<p>Land use classification studies help to quantify the changes in forest cover that may occur at a given site over time. This quantification helps us understand the effect of the natural and anthropogenic processes over the study site. Activities such as agriculture, cattle ranching and illegal logging, which in turn are related to the evolution of the site's public policies, can be evaluated through classification studies. Tenosique area, in the southeast of Mexico, is a clear example of the consequences of these programs, being largely benefited by economic consent for agriculture and more for cattle ranching, and, suffering,  in 1974, a complete  turn in productivity activities because it was given full support in exploration and obtainment of hydrocarbons. This led to a crisis that left the area devastated and later became a protected area in 2008, which resulted in illegal logging, and land use for agriculture within the tropical forest, among others. With remote sensing, the task of quantifying the effect of public policies has become increasingly influential and many studies are being carried out to evaluate the current state of Tenosique. However, the results are known to depend directly on the images and methodologies used for this task.Because of this, this project, proposes, in a practical exercise, to determine how much these results may vary with respect to the images used as input for the supervised classification, and if this variation is significant enough to establish rules of operation on methodologies and determine ranges of the parameters of the images to perform a better land use classification. The aim of this project is to determine the margin of variability in the classification result over a given study area, using images from different satellite platforms, Landsat and RapidEye, together with the analysis of the properties of each image, when acquired by the satellite. In addition, the degree of affectation in the image by meteorological changes such as tropical haze in the source image and its respective corrected image was evaluated. The main results are:  individualization of complications and advantages derived from the resolution of the images, identification of the main steps for the possible corrections that can be needed for the images, advantages that are used for analyzing the metadata before doing some process to the images and finally, presenting a decision tree based on this information. It is important to emphasize that this study allows us to delimit the scope and limitations of the land use classifications made in the study area. Acknowledgments: Tania Ximena for the Planet images and Humberto Abaffy-Castillo, Ulises Gracía-Martínez and Mario Seinos-Jiménez for technical help in the project.</p>

<p>Mexico City has suffered for many years from the phenomenon of land subsidence because the city is located within the limits of the old Lake Texcoco. The lithological materials that constitute the lake area are deposits, mainly clayey, of low consolidation, that compose the upper aquitard of the city, from which volumes of water have been extracted that have caused the clayey materials to rearrange causing the subsidence of the land, thus leading to visible affectations in buildings and communication routes. The subsidence of the city is not presented homogeneously as there are regions of the city that present greater settlement than others, since previous studies have shown that studying the phenomenon regionally leaves more doubts than certainties due to the complexity of the sedimentary material of the lake plain since this deposit is mainly composed of clays of various origins, in addition to being interbedded with volcanic materials.</p> <p>This study aims to identify areas within the city, with similar characteristics that allow us to understand the behavior of land subsidence and its relationship with the reduction of the static groundwater level. To do this, data on the vertical displacement of the terrain were obtained using the InSAR technique and associated with the drawdown values ​​of the static level to verify if there is a direct relationship between the extraction of groundwater and the descent of the terrain. It was considered that in the old Lake of Texcoco, there was a presence of salty and sweet waters, which would be decisive in forming different clay minerals in the lake plain. For this reason, it was decided to divide the city according to the environment that governed the site when Lake Texcoco existed. Four study areas were proposed: Lake Texcoco area, which is located northeast of the city where brackish waters predominated; the Northeast area of ​​the town, where the ancient city of Tenochtitlán was located and where fresh waters dominated; the Xochimilco Lake Zone, which had fresh waters and a higher elevation than the Tenochtitlán zone; and the Lake Chalco Zone, which presents characteristics similar to those of Lake Xochimilco.</p> <p>The results of the study show that zoning the lake plain into 4 regions allows for a linear relationship of the variables of vertical displacement of the terrain and dejection (decrease) of the static level of groundwater, showing that there is a direct relationship between both variables, contrary to what recent studies showed since when studying the phenomenon regionally, the results showed little or no linear relationship between land settlement and the drop in the static level.</p>

