Thomas Burbey | Virginia Tech (original) (raw)

Papers by Thomas Burbey

Revista mexicana de ciencias geológicas, Nov 22, 2018

$Research paper thumbnail of Hydraulic fracture characterization resulting from low-viscosity fluid injection: Implications for CO2 sequestration$

AGU Fall Meeting Abstracts, Dec 1, 2013

Hydrogeology Journal, Jul 5, 2018

The investigation involves a temporal and spatial analysis to characterize recharge in the Aguasc... more The investigation involves a temporal and spatial analysis to characterize recharge in the Aguascalientes valley in central Mexico. The results are based on a two-part methodological strategy using a geospatial and numerical analysis. Results from the geospatial analysis are based on the analytical hierarchical process (AHP) method, which involves developing a zoning map that qualifies the conditions for groundwater recharge in the valley. In addition, one-dimensional numerical modeling based on the van Genuchten equation was applied for various soil column configurations to estimate the transit time of recharge through the vadose zone. The analysis was performed over a 20-year period from 1995 to 2015. The results of the geospatial analysis indicate that the optimal area for groundwater recharge is the lower zone of the valley, particularly the portion influenced by surface discontinuities. The shortest estimated period of recharge for water to pass through the vadose zone is approximately 4.25 years.RésuméL’étude implique une analyse spatio-temporelle pour caractériser la recharge dans la vallée d’Aguascalientes du centre du Mexique. Les résultats sont fondés sur une démarche méthodologique en deux parties, recourant à une analyse géospatiale et numérique. Les résultats de l’analyse géospatiale sont basés sur la méthode du processus hiérarchisation analytique (PHA), qui consiste à élaborer une carte de zonage qualifiant les conditions de la recharge des eaux souterraines dans la vallée. De plus, un modèle numérique uni-dimensionnel basé sur l’équation de Van Genuchten a été appliqué pour des configurations variées de colonne de sol, afin d’estimer le temps de transit de la recharge à travers la zone vadose. L’analyse a été réalisée sur une période de 20 ans, allant de 1995 à 2015. Les résultats de l’analyse géospatiale indiquent que la zone optimale pour la recharge des eaux souterraines est la partie basse de la vallée, particulièrement la portion influencée par des discontinuités de surface. Le temps de recharge estimé le plus court pour le passage de l’eau à travers la zone vadose est approximativement de 4.25 ans.ResumenLa investigación involucra un análisis temporal y espacial para caracterizar la recarga en el Valle de Aguascalientes en México central. Los resultados se basan en una estrategia metodológica de dos partes utilizando análisis numérico y geoespacial. Los resultados del análisis geoespacial se basan en el método proceso analítico jerárquico (AHP), el cual involucra el desarrollo de un mapa de zonificación que califica las condiciones para la recarga en el valle. Adicionalmente, un modelo numérico unidimensional basado en la ecuación de van Genuchten se aplicó en varias configuraciones de columna de suelo para estimar el tiempo de tránsito de recarga a través de la zona vadosa. El análisis se aplicó en un periodo de 20 años desde 1995 hasta 2015. El resultado del análisis geoespacial indica que las áreas óptimas para la recarga de agua subterránea son la zona sur del valle, en particular la porción influenciada por las discontinuidades superficiales. El tiempo más corto estimado para la recarga de agua a través de la zona vadosa es de aproximadamente 4.25 años.摘要本研究涉及到了时空分析,以描述墨西哥中部阿瓜斯卡连特斯河谷补给的特征。结果基于采用地理空间和数值分析的两部分方法策略。地理空间分析得到的结果基于解析分层过程方法,这种方法涉及到绘制能够满足河谷地下水补给条件的分区图。此外,针对各种土柱配置应用基于van Genuchten方程式的一维数值模拟估算补给通过包气带的运移时间。对1995年到2015年20年长的情况进行了分析。地理空间分析结果表明,地下水补给的最优区域是河谷的下游,特别是受到表层不连续影响的区域。水通过包气带最短的补给时间估算为大约4.25ResumoA investigação envolve uma análise temporal e espacial para caracterizar a recarga no vale de Aguascalientes, no México central. Os resultados são baseados em uma estratégia metodológica de duas partes usando uma análise geoespacial e numérica. Os resultados da análise geoespacial são baseados no método do processo analítico hierárquico (AHP), que envolve o desenvolvimento de um mapa de zoneamento que qualifica as condições para recarga subterrânea no vale. Além disso, a modelagem numérica unidimensional baseada na equação de van Genuchten foi aplicada para várias configurações de colunas de solo para estimar o tempo de trânsito da recarga através da zona vadosa. A analise foi realizada ao longo de um período de 20 anos, de 1995 a 2015. Os resultados da análise geoespacial indicam que a área ideal para a recarga das águas subterrâneas é a zona inferior do vale, particularmente a porção influenciada por descontinuidades superficiais. O menor tempo estimado de recarga da água para passar pela zona vadosa é de aproximadamente 4.25 anos.

