Examinando por Materia "Remote sensing"
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Ítem Ahora es posible evitar otra tragedia por el fenómeno de La Niña(2020-12-01) Martinez Guerrero, Christian Alexander; Christian Alexander Martinez-Guerrero; Restrepo, Juan; Kettener, Albert; Brakenridge, Robert; Vicerrectoría de Descubrimiento y CreaciónÍtem Analyzing Long-Term Availability of Urban Green Space by Socioeconomic Status in Medellin, Colombia, Using Open Data and Tools(Institute of Electrical and Electronics Engineers Inc., 2020-01-01) Patino J.E.; Patino J.E.; Universidad EAFIT. Departamento de Ciencias; Research in Spatial Economics (RISE)The availability of green spaces is an important issue for urban populations worldwide, given the benefits that the green spaces provide for health, well-being, and quality of life. But urban green spaces are not always distributed equally for different population groups within cities. Latin America is the second most urbanized region of the world, but there are few published studies analysing the green space availability for different urban population groups, and less so analysing the long-term trends. This work presents an analysis of long-term availability of urban green spaces by different socioeconomic status population groups in Medellin city, Colombia, using open geospatial data and open software tools. The results indicate that disparities between different groups have been decreasing in the last years, but there are still efforts to do. Showing this kind of analysis based on open data and tools is essential as it opens the possibility for replicating it in other cities with scarce budgets. © 2020 IEEE.Ítem Aplicación de redes de sensores inalámbricos (WSN) en un sistema de seguridad para los equipos móviles de la Universidad EAFIT(Universidad EAFIT, 2011) Villada Ramírez, Juan Camilo; Ospina Mendoza, Sandra Patricia; Jaramillo Jaramillo, Mario; Medina Sánchez, WilsonÍtem Correlation of Morphometric Variables for Landslides in the Combeima River Basin, Colombia(Universidad EAFIT, 2020-06-19) Santa-Ramírez, Gabriel; Cuevas-González, Juan; Leal-Villamíl, Julián; Muñoz-Ramos, Jader; Universidad del TolimaThis study was carried out in order to estimate the morphometric variables of the landslides found in Combeima river basin (Tolima, Colombia) and obtain possible statistical correlations. To obtain the morphometric characteristics of the landslides, we used a database with historical landslides, a RapidEye image from 2010 and an orthophotomosaic from 2009, where the landslides were visually identified. The morphometric characteristics were defined through a geographic information system and bivariate analyzes were ran between the morphometric variables to establish their correlations. The results allowed to identify 121 landslides, with an average area of 1,974.97 m2 and Birnbaum-Saunders type distribution. It was found that the slip area morphometric variable correlates with the total length (R2=0.9414), the length of the center line (R2=0.9368) and the width of the surface of rupture of this (R2=0.8915). These data could be used to infer the volume of the mass involved in the event and its potential effects . This result would allow the landslide area to be used as support in decision-making in the planning of the territory in the Combeima river basin.Ítem Definición de zonas de descarga hídrica por medio de análisis geomorfológico e imágenes térmicas en la cuenca del río Piedras, Jericó-Antioquia(2021) Arias Galvis, Santiago; Betancourt Ortiz, Joseph; Uribe Jaramillo, Marcela; Villada Arias, Isabel CristinaThis is a graduate work looking for the title of geologist, where water discharge zones of aquifers were identified in the Piedras river basin in Jericó-Antioquia; by means of heuristic analysis of thermal images, and geomorphological models such as: slopes, slope orientation, curvatures and lineaments; developed from a digital elevation model with a spatial resolution of 10m. A 3D model was achieved where the internal flows of the watershed were identified in a conceptual way, integrating the discharge zones, lineaments and potential aquifer water recharge zones from the master's work of Isabel Cristina Arias Villada. Finally, a validation of the different discharge zones identified with the mapping of water source points from the first order drainage mapping of the IGAC (Agustin Codazzi Geographic Institute) is carried out.