Omar Delgado-Rodriguez - Academia.edu (original) (raw)

Papers by Omar Delgado-Rodriguez

Electrical Resistivity and Conductivity, 2017

In the coastal aquifer of the lowlands on the right side of the river Sinaloa there is need for f... more In the coastal aquifer of the lowlands on the right side of the river Sinaloa there is need for fresh water for agricultural development since, around 15% of the water used in agricultural irrigation, is from underground sources. This situation is exacerbated in periods of drought, which promotes drilling with the risk of finding brackish water in them; besides, there is the risk of not meeting water demand due to low hydraulic transmissivity (T) of the aquifer, putting at risk the drilling costs that this implies. In this sense, the determination of T and K (hydraulic conductivity) is important for the development and management of groundwater exploitation of the study area. Generally by means of pumping tests in wells, T is obtained, with high costs, so there are few values of T. K is generally obtained by wells and laboratory test. The aim of this chapter is to establish an empirical relationship between T and K with Dar-Zarrouk parameter in porous media, transverse resistance (T R), in addition to a characterization of the water quality through the electrical resistivity. This parameter is estimated from surface resistivity measurements, which are more economical in relation to the pumping tests; thus, T was characterized in the study area. The coefficient of correlation of the exponential adjustment is 0.79 and the relation is

Geofisica Internacional, Apr 1, 1995

1: 500 000, a partir del mapa prelirnirtar confeccionado teniendo en cuenta las mediciones de cub... more 1: 500 000, a partir del mapa prelirnirtar confeccionado teniendo en cuenta las mediciones de cubrimiento de los transmisores de onda media realizado por el ICRT y el MINCOM, y una camp!liia de mediciones de la intensidad del campo realizado a lo largo de todo el pafs. Para la realizaci6n de las medl.ciones y la elaboraci6n de las mismas se utiliz6 un metodo experimental simplificado, que permiti6 un uso 6ptimo de toda la informacion disponible. Finalmente se realiza un analisis del mapa de acuerdo con los tipos de suelos y el relieve del terreno. PALABRAS CLAVE: Conductividad electrica equivalente, tipo genetico de suelos, atenuaci6n del campo, ondas de radio.

Geofísica Internacional

Se presenta un mapa de la conductividad eléctrica de la República de Cuba a escala 1: 500 000, a ... more Se presenta un mapa de la conductividad eléctrica de la República de Cuba a escala 1: 500 000, a partir del mapa preliminar confeccionado teniendo en cuenta las mediciones de cubrimiento de los transmisores de onda media realizado por el ICRT y el MINCOM, y una campaña de mediciones de la intensidad del campo realizado a lo largo de todo el país. Para la realización de las mediciones y la elaboración de las mismas se utilizó un método experimental simplificado, que permitió un uso óptimo de toda la información disponible. Finalmente se realiza un análisis del mapa de acuerdo con los tipos de suelos y el relieve del terreno.doi: sin doi

Land, Apr 13, 2023

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Geofisica Internacional, 2021

El conocimiento de las propiedades del suelo agrícola es crucial para la selección óptima de los ... more El conocimiento de las propiedades del suelo agrícola es crucial para la selección óptima de los tipos de cultivo, riego y fertilización. Este estudio contiene los resultados de la aplicación en campo y en laboratorio de mediciones eléctricas para obtener el contenido de finos, la porosidad, la conductividad hidráulica y la capacidad de intercambio catiónico (CIC) en tres parcelas agrícolas dedicadas al cultivo de la cebada. Los valores del contenido de finos se obtuvieron mediante mediciones eléctricas en muestras de suelo de laboratorio y el algoritmo de Ryjov, que es comparable a los valores calculados a partir del análisis textural de Bouyoucos. En la parcela agrícola A, un perfil de Tomografía de Resistividad Eléctrica (TRE), junto con las mediciones de la humedad y la salinidad del suelo, muestran resultados de alta resolución para determinar las propiedades del suelo, a partir de una clara imagen del espesor del suelo, así como la identificación de sus horizontes. Un estudio de rápido avance con el método Perfilaje Eléctrico (PE) fue realizado en las tres parcelas, resultando en mapas de propiedades del suelo. Las parcelas muestran rango de valores de CIC como: A-bajo, B-moderado y C-alto. Este resultado se ajusta a los rendimientos de los cultivos por hectárea y al análisis de fertilidad realizado en cada parcela, lo que confirma no sólo la eficacia del método PE y del algoritmo de Ryjov para el estudio de las propiedades del suelo agrícola. PALABRAS CLAVE: propiedades del suelo agrícola, perfilaje eléctrico, tomografía de resistencia eléctrica, algoritmo de Ryjov.

