3 Researches Seminar.docx

PRIORITIZING LEVEE IMPROVEMENTS

ABSTRACT

Meunier, Brian J. M.S.C.E., Purdue University, December 2011. Prioritizing Levee Improvements. Major Professor: Venkatesh Merwade.

Levees exist all over the United States, which protect land and property from devastating floods. Many of these levees are more than half of a century old, and were initially intended to serve as protection for farmland; however, increases in development and urban sprawl have caused a rise in the number of homes being sheltered by levees that were not designed with the necessary level of protection. A lack of inclusive record keeping and inspection has left many levees in dire need of costly repairs. This study attempts to define a practical and economical means of prioritizing levee repairs based on the economic risk posed by the breaching of impaired levees and the expected improvement costs for returning the levees to a safer condition. A framework for a simplified breach damage analysis is proposed through a case study of five levees in a flood-prone area in central Indiana. Current analysis methods are examined and compared to the proposed methodology.

Results of the case study provide a means of analytically prioritizing levee repairs, reveal pitfalls of the current standards of practice, and identify future research needs for advancement of the prioritization procedure. The use of an unsteady-flow analysis with storage areas to represent the protected areas is identified as a key component to a realistic characterization of the physical system. Comparisons between breach results, economic costs, and characteristics of the protected areas reveal no apparent correlations, suggesting a need for a ranking parameter. A Priority Ratio is identified in the case study results and suggested for use.

OPTIMAL DESIGN OF LEVEE AND FLOOD CONTROL SYSTEMS

ABSTRACT

Flooding often threatens riverine and coastal areas, particularly urbanized flood-prone areas that are densely populated and high-valued, which causes damages to life, property, society and the economy. Upstream flood reservoir operations and downstream levee construction are two common ways to protect from flooding. Most traditional risk-based analyses for optimal levee design focus primarily on overtopping failure, and few risk analysis studies explicitly include the more frequently observed intermediate geotechnical failures. This study first develops a riskbased optimization model for single levee designs given two simplified levee failure modes: overtopping and overall intermediate geotechnical failures. The optimization minimizes the annual expected total cost, which sums the expected annual damage cost and annualized construction cost. This optimization model is then extended to examine a common simple levee system with levees on opposite riverbanks, allowing flood risk transfer across the river. The economic optimality of asymmetric levee system is demonstrated mathematically and analytically, for overtopping failure, overall intermediate geotechnical failure and a combination of failure modes. Where residual flood risk is completely transferred to the low-valued riverbank at economic optimality, individuals may be compensated for the transferred flood risk to guarantee and improve outcomes for all parties. Such collaborative designs of the two levee system are economically optimal for the whole system. However, rational and self-interested land owners that control levees on each river bank separately often tend to independently optimize their levees. By applying game theory to the simple levee system, the cooperative game with a system-wide economically optimal design and the single-shot noncooperative Nash equilibrium are identified, and the successive repeated non-cooperative reversible and irreversible games are examined. Compensation for the transferred flood risk can be determined by comparing different types of games and implemented with land owners’ agreements on allocations of flood risk and benefits. The resulting optimized flood risks to a downstream leveed area would further affect the upstream reservoir’s operation in optimizing flood hedging prereleases, which would create a small flood downstream by pre-storm release to reduce the likelihood of a larger more damaging flood in the future.

PROTOTYPING AND TESTING OF NOVEL FLOOD PROTECTION SYSTEMS

ABSTRACT

The market for flood protection systems has seen considerable growth in recent years. In the wake of global natural disasters with increasing frequency and severity, the demand for flood protection solutions is increasing. AquaFence is a Norwegian company specializing in development and production of flood protection systems that are tested and certified according to international standards. The company is currently offering temporary medium- and large-scale systems. Since AquaFence’s current products are mainly intended for large-scale applications and extreme flood levels, it is desirable to develop a new, inexpensive system targeted at the consumer market.

This thesis describes the early development stages of novel consumer flood protection systems. The development process has emphasized prototyping and experimentation as a strategy to front-load the development, which is outlined by a literature study. A framework for the development and a set of quantitative and qualitative measures for the systems being designed were established. The development has been based on rigid-flexible hybrid systems, combining desired aspects from each.

As consumer flood protection systems represent an immature market with little knowledge to base the development on, generating and capturing knowledge has been a priority. Furthermore, the thesis describes the development and application of a program for capturing and reusing the knowledge obtained during this project. Knowledge was primarily gained through prototyping and by designing and conducting experiments. The feasibility of using PVC canvas in hybrid systems in terms of stability was investigated. The test setup used to investigate this also showed great potential for testing overall stability of systems. In addition, a new innovative way for testing gaskets, independent of system design, was designed and performed. Lastly, the thesis describes two promising concepts for consumer flood protection systems and points out further work that needs to be completed in order to move the products towards industrialization.