<p>Urbanization is the dominant force shaping social, economic, and environmental life in the 21 century. Urban areas will become essential to achieve the Sustainable Development Goals (SDGs) established by the United Nations in their 2030 Agenda. Local governments must identify the vulnerable ecosystems to make cities inclusive, safe, and resilient (SDG 11). In Latin America, urban rivers are vulnerable ecosystems, negatively impacted by rapid urbanization. Furthermore, detailed geospatial information of urban rivers is not updated frequently, therefore available data doesn’t reflect changes occurring due to rapid urban development processes affecting the quality of water, sediments, or vegetation health. This research uses a GIS-based multicriteria decision analysis (GIS-MCDA) for the environmental assessment of the Pesqueria River as a decision tool to facilitate mitigation focused strategies. The developed method has used the pixel to pixel data from socio-economical, environmental, topographical, geological, and hydrological factors affecting the environmental health of urban rivers. Census data, geological formation or soil type were obtained from official information; reflectance indices and vegetation height were obtained using aerial photogrammetry with near-infrared and red bands; terrain and hydrological analysis used digital elevation models derived from LIDAR; land cover was created using a SENTINEL 2 image; and water quality data was obtained from field sampled raised and analyzed with traditional laboratory analysis of Chemical Oxygen Demand and validated also with official data. Results implied the generation of the thematic maps with ranges from 1 (very low quality) to 5 (very high quality) according to the environmental quality assessment. For the GIS-MCDA, the values of each map were converted to the same scale, each criterion was weighted in function of its importance according to the literature review and the objective of this research, and there were aggregated by the way of a lineal combination. The result is a map that shows the level of mitigation or conservation priority along the river. This map can offer information to the stakeholders in a relatively short time and accelerate the actions aimed to protect the quality of this important urban ecosystem. </p>

<p>It is well known that groundwater overexploitation can generate land subsidence due to the compaction of compressible aquitards. Mexico City's soils are an important example of highly compressible lake sediments in compaction due to groundwater extraction that have significantly damaged the urban and commercial building structures. Previous studies indicate that there is annual subsidence of 15 to 25 cm in the Mexico City International Airport, 10 cm in downtown, and between 10 to 15 cm in the Southeast Mexico City area. Soil fracturing is an indicator of differential subsidence that has damaged buildings and infrastructure, including hydraulic pipes, sidewalks, and pavements. For this reason, it is necessary to carry out specific studies related to topographic deformation. This talk presents a characterization of the terrain changes over time and a zoning map for Mexico City subsidence susceptibility. To this end, free access elevation models generated from 2000 to 2018 by different sensors and methodologies were compared. The resulting model is validated by mapping information from active GPS stations, whose data is also freely available. Besides, a spatial comparison of land subsidence areas and sites previously identified as flooding and aquifer overexploitation areas is presented. The results will serve as a basis for future monitoring to be carried out in the area with high-resolution tools.</p>

<p>Currently, natural areas are being devastated by anthropogenic activity. Activities such as agriculture, illegal logging, non-organic farms, and livestock exploitation, disrupt an ecosystem that has been in balance for many years. Therefore, regulations implemented by governments are required for their preservation. However, these regulations are not always the most used in terms of conservation. Such is the case of the town "Tenosique", in this area is one of the most important rivers in Mesoamerica, the Usumacinta River, which is a great regulator of ecological processes and is connected to Mexico with Guatemala. This site has been under the influence of regulations applied to the economic impulse of the area, whether for agricultural and livestock activities, which has affected the apparent vegetation cover, unlike Guatemala that has opted for regulations with a forest conservation approach. These policies sought to boost the agricultural sector, but many deforested areas to carry out this activity turned out not to be suitable due to the type of soil. With the change of regime, financing ends and with it economic activity decreases, leaving the area quite affected and the communities with financial problems. Recently, conservation and protection actions were implemented in the area together with support for these communities. The proximity between Mexico and Guatemala visually shows the results of the application of different public policies. The objective of this study is to quantify the loss and gain of vegetation over time from satellite images of the area, in order to compare this statistic with the different government programs of each era. For this, at least 10 multispectral satellite images of free access will be used, from the Landsat 7 satellite, which has 30 meters of resolution but visually adjustable to 15 meters with the union of its panchromatic channel, and that cover a time range from 1999 to 2020. On these, two processes will be carried out: 1) a normalized vegetation index calculation and 2) a supervised classification. With which it is intended to measure the area and the greenness of a mask of the vegetation cover. The results will serve to update the projects carried out on the site and detect areas of priority interest resolution for larger projects, as well as the future estimation of the critical state of the site regarding the loss of vegetation cover and quantify the conservation efforts that have been carried out. carried out from 2008 to the present.</p>