Abstract & Conceptual Questions Environmental Hazards on the US-Mexico Border: The Case of Ambos Nogales by Mark Finco & George Hepner Jump Point: About the Case Study Case Study Abstract Conceptual Questions How to Order the Casebook About the Case Study This case study abstract is from: GeoSystems Today: an Interactive Casebook. Each printed case (in the book) starts with a list of Questions to be Explored followed by Key Learning Outcomes. An Overview and Background section then introduces the essential geosciences concepts and issues followed by a section entitled The Human Dimension. The latter section presents an integrated perspective on the "nature-society" linkages and policy implications of the case. At the end are Some Recommended Readings for more in-depth study. After you study the basic written text, and possibly do some background reading in a related textbook such as The Blue Planet: An Introduction to Earth System Science, you should take an online Virtual Tour and do the Self-Study Exercise found at the end of each case. At this point you should be ready to discuss the Conceptual Questions at the end of each case (they are repeated here as well). A suggestion–though the conceptual questions could be discussed with only the textual material as background, exploration of the online material as well would deepen your understanding and capacity to contribute meaningfully to a discussion. You are also strongly encouraged to explore some of the advanced material listed under More Activities and Learning Resources. How much more to explore is only limited by your time, interest, ingenuity and motivation! Back to Top Case Abstract This learning activity will examine human-environment interactions of bi-national urban regions (twin cities) along the US-Mexico border. The case looks specifically at Nogales, Arizona and Nogales, Sonora, together known as Ambos Nogales. The focus is on understanding the vulnerability of the inhabitants of these cities to a chemical emergency that might occur on the Mexican side and its potential impact on the US side. This case is particularly useful for assessing the peculiar problems of trans-boundary and trans-national environmental contamination issues. Primary Objectives The primary objective of this case is to demonstrate the interaction of the dispersion of a contaminant gas with the local patterns of topography and human settlement. It also illustrates how a GIS (Geographical Information Systems) might be used to model and simulate chemical emergencies so that urban planners and emergency personnel can respond more effectively and hopefully prevent such events. This case will also illustrate how the concept of vulnerability is applied in the study of natural or human-induced hazards within the earth systems sciences. Background U.S. interaction across the borderlands with Mexico has a long and tortuous history dating back to the colonial and later Independence era - remember the "Alamo" incident and the creation of the State of Texas and the Mexican-American War. During the American Civil War, the borderlands region of Mexico increased in importance as a major funnel for both smuggling and legitimate trade. Later, during the period leading up to the Mexican Revolution, cross-border incidents such as the infamous "chase for Pancho Villa" by the U.S. military added to the region’s colorful history. The focus of this case study Ambos Nogales is located on the US-Mexico border. It is the name used for both Nogales, Arizona in the US and Nogales, Sonora in Mexico. Today, the US-Mexico border separates two very distinct nations at peace. Yet the border separates Mexico, a developing country with an average income of approximately $2,000-3,000 per year, and the United States of America, an economically developed nation with an average income of $18,000-20,000 per year. Most twin cities along the US-Mexican border have a common population distribution pattern. Typically, t the Mexican city has a much higher population. Nogales, Arizona has a population of approximately 20,000, while more than 200,000 people live in Nogales, Sonora. It is not unusual for Mexican border cities to have a 10:1 differential in total population (see maps later in the case study). In fact, the borderlands of Mexico in conjunction with the Sunbelt in the US have become one of the most politically and economically dynamic regions in the world. The sheer amount of interaction—movement of goods and people across it—surpasses any other in the world. Furthermore, most Americans do not realize that trade across the border with Mexico now makes it our second most important trading partner. Unfortunately, this complex bi-national relationship, for better or worse, has given rise to a whole spectrum of perceptions about the borderlands and each other’s country and people that often reflects quite disparate feelings about the ethnic, political, historical, socio-economic and demographic issues that bind us together. Some of the perceptions are true, but many are fallacious. One of the most important industrial-economic developments in