Earth Sciences Research Journal

URI permanente para esta colecciónhttps://repositorio.unal.edu.co/handle/unal/261

Examinar

Envíos recientes

Mostrando 1 - 20 de 373
  • No hay miniatura disponible
    Ítem
    Letter from editor
    (UNIVERSIDAD NACIONAL DE COLOMBIA, 2013) Vargas, Carlos
    Find available in your hands or just a click far this new number of the Earth Sciences Research Journal. It has been the product of a hard work not only for the authors but also for all people related to this project. During 17 years we have been here struggling for being a bridge between all scientific world in our knowledge fields. It has been not easy but we are here and we will be here for long time now.A project of a scientific journal, located in a country as Colombia and aimed to contribute in the entirely world as source of first quality information, hand in hand with so many publications in countries with a better development index, its a titanic task which just be earned thanks to all of you, readers, authors, contributors, critics, reviewers, staff workers.Our country currently is planning a new characterization of journals as this one you are reading now. Thanks to our tiredless work now we can warrant to every one of our users than we are going to keep our category as a journal of first quality. But we need your support.As part of our compromise this time we offered important papers in the development of the Earth Sciences which we are completely sure are necessary in the current state of art.Our first article in this number come from the Persian Gulf with an intelligent model based in probabilistic neural networks to produce a quantitative formulation between seismic attributes and hydraulic flow units. Based on the results of this study the exploration success rate and the costs reduction would be improved through the application of more reliable output results in hydrocarbon explorations programs.As it has been traditionally in our journal, an important percentange of the papers are related to hydrogeology studies. From different countries, we present four papers analyzing groundwater potential zonation, psychochemical characteristics, spatio-temporal variability of an aquifer in Iran and nutrients loads in drainage water from a costal irrigated area. Other manuscript is an evaluation of the forecasting performance of two nonlinear models using stream flow data of the Kızılırmak River, the longest one in Turkey.In seismology two importants submissions deploy, in one hand, an analysis of the Rayleigh-wave ellipticity to determine the local crustal structure (based in Spain) and an analysis of two-dimensional principal components during the earthquake which took place in Papua New Guinea on 7 July 2013, in the other hand.From Colombia an important group of metamorphic rocks were studied to obtain the pressure-temperature conditions in a petrogrpahic analysis from mineral assemblages which indicated a prograde regional metamorphism.We close this edition with important works in ore deposits and geotechnics coming from LatinAmerica and Turkey.Finally we want to thank to the reviewers who have made possible this volume.Carlos A. VargasEditor
  • Miniatura
    Ítem
    Titaniferous magnetite and barite from the san gregorio de polanco dike swarm, paraná magmatic province, uruguay
    (UNIVERSIDAD NACIONAL DE COLOMBIA, 2013) Muzio, Rossana; Scaglia, Fernando; Masquelin, Henri
    The San Gregorio de Polanco Dike Swarm (Tacuarembó Department, Uruguay) is the southernmost set of dikes in the Paraná Magmatic Province of Uruguay. Five major dikes have been identified with two main structural trends: N140º–N170º and N50º–N80º. The dikes have tholeiitic affinities and are composed of plagioclase (An55), augite and augite-pigeonite, relicts of olivine and opaque minerals. These rocks have high contents of Fe–Ti oxides (titanomagnetites), the mineralogical and textural characteristics of which have been studied using scanning electron microscopy and energy dispersive spectrometry techniques (SEM – EDS). These features, along with other mineralogical and textural relationships, have been used to propose the following crystallization sequence for the dikes: (i) crystallization of olivine, plagioclase and Ca-rich pyroxene phenocrysts; (ii) precipitation of the first population of Ti-magnetite; (iii) crystallization of plagioclase and pyroxene in the groundmass; (iv) partial dissolution of Ti-magnetite by reaction with magmatic fluids; (v) crystallization of the second population of Ti-magnetite and finally, (vi) crystallization of interstitial barite. ResumenEl Haz de Diques de San Gregorio de Polanco (Departamento de Tacuarembó, Uruguay) es la ocurrencia más meridional de diques pertenecientes a la Provincia Magmática Paraná en Uruguay. Fueron identificados cinco 5 diques principales con dos direcciones estructurales principales: N140º - N170º y N50º - N80º, respectivamente. Son diques de afinidad tholeítica compuestos por plagioclasa (An55), augita y augita-pigeonita, relictos de olivina y minerales opacos. Estos diques se caracterizan por el alto contenido de óxidos de Fe y Ti (titanomagnetitas), cuyas características mineralógicas y texturales fueron estudiadas con microscopio electrónico de barrido y espectrometría de energía dispersiva (SEM-EDS), incluyendo mapeos composicionales. Estas características junto con otras relaciones mineralógico-texturales presentes en estas rocas permitieron proponer la siguiente secuencia de cristalización: (i) cristalización de fenocristales de olivina, plagioclasa y piroxenos cálcicos; (ii) precipitación de una primera población de titanomagnetita, (iii) cristalización de plagioclasa y piroxenos conformando la matriz; (iv) disolución parcial de la primera población de titanomagnetitas por reacción con fluidos magmáticos; (v) cristalización de la segunda población de titanomagnetitas y finalmente, (vi) cristalización de barita intersticial.