Ítem Erratum: Monitoring water discharge and floodplain connectivity for the Northern Andes utilizing satellite data: A tool for river planning and science-based decision-making (Journal of Hydrology (2020) 586, (S0022169420303474), (10.1016/j.jhydrol.2020.124887))(ELSEVIER SCIENCE BV, 2020-01-01) Restrepo A J.D.; Kettner A.J.; Robert Brakenridge G.; Universidad EAFIT. Departamento de Geología; Ciencias del MarRiver discharge data and magnitudes of floods are often not readily available for decision makers of many developing nations, including Colombia. And this while flooding for these regions is often devastating, causing many fatalities and insurmountable damage to the most vulnerable communities. During the wet season, in strong La Niña years, infrastructural damages of over $US 7.2 billion have occurred. Mitigation of such natural disasters lacks data-supported scientific approaches for evaluating river response to extreme climate events. Here, we propose a satellite-based technique to measure river discharge at selected sites for the main northern Andean River, the Magdalena. This method has the advantage of back calculating daily river discharges over a period of two decades, and thus making it possible to calculate return intervals of significant flood events. The study shows that satellite based river discharges well capture a) the inter-annual variability of river discharge; b) the natural seasonality of water discharge along the floodplains; and c) peak discharges that were observed during La Niña conditions between 2008 and 2011. The last is likely more accurate compared to ground-based gauging stations, as ground-based stations tend to overflow during large flood events and as such are hampered to accurately monitor peak discharges. Furthermore, we show that these derived discharges can form the base to study river-floodplain connectivity, providing environmental decision makers with a technique that makes it possible to better monitor river and ecosystem processes. © 2020 Elsevier B.V.Ítem Forest cover change detection with synthetic aperture radar satellite data(Universidad EAFIT, 2022) Guisao Betancur, Ana Maria; Marulanda Tobón, AlejandroÍtem Imaging polarimeters based on liquid crystal variable retarders: An emergent technology for space instrumentation(SPIE-INT SOC OPTICAL ENGINEERING, 2011-01-01) Alvarez-Herrero, A.; Uribe-Patarroyo, N.; García Parejo, P.; Vargas, J.; Heredero, R.L.; Restrepo, R.; Martínez-Pillet, V.; Del Toro Iniesta, J.C.; López, A.; Fineschi, S.; Capobianco, G.; Georges, M.; López, M.; Boer, G.; Manolis, I.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaThe use of Liquid Crystal Variable Retarders (LCVRs) as polarization modulators are envisaged as a promising novel technique for space instrumentation due to the inherent advantage of eliminating the need for conventional rotary polarizing optics hence the need of mechanisms. LCVRs is a mature technology for ground applications; they are wellknow, already used in polarimeters, and during the last ten years have undergone an important development, driven by the fast expansion of commercial Liquid Crystal Displays. In this work a brief review of the state of the art of imaging polarimeters based on LCVRs is presented. All of them are ground instruments, except the solar magnetograph IMaX which flew in 2009 onboard of a stratospheric balloon as part of the SUNRISE mission payload, since we have no knowledge about other spaceborne polarimeters using liquid crystal up to now. Also the main results of the activity, which was recently completed, with the objective to validate the LCVRs technology for the Solar Orbiter space mission are described. In the aforementioned mission, LCVRs will be utilized in the polarisation modulation package of the instruments SO/PHI (Polarimetric and Helioseismic Imager for Solar Orbiter) and METIS/COR (Multi Element Telescope for Imaging and Spectroscopy, Coronagraph). © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).Ítem Landslide susceptibility assessment in mountainous and tropical scarce-data regions using remote sensing data : a case study in the Colombian Andes(Universidad EAFIT, 2017) Ruiz Vásquez, Diana; Aristizábal, EdierLandslides triggered by rainfall are one of the most frequent causes for natural disasters in the tropical and mountainous countries, such as Colombia. However landslide susceptibility assessments are often limited due to the scarcity of reliable observations and available information, particularly in remote high-mountain regions. Although Colombia is a tropical and mountainous terrains dominated by landslide prone region, it has little availability of data for landslide susceptibility assessment. This study presents the application of a logistic regression model to assess landslide susceptibility in the La Liboariana catchment. It is a basin on a tropical inaccessible terrain in northern Colombian Andes, where on May 18th, 2015, more than 40 landslides and an associated flash flood and debris flow afterwards killed 104 inhabitants. The applied approach is based on free access remote sensing tools to complete and obtain the missing landslide causative factors. To select key factors related to landslide occurrence the prediction and successes performance of the susceptibility maps for each combination of landslide causative factors was estimated using the Receiver Operating Characteristics (ROC). The results show that only three factors gave the best predicting accuracy. All the factors were obtained by free remote sensing tools, indicating they can provide enough information to achieve a successful approach to landslide susceptibility assessment in complex terrains as the study area. This suggests that the proposed approach could be implemented in several tropical regions with similar characteristics based only in free access information.