the region that is affecting all aspects of life has been the phenomenal growth of transnational manufacturing facilities called maquiladoras. Most of this growth has occurred since the 1965 passage of the Mexican Border Industrialization Program. Approximately 80 maquiladora plants involved in electronics assembly, plastics fabrication and automotive part production are located in Nogales, Sonora. Throughout the border region, there are more than 2,300 maquiladoras with over 600,000 employees. The growth of maquiladoras in the border region has been stimulated by many factors including: lower labor costs, tariff and value-added tax differentials, and limited enforcement of environmental regulations. Geographic proximity of the transnational and local firms to the huge U.S. market has been a major attraction, as well as the various tax and investment advantages offered by the governments on both sides of the border (see South 1990; and Khosrow 1990). It is not surprising, therefore, that northern Mexico has the lowest unemployment rate in the country and attracts millions of migrants from poorer regions to the south. Many migrants stay permanently or use the borderlands as a staging area to attempt eventual migration (legal and illegal) into the equally dynamically changing and growing Sunbelt of the United States (see Massey, Douglas S. 1987). Long term permanent residents of northern Mexico, or Norteños as they are called, share many cultural and linguistic patterns that add to the region’s uniqueness. The language, for instance, includes many "Anglicisms" which some call Spanglish (and vice-versa). Long term interaction between the "Anglos" and "non-Anglos" in the region has created what Louis Casagrande calls one of the "five nations of Mexico"—Mex-America. You may want to read more about this unique region and its complex ethnic and settlement history by consulting Casagrande, Louis B. 1987—see also: Arreloa, D., Curtis, J. 1993 and Martinez, Oscar J. 1994. Natural regions of vegetation, soils, water drainage and air movement greatly affect the human-spatial characteristic of the region’s landscape. Topography has been particularly influential in defining the urban development pattern in Nogales. Note how the urbanized area of Ambos Nogales extends along a narrow valley surrounded by a very steep and complex terrain. Primary transportation routes, such as the highway and the railroad, also follow the valley. The growth and expansion of residential and commercial land use also conform to the configurations of the landscape. The major centers of industrial land use are located in the southwest and extreme southern portions of the valley on the principal transportation routes that focus on the Nogales, Sonora border crossing. Groundwater aquifers underlying the Santa Cruz River channel are the primary water sources for the citizens of both cities. The watershed and airshed boundaries are heavily influenced by the landform features and relative relief of the region. Finally, note how the national and state boundaries cut across the natural landscape in straight lines, often completely at odds with natural ecosystem and topographical boundaries. The unique topography, relative relief and consequent land use patterns make exposure to the risk of contamination by liquid and airborne hazardous materials an issue of great concern to residents on both sides of the border. For one thing, the approximate elevations of the major industrial zones in Nogales, Sonora are 1250- 1300 meters while the elevations of the primary business and residential areas are somewhat lower at 1150-1200 meters. In the event of a toxic spill, hazardous contaminants released into the air would follow pathways from the higher elevation industrial to the lower elevation commercial and residential areas. Furthermore, the steep-sided valley configuration would tend to contain airborne contaminants within the populated area for a longer duration, thereby increasing the potential risk to human health. Also, the destination of any surface or sub-surface liquid contaminants would be the spatially constrained aquifers along the Santa Cruz River from which thousands of people farther north in Arizona pump their potable water. As noted earlier, most of the maquiladoras in Nogales, Sonora are located in the industrial zones at the southern end of the urbanized area. These industrial sites are potential sources of liquid and dense gaseous hazardous materials such as LPG, carbon tetrachoride, and freon. If human control and regulatory mechanisms should fail, for whatever reason, the probabilities of a severe chemical emergency are high. In sum, the geographic nexus of human settlement pattern and industrial activities in association with an unusual set of environmental conditions forms the basis for high vulnerability for specific groups of people. It is interesting to note that unlike the United States, poorer residential areas on the Mexico side of the border are located upslope on the hillsides and wealthier neighborhoods are downslope in the valley bottom. In case of a hazardous