  • Miniatura
    Ítem
    Letter from the editor
    (UNIVERSIDAD NACIONAL DE COLOMBIA, 2013) Vargas J., Carlos A.
    Dear readers and contributors of the Earth Sciences Research Journal,Thanks again to be part of this interesting professional journal. With pretty proud I want to present this new issue (17:1, June-2013) with interesting research products coming from Antarctic continent,Mexico, Botswana, India, Turkey, Nigeria and Iran. Currently, ESRJ is covered in the top scientificIndex and Bibliographic Database as Academic Search Complete, DOAJ, Fuente Académica, GeoRef,Scopus, ISI web of Knowledge, Latindex, SciELO, Ulrich, Publindex, e-Revistas, and Academic One-file. And we expect in the future turn into one of the most referred journal in this field of knowledge...
  • Miniatura
    Ítem
    Detecting ionospheric precursors of a deep earthquake (378.8 km) on 7 july 2013, m w=7.2, in papua new guinea under a geomagnetic storm: two-dimensional principal component analysis
    (UNIVERSIDAD NACIONAL DE COLOMBIA, 2013) Lin, Jyh-Woei
    Two-dimensional ionospheric total electron content (TEC) data were collected during the time period from 00:00 on 2 July to 12:00 UT on 08 July 2013. This period spanned 5 days before to 1 day after a deep earthquake (378.8 km) in Papua New Guinea at 18:35:30 on 7 July 2013 UT (Mw=7.2). Data were examined by two-dimensional principal component analysis (2DPCA) to detect TEC precursors related to the earthquake because TEC precursors have usually appeared in earlier time periods (Liu et al. 2006). A TEC precursor was highly localized around the epicenter on 6 July for 5 minutes, from 06:00 to 06:05. Ionizing radiation from radon gas release could possibly have caused the anomalous TEC fluctuation through, for example, a density variance. The plasma might have experienced large damping to cause short-term TEC fluctuations, and the gas released in a small amount in a short time period. 2DPCA can also identify short-term TEC fluctuations, but this fluctuation lasted for a considerable length of time. Other background TEC anomalies caused by the geomagnetic storm, small earthquakes and non-earthquake activities, e.g., equatorial ionization anomaly (EIA), resulted in small principal eigenvalues. Therefore, the detection of TEC precursors through large eigenvalues was not due to these background TEC anomalies. ResumenDatos del contenido total de electrones ionosféricos en dos dimensiones (TEC) fueron medidos durante el período del 2 de julio de 2013, a las 0:00:00 horas GMT., hasta las 12:00 GMT. del 8 de julio. En este lapso se abarcan cinco días antes y un día después de un terremoto profundo (378,8 kilómetros) en Papúa Nueva Guinea, que se presentó a las 18:35:30 del 7 de julio (M w =7.2). Los datos fueron examina- dos a través de los componentes principales en dos dimensiones (2DPCA) para detectar los precursores TEC relacionados al terremoto (Liu et al. 2006). Un precursor de los TEC fue localizado alrededor del epicentro el 6 de julio durante 5 minutos, desde las 06:00 a las 06:05. La radiación ionizada por la liberación de radón podría haber causado la fluctuación anómala de los TEC a través de, por ejemplo, una variación de densidad. El plasma podría haber experimentado una fuerte humectación lo que cau- saría fluctuaciones cortas de los TEC y la liberación de gas en pequeñas cantidades en poco tiempo. A través de los 2DPCA también se pueden identificar fluctuaciones cortas de los TEC, pero estas últimas duraron por un tiempo considerable. Otras anomalías en el entorno de los TEC causadas por tormentas geomagnéticas, pequeños terremotos y actividades no sísmicas, por ejemplo la anomalía ecuatorial de ionización (EIA, en inglés), resultaron en pequeños autovalores principales. Por lo tanto, la detección de precursores TEC a través de grandes valores propios no se debe al entorno de estas anomalías en los TEC.
