Mexico | EPFL Graph Search

Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatemala, Belize, and the Caribbean Sea; and to the east by the Gulf of Mexico. Mexico covers 1,972,550 km2 (761,610 sq mi), making it the world's 13th-largest country by area; with a population of over 126 million, it is the 10th-most-populous country and has the most Spanish speakers. Mexico is organized as a federal republic comprising 31 states and Mexico City, its capital. Human presence in Pre-Columbian Mexico goes back to 8,000 BCE. It became one of the world's six cradles of civilization. The Mesoamerican region was home to many intertwined civilizations, including the Olmec, Maya, Zapotec, Teotihuacan, and Purepecha. The Aztecs dominated the region in the century before European contact. In 1521, the Spanish Empire and its indigenous allies conq

Recycler l'eau à Mexico: la station d'épuration, un générateur d'opportunités urbaines

Steffan Heath, Edouard Philippe

Depuis un demi-siècle, Mexico et ses millions d'habitants font face à une surexploitation massive des ressources hydriques locales. L'eau souterraine de l'aquifère, qui constitue la source principale d'approvisionnement en eau de la ville, se trouve dans un état critique d'épuisement résultant de l'extension démesurée de la ville empêchant sa recharge. Afin de réduire le stress actuel sur l'aquifère, la ville doit mieux exploiter les sources d'eau locales à disposition: les eaux usées et pluviales. La création de nouvelles stations d'épuration (STEP) apparait donc comme un enjeu majeur. Cependant, afin de pouvoir projeter une nouvelle STEP dans un tissu urbain dense, il nous semble essentiel de lui donner un nouveau statut, afin que sa présence en ville ne provoque plus un sentiment de rejet, mais représente plutôt une opportunité. En effet, l'énergie ainsi que d'autres produits dérivés résultant du processus de traitement peuvent être bénéfiques à d'autres programmes. Dans le cadre de notre projet, nous proposons donc de combiner la STEP avec une piscine municipale pour démontrer le potentiel de ce principe. Situé à l'Ouest de la ville, le projet est implanté dans une aire dont le tissu urbain recouvre un sol propice à la recharge de l'aquifère. Dans cette zone particulière nommée URA (Urban Recharge Area), se trouve une série de barrages de rétention qui intercepte les rivières, souvent très polluées. En plaçant notre projet en aval de l'un de ces barrages, la STEP génère un corridor vert, où l'eau traitée permet la revitalisation de la rivière jusqu'à son infiltration dans un parc situé 1.5 km en aval. La piscine, preuve urbaine de l'intégration de la STEP, est la première séquence de ce corridor vert.

2012

Improvement of an urban turbulence parametrization for meteorological operational forecast and air quality modeling

Clive Muller

During the last century, urban pollution has increased with the growth of cities. Urban air quality has become a high priority as it is directly linked to concerns such as human exposure and health. The present work is dedicated to urban air quality modeling with focus on urban meteorology. The main goal is to improve meteorological and air quality simulations in urban areas. Based on measurements and numerical air quality simulations, Chapter 3 describes the meteorological situation and tests an emission inventory for an ozone pollution episode in Mexico City (2 March 1997), in order to determine the principal factors to be accounted in an air quality study. The Mexico City case shows the great influence of meteorological conditions and pollutant emissions on air quality. A thorough understanding of the phenomena governing the meteorological conditions, like small scale convergence, and an accurate emission inventory validated by VOC measurements in the city, are sensitive elements in an air quality study. In Chapter 4, the presence of an Urban Heat Island (UHI) is underlined over the city of Basel (Switzerland) with the BUBBLE measurements. Further on, the ability of aLMo (the operational weather prediction model of MeteoSwiss) to reproduce the effect of a city on the boundary layer atmospheric flow fields is investigated. Results show that aLMo is not able to reproduce the UHI and hence that its surface scheme based on the Monin-Obukhov Similarity Theory (MOST) is not adapted for the urban areas. Therefore, the Buildings Effects Parametrization (BEP) which has been developed by Martilli et al.(2002) especially for urban areas, is implemented in aLMo. Results show that alMo is now able to reproduce the main behavior of the urban boundary layer as the UHI and BEP has hence a real enhancement potential for aLMo. Chapter 5 shows the sensitivity of aLMo with respect to its vertical resolution. In order to limit the sensitivity of aLMo to the grid resolution, BEP is modified. The mesoscale model furnishes the upper boundary conditions for the inner calculation of BEP. That is, BEP recalculates independently the vertical profiles of wind, temperature and energy based on the surface fluxes of momentum, heat and turbulent kinetic energy. The results obtained show a decrease in the sensitivity to the resolution and a better agreement with the measurements. Furthermore, the modified version of BEP gives additional meteorological fields (temperature, wind and TKE) in the urban canopy. The computed temperature in the urban canopy shows a good agreement with measurements in a Basel street canyon. This work shows that it is not necessary to have a high resolution for taking into account modification of the atmospheric flow fields induced by a city.

EPFL2007

Urban Scars: From invisible to visible – In Beijing and Mexico City

Florence Graezer Bideau, Lesslie Astrid Herrera Quiroz, Yves Pedrazzini

Memory is a process that works through the identification of social references within a spatial framework, without physical marks necessarily found in the tangible present. Nonetheless, these references subsist in representations from the past and continue to influence current urban realities. A city is an evolving structure containing different artifacts that relate directly to their importance to a given social group. Usually, but not exclusively, such places have strong historical and memorial significance and are recognized as heritage. Thus, as spaces evolve, inhabitants’ emotional bonds are sometimes at odds with the interactions of other actors. These dual interactions generate rivalries and controversies about uses and perceptions of the space. Traces left on the collective memory by violent urbanization processes can be identified by understanding the city through such intangible experiences. Using these principles—notably that forgetting is not equivalent to the destruction of a mnemonic device—we analyze the spatial and social experiences of controversial memories in two different cultural contexts; the Historic Center of Mexico City (Mexico) and the Gulou area of Beijing (China). The Mexican case study looks at a dominant discourse of urban heritage focused on tangible heritage conservation, which has often ignored the importance of local social memories. The Chinese case study scrutinizes the community’s memories in the context of rapid and radical transformation led by the local government’s urban policies and regulations.

Icono 142017

Improvement of an urban turbulence parametrization for meteorological operational forecast and air quality modeling

Clive Muller

EPFL2007