Ítem Measuring intra-urban poverty using land cover and texture metrics derived from remote sensing data(ELSEVIER SCIENCE BV, 2015-03-01) Duque, Juan C.; Patino, Jorge E.; Ruiz, Luis A.; Pardo-Pascual, Josep E.; Universidad EAFIT. Departamento de Economía y Finanzas; Research in Spatial Economics (RISE)This paper contributes empirical evidence about the usefulness of remote sensing imagery to quantify the degree of poverty at the intra-urban scale. This concept is based on two premises: first, that the physical appearance of an urban settlement is a reflection of the society; and second, that the people who reside in urban areas with similar physical housing conditions have similar social and demographic characteristics. We use a very high spatial resolution (VHR) image from one of the most socioeconomically divergent cities in the world, Medellin (Colombia), to extract information on land cover composition using per-pixel classification and on urban texture and structure using an automated tool for texture and structure feature extraction at object level. We evaluate the potential of these descriptors to explain a measure of poverty known as the Slum Index. We found that these variables explain up to 59% of the variability in the Slum Index. Similar approaches could be used to lower the cost of socioeconomic surveys by developing an econometric model from a sample and applying that model to the rest of the city and to perform intercensal or intersurvey estimates of intra-urban Slum Index maps. (C) 2014 Elsevier B.V. All rights reserved.Ítem A Method for Detecting Coffee Leaf Rust through Wireless Sensor Networks, Remote Sensing, and Deep Learning: Case Study of the Caturra Variety in Colombia(Universitatea Politehnica Bucuresti, 2020-01-19) Velasquez, D.; Sánchez, A.; Sarmiento Garavito, Sebastián; Toro, M.; Maiza Galparsoro, Mikel; Sierra Araujo, Basilio; Velasquez, D.; Sánchez, A.; Sarmiento Garavito, Sebastián; Toro, M.; Maiza Galparsoro, Mikel; Sierra Araujo, Basilio; Universidad EAFIT. Departamento de Ingeniería de Sistemas; I+D+I en Tecnologías de la Información y las ComunicacionesAgricultural activity has always been threatened by the presence of pests and diseases that prevent the proper development of crops and negatively affect the economy of farmers. One of these pests is Coffee Leaf Rust (CLR), which is a fungal epidemic disease that affects coffee trees and causes massive defoliation. As an example, this disease has been affecting coffee trees in Colombia (the third largest producer of coffee worldwide) since the 1980s, leading to devastating losses between 70% and 80% of the harvest. Failure to detect pathogens at an early stage can result in infestations that cause massive destruction of plantations and significantly damage the commercial value of the products. The most common way to detect this disease is by walking through the crop and performing a human visual inspection. As a result of this problem, different research studies have proven that technological methods can help to identify these pathogens. Our contribution is an experiment that includes a CLR development stage diagnostic model in the Coffea arabica, Caturra variety,scale crop through the technological integration of remote sensing (through drone capable multispectral cameras), wireless sensor networks (multisensor approach), and Deep Learning (DL) techniques. Our diagnostic model achieved an F1-score of 0.775. The analysis of the results revealed a p-value of 0.231, which indicated that the difference between the disease diagnosis made employing a visual inspection and through the proposed technological integration was not statistically significant. The above shows that both methods were significantly similar to diagnose the disease. © 2020 by the authors.