  • Miniatura
    Ítem
    Debris flow susceptibility mapping in a portion of the andes and preandes of san juan, argentina using frequency ratio and logistic regression models
    (UNIVERSIDAD NACIONAL DE COLOMBIA, 2013) Esper, Maria Yanina
    In this study, the frequency ratio and logistic regression models are applied and verified for the analysis of debris flow susceptibility in a portion of the Dry Frontal Andes and Occidental Preandes of San Juan at approximately 30°S latitude, through aninvestigation based on a Geographic Information System (GIS). The site under study covers an area of 2175.9 km2 with a debris flow area of 42.45 km2. For this purpose, thematic layers including debris flow inventory, lithology, elevation, slope, aspect, and solar radiation were used. The debris flow inventory map was prepared by interpreting aerial photographs and satellite images and was supported by field surveys. Lithology was extracted from an existing geological map. Slope, aspect and solar radiation were calculated from a Digital Elevation Model created from SRTM (Shuttle Radar Topographic Mission) and topographical maps. The relationship between the variables and the debris flow inventory was calculated using the frequency ratio and logistic regression models. Both models helped to produce debris flow susceptibility maps that classified susceptibility into five categories: very low, low, moderate, high and very high. Subsequently, each debris flow susceptibility map was compared with known debris flow locations and tested. The frequency ratio model (accuracy is 82.71%) was more accurate than the logistic regression model (accuracy is 75.64%) for predictons of the high and very high categories. ResumenEn este trabajo se aplican, mediante el uso de Sistemas de Información Geográfica, dos modelos estadísticos en la evaluación de la susceptibilidad del terreno a la ocurrencia de flujos de detritos, la relación de frecuencias (Fr) y la regresión logística. El área de estudio comprende un sector de Cordillera Frontal y de Precordillera Occidental a los 30°S de latitud media. Se crearon mapas de elevación, pendiente, insolación, orientaciones, estratigrafía y un inventario de flujos de detritos. Este último, a partir de la interpretación y análisis digital de fotografías aéreas e imágenes satelitales. La estratigrafía fue obtenida a partir de cartas geologicas preexistentes. Las pendientes, orientaciones e insolación fueron calculadas, a partir de un modelo digital de elevaciones. Los mapas de susceptibilidad generados han sido reclasificados en cinco categorías: muy baja, baja, moderada, alta y muy alta. Finalmente, estos mapas, fueron validados espacialmente y como resultado se observa que el modelo Fr predice mejor (82,71%) que la regresión logística (75,64%) para las clases alta y muy alta.
  • Miniatura
    Ítem
    Corrigendum
    (UNIVERSIDAD NACIONAL DE COLOMBIA, 2012) Vargas, Carlos
    Presentamos excusas a nuestros lectores y al antropólogo Javier Andrés Sandoval Andrade puesto que en el Vol 15 No 2 del 2011 de la revista Earth Science research Journal (ESRJ) se publicó el articulotitulado "Quaternary dating by electron spin resonance (ESR) applied to human tooth enamel" en el cual no se hace un correcto pie de página de la figura 1, ya que no es tomada de (Groot, 1992)como reza la misma, sino que es tomada de la tesis de pregrado titulada DATACIÓN DE RESTOS HUMANOS PREHISPÁNICOS A TRAVÉS DE ESMALTE DENTAL USANDO RESONANCIAPARAMAGNÉTICA ELECTRÓNICA (EPR) (2010). Asimismo, no corresponde al sitio arqueológico Aguazuque, sino que corresponde al sitio arqueológico Checua.CorrigendumWe apologize to our readers and the antropology Javier andres Sandoval Andrade because in the Vol 15 Issue 2 year 2011 in the Earth Science Research Journal (ESRJ) published the article entitled "Quaternary dating by electron spin resonance (ESR) applied to human tooth enamel" which there is an incorrect footnote in the Figure 1 as it is not quoted from (Groot, 1992), but it is taken from the undergraduate thesis entitled DATACION DE RESTOS HUMANOS PREHISPANICOS A TRAVES DE ESMALTE DENTAL USANDO RESONANCIA PARAMAGNETICA ELECTRONICA (EPR) (2010). Also, this figure do not correspond with the Aguazuque arqueological site, but it is from the Checua arquelogical site.Carlos VargasEditor-in-ChiefEarth Science Research Journal
  • Miniatura
    Ítem
    Letter from the editor
    (UNIVERSIDAD NACIONAL DE COLOMBIA, 2012) Vargas, Carlos
    Greatly appreciated readers of ESRJ,I am pleased to bring you Vol. 16(2) 2012 which contains interesting articles related to applying methods regarding seismic prospecting, geotechnics, geomorphology, seismology and geochemistry insuch varied countries as Japan, Turkey, Iran, Nigeria and Cameroon. Procedures for suitably treating seismic signals by using discrete wavelet transform (DWT), or treating clays aimed at modifying theirphysical attributes form part of the basic contributions regarding seismic engineering and geotechnics' immense usefulness......
