Case Studies

As an urbanized river-dominated delta, New Orleans, Louisiana, ranks among the most experimental of cities, a test of whether the needs of a stable human settlement can coexist with the fluidity of a deltaic environment—and what happens when they do not.

That natural environment bestowed upon New Orleans numerous advantages, among them abundant fresh water, fertile soils, productive wetlands and, above all, expedient passage between maritime and continental realms. But with those advantages came exposure to potential hazards—an overflowing Mississippi River, a tempestuous Gulf of Mexico, sinking soils, eroding coasts, rising seas, biotic invasion, pestilence, political and racial discord, conflagration—made all the worse by the high levels of social vulnerability borne by all too many members of New Orleans’ population. More so than any other major metropolis on the North American continent, this history of disaster and response is about the future of New Orleans as much as it is about the past.

This article examines two dozen disasters of various types and scales, with origins oftentimes traceable to anthropogenic manipulation of the natural environment, and assesses the nature of New Orleans’ responses. It frames these assessments in the “risk triangle” framework offered by David Crichton and other researchers, which views urban risk as a function of hazard, exposure, and vulnerability. “Hazard” implies the disastrous event or trauma itself; “exposure” means human proximity to the hazard, usually in the form of settlement patterns, and “vulnerability” indicates individuals’ and communities’ ability to respond resiliently and adaptively—which itself is a function of education, income, age, race, language, social capital, and other factors—after having been exposed to a hazard.

This is an advance summary of a forthcoming article in the Oxford Research Encyclopedia of Natural Hazard Science. Please check back later for the full article.

Hindu Kush is a high mountain system located in the immediate west of Karakorum and Himalayas. It is the greatest watershed of River Kabul, River Chitral, River Swat, and River Panjkora in Pakistan and the Amu River in Central Asia. The Hindu Kush system hosts numerous glaciers, snow-clad mountains, and fertile river valleys; it also supports a large population and provides year-round water to replenish streams and rivers. The study region is vulnerable to a wide range of hazards including floods, earthquakes, landslides, drought, and desertification. However, in the Hindu Kush region, riverine and flash floods frequently occur as well as extreme hydro-meteorological events. The upper reaches experience characteristics of flash floods, whereas the lower reaches experience river floods. In the upstream areas, flash floods are sudden and more destructive in nature. Every year in summer, monsoonal rainfall, together with the heavy melting of snow, ice, and glaciers accelerates discharge in rivers. Climate change has a strong relationship with trends in temperature and resultant changes in rainfall pattern and river discharge. In the wake of observed climate change, there is a rising trend in temperature, which indicates the early and rapid melting of snow and glaciers in the catchment areas. The analysis reveals that in the late 20th and early 21st centuries a radical change in behavior of numerous valley glaciers has been noted. Similarly, a fluctuation in the amount of snowfall occurrences together with its timing and seasonality has been recorded. In addition, the spatial and temporal scales of violent weather events have grown during the past thirty years. Such changes in water regimes including the frequent but substantial increase in heavy precipitation events and rapid melting of snow in the headwater region, siltation in active channels, excessive deforestation in the past three decades, human encroachments onto the active flood channel and the bursting of temporary dams have further escalated the flooding events. Analysis reveals that the Hindu Kush region is beyond the reach of existing weather RADAR network and hence flood forecasting and early warning is ineffective. In the study region, almost every year, the floodwater overflows the levees and causes damages to standing crops, infrastructure, sources of livelihood. And worst of all, there are human casualties.

Floodplains are ecologically diverse and important sources of livelihood for rural people. Bangladesh is one of the most floodplain-dominated countries and supports the highest density of rural population in the world. The experience of Bangladesh in floodplain management efforts provides evidence, lessons, and insights on a range of debates and advances in the management of floodplain natural resources, the challenges of climate change, and the role of local communities in sustaining these resources and thereby their livelihoods. Although floodplain areas are primarily used for agriculture, the significance and value of wild common natural resources—mainly fish and aquatic plants—as sources of income and nutrition for floodplain inhabitants has been underrecognized in the past, particularly with respect to poorer households. For example, capture fisheries—a common resource—have been adversely impacted by the building of embankments and sluice gates and by the conversion of floodplains into aquaculture farms, which also exclude poor subsistence users from wetland resources. More generally, an overreliance on engineering “solutions” to flooding that focused on enabling more secure rice cultivation was criticized, particularly in the early 1990s during the Flood Action Plan, for being top down and for ignoring some of the most vulnerable people who live on islands in the braided main rivers. Coastal embankments have also been found to have longer term environmental impacts that undermine their performance because they constrain rivers, which silt up outside these polders, contributing, along with land shrinkage, to drainage congestion. Locals responded in an innovative way by breaking embankments to allow flood water and silt deposition in to regain relative land levels.