Ítem A Method for Detecting Coffee Leaf Rust through Wireless Sensor Networks, Remote Sensing, and Deep Learning: Case Study of the Caturra Variety in Colombia(Universitatea Politehnica Bucuresti, 2020-01-19) Velasquez, D.; Sánchez, A.; Sarmiento Garavito, Sebastián; Toro, M.; Maiza Galparsoro, Mikel; Sierra Araujo, Basilio; Universidad EAFIT. Departamento de Ingeniería Mecánica; Estudios en Mantenimiento (GEMI)Agricultural activity has always been threatened by the presence of pests and diseases that prevent the proper development of crops and negatively affect the economy of farmers. One of these pests is Coffee Leaf Rust (CLR), which is a fungal epidemic disease that affects coffee trees and causes massive defoliation. As an example, this disease has been affecting coffee trees in Colombia (the third largest producer of coffee worldwide) since the 1980s, leading to devastating losses between 70% and 80% of the harvest. Failure to detect pathogens at an early stage can result in infestations that cause massive destruction of plantations and significantly damage the commercial value of the products. The most common way to detect this disease is by walking through the crop and performing a human visual inspection. As a result of this problem, different research studies have proven that technological methods can help to identify these pathogens. Our contribution is an experiment that includes a CLR development stage diagnostic model in the Coffea arabica, Caturra variety,scale crop through the technological integration of remote sensing (through drone capable multispectral cameras), wireless sensor networks (multisensor approach), and Deep Learning (DL) techniques. Our diagnostic model achieved an F1-score of 0.775. The analysis of the results revealed a p-value of 0.231, which indicated that the difference between the disease diagnosis made employing a visual inspection and through the proposed technological integration was not statistically significant. The above shows that both methods were significantly similar to diagnose the disease. © 2020 by the authors.Ítem Monitoring water discharge and floodplain connectivity for the northern Andes utilizing satellite data: A tool for river planning and science-based decision-making(ELSEVIER SCIENCE BV, 2020-07-01) Restrepo A, Juan D.; Kettner, Albert J.; Brakenridge, G. Robert; Universidad EAFIT. Departamento de Geología; Ciencias del MarRiver discharge data and magnitudes of floods are often not readily available for decision makers of many developing nations, including Colombia. And this while flooding for these regions is often devastating, causing many fatalities and insurmountable damage to the most vulnerable communities. During the we season, in strong La Nina years, infrastructural damages of over $US 7.2 billion have occurred. Mitigation of such natural disasters lacks data-supported scientific approaches for evaluating river response to extreme climate events. Here, we propose a satellite-based technique to measure river discharge at selected sites for the main northern Andean River, the Magdalena. This method has the advantage of back calculating daily river discharges over a period of two decades, and thus making it possible to calculate return intervals of significant flood events. The study shows that satellite based river discharges well capture a) the inter-annual variability of river discharge; b) the natural seasonality of water discharge along the floodplains; and c) peak discharges that were observed during La Nina conditions between 2008 and 2011. The last is likely more accurate compared to ground-based gauging stations, as ground-based stations tend to overflow during large flood events and as such are hampered to accurately monitor peak discharges. Furthermore, we show that these derived discharges can form the base to study river-floodplain connectivity, providing environmental decision makers with a technique that makes it possible to better monitor river and ecosystem processes.Ítem Seasonal analysis of the atmosphere during five years by using microwave radiometry over a mid-latitude site(Elsevier Ltd, 2019-01-01) Bedoya-Velásquez A.E.; Navas-Guzmán F.; de Arruda Moreira G.; Román R.; Cazorla A.; Ortiz-Amezcua P.; Benavent-Oltra J.A.; Alados-Arboledas L.; Olmo-Reyes F.J.; Foyo-Moreno I.; Montilla-Rosero E.; Hoyos C.D.; Guerrero-Rascado J.L.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica AplicadaThis work focuses on the analysis of the seasonal cycle of temperature and relative humidity (RH) profiles and integrated water vapor (IWV) obtained from microwave radiometer (MWR) measurements over the mid-latitude city of Granada, southern Spain. For completeness the study, the maximum atmospheric boundary layer height (ABLHmax) is also included. To this end, we have firstly characterized the HATPRO-RPG MWR errors using 55 co-located radiosondes (RS) by means of the mean-bias (bias¯) profile and the standard deviation (SDbias) profile classified under all-weather conditions and cloud-free conditions. This characterization pointed out that temperature from HATPRO-MWR presents a very low bias¯ respects RS mostly below 2.0 km agl, ranging from positive to negative values under all-weather conditions (from 1.7 to -0.4 K with SDbias up to 3.0 K). Under cloud-free conditions, the bias was very similar to that found under all-weather conditions (1.8 to -0.4 K) but with smaller SDbias (up to 1.1 K). The same behavior is also seen in this lower part (ground to 2.0 km agl) for RH. Under all-weather conditions, the mean RH bias