  • Miniatura
    Ítem
  • Miniatura
    Ítem
  • Miniatura
    Ítem
    Investigation of the geochemical signatures and conditions of formation of metacarbonate rocks occurring within the mamfe embayment of south-eastern nigeria
    (UNIVERSIDAD NACIONAL DE COLOMBIA, 2012) Ephraim, Bassey Edem
    Hitherto unknown metacarbonate deposits constitute parts of the Cretaceous Mamfe embayment which straddles the border between south-eastern Nigeria and western Cameroon. The rock is characterisedby a high concentration of LOI, CaO and MgO and depleted content of various insoluble components. Assuming all the CaO and MgO content of the rock were related to calcite and dolomitephases, these two minerals would account for around 22.5 wt% and 76.3 wt% on average, respectively. Among the trace elements investigated, only Ba, Cs, Rb, Sr, Nb, Pb, Zr, Cd, Cu, Ni, U, Y andZn display concentrations beyond their detection limits. Chondrite normalised rare earth element patterns show that the rock under investigation show moderate to strong fractionation of light rareearth elements (LREEN) over heavy rare earth elements (HREEN) and distinct negative Eu anomaly. Multivariate statistical treatment and variation plots revealed several geochemical interrelationships,among which are the SiO2 - Al2O3 - K2O - TiO2 -Fe2O3 - Ba - Nb - Rb - Zr links which is associated with the rock's silicate fraction. The carbonate fraction comprises CaO, MgO, Sr, Pb and Cu. Theoverall geochemical signatures support development of the metacarbonate deposit from sedimentary carbonate materials that was deposited in a saline, shallow-marine, low-energy seawater environment.The consistency of the rock's chemical properties can be attributed to the relative stability experienced during the parent sedimentary materials' deposition.
  • Miniatura
    Ítem
    Adaptive seismic ground roll attenuation using the double density dual tree discrete wavelet transform (dwt) method
    (UNIVERSIDAD NACIONAL DE COLOMBIA, 2012) Goudarzi, Ali; Riahi, M A
    Seismologists working on the reflection of seismic data have been dealing with noise and trying to attenuate noise as much as possible without damaging a particular signal. Many methods have been used to removenoise types, each being partially effective. None of the transforms have been ideal and, even at the point of transform, noise becomes added to data. The double density dual tree (DDDT) discrete wavelet transform(DWT) method was used in this paper to attenuate noise in pre-stack and post-stack seismic data.Wavelet domain ground roll analysis (WDGA) was used for finding ground roll energy in the wavelet domain; it is a substitute method for thresholding in seismic data processing.The DDDTDWT method has four wavelets and two scaling functions. Using this method, shot gather data decomposes to sub-scales and each scale contains coefficients related to a particular signal.The procedure involved applying distinct wavelets and scaling functions to data and then eliminating the coefficient of noise from inverse DDDTDWT using the WDGA technique. The inverse transformprovided a section without noise; double density DWT and dual tree DWT methods were combined (i.e. each method having its own characteristics and advantages).
  • Miniatura
    Ítem
    The impacts of alkaline mine drainage on ba, cr, ni, pb and zn concentration in the water resources of the takht coal mine, iran
    (UNIVERSIDAD NACIONAL DE COLOMBIA, 2012) Dahrazma, B; Kharghani, M
    The release of heavy metals into the environment represents one of the most important environmental effects involved in extracting coal; it needs to be studied more fully. The present research investigatedthe effects of coal-mining in an alkaline environment and alkaline mine drainage in the Takht coal mine regarding the distribution of selected heavy metals (Zn, Pb, Ni, Cr and Ba) on the region's surface andground water . The mine is located 12 Km southeast of Minoodasht, in Golestan province in northern Iran. Samples were collected from groundwater and surface water resources upstream and downstream of themine. The elements' concentrations were measured by the inductively-coupled mass spectrometry (ICPMS) method. The results showed that an alkaline environment was responsible for producing alkaline minedrainage due to the presence of limestone; this caused high pH (8.41) in the area's groundwater resources. Mining activities increased Ba, Cr, Ni, Pb and Zn concentration in the groundwater from 3.39, 0.5, 0.2,0.5, 9.2 ppb to 83.52, 2.2, 0.6, 2.6, 48.3 ppb and from 68.7, 0.5, 1.3, 0.8, 172.6 ppb to 91, 1.2, 4.5, 1.3, 27.6 ppb in surface water, respectively. Due to the basic environment, heavy metal accumulation in the bedsediment for both tunnel effluents and runoffs was higher than during the soluble phase. pH was the main controlling factor in elements' solubility and their distribution in the environment. Increased Ba concentrationin water resources was due to high Ba concentration in the coal, coal tailing and in quarry tailings.