Resistivity method is used extensively in environmental impact studies. In this work, the results... more Resistivity method is used extensively in environmental impact studies. In this work, the results of the geoelectrical characterization of a hydrocarbons contaminated site are presented. Although the contamination grade of the study area is low, were mapped two contaminated zones into sandy aquifer. In addition, petrophysical parameters were estimated by recalculate of ground and water resistivity values in clay content, porosity and CEC values. Anomalous values of clay content, porosity and CEC indicate the presence of hydrocarbon contaminants. The correlation between geoelectrical results, petrophysical parameters and hydrocarbons contamination was verified in laboratory by electrical measurements made in pure and contaminated sand samples.

Polish Journal of Environmental Studies, Sep 28, 2017

In most coastal areas in Mexico, there is an increase in housing development and facilities for t... more In most coastal areas in Mexico, there is an increase in housing development and facilities for tourism, consequently resulting in a negative impact on the environment. Due to this, an awareness of the critical role of groundwater in sustaining coastal populations, economies, and ecosystems is growing. The coastal zone of Sinaloa State is classified as an area with a high presence of saline groundwater in Mexico. The present work was performed in the Las Glorias Beach, Guasave, Sinaloa, Mexico. The results of the analysis of 19 soil and groundwater samples indicate the predominance of sandy soil and a wide range of water salinity, from slightly saline to brine. An electromagnetic profiling (EMP) survey was performed at the study site showing a low apparent electrical conductivity zone parallel to the coastline as indicative of the possible presence of fresh and/or slightly saline water. Apparent electrical conductivity values were compared with electrical conductivity values measured in groundwater samples collected in wells, resulting in a positive linear correlation (R = 0.97). This linear relation is explained by a φξ electromagnetic analytic model when 5.36 ≤ σ a ≤ 85.87 mS/cm. The linear relation was used to recalculate the apparent electrical conductivity values from EMP survey into electrical conductivity values of groundwater and, therefore, TDS values. The TDS map indicates the presence of a barrier of fresh/slightly saline groundwater parallel to the coastline that keeps a fragile balance that prevents the advance of saltwater intrusion from the sea of Cortés and from brine zones located in the northern part of the site. The advance of erosion in Las Glorias Beach exposes