Since the early 1990s Bangladesh has adopted a more participatory approach to floodplain management, piloting and then expanding new approaches; these have provided lessons that can be more general applied within Asia and beyond. Participatory planning for water and natural resource management has also been adopted at the local level. Good practices have been developed to ensure that disadvantaged, poor stakeholders can articulate their views and find consensus with other local stakeholders. The management of smaller water-control projects (up to 1,000 ha) has been taken on by community organizations, and in larger water-control projects, there is collaborative management (also called “co-management”) among a hierarchy of groups and associations and the appropriate government agency. In fishery and wetland management, many areas have been managed by community organizations to sustainably restore common resources, although their rights to do this were lost in some cases. Associated with community management are successful experiments in adopting a more system-based approach, called “integrated floodplain management,” which balances the needs of agriculture and common natural resources, for example, by adopting crops with lower water demands that are resilient to less predictable rainfall and drier winters, and enable communities to preserve surface water for wild aquatic resources. Bangladesh also has had success in demonstrating the benefits of systematic learning among networks of community organizations, which enhances innovation and adaptation to the ever-changing environmental challenges in floodplains.

With a continuous global increase in flood frequency and intensity, there is an immediate need for new science-based solutions for flood mitigation, resilience, and adaptation that can be quickly deployed in any flood-prone area. An integral part of these solutions is the availability of river discharge measurements delivered in real time with high spatiotemporal density and over large-scale areas. Stream stages and the associated discharges are the most perceivable variables of the water cycle and the ones that eventually determine the levels of hazard during floods. Consequently, the availability of discharge records (a.k.a. streamflows) is paramount for flood-risk management because they provide actionable information for organizing the activities before, during, and after floods, and they supply the data for planning and designing floodplain infrastructure. Moreover, the discharge records represent the ground-truth data for developing and continuously improving the accuracy of the hydrologic models used for forecasting streamflows. Acquiring discharge data for streams is critically important not only for flood forecasting and monitoring but also for many other practical uses, such as monitoring water abstractions for supporting decisions in various socioeconomic activities (from agriculture to industry, transportation, and recreation) and for ensuring healthy ecological flows. All these activities require knowledge of past, current, and future flows in rivers and streams.

Given its importance, an ability to measure the flow in channels has preoccupied water users for millennia. Starting with the simplest volumetric methods to estimate flows, the measurement of discharge has evolved through continued innovation to sophisticated methods so that today we can continuously acquire and communicate the data in real time. There is no essential difference between the instruments and methods used to acquire streamflow data during normal conditions versus during floods. The measurements during floods are, however, complex, hazardous, and of limited accuracy compared with those acquired during normal flows. The essential differences in the configuration and operation of the instruments and methods for discharge estimation stem from the type of measurements they acquire—that is, discrete and autonomous measurements (i.e., measurements that can be taken any time any place) and those acquired continuously (i.e., estimates based on indirect methods developed for fixed locations). Regardless of the measurement situation and approach, the main concern of the data providers for flooding (as well as for other areas of water resource management) is the timely delivery of accurate discharge data at flood-prone locations across river basins.

Media have always played an important role in times of emergency and disaster. Undersea cables, international news agencies, the press, radio and television, and, most recently, digital and mobile technologies—all have played myriad and complex roles in supporting emergency response and notification, and in helping constitute a shared experience that can be important to social mobilization and community formation. The geographical location of disasters and the identities of victims, the increasingly visual nature of disaster events, and the ubiquitous nature of media in our lives, all shape and influence which kinds of emergencies attract global media and public attention, and how we come to understand them.

Globalization has compressed time and space such that a whole range of disasters—from natural events (cyclones, earthquakes, and hurricanes) to industrial accidents and terrorist attacks—appear on our television and mobile screens with almost daily frequency. There is nothing inherent about these events that give them meaning—they occur in a real, material world; but for many of us, our experience of these events is shaped and determined in large part by our interactions with media industries, institutions, and technologies. Understanding the media’s construction of these events as disasters provides important insight into the nature of disaster mitigation, response and recovery.