materials spill, the upslope (poorer residential) locations may be in a more advantageous position in Mexico. This pattern is often reversed on the U.S. side of the border. This partially reflects differing patterns of urbanization in Latin America as compared to United States. Although not the only factor, gravity is the major force acting upon liquid and gaseous materials released from industrial sites during an emergency. As noted earlier, the release of a liquid or gaseous contaminant from one of the industrial complexes in Nogales, Mexico would disperse toward the areas of highest residential density and commercial activity. The rate of dispersal and potential severity of a chemical emergency would depend on such factors as the amount and toxicity of the material released, its rate of dispersal and physical/chemical state (gaseous, particulate, or fluid), the potential for synergistic interactions with other events (e.g. earthquake, flood, fire), and local microclimatic and hydrological conditions at the time of dispersal. Though the technical disciplines of environmental toxicology, geology and industrial hygiene have given us many sophisticated scientific tools and concepts for better understanding and analyzing toxic spills associated with modern industrial activity, the actual capacity to respond effectively and rapidly in a given chemical emergency is more often a function of human-cultural management issues and not just technical scientific knowledge or capacity. Consequently, the actual vulnerability of specific industrial workers or local residents within a given dispersion area such as the Ambos Nogales valley is often a function of less objective human factors such as: availability, training, readiness and effectiveness of local or off-site emergency response personnel; transportation and communications (time-distance relationships) for either "escape" by the victims or "response and mitigation" by appropriate authorities; local and regional (bi-national) politics; patterns of local land use planning, zoning and environmental regulation; social class and cultural perceptions of hazards; population density, health, age and socio-economic characteristics of residents in the areas concerned; and quality and maintenance of urban infrastructure systems including water, gas, transportation and electricity. These varied factors express themselves on a given landscape in complex spatial patterns that are often quite difficult to integrate into a coherent whole. Mapping or modeling "potential emergency scenarios" with a GIS has been shown to be a particularly useful tool for planning for, preventing and mitigating such emergencies. Several different maps (see virtual Tour) were produced from a computerized geographic information system (GIS) to integrate the socio-economic factors that contribute to the vulnerability of a community. Maps like these, that show vulnerability, can be integrated with chemical dispersion models to evaluate which groups of people might be most vulnerable to an accidental release of a dense gaseous contaminant. It also helps us assess the socio-economic relationships associated with those groups most likely to be affected—factors such as housing density and quality, poverty and social class, transportation access, availability of public services, access to health care, education, and even perceptions of risk. In conclusion, effective response as well as analysis of potential environmental hazard scenarios requires integrating knowledge from many fields of study that span from the humanities to the social, physical and natural sciences. The Earth systems science (ESS) approach discussed in this book has attempted to show the advantages of an "integrative" systems approach to solving "real world" problems such as chemical contamination hazard risk. This system is particularly helpful in improving our understanding of the spatial relationships involved in such issues. Back to Top Conceptual Questions The key questions for you to examine are the following: Why are Ambos Nogales and other borderland Mexican cities such favorable geographic locations for large urban regions and industrial complexes such as maquiladoras. What do you think contributes to the great variation in population totals in these "sister cities"? What physical and cultural characteristics are unique to the Nogales region, in contrast to those it shares with other U.S.-Mexico border cities? Is there such a thing as a "borderland" urbanization pattern? How would a hazardous contamination "event" be different if this area had flat topography, more precipitation and was not located on an international border? Would the hazard be greater or less? Why? What political, economic, historical, ethnic, or socio-cultural patterns on either side of the border exacerbate or mitigate the potential for such events? Back to Top How to Order the Casebook You can order the printed casebook and see other related resources from John Wiley & Sons, Inc at the following URL: www.wiley.com/college/ Back to Top GO TO THE VIRTUAL TOURS AND EXERCISES Created 7 March 1999 .