Examinando por Materia "GIS"

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    Análisis multi-temporal de la erosión en el área protegida Ensenada de Rionegro (Antioquia) con miras a geoconservación
    (Universidad EAFIT, 2020) Zapata Herrera, Juan Fernando; Marín Cerón, María Isabel
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    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 Tolima
    This 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.
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    Estimation of groundwater recharge potential using MIF techniques in the Tatacoa desert, Huila, Colombia
    (Universidad EAFIT, 2022) Salazar Holguín, Daniel; Jaramillo Uribe, Marcela
    The Tatacoa desert, in the department of Huila, Colombia, is located between the Magdalena River and the Eastern Mountain Range. It is an arid zone, with a lot of erosion, classified as a tropical dry forest with maximum temperatures of 40 °C. The climatic and hydrogeological conditions produce problems related to water resources in the area, since, during the summer, 90 % of the streams dry up, causing a problem of drought in the municipality of Villavieja; however, there is underground water, but it is exploited in an empirical and not scientific way. The little hydrogeological knowledge comes from the Institute of Hydrology, Meteorology and Environmental Studies (IDEAM) studies, where it is made clear that the area belongs to the Neiva-Tatacoa-Garzon aquifer system, but there is not enough information to develop studies that allow the sustainable use of groundwater resources. For this reason, it was decided to carry out this study, which is part of a larger project of the EAFIT University, which seeks to expand the hydrogeological knowledge of this aquifer system. The objective of this work was to make a map of potential groundwater recharge zones, using geographic information data and satellite images of six geological factors: lithology, drainage density, slope gradient, land use/cover (LULC), guidelines and type of soil; these were chosen by the work team. The thematic layers of the factors were also transformed into raster and reclassified, according to a weight calculated from the multiple influence factor (MIF) methodology. The groundwater recharge potential (GWRpot) map obtained was divided into five categories: very poor, poor, moderate, high and very high. Finally, the results indicate that 83 % of the study area has moderate to very high potential and it is mainly located between the western and central zones.
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    Expanding level of coastal armouring: Case studies from different countries
    (COASTAL EDUCATION & RESEARCH FOUNDATION, 2011-01-01) Stancheva, M.; Rangel-Buitrago, N.; Anfuso, G.; Palazov, A.; Stanchev, H.; Correa, I.; Universidad EAFIT. Departamento de Ingeniería; Ciencias del Mar
    Concreting the natural shoreline by use of traditional hard protective structures, as well as by port/harbour developments is commonly known as coastal armouring. Over the recent decades the expanding level of coastline hardening and its adverse impacts on the environment has arisen as one of the most critical problems all over the world. Therefore, our goal in this study was to demonstrate the crucial issue of progressive extent of technogenous coastal occupation by two case studies from different countries in Europe and in South America: Bulgaria and Colombia. To assess direct impact of armouring on the coastline and adjacent areas two case areas were selected for detailed investigation: an 18 km long coastline of the large Varna Bay (Bulgarian Black Sea coast) and 349 km long littoral of the Cartagena municipality (Caribbean coastline of Colombia). An indicative coastal segmentation of the both case sites by geomorphologic and engineering criteria was first implemented in GIS environment. As well as, for quantitative assessment of the influence of all maritime structures (port and coast-protection) on the studied coasts the coefficient of technogenous impact K was explored. A GIS methodology was applied for data processing, mapping the natural landforms/structures and to evaluate the technogenous impact on the both coastlines. The identified high extent of impacts due to built hard defence structures along the selected study areas in Bulgaria and Colombia could be considered as indicative of the large technogenous occupation of the coasts and the increasing level of shoreline armouring as a global issue.
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    An integrated approach for the assessment of land-based pollution loads in the coastal zone
    (ACADEMIC PRESS LTD ELSEVIER SCIENCE LTD, 2018-10-31) Tosic M.; Restrepo J.D.; Izquierdo A.; Lonin S.; Martins F.; Escobar R.; Universidad EAFIT. Departamento de Geología; Ciencias del Mar
    The identification and prioritization of pollution sources is essential to coastal zone management. This task is complicated when a variety of pollution sources are found and by limited data availability, which can result in an inconclusive assessment and differing public perceptions, ultimately hindering the progress of management actions. This is the case in Cartagena Bay (Colombia), a Caribbean hot-spot of pollution, which receives large freshwater discharges from the Magdalena River drained via the Dique Canal along with coastal industrial effluents and untreated domestic wastewater from parts of the coastal population. This study presents a methodology for the integrated assessment of anthropogenic pollution sources discharged into the coastal zone by estimating their loads and comparing their relative contributions to receiving coastal waters. Given the lack of available data on discharges and water quality, an integrated approach is applied by combining various methods of load estimation while emphasizing the importance of calculating confidence intervals for each load value. Pollution loads from nearby sources of domestic wastewater, coastal industrial effluents and continental runoff were assessed with respect to their contributions of coliforms, total suspended solids, nitrogen, phosphorus, and biological oxygen demand (BOD). Loads from the canal's surface runoff were calculated with monthly discharge and water quality data. Domestic loads were computed using GIS analyses of population and sewerage coverage in combination with export coefficients of daily load per capita. Industrial loads were estimated based on previous studies. Results show that each type of land-based source is responsible for different pollution impacts observed in Cartagena Bay. Occasionally, inadequate recreational water quality can be attributed to nearby sources of domestic wastewater, which contribute the highest coliform load (6.7 ± 3.9 × 1015 MPN/day). Continental runoff via the Dique Canal contributes the greatest sediment load (2.5 ± 1.9 × 103 t/day) causing the bay's turbid plumes and related ecosystem issues. Hypoxic conditions in the bay can be attributed to all three pollution sources which all discharge significant BOD loads (2–8 t/day), while the highest total phosphorus load comes from the Dique Canal (3.2 ± 2.4 t/day) and the highest nitrogen loads flow from the canal (3.7 ± 3.1 t·NO3-N/day) and the industrial sector (3.1 ± 4.1 t·N/day). Given that these loads are projected to increase in future years, this study highlights the importance of prioritization and mitigation in coastal pollution management and demonstrates a method that could be applied in other places with similar problems in the Wider Caribbean Region. © 2017 Elsevier Ltd
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    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, Edier
    Landslides 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.