Numerical modeling of effects of extreme precipitation and flooding on earthen levees under a changing climate

• Main Author: Jasim, Firas
• Format: Text
• Language: unknown
• Published: Scholars Junction 2019
• Subjects: Climate Change; numerical Modeling; Earthen Levees; Extreme Events; Sherman Island
• Online Access: https://scholarsjunction.msstate.edu/td/3327; https://scholarsjunction.msstate.edu/cgi/viewcontent.cgi?article=4326&context=td

Adaptation to climate change requires a careful evaluation of the infrastructure performance under extreme events in a changing climate. Earthen levees are critical infrastructure systems, which play a vital role to the country’s safety, environment, and economic security. The main objective of this study is to quantitatively assess the integrity of earthen levees subject to extreme precipitation and flooding under a changing climate. A multi-disciplinary modeling framework is developed and applied to two earthen levees, Elkhorn and Sherman Island levees, in California. Patterns of extreme precipitation and flooding are obtained for the study areas under current and future climate. A nonstationary framework is employed, which accounts for climate change-induced changes in statistics of future extreme precipitation. The precipitation and flooding data are then applied as hydraulic loads in a set of fully coupled stresslow finite element simulations to determine the factory of safety (FOS) and probability of failure (Pf) of the levees for different scenarios. The Pf values are used to develop fragility curves, which can provide valuable tools for risk assessments. The modeling framework is used to study three distinct yet interrelated problems. The first problem assesses the performance of the Elkhorn levee using historical and projected future precipitation patterns. The results show that Pf increases 3%-12% under the projected extreme precipitation compared to the baseline scenario. The second problem involves quantifying the effects of changes in future streamflow on the fragility behavior of the Elkhorn levee considering multiple modes of failure. For the cases examined, incorporating future floods leads to up to 23% reduction in FOS and 95% increase in Pf. The third problem assesses the fragility behavior of the Sherman Island levee under compound flooding (induced by coastal, fluvial and pluvial processes), an overlooked aspect in the majority of the existing flood hazard analyses. Results show that considering compound flooding leads to 22% and 30% reductions in FOS for 2- and 50-year recurrence intervals, respectively. Using the projected future pluvial flooding increases Pf by 13%. Findings of this research suggest that risk assessments based on historical records can significantly underestimate the levee’s Pf in a changing climate.