Engineering topics

McPherson, Timothy N.

Publications and source records attributed to McPherson, Timothy N..

4 records

DOE OSTI2023

Extremely rapid, Lagrangian modeling of 2D flooding: A rivulet-based approach

Estimates of potential flood inundation areas and depths are critical to informing the preparedness, response, and investment decisions of many government agencies and private sector organizations, especially under a changing climate. The standard modeling approaches, however, are often either computationally intensive or constrained in their accuracy or applicability. A novel, rivulet-based, 2D model of pluvial flooding is described in this article that is 10,000 to 10 million times less computationally complex than the full solution of the shallow water equations, yet achieves inundation area hit rates of between 0.8 and 0.9 and relative absolute mean errors of 10%-20% across a wide range of flow depths. This combination of accuracy and efficiency will enable real-time depth estimates during flood events, detailed sensitivity analyses, and the generation of large ensembles to support broad uncertainty analyses.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2020

Evaluating Resilience of Water Distribution Networks to Operational Failures from Cyber-Physical Attacks

Water cyber-physical systems (CPSs) have gained increasing interest to improve operational efficiency and reliability. However, due to growing exposure to cyber-physical attacks, cybersecurity and resilience against the attacks have become significant concerns. There have been efforts to improve cybersecurity in water CPSs, yet few attempts to investigate resilience against cyber-physical attacks. This study contributes to characterizing resilience of a water CPS and investigating potential resilience strategies. An advanced resilience measure integrating withstanding, absorptive, adaptive, and restorative capability of a system is proposed and applied to the C-town water distribution network (WDN) for 15 failure set scenarios with a pressure-driven hydraulic simulation. The results provide identification of failure sets and unfavorable operational conditions that make the system more vulnerable to the cyber-physical attacks and in turn produce low resilience and capabilities. It is also found that, after recovery of a disrupted component, adjustment of overall operational interactions across system components is needed for complete restoration of disrupted functionality. The findings provide insights on infrastructure investment with resilience strategies in cyber and physical water system domains.

Shin, Sangmin↗

DOE OSTI2018

A partition of the combined impacts of socioeconomic development and climate variation on economic risks of riverine floods

Nonstationarities in both climate and socioeconomic systems play a role in flood risk. Based on a data-driven case study in an urbanized watershed subjected to nonstationary factors in climate (rain, snow, and rain on snow) and socioeconomic conditions (e.g., built environment market changes), a multi-scale, multi-model approach was adopted to develop local-scale flood hazard predictions and an analytical framework was developed to quantify the associated flood risk. The case study shows that socioeconomic development can have a comparable contribution as climate variability when evaluating the expected annual damage. Here, the relative contributions from socioeconomic development, in some cases, do not necessarily compound the risk, but can, in fact, act as a mitigating factor in annualized risk. Timelines of risk management planning are an important factor to consider. Socioeconomic factors such as market value can produce non-linear and reversed trends in flood impact assessments within the 10-year time frame. Further, the nonstationarity of climate and development conditions together was shown to cause up to 43% of the variation in risk estimates and up to 70% of the variation in the benefit-cost effectiveness.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2018

Detectability-Based Resilience of Water Distribution System Using Failure Finger Print

This study introduces a detectability-based sensor localizing framework to enhance the resilience of water distribution systems. The framework includes leakage detection and resilience assessment. A feasibility test and a sensitivity analysis prove the framework successfully can detect correct leakage location. The resilience measure was found to increase for higher detectability and shorter identification time. The sensor location is constrained by minimizing the number of sensors and maximizing the detectability and resilience. Results show that two sensors will efficiently detect burst leakage in the studied network. Detectability varies from 71.3% to 99.4% depending on the location of two sensors, while resilience value was reduced by 7.5%. Estimated water loss due to detection time lag are almost 111 ML, which may lead to significant direct and indirect economic loss.

Lee, Seungyub↗