Boletín de la Sociedad Geológica Mexicana, Aug 1, 2013

Caracterización geoquímica y geoeléctrica de un sitio contaminado por hidrocarburos en el estado ... more Caracterización geoquímica y geoeléctrica de un sitio contaminado por hidrocarburos en el estado de Puebla 405 Resumen Dos métodos son utilizados para caracterizar un sitio contaminado con hidrocarburos: muestreo de suelo y análisis químico como método directo y tomografía de resistividad eléctrica (ERT, por sus siglas en inglés) como método indirecto. La caracterización con el método directo se basó en la NOM-138-SEMARNAT/SS-2003, donde se obtuvieron 42 muestras, incluidos 4 duplicados, con lo que se detectó que el contaminante principal en el subsuelo es diésel, siendo el volumen de suelo afectado aproximadamente 1301 m 3. El método ERT se realizó en dos etapas: seis perfiles en la primera etapa, paralelos entre sí con una distancia entre ellos de 4 m, con un arreglo electródico dipolo-dipolo con una separación entre electrodos de 0.5 m. En la segunda etapa se realizaron dos perfiles ubicados en los extremos noroeste y sureste del sitio utilizando un arreglo Wenner-Schlumberger con una separación entre electrodos de 0.75m (cerca de los puntos de muestreo con mayores niveles de contaminación PUE1 y PUE18), cuyo resultado muestra una posible delineación del contaminante, en correspondencia con el análisis granulométrico realizado en las muestras de suelo, el cual indica la existencia de un suelo arenoso de alta permeabilidad. A pesar de que la ubicación y longitud de los perfiles de ERT en ambas etapas estuvieron afectadas por la accesibilidad al sitio, los resultados muestran claramente anomalías de alta resistividad (ρ > 600 Ohm-m) asociadas a la presencia de una cobertura resistiva que incluye contaminación reciente por hidrocarburos. La estratigrafía compuesta de sedimentos arenosos propios del sitio manifiesta variaciones de resistividades entre 25 y 150 Ohm-m debidas a variaciones de humedad. Tanto los resultados del muestreo de suelo y análisis químico, como los de ERT, indican que la contaminación es en general de poca extensión horizontal; sin embargo, dos perfiles de ERT muestran una capa geoeléctrica de mayor extensión, con valores de resistividad inferior a los 10 Ohm-m como señal evidente de contaminación madura, aunque se requiere de nuevas perforaciones y muestreo de suelo para su confirmación. Palabras clave: caracterización, contaminación puntual, hidrocarburos, tomografía eléctrica. Resumen Two methods are used to characterize a site contaminated with hydrocarbons: soil sampling and chemical analysis as direct methods, and electrical resistivity tomography (ERT) as an indirect method. The application of the direct method was based on the NOM-138-SEMARNAT/SS-2003; 42 soil samples were collected, including 4 duplicates, concluding that the main contaminant in the subsoil is diesel and that the volume of affected soil is approximately 1301 m 3. The ERT method was carried out in two stages: six profiles in the first stage, parallel to each other, with a distance of 4 m between them, using a dipole-dipole arrangement with a distance of 0.5 m between electrodes. In the second stage, two profiles located in the northwest and southeast ends of the site using a Wenner-Schlumberger array with a separation of 0.75 m between electrodes (near the points PUE1 and PUE18, which are the most polluted)may provide the possible delineation of the contaminant in correspondence to the granulometric analysis performed in soil samples, which indicates

EAEJA, Apr 1, 2003

We propose an updated model of the Chicxulub impact structure based on modeling of the aeromagnet... more We propose an updated model of the Chicxulub impact structure based on modeling of the aeromagnetic anomaly data, which incorporates electromagnetic sounding models and UNAM and CSDP borehole information. Modeling takes into account the relative contributions of the induced and remanent components. Studies of the magnetic susceptibility variation in the UNAM and Yaxcopoil boreholes along the lithologic column in the

Estudios Sociales, Dec 1, 2015

Landslides, Aug 10, 2020

Multidisciplinary approaches for the characterization of deep-seated landslides (DSLs) are useful... more Multidisciplinary approaches for the characterization of deep-seated landslides (DSLs) are useful in comprehending the internal and external dynamics of the phenomena. This paper examines and characterizes the active Cañón de Yerbabuena DSL (in Ahualulco, San Luis Potosi, Mexico), for which there are over 30 years of damage records to Federal Highway 63. Hence, the integrated study carried out includes lithological and structural characterization, geomorphological mapping, Persistent Scatterer Interferometry (PSI) analysis, and electrical geophysical surveys. The slope deformation extends over the highly weathered and fractured volcanic rocks of the Ahualulco Volcanic Complex in an area comprising 741,000 m 2 and mobilizes an estimated rock volume of 6,950,459 m 3 . Geomorphological features within the DSL include a counter-scarp, minor scarps, tension cracks, small landslides, avalanche breccias, toppling, and colluvial deposits. Furthermore, the velocity rate in the upper section of the slope reaches up to 10 mm/year with a linear behavior that changes to a faster non-linear deformation (up to 30 mm/year) in the middle-lower part of the DSL. This change is the result of a multiple-complex dynamic linked to the presence of two normal faults fragmenting the middle section of the slope and an interbedded volcaniclastic clayey-siltstone layer acting as a possible sliding plane; the latter being defined by a resistivity survey. The acceleration of the velocity rates at the foot of the DSL are linked to torrential rains in the area and cause the most severe damage to the highway. Furthermore, the general slow deformation within the DSL is triggered by severe erosion from the seasonal river at the foot and the run-off on both flanks.

