Cover Image
close this bookIDNDR - Informs - Number 09-10, Special Edition, 1996 (IDNDR)
close this folderSpecial topic
View the document(introductory text...)
View the documentForum: Cities at risk: Environmental degradation and urban disasters
View the documentForum: South America's local governments and disaster management
View the documentParaguay: Pilot project on Asuncion's coastal fringe
View the documentInternational seminar on the role of local governments in disaster prevention and mitigation 23-25 April, 1996
View the documentGovernment of Costa Rica promotes risk reduction program for vulnerable communities
View the documentFirst south American conference on local governments and organizations confronting disasters and emergencies

Forum: Cities at risk: Environmental degradation and urban disasters

Allan Lavell
Latin American Federation of Social Sciences (FLACSO) Secretariat, "LA RED", Costa Rica

Currently, 75% of the Latin American population lives in urban environments. By the year 2025, according to United Nations projections, this ratio will increase to 85%. Urban economies in the region account for between 60% and 80% of the Gross National Product.

The great majority of the region's largest cities (not to mention medium-sized and small cities) are located in areas at risk from a variety of natural hazards, particularly earthquakes, floods, landslides and tidal waves.

Historically, the propensity of many cities to disasters has been well documented, from the destruction of Lima (1746) and Antigua Guatemala, to the more recent seismic disasters in Huaraz, Peru (1970), Managua (1972), Guatemala City (1976), Popayán (1984), Mexico City (1986) and San Salvador (1986); the great floods of Buenos Aires (from 1985 onwards); the massive landslides in Rio de Janeiro, Bahia and Recife in Brazil (1988 onwards), and the destruction of Armero, Colombia by a mud-slideMud-slide?, the result of the eruption of Nevado de Ruiz Volcano in 1985.

The risk factors and potential disasters to which cities are exposed by the interaction of natural events, aggravated by a vulnerable social environment, are complicated still further by the rapid evolution of a series of risks posed by the processes of industrialization and changes in transportation and commercial patterns typical of a "modern" economy. The threats are compounded by the very growth of cities, which often occurs in an anarchic, laisser faire fashion, without adequate controls over the process of urban development. The damage and loss of life caused by the explosions of a gas pipeline in Northern Mexico City in 1984, of gas pipelines in Guadalajara (1992), and most recently of a shopping center in Sao Paulo, are simply the most notorious anthropic disasters of the past decades. But no less significant, in terms of urban risk, are the high levels of air, water and soil pollution in many cities of the region, particularly Mexico City, Sao Paulo, Lima, and Santiago, which pose a direct threat to the health of the population. One should not leave out the growing number of catastrophic urban fires, or even the devastation wrought by urban terrorism, e.g., the activities of armed groups in Lima or the destruction of the Jewish Center in Buenos Aires.

Events of great magnitude such as those mentioned above capture the national and international headlines. But cities are exposed on a daily basis to smaller-scale risks which are, however, growing in frequency and intensity. These are laying the ground for future events of greater magnitude; what is more, their cumulative impact may well exceed that of a single event of great magnitude but relatively rare occurrence.

Settlement density, centralization and concentration, the interdependent nature of urban functions, and the synergy generated by a city, make it inevitable that the impact of certain physical events will have profound repercussions not only for the urban structure itself but at the regional, national, and potentially international level. The trend towards the concentration of poverty in cities remains unchecked, with all sorts of dramatic implications for the vulnerability of the population. In addition, the trend towards urban predominance will continue in the foreseeable future. It is highly likely that urban infrastructure will l double in the next 25-35 years. Exposure to risk will increase accordingly, as will the likelihood of greater absolute losses. The growth in the number and variety of hazards which has characterized the last 30 years will tend to continue; in fact, it will be aggravated by the potential impact of climate changes and changes in the ocean level associated with atmospheric pollution and the thinning of the ozone layer. The coastal location of a significant number of key urban centers in Latin America and the Caribbean would then become an additional risk factor.

Until now, urban disaster assessment has focused on the losses suffered, the social and economic impact of events, and the response of the State and civil society, with some attention paid to the question of social vulnerability. When looking at hazards, research has concentrated on those described as natural (particularly earthquakes, volcanic eruptions and hurricanes), using as its tools inventories and maps forecasts and predictions. predictions These approaches are no longer sufficient, either in terms of research, or from the point of view of trying to provide feedback to decision-makers and the general public about the options available for prevention and mitigation in the future.

From our perspective, the problem of urban risk and disasters must be understood within a broader framework of urban environmental degradation and management, and which cannot ignore intricately interconnected factors at the urban-regional level. Degradation, in this sense, involves "a reduction in degree" and "changes in a system's homeostasis", such that the urban system in questions suffers from a reduction of its productivity. When looking at the urban environment (and the urban-regional environment), we would not only be thinking of the natural environment or ecosystem, but also of the socially constructed environment: the city and its physical structures, its social and cultural patterns, and so on.

The importance of such an approach is made clear by the recognition of two irrefutable facts.

First, even accepting the great destructive or disruptive potential of natural events of great magnitude, such as quakes, volcanic eruptions and hurricanes, it is likely that the most persistent and perceptible urban hazards are created by human action, even if they have a "natural" manifestation. An example would be the floods caused by deforestation, silting in river-beds, and the blockage of canals by solid-waste deposits. Further examples would be the landslides produced by the undermining of slopes, or the urban "droughts" caused by the irrational and competitive use of water resources Such "socio-natural " hazards, as well as others related to anthropic pollution or technology, are problems faced every day by decision makers and the general public. Great earthquakes or hurricanes, on the other hand, are sporadic and relatively infrequent. Moreover, anthropic hazards can by definition be controlled by human action. It would certainly be possible to develop effective reduction policies, so long as there is a clear understanding of causes and responsibilities, and political consensus develops on the need to control harmful practices. What is needed is to see these practices as an "unacceptable risk".

Secondly, the degradation of the constructed environment (including its social, organizational and cultural dimensions) plays an increasingly important role in creating or increasing risk conditions. Inappropriate urban construction patterns, together with the absence or poor maintenance of rainwater drainage systems, are responsible for more urban floods than purely natural causes. (Consider the case of Buenos Aires.) Settlements of increasing density near rivers or lakes without proper treatment of sewage and solid waste lead to pollution levels in the water that threaten public health and set the stage for growing urban epidemics.

Cites at risk. (a)

Cites at risk. (b)

Finally, the increase of social vulnerability and the financial crisis of cities produce constant urban environmental degradation, posing risks which grow day by day.