Engineer Research and Development Center - Environmental Laboratory

Risk and Decision Science Team

Compounding Threats

DESCRIPTION

Quantifying resilience measures for interconnected compounding threats. ERDC has identified a need for multi-hazard approaches to risk and resilience modeling for compounding threats. The threats posed by hazards, whether natural or manmade, are typically addressed separately for modeling purposes. However, when these threats occur concurrently, they can have non-linear impacts on communities. An integrated approach is needed to quantitatively model the complex interactions between compounding threats for a collective response because an appropriate response to a single threat alone can worsen the impacts of the other threat.


CASE STUDY: Enhancing Community Resilience through Accessibility of Critical Infrastructures - New York City

The goal of the New York City case study was to develop a tool to quantify resilience of the emergency management system. The system consists of the road network and locations of critical infrastructures. The critical function for the system is to provide accessibility of critical infrastructures. Disruptions of the system were modeled by degradation of road segments.

A line graph with y-axis labeled Critical Function (System Performance) with no intervals and x-axis labeled with a blue arrow to the right with sections labeled Plan, Absorb, Recover, and Adapt. Above that on the x-axis are intervals of t0 (Impact), t1 (Peak), and t2 (Recovered) for Time. The graph is divided with a vertical dashed line about 1/4 from the left with the first section labeled in blue as Normal times. A black line with tight sine waves comes from the left through that section them dips like a wave in the central section. The central section is about 2/3 of the width followed by another vertical dashed line, labeled with red text reading Under Crisis. the black graphline starts to recover upwards and back into the sine wave pattern on the right section. THe far right is about 1/4 of the field and is again labeled Normal times.

Critical Function (System Performance): How accessible are critical infrastructures by the road network?

Three map images labeled Road Network G=(V,E), Critical Points P-{p1,..., pN}, and Accessible Regions. Each map shows highlighted issues: first Nodes V: Road Intersections, then Points P: Critical Infrastructure Locations, then Green Nodes: Accessible Regions Red Nodes: Inaccessible Regions.
Two map images labeled Different Types of Critical Infrastructures. THe left map is covered with scattered dots of Orange-EMS Station, Red - Fire Stations, Green - Hospitals, and Blue - Police Stations. An arrow labeled Accessibility Analysis for each Critical Infrastructure points to the right map. The right map has areas circled with red and orange colors labeled Underserved Regions. A key is headed Number of Services with red (0), orange (1) yellow (2), green (3), and blue (4).
New York City was evaluated for normal operating times access to emergency services and underserved regions were identified.

Threat Modeling: In rare cases, disruptions to New York City will occur and they will reduce the functionality of the city. These artificial or natural disruptions are modeled by degradation of road segments. The roads affected by disruptions are impassible, causing increase in travel time and reduction in accessibility.

Three maps. The first is headed Beginning of flood and shows blue water line encroaching from the shoreline. The center map is titled Intermediary Flood and shows continued encroching waters with red lines indicating damaged roads. The third map is headed Peak of the flood and shows even further water inundations and more severere road damage.

Crisis Modeling: Which regions lose emergency services?

Three maps titled Beginning of the Flood, Intermediary Flood, and Peak of the Flood. Beneath is a key for Green: Maximum Accessibility, Yellow: Medium Accessibility, Orange: Minimal Accessibility, and Red: No Access. The first map shows edges of mostly orange and yellow marking. The center shows many red markings, and the right map shoes dense red markings with Areas circled and labeled Previously Underserved Regions and Emerging Underserved Regions.

Under such crisis, we again measure the accessibility to critical infrastructures. Depending on the severity of the threat, we may see additional vulnerable regions or worsening of existing vulnerable regions. Analyzing the rate of degradation characterizes the absorption phase which is essential to quantifying resilience. Another essential piece in quantifying resilience is the recovery phase.


Problem

How to quantify resilience of the emergency management system. ERDC has identified a need for multi-hazard approaches to risk and resilience modeling for compounding threats. The threats posed by hazards, whether natural or manmade, are typically addressed separately for modeling purposes.


Solution

Under such crisis, we again measure the accessibility to critical infrastructures. Depending on the severity of the threat, we may see additional vulnerable regions or worsening of existing vulnerable regions. Analyzing the rate of degradation characterizes the absorption phase which is essential to quantifying resilience. Another essential piece in quantifying resilience is the recovery phase.


Impact

Quantifying resilience measures for interconnected compounding threats.