ranged from 3.0 to -4.0% with SDbias between 10 and 16.3% while under cloud-free conditions the bias ranged from 2.0 to -0.4% with SDbias from 0.5 to 13.3%. Above 2.0 km agl, the SDbias error increases considerably up to 4 km agl (up to -20%), and then decreases slightly above 7.0 km agl (up to -5%). In addition, IWV values from MWR were also compared with the values obtained from the integration of RS profiles, showing a better linear fit under cloud-free conditions (R2 = 0.96) than under all-weather conditions (R2 = 0.82). The mean bias under cloud-free conditions was -0.80 kg/m2 while for all-weather conditions it was -1.25 kg/m2. Thus, the SDbiasfor all the statistics (temperature, RH and IWV) of the comparison between MWR and RS presented higher values for all-weather conditions than for cloud-free conditions ones. It points out that the presence of clouds is a key factor to take into account when MWR products are used. The second part of this work is devoted to a seasonal variability analysis over five years, leading us to characterize thermodynamically the troposphere over our site. This city atmosphere presents a clear seasonal cycle where temperature, ABLHmax and IWV increase from winter to summer and decrease in autumn, meanwhile RH decreases along the warmer seasons. This city presents cold winters (mean daily maximum temperature: 10.6 ± 1.1 °C) and dry/hot summers (mean daily maximum temperature of 28.8 ± 0.9 °C and mean daily maximum of surface RH up to 55.0 ± 6.0%) at surface (680 m asl). Moreover, considering temporal trends, our study pointed out that only temperature and RH showed a linear increase in winters with a mean-rate of (0.5 ± 0.1) °C/year and (3.4 ± 1.7) %/year, respectively, from ground to 2.0 km agl, meanwhile IWV presented a linear increase of 1.0 kg·m-2/year in winters, 0.78 kg·m-2/year in summers and a linear decrease in autumns of -0.75 kg·m-2/year. © 2018 Elsevier B.V.Ítem Structural Controls on Geothermal Systems along the Northern Andes of Colombia : An Integrated Remote Sensing Analysis of the Dabeiba and Sibundoy Valley Geothermal Fields(Universidad EAFIT, 2024) Montoya Londoño, Nicolás; Marín Cerón, María IsabelThis study employs a combination of remote sensing techniques and geothermal analysis to investigate the structural and thermal characteristics of two geothermal systems in Colombia. By utilizing Mark's proposal (1992) for delimitating lineaments, and Principal Component Analysis (PCA) for generating shadow models, the research highlights regional and local structural features that are closely associated with geological structures. Fault systems and lineaments emerge as crucial elements influencing subsurface fluid flow, heat transfer, and the development of geothermal reservoirs. The integration of remote sensing data with advanced structural analysis techniques reveals significant factors shaping geothermal dynamics in the region. These findings emphasize the necessity of considering structural controls in the exploration and sustainable management of geothermal resources. The study focuses on the Dabeiba Geothermal System (DGS), potentially linked to a Miocene extensional event, emphasizing the role of fault structures, especially in the Guineales Formation, as conduits for fluid flow and heat migration from deep sources. The complex structural zones with different degrees of deformation and fracture densities directly influence the advection of the isotherms near the Dabeiba-Pueblo Rico suture zone. This geothermal play system is dominated by fault-controlled non-magmatic convection, where convection occurs predominantly along fault lines and is accompanied by meteoric water infiltration along their traces. The Sibundoy Valley Geothermal System (SVGS) as a typical example of a mixed geothermal system, where heat originates from a young magmatic source but is mainly controlled by deep faults within a pull-apart basin. These faults not only influence the distribution of monogenetic volcanoes but also shape the spatial arrangement of hydrothermal springs. The interaction between geological structures and fluid flow patterns highlights the complexity of geothermal systems. Furthermore, the presence of partial crystallizations and unique caldera geometries leads to the formation of seal layers or condensate layers, redirecting both meteoric water recharge fluxes and volcanic heat fluxes, significantly impacting hydrogeological and geothermal dynamics. This research contributes valuable insights for the geoscientific and energy exploration communities, informing decision-making processes for the assessment and development of geothermal resources.Ítem Tecnología satelital mide los niveles del río Magdalena(Universidad EAFIT, 2020-12-01) Martinez Guerrero, Christian Alexander; Martinez-Guerrero, Christian Alexander; Restrepo A, Juan D.; Kettner, Albert J.; Brakenridge, G.Robert; Hidrología de los Andes del Norte