$Research paper thumbnail of Advances in geotechnical characterization of soil fracturing in Mexico City basin$

IAHS-AISH publication, Sep 4, 2010

Proceedings of IAHS, Apr 22, 2020

Environmental Earth Sciences, 2017

Environmental Earth Sciences, 2014

Vertical deformation was measured at 14 benchmarks within the urban area of Jocotepec Mexico usin... more Vertical deformation was measured at 14 benchmarks within the urban area of Jocotepec Mexico using first-order leveling methods and then spatially analyzed in relation to land subsidence and soil discontinuity patterns. The study area is located within the western portion of the Chapala basin, middle-west Mexico. Observations of vertical surficial deformation were made at each benchmark (September and November 2012) relative to a fixed station and compared to an initial survey of each benchmark (April 2012). Results indicate that a maximum subsidence of 7.16 cm over the 8-month measurement interval occurs near downtown coincident with the largest levels of drawdown and translates to a maximum subsidence rate of 0.89 cm/month for the sampling period. Two benchmarks located northwest and southeast of the urban area exhibited uplift of 2.8 and 0.76 cm, respectively, suggesting a complex mechanical response between the sedimentary soil units and the factors causing deformation. A potential spatial relationship exists between subsidence patterns and soil discontinuities. Four separate cones of groundwater depression were observed with two being coincident with subsidence bowls downtown and south of the urban area; however, there is no clear relationship between drawdown and subsidence in the remaining areas. Hydrogeologic reconstructions reveal alternating sequences of alluvial aquifers and highly deformable lacustrine aquitards. An analysis of the soil discontinuities reveals that they are directly aligned with the patterns of vertical deformation.

Environmental Modelling and Software, Sep 1, 2021

Journal of Hydrology, 2022

Environmental Modelling and Software, Mar 1, 2021

Hydrological Processes, Aug 2, 2016

Las Vegas Valley has had a long history of groundwater development and subsequent surface deforma... more Las Vegas Valley has had a long history of groundwater development and subsequent surface deformation. InSAR interferograms have revealed detailed and complex spatial patterns of subsidence in the Las Vegas Valley area that do not coincide with major pumping regions. This research represents the first effort to use high spatial and temporal resolution subsidence observations from InSAR and hydraulic head data to inversely calibrate transmissivities (T), elastic and inelastic skeletal storage coefficients (Ske and Skv) of the developed‐zone aquifer and conductance (CR) of the basin‐fill faults for the entire Las Vegas basin. The results indicate that the subsidence observations from InSAR are extremely beneficial for accurately quantifying hydraulic parameters, and the model calibration results are far more accurate than when using only groundwater levels as observations, and just a limited number of subsidence observations. The discrepancy between distributions of pumping and greatest levels of subsidence is found to be attributed to spatial variations in clay thickness. The Eglington fault separates thicker interbeds to the northwest from thinner interbeds to the southeast and the fault may act as a groundwater‐flow barrier and/or subsidence boundary, although the influence of the groundwater barrier to this area is found to be insignificant. Copyright © 2016 John Wiley & Sons, Ltd.

