitation record to evaluate the sustainability of water conservation practices.

A Multi-objective Evolutionary Computation Approach to Hazards Mitigation Design for Water Distribution Systems

One of the critical public safety roles for water distribution systems (WDS) is suppression of urban fire events. Previous studies have investigated WDS rehabilitation for mitigation of potential fire events with a major focus on improving fire flows by pipe enlargement. However, pipe enlargement can cause water quality problems and place public health at risk during normal operational periods. Thus a novel approach is required to effectively address the conflicting goals of the WDS: reliable delivery of water during normal as well as emergency conditions, meeting water quality standards, and finding cost-effective design and rehabilitation options. In this study an evolutionary computation-based multi-objective optimization-simulation framework is developed to design effective mitigation strategies for urban fire events for water distribution systems with three objectives: (1) minimizing fire damages, (2) minimizing water quality deficiencies, and (3) minimizing the cost of mitigation. An elitist non-dominated sorting genetic algorithm (NSGA-II) is modified by incorporating an evolution strategy (ES) to address difficulties for heuristic algorithms posed by WDS problems. Implementation of this methodology generates Pareto-optimal solution surfaces that express the trade-off relationship between fire damage, water quality, and least cost objectives. Thus, the method provides decision makers with the flexibility to choose a mitigation plan for urban fire events best suited for their circumstances. Each Paretooptimal solution comprises a set of pipes to be enlarged to achieve increased fire flow and the corresponding diameters of these pipes. The algorithm is illustrated with several test functions. The Micropolis virtual city is then used to demonstrate the application of the proposed methodology to a complex WDS.