  • Miniatura
    Ítem
    Statistical correlation between b-value and fractal dimension regarding turkish epicentre distribution
    (UNIVERSIDAD NACIONAL DE COLOMBIA, 2012) Öztürk, Serkan
    This study was aimed at analysing the relationship between seismic b-value and fractal dimension Dcvalue for Turkish epicentres. The earthquake catalogue consisting of 99,737 instrumentally-registeredTurkish events was analysed for the period between 1970 and 2011; Turkey was divided into 55 tectonic zones for making a detailed comparison. The b-values were calculated by the maximum likelihoodmethod and the Dc-values were obtained with 95% confidence limits by linear regression. The results showed that higher Dc-values were associated with lower b-values and this could have been an indicationof relatively high stress intensity and stronger epicentre clustering in these regions.Orthogonal regression was used to estimate a suitable statistical correlation between two seismotectonic parameters; the Dc = 2.44 - 0.30*b relationship was obtained with a strong negative correlation(r = -0.82) between b-value and Dc-value for Turkish earthquake distribution. This seemed to agree with other regional results obtained for different parts of Turkey and the rest of the world.
  • Miniatura
    Ítem
    Surfactant modified clays’ consistency limits and contact angles
    (UNIVERSIDAD NACIONAL DE COLOMBIA, 2012) Akbulut, S; Nese, Z; Arasan, S
    This study was aimed at preparing a surfactant modified clay (SMC) and researching the effect of surfactants on clays' contact angles and consistency limits; clay was thus modified by surfactants formodifying their engineering properties. Seven surfactants (trimethylglycine, hydroxyethylcellulose  octyl phenol ethoxylate, linear alkylbenzene sulfonic acid, sodium lauryl ether sulfate, cetyl trimethylammonium chloride and quaternised ethoxylated fatty amine) were used as surfactants in this study. The experimental results indicated that SMC consistency limits (liquid and plastic limits) changedsignificantly compared to those of natural clay. Plasticity index and liquid limit (PI-LL) values representing soil class approached the A-line when zwitterion, nonionic, and anionic surfactant percentageincreased. However, cationic SMC became transformed from CH (high plasticity clay) to MH (high plasticity silt) class soils, according to the unified soil classification system (USCS). Clay modifiedwith cationic and anionic surfactants gave higher and lower contact angles than natural clay, respectively.
  • Miniatura
    Ítem
    The geomorphic history of the ainoura plain, kyushu, japan, based on excavation of the monzen ruins
    (UNIVERSIDAD NACIONAL DE COLOMBIA, 2012) Mori, H; Shimoyama, S; Soejima, K
    The complex coastline of north-western Kyushu, Japan, consisting of cliffs, steep-sided inlets and archipelagos, has resulted from subsidence in mountainous terrain; the region's populated river valleys,having narrow alluvial plains, often suffer rock avalanches. The Ainoura plain is one such alluvial plain. Excavation of the Monzen ruins on the Ainoura Plain by the Nagasaki Prefectural Board of Educationhas revealed the plain's geomorphic history regarding how the gravels and associated muds and sands were deposited during the last several thousand years. Regarding alluvial succession, mud and sand firstfilled in the trough, possibly as part of the transgression caused by the Holocene climatic optimum, and gravel later began to replace parts of the sand and mud layers by successive erosion and sedimentation,thereby raising riverbed level. It was confirmed that such conglomerate from the Ainoura plain was derived from the Hokusho landslide area in the hinterland because there is no conglomerate layer inthe Hino plain (a small plain southeast of the Ainoura plain). The Ainoura River's thalweg shows that the Monzen ruins are located at a sudden reduction in its gradient, thereby accounting for the thicknessof coarse clastic material in that area. The reconstructed Ainoura plain's paleoshoreline during the Holocene climatic optimum is also reported. The paleoshoreline did not move much until people beganto reclaim land; it would thus be expected that the similar deposition would happened on the Ainoura plain inside this paleoshoreline.
