For the Instructor

These student materials complement the Coastal Processes, Hazards and Society Instructor Materials. If you would like your students to have access to the student materials, we suggest you either point them at the Student Version which omits the framing pages with information designed for faculty (and this box). Or you can download these pages in several formats that you can include in your course website or local Learning Managment System. Learn more about using, modifying, and sharing InTeGrate teaching materials.

Initial Publication Date: December 7, 2016

Module 10: Understanding and assessing coastal vulnerabilities

Overview

Why do coastal hazards cause more damage and suffering in some places than in others? As you have already learned in this course, this is a complex and difficult question. Answering it requires understanding how the local frequency and intensity of these hazards interacts with a diverse set of coastal processes, landforms, infrastructure, and social systems to harm people and things they value. Yet answering this question is also essential for policy making. If governments and other coastal decision makers would like to prioritize spending and other scarce resources to protect their most vulnerable people, places, and property, then they must understand where damage and suffering are likely to be greatest.

For example, imagine that a policy maker at the United Nations has been asked to determine how best to invest $100 million to reduce vulnerability to tropical cyclones. As you now know, many factors contribute to the significant regional variation in the death and destruction caused by tropical cyclones, making it difficult to determine where it would be best to invest these resources. Tropical cyclones are common in some ocean basins (such as the Pacific and the North Atlantic), rare in others (such as the South Atlantic), and absent in still others (such as the Arctic), so it may be sensible for the policy maker to focus her investment in areas with more storms. Even where storms are common, they will only cause harm if they affect areas where people or things that they value are located; thus, our policy maker might also consider population density as an additional criterion for investment.

However, when a storm does strike a populated area, the amount of harm caused will depend on a complex interaction among several local physical and social factors. Long, narrow bays may worsen storm surge (as was observed during Sandy on the Long Island Sound), while certain kinds of coastal vegetation (such as mangroves) may protect coastal property from rising water. As seen during Hurricane Katrina, evacuation orders can save lives, but only if people have access to transportation, housing, and other resources needed to leave their homes and live elsewhere. And, as Typhoon Haiyan demonstrated, devastation can be extreme when a strong storm hits an area where buildings are built in hazard zones and are not designed to withstand high winds or surge. Thus, to assess vulnerability effectively, compare the vulnerability of different people and places, and allocate resources accordingly, our policy maker would first need a consistent way to integrate these many factors into an overall vulnerability assessment.

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Tsunami Vulnerability

While the above example involves vulnerability to tropical cyclones, assessing vulnerability to other coastal hazards is often just as challenging. Drawing on what you have already learned in the course:

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Question - Essay

Brainstorm three factors that you think are important in explaining the regional variation in damage and suffering caused by tsunami. Based on these factors, which countries or major cities do you think are most vulnerable to tsunami?

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ANSWER:
There are many reasons why some areas may experience more damage and suffering from tsunami than others. For example, countries with shorelines on seismically active ocean basins – such as countries around the Pacific Ocean's "ring of fire" – generally experience more frequent and damaging tsunami than countries with shores bordering less seismically active basins, such as the Atlantic. Coastal topography also plays a role: coasts with cliffs or steep slopes will experience less damage from tsunami than coasts with gradual slopes or flat terrain. Human factors that may affect the severity of damage and injuries include building quality, warning systems, and the strength of local institutions for disaster preparedness and response.

To address policy makers' needs, physical and social scientists have worked together to develop vulnerability models and assessments. While many different models and assessments have been proposed, for the purposes of this course we will use a three-dimensional model that is popular with policy makers and has been adopted by the Intergovernmental Panel on Climate Change. In our model, vulnerability refers to the degree to which people or the things they value are susceptible to, or are unable to cope with, the adverse impacts of coastal hazards. As explained in the next section, vulnerability is a product of its three dimensions: exposure, sensitivity, and adaptive capacity. While vulnerability has been used previously in this course to describe general susceptibility to harm from coastal hazards, in this and all subsequent modules this more precise definition will be assumed.

This module provides an introduction to vulnerability, its three dimensions, and a standard vulnerability assessment tool. In the following modules, you will learn how this vulnerability model and assessment tool can guide policy making for both acute coastal hazards (such as hurricanes and tsunami) and chronic coastal hazards (such as sea level rise).