Spatial and temporal land cover changes in Terminos Lagoon Reserve, Mexico.

Terminos Lagoon ecosystem is the largest fluvial-lagoon estuarine system in the country and one of the most important reserves of coastal flora and fauna in Mexico. Since the seventies, part of the main infrastructure for country's oil extraction is located in this area. Its high biodiversity has motivated different type of studies including deforestation processes and land use planning. In this work we used satellite image analysis to determine land cover changes in the area from 1974 to 2001. Our results indicate that tropical forest and mangroves presented the most extensive losses in its coverage. In contrast, urban areas and induced grassland increased considerably. In 2001 more than half of the ecosystem area showed changes from its original land cover, and a third part of it was deteriorated. The main causes of deforestation were both the increase in grassland and the growth of urban areas. However, deforestation was attenuated by natural reforestation and plant canopy recovery. We conclude that the introduction of cattle and urban development were the main causes for the land cover changes; however, the oil industry activity located in the ecosystem, has promoted indirectly to urban growth and rancher boom.

Spatial and temporal land cover changes in Terminos Lagoon Reserve, Mexico

Terminos Lagoon ecosystem is the largest fluvial-lagoon estuarine system in the country and one of the most important reserves of coastal flora and fauna in Mexico. Since the seventies, part of the main infrastructure for country’s oil extraction is located in this area. Its high biodiversity has motivated different type of studies including deforestation processes and land use planning. In this work we used satellite image analysis to determine land cover changes in the area from 1974 to 2001. Our results indicate that tropical forest and mangroves presented the most extensive losses in its coverage. In contrast, urban areas and induced grassland increased considerably. In 2001 more than half of the ecosystem area showed changes from its original land cover, and a third part of it was deteriorated. The main causes of deforestation were both the increase in grassland and the growth of urban areas. However, deforestation was attenuated by natural reforestation and plant canopy recovery. We conclude that the introduction of cattle and urban development were the main causes for the land cover changes; however, the oil industry activity located in the ecosystem, has promoted indirectly to urban growth and rancher boom. Rev. Biol. Trop. 58 (2): 565-575. Epub 2010 June 02.

El ecosistema de Laguna de Términos es el más grande sistema fluvio lagunar estuarino del país y una de las reservas más importantes de flora y fauna costera en México. Desde la década de los setentas, parte de la infraestructura necesaria para la explotación del petróleo en el país se encuentra localizada en esta área. Su importante biodiversidad ha motivado diferentes estudios en el área que incluyen procesos de deforestación y ordenamiento del territorio. Se realizó un análisis de imágenes de satélite para determinar los cambios de uso del suelo y vegetación en el área entre 1974 y 2001. Los resultados indican que la selva tropical y el mangle presentan las mayores pérdidas de cobertura. En contraste, las áreas urbanas y los pastos inducidos han incrementado considerablemente su extensión. En el año 2001 más de la mitad del área ocupada por el ecosistema mostró cambios en sus coberturas originales y una tercera parte estaba deteriorada. La deforestación fue causada principalmente por el incremento de los pastizales y el crecimiento de las áreas urbanas. Sin embargo, estas pérdidas fueron atenuadas por la regeneración natural. Se concluye que la introducción de pasto para la ganadería y el desarrollo urbano fueron las principales causas de los cambios de uso de suelo, sin embargo, la industria petrolera asentada en el ecosistema ha fomentado indirectamente el crecimiento urbano y el auge ganadero.

Groundwater vulnerability assessment for organic compounds: fuzzy multi-criteria approach for Mexico city.

This study was based on a groundwater vulnerability assessment approach implemented for the Mexico City Metropolitan Area (MCMA). The approach is based on a fuzzy multi-criteria procedure integrated in a geographic information system. The approach combined the potential contaminant sources with the permeability of geological materials. Initially, contaminant sources were ranked by experts through the Analytic Hierarchy Process. An aggregated contaminant sources map layer was obtained through the simple additive weighting method, using a scalar multiplication of criteria weights and binary maps showing the location of each source. A permeability map layer was obtained through the reclassification of a geology map using the respective hydraulic conductivity values, followed by a linear normalization of these values against a compatible scale. A fuzzy logic procedure was then applied to transform and combine the two map layers, resulting in a groundwater vulnerability map layer of five classes: very low, low, moderate, high, and very high. Results provided a more coherent assessment of the policy-making priorities considered when discussing the vulnerability of groundwater to organic compounds. The very high and high vulnerability areas covered a relatively small area (71 km(2) or 1.5% of the total study area), allowing the identification of the more critical locations. The advantage of a fuzzy logic procedure is that it enables the best possible use to be made of the information available regarding groundwater vulnerability in the MCMA.