  • Miniatura
    Ítem
    Nonlinear forecasting of stream flows using a chaotic approach and artificial neural networks
    (UNIVERSIDAD NACIONAL DE COLOMBIA, 2013) Tongal, Hakan
    This paper evaluates the forecasting performance of two nonlinear models, k-nearest neighbor (kNN) and feed-forward neural networks (FFNN), using stream flow data of the Kızılırmak River, the longest river in Turkey. For the kNN model, the required parameters are delay time, number of nearest neigh- bors and embedding dimension. The optimal delay time was obtained with the mutual information function; the number of nearest neighbors was obtained with the optimization process that minimi- zes RMSE as a function of the neighbor number and the embedding dimension was obtained with the correlation dimension method. The correlation dimension of the Kızılırmak River was d = 2.702, which was used in forming the input structure of the FFNN. The nearest integer above the correlation dimension (i.e., 3) provided the minimal number of required variables to characterize the system, and the maximum number of required variables was obtained with the nearest integer above the value 2d + 1 (Takens, 1981) (i.e., 7). Two FFNN models were developed that incorporate 3 and 7 lagged discharge values and the predicted performance compared to that of the kNN model. The results showed that the kNN model was superior to the FFNN model in stream flow forecasting. However, as a result from the kNN model structure, the model failed in the prediction of peak values. Additionally, it was found that the correlation dimension (if it existed) could successfully be used in time series where the determina- tion of the input structure is difficult because of high inter-dependency, as in stream flow time series. ResumenEste trabajo evalúa el desempeño de pronóstico de dos modelos no lineares, de método de clasificación no paramétrico kNN y de redes neuronales con alimentación avanzada (FNNN), usando datos de flujo del río Kizilirmak, el mayor de Turquía. Para el modelo kNN, los parámetros requeridos son tiempo de retraso, número de vecindarios cercanos y dimensión de encrustamiento. El tiempo óptimo de retraso fue obtenido con la función de información mutua; el número de vecindarios cercanos fue obtenido con la optimización de procesos que minimizan el RMSE como una función del número de vecindarios y la dimensión de incrus- tación fue obtenida con el método de dimensión correlativa. La dimensión de correlación del río Kizilirmak fue utilizado en la formación de la estructura de ingreso de las redes FFNN. La integración cercana sobre la dimensión de correlación proveyó el número mínimo de variables requeridas para caracterizar el sistema y el número máximo de variables requeridas fue obtenido con el número entero por encima del valor (Takens, 1981). Se desarrollaron dos modelos de redes FNNN que incorporan 3 y 7 valores de descargas retrasadas y el desempeño de predicción comparado con el modelo kNN. Los resultados muestran que el modelo kNN fue superior al modelo de redes FFNN en el flujo de pronósticos. Sin embargo, como un resultado del modelo de estructura kNN, el modelo falla en los valores pico. Adicionalmente, se encontró que la dimensión de correla- ción (de existir) podría ser usada eficientemente en series temporales donde la determinación de estructura de ingreso es difícil por la gran interdependencia, como en las series temporales de flujo.
  • Miniatura
    Ítem
    Biogeochemical and engineering characteristics of soils and groundwater around a dumpsite
    (Universidad Nacional de Colombia, 2013) Odukoya, Sesan; Oresanya, O.; Abimbola, Akinlolu Festus
    An active dumpsite in Lagos Southwestern Nigeria was monitored to test the efficiency of natural attenuation in the reduction of contaminants by determining biogeochemical and engineering properties of soils and groundwater within and around the site. From the Casagrande Plasticity Chart, the soil can be classified as clay or silts of intermediate to high plasticity, thickness of the unsaturated zone is between 10-20m, and permeability is low between 1.96x10-5 and 41.8x10-5 m/s. The appropriate microorganisms such as bacteria, viruses and fungi which are required for natural attenuation were naturally present. Nutrients such as calcium, copper, magnesium, manganese, potassium, sodium, and zinc as well as electron donor (Organic carbon) and electron acceptor (oxygen, nitrate, sulphate, iron) were also present in various amount for effective natural attenuation processes. All the parameters analysed in water samples were within Environmental protection agency standard except Fe, Na, Cl, NO3, Al, Ba, Ni, Total Bacteria and Total Fungi. Phenol and Total viral count were not detected in the two boreholes but they showed values as high as 10000MPN/100ml and 230CFU/100ml, respectively in leachates. The concentrations of contaminants in the soils were very high and inversely proportional to depth.
  • Miniatura
    Ítem
    An approximate method for estimating nutrient loads in drainage water from a coastal irrigated area
    (UNIVERSIDAD NACIONAL DE COLOMBIA, 2013) Giakoumakis, S.; Alexakis, D.; Gotsis, D.