Geofisica Internacional, 2012

Knowledge of soil petrophysical parameters is very useful for agricultural and environmental impa... more Knowledge of soil petrophysical parameters is very useful for agricultural and environmental impact analysis. Therefore, it is important to develop techniques and methodologies to help obtain soil petrophysical maps both quickly and inexpensively. This paper shows two techniques for estimating clay content, porosity and cation exchange capacity from electrical measurements. The first one, based on soil resistivity measurements (SRM), is performed in the laboratory. The second technique, ERT&WRM, uses the Electrical Resistivity Tomography (ERT) and groundwater resistivity measurements (WRM) in the field. A geoelectrical study was carried out in a sandy-loam site and the results were compared to those determined by particle size analysis using the Bouyoucos technique for textural analysis. The SRM technique was more accurate but slower than the ERT&WRM technique. The obtained results suggest a new application of geoelectrical methods for precision farming, both for analysis of soil samples in the laboratory using SRM technique and to evaluate large tracts of agricultural land using ERT&WRM technique.

Science of The Total Environment, Mar 1, 2020

Alluvial and gypsum karst geological transition favors spreading arsenic contamination in Matehua... more Alluvial and gypsum karst geological transition favors spreading arsenic contamination in Matehuala, Mexico,

InTech eBooks, May 9, 2018

Electrical methods are effective tools for the characterization of oil-contaminated sites and are... more Electrical methods are effective tools for the characterization of oil-contaminated sites and are applied in defining the geometry of the contaminated plume and in designing the remedial process. The optimal methodology integrates geoelectric methods, data processing, and interpretation techniques. Electromagnetic profiling is a reliable and fast method used to provide the configuration of oil-contaminated plume from apparent resistivity map and used to guide the subsequent electrical resistivity tomography survey. From advanced field work methods, data processing, and interpretation procedures, electrical resistivity tomography survey provides the three-dimensional (3D) configuration of the contaminated plume, migration pathways, location of active contaminated sources, and information about lithology. For separate contaminated and clean zones, a petrophysical modeling is used for the calculation of soil resistivity based on groundwater salinity. Taking the pore-water salinity value into account, an inversion algorithm recalculates resistivity maps into maps of clay content, porosity, and cation exchange capacity, allowing a more accurate determination of the volume of contaminated soil. From clay content data, hydraulic conductivity values are calculated for determining the groundwater vulnerability due to vertical migration of contaminants from upper layers. The optimal geoelectric methodology is an efficient procedure to assess hydrocarbon-contaminated sites, with emphasis on large sites with deeper groundwater table.