    In this work an estimation of nutrient loads (expressed as Dissolved Inorganic Nitrogen and Inorganic Phosphorous) in drainage water from a coastal irrigated area, was undertaken. The procedure is based on the calculation of drainage discharge with the use of data from the drainage pumping station and then on the assessment of the concentrations of nutrients in drainage water. The case study examined is the cultivated land of Agoulinitsa (Peloponnese - Greece). Results from this study could be useful for taking the necessary measures for environmental protection.Resumen En este trabajo, se emprendió una estimación de las cargas de nutrientes (expresados como Nitrógeno Inorgánico Disuelto y Fósforo Inorganico) en las aguas bombeadas desde una área de irrigación costera. El procedimiento está basado en el cálculo de descarga de la cuenca con el uso de datos desde la estación de bombeo y con la medida de concentración de nutrientes en el agua bombeada. El caso de estudio pro- puesto es la región cultivada de Agoulinitsa (Peloponeso - Grecia). Los resultados de este estudio podrán ser útiles para tomar las medidas necesarias para la protección del medio ambiente.
  • Miniatura
    Ítem
    Spatio-temporal variability of groundwater depth in the eghlid aquifer in southern iran
    (UNIVERSIDAD NACIONAL DE COLOMBIA, 2013) Delbari, Masoomeh; Bahraini Motlagh, Masoud; Amiri, Meysam
    Groundwater is the main water source for domestic and agricultural use in Eghlid, a city located in Fars province in southern Iran. Here, spatial and temporal changes in groundwater depth were monitored by using geostatistical methods at 41 observation wells in Eghlid during the wet and dry seasons of 1997, 2003 and 2010. Experimental semivariograms were calculated and modeled with the GS+ (Gamma Design Software, Plainwell, Michigan USA),and groundwater depth was inter- polated by using the ordinary kriging (OK), simple kriging (SK) and inverse distance weighting (IDW) methods within the GIS environment. Moreover, groundwater depth fluctuations over 13 years (from 1997 to 2010) were calculated and mapped for wet and dry periods. The groundwater depth in the Eghlid aquifer exhibited a strong spatial correlation that followed a spherical model for three years. However, the spatial correlation distance was larger for both seasons in 1997 (grea- ter than 27 km) than in 2003 (22 to 27 km) and 2010 (23 to 25 km). The cross-validation results indicated that OK resulted in the lowest root mean square error (RMSE) and mean error (ME) and was the most appropriate method for interpolating groundwater depth. Therefore, OK was used to map the spatial distribution of the groundwater depth over the study area. The resulting maps indicated that the spatial variability of groundwater depth was greater during the wet season than during the dry season over three years. In addition, changes in the depth to groundwater occurred more slowly during the wet seasons than during the dry seasons. Furthermore, the ground water depth decreased slightly from 1997 to 2003 and decreased considerably (2-13 m) from 2003 to 2010. Moreover, the decrease in the groundwater depth was more notable in the central to west and southern regions of the aquifer. Thus, these regions are critical and should be managed carefully to optimize groundwater resource exploitation. ResumenLas aguas subterráneas son la principal fuente hídrica para el uso doméstico y agrícola en Eghlid, una ciudad ubicada en la provincia de Fars, al sur de Irán. Aquí, los cambios temporales y espaciales en la profundidad de las aguas subterráneas se sondean a través de métodos geoestadísticos en 41 pozos de observación en Eghlid durante las estaciones de verano e invierno de 1997, 2003 y 2010. Se calcularon semivariogramas experimentales y se modelaron con el programa informático GS+, y la profundidad de las aguas subterráneas se interpolaron por el uso de krigging ordinario (OK), krigging simple (SK) y mé- todos de ponderación de distancia inversa (IDW) dentro del ambiente GIS. Sin embargo, la fluctuación de profundidad de las aguas subterráneas en cerca de 13 años (de 1997 a 2010) se calculó y se mapeó para las temporadas húmeda y seca. La profundidad de las aguas subterráneas en el acuífero de Eghlid muestra una fuerte correlación que sigue un modelo esférico de tres años. Sin embargo, la distancia de correlación espacial fue mayor para ambas temporadas en 1997 (mayor que 27 km.) y en 2003 (22 a 27 km.) y 2010 (23 a 25 km.). Los resultados de validación cruzada indicaron que el producto OK en la raíz cuadrada media de desviación más baja (RMSE) y Error Medio (EM) fueron los métodos más apropia- dos de interpolación de la profundidad de aguas subterráneas. Por lo tanto, el OK fue usado para mapear la distribución espacial de la profundidad de las aguas profundas en el área de estudio. El resultado de los mapas indican que la variabilidad espacial de la profundidad de aguas subterráneas fue mayor durante la temporada húmeda que durante la temporada seca en tres años. Adicionalmente, la profundidad de las aguas subterráneas fue menor durante la temporada húmeda que durante la temporada seca. Además, el nivel de las aguas profundas cedió ligeramente desde 1997 a 2003 y cayó considerablemente (de 2 a 13 metros). Además, el decrecimiento en el nivel de las aguas profundas fue más notable en las regiones de oeste, centro y sur del acuífero. Por ende, estas regiones son críticas y se deben manejar cuidadosamente para optimizar el recurso de explotación de las aguas subterráneas.
  • Miniatura
    Ítem
    The assessment of slope stability and rock excavatability in a limestone quarry
    (UNIVERSIDAD NACIONAL DE COLOMBIA, 2013) Karaman, Kadir; Ercikdi, Bayram; Kesimal, Ayhan
    The aim of this study is to evaluate the stability and excavatability of newly stripped rock slopes (slope 1 (SN–1), slope 2 (SN–2), and slope 3 (SN–3)) in a limestone quarry. These are new production sites with comparable geological formations along the southern part of the quarry where three planar failures were previously observed. For this reason, detailed fieldwork was performed to determine the properties (spacing, roughness, etc.) of the discontinuities of the rock slopes in the study area. The shear strength parameters of the discontinuities and the point load strength index (Is(5o)) and the uniaxial compressive strength (UCS) of rock samples obtained from the study area were tested in the laboratory. The stability of the slopes was assessed using kinematic analysis and an orientation–dependent and orientation–independent slope stability probability classification (SSPC) system. The results of the SSPC system analyses were compared with those of the slope mass rating (SMR). The kinematic analysis shows that planar, wedge and toppling failures are unlikely in the slopes of the study area. The orientation–dependent SSPC analysis revealed that SN–2 would experience sliding failure if its dip angle is greater than 66°. The slopes were shown to have a stability probability of ≥80%, provided that a pneumatic hammer or blasting methods are used for the excavation. However, the maximum slope height (Hmax) in blasting operations is required to be lower for durable slope faces. Furthermore, the SMR analysis has indicated that SN–1 and SN–2 will most likely lose their stability when blasting is used as an excavation method. The rock slopes could be excavated by pneumatic hammer because the category of excavatability of the rock was determined to be ‘easy ripping.’ Based on the kinematic, SSPC and SMR analyses, the angles for a safe slope are proposed to be 70°, 66° and 75° for SN–1, SN–2 and SN–3, respectively, with a slope height of 8 m. ResumenEl objeto de este estudio es evaluar la estabilidad y la medida de excavación de nuevas pendientes rocosas descubiertas (slope 1 (SN–1), slope 2 (SN–2), y slope 3 (SN–3)) en una cantera de caliza. Estos son nuevos sitios de producción con formaciones geológicas similares en la parte sur de la mina. Por esta razón se llevó a cabo un trabajo de campo detallado para determinar las propiedades (espaciado, irregularidades, etc.) de las discontinuidades en las pendientes rocosas del área de estudio. En un laboratorio se evaluaron los parámetros de fuerza de las discontinuidades, el índice de punto de carga (Is(5o)) y la fuerza de comprensión monoaxial (UCS) de las muestras de rocas tomadas en el área de estudio. La estabilidad de las pendientes fueron medidas a través de un análisis kinemático y de un sistema de clasificación de estabilidad probable (SSPC) en orientación-dependiente y orientación-independiente. Los resultados del análisis al sistema SSPC fueron cotejados con las clasificaciones de masa de las pendientes (SMR). El análisis kinemático muestra que las fallas planas, de bloque y de tope son improbables en las pendientes del área de estudio. Los análisis SSPC de orientación-dependiente muestran que la SN-2 podría presentar fallas de deslizamiento ya que el ángulo de la cuesta es mayor a 66°. Las pendientes evidencian una probabilidad estable de ≥80% si se utiliza un martillo neumático o métodos de explosión para la excavación. Sin embargo, la pendiente de máxima altura (Hmax) en operaciones de explosión debe ser menor para garantizar la duración de las fachadas de las pendientes. Además, los análisis SMR indicaron que la SN-1 y la SN-2 son más propensas a perder su estabilidad si se utilizan métodos de excavación con explosivos. Las pendientes rocosas podrán ser excavadas con martillo neumático ya que la medida de excavación de la roca fue determinada como de "fácil explotación". Basado en los análisis kinemático, SSPC y SMR, los ángulos propuestos para una pendiente segura son de 70°, 66° y 75° para las pendientes SN–1, SN–2 y SN–3, respectivamente, con una pendiente de altura de 8 m.