Near Surface Geophysics, Jul 1, 2011

In this paper, we present an electromagnetic surface technique for the integrity inspection of bu... more In this paper, we present an electromagnetic surface technique for the integrity inspection of buried pipelines groups. The inspection includes the determination of the pipeline plan location and depth, assessment of insulation-coating quality and cathodic protection conditions. This technique is based on the approximation of a metallic pipeline by a heterogeneous transmission line. In the transmission line model, the degree of coating damage (disbanded or cracked insulation) corresponds to the leakage resistance that is defined by the coating resistance and environmental resistivity. Using the transmission line model, we simulated the voltage and current distributions along a pipeline created by the cathodic protection system or an external generator in a low-frequency range. The calculations were performed for both a single pipeline and interconnected pipelines with different insulation-coating quality (model of a common cathodic protection system). We describe the field operations, which consist of measurements of the magnetic field created by the current flowing into a pipeline, voltages on the cathodic protection control posts and soil resistivity. To find the pipeline position, depth and current we apply the interactive inversion of the magnetic-field data obtained along the profiles orthogonally oriented to the pipeline-group route. The interpretation of the field data includes: calculating the leakage current (the current difference on the measuring interval) for each pipeline, determining the leakage resistance (the voltage to the leakage-current ratio) and assessing the insulation-coating resistance taking into account the surrounding soil resistivity. We present practical examples of the integrity inspection of interconnected pipelines group in Mexico. The successful results achieved allow us to recommend this electromagnetic technique for quantitative inspection of the technical conditions of interconnected pipelines. external electromagnetic and electrical methods on the earth surface are applied. Electrical methods such as close interval pipe-to-soil potential and direct current and alternating current voltage gradients use measurements of the electric field to assess the effectiveness of cathodic protection and to locate defects of the insulation coating (Masilela and Pereira 1998; Pawson 1998). The disadvantages of these methods consist in their dependence on soil characteristics (soil resistivity, pore-fluid mineralization and saturation) and requirements of prior knowledge of the pipeline position. To determine the pipeline trajectory and coating quality, the pipeline current mapper technique applies magnetic field measurements above a pipeline (Radiodetection 2009). The methods mentioned above provide only qualitative information about the insulation-coating condition and can only be used for detecting the damage zones. However, in the case of pipelinegroup inspection, the results obtained with these methods are www.eage.org

Near Surface 2009 - 15th EAGE European Meeting of Environmental and Engineering Geophysics, 2009

At several SAGEEP conferences we presented resistivity technology for oil contamination study. So... more At several SAGEEP conferences we presented resistivity technology for oil contamination study. Soil resistivity and groundwater salinity measurements were recalculated into petrophysical parameters: clay content, porosity and cation exchange capacity. For uncontaminated sandy-clay soil these parameters are close to real ones. For contaminated soil these parameters are apparent ones, but can be used as good contamination indicators. The real cause of petrophysical anomalies is an increase of superficial conductivity greater than electrolytic conductivity change in pore space of contaminated soil, as it was found by Abdel Aal et al. (2004) with spectral IP method. We suppose that DC resistivity also can give information about superficial conductivity, which is the main cause of resistivity and petrophysical anomalies at contaminated sites. Superficial conductivity for soil is estimated on clay content (calculated on soil resistivity), groundwater salinity and clay conductivity. Clay conductivity depends on pore water salinity and cation exchange capacity of clay. Anomalous clay content reflects an increase of internal surface area whereas anomalous cation exchange capacity reflects an increase of surface charges at the mineral grainelectrolyte interface. Practical examples of superficial conductivity estimation at oil contaminated sites are demonstrated and compared with resistivity and petrophysical anomalies.

Symposium on the Application of Geophysics to Engineering and Environmental Problems 2006, 2006

We considered clay content in loose soil as the factor mostly influencing on hydraulic conductivi... more We considered clay content in loose soil as the factor mostly influencing on hydraulic conductivity (filtration coefficient). We collected and analyzed some published experimental data about hydraulic conductivity relation with soil lithology and clay content in the form of grain size. Also we performed some theoretical modeling modifying well-known formulas to include clay content in them. Experimental and calculated data showed quite good coincidence. Correlation between hydraulic conductivity and clay content seemed better, than correlation between hydraulic conductivity and resistivity. We created some approximation formulas relating filtration coefficient with clay content. Clay content in soil can be estimated on soil resistivity obtained from VES data interpretation and from groundwater salinity found from its resistivity. Then filtration coefficient is determined on clay content. Some examples of this method practical application at clean and oil contaminated areas are presented. We considered anomalies of decreasing filtration coefficient in contaminated zones not as a real effect, but as a good indicator of contamination, though in several publications there were some indications of hydro geological changes in soil properties due to oil contamination.