Hydrogeology Journal, Aug 6, 2020

Many regions of the earth are experiencing land subsidence owing to aquifer-system compaction, a ... more Many regions of the earth are experiencing land subsidence owing to aquifer-system compaction, a consequence of groundwater depletion manifesting as excessive groundwater drawdown. The relation between groundwater drawdown and land subsidence caused by aquifer-system compaction is nonstationary in space and time due to the highly heterogeneous aquifer material, hydraulic and mechanical properties, and spatio-temporal variations in aquifer recharge and groundwater extraction. Annual land subsidence maps are developed using geographical time-slice weighted regression (GTSWR) and geographical temporal weighted regression (GTWR). Considering these spatiotemporal regressions, groundwater drawdown is used as the input parameter to estimate spatial and temporal patterns of land subsidence in both Changhua and Yunlin counties, Taiwan, for an 8-year period. Results indicate that the GTSWR or GTWR models yield greater accuracy with a lower root mean square error (RMSE) than linear regression (LR). The correlation between the predicted and observed data for LR, GTSWR and GTWR is 0.31, 0.93 and 0.94, respectively. In the spatiotemporal models, areas with smaller model coefficients represent over-consolidated sediments, whereas the areas with larger coefficients represent where sediments are normally consolidated. Normally consolidated sediments tend to produce the greatest amount of land subsidence. Annual subsidence patterns reveal that greater levels of subsidence are progressing inland. The greatest level of subsidence occurs in central Yunlin (7 cm/year) due to groundwater extraction. The spatio-temporal regression model is used to predict the effects of reduced groundwater extraction for different areas based on two scenarios of 30 and 50% reductions in groundwater drawdown.

Journal of Hydrology: Regional Studies, Feb 1, 2023

Journal of Hydrology: Regional Studies, 2021

Abstract Study region Choshui River alluvial fan, Taiwan. Study focus Land subsidence caused by g... more Abstract Study region Choshui River alluvial fan, Taiwan. Study focus Land subsidence caused by groundwater overexploitation is a critical global problem. The spatial distribution of land subsidence is crucial for effective environmental management and land planning in subsidence prone areas. Because of the nonlinear relationship between subsidence and drawdown due to groundwater exploitation in heterogeneous aquifers, a spatial regression (SR) model is developed to effectively estimate nonlinear and spatially varying land subsidence. Considering various data inputs in the Choshui River alluvial fan, the SR model offers a robust method for accurately estimating the spatial patterns of subsidence using only drawdown as input data. New hydrological insights for the region Without requiring extensive calibration or an elaborate numerical groundwater flow and subsidence model, the model provides annual subsidence patterns using a spatially varying relationship between drawdown and resulting land subsidence. Results show that the largest water-level cone of depression occurs in the distal fan area. Nonetheless, the calculated subsidence bowl closely approximates the observed one located much farther inland. The root-mean-square-errors (RMSEs) of annual subsidence is less or equal to 0.76 cm for the SR. Results indicate that the SR model reasonably estimates the spatial distribution of the skeletal storage coefficient in the aquifer system. The large coefficient that represents high potential of inelastic compaction occurs in the southern inland area, whereas the small coefficient that represents elastic compaction occurs in the northern area and proximal fan. Furthermore, this method can be used efficiently for subsidence management/ regulation and might be widely used for subsidence estimation solely based on drawdown.

Science of The Total Environment, 2019

Hydrological Processes, 2017

Surface coal mining has altered land cover, near‐surface geologic structure, and hydrologic proce... more Surface coal mining has altered land cover, near‐surface geologic structure, and hydrologic processes of large areas in central Appalachia, USA. These alterations are associated with changes in water quality such as elevated total‐dissolved solids, which is usually measured via its surrogate, specific conductance (SC). The SC of valley fill effluent streams is a function of fill construction methods, materials, and age; yet hydrologic studies that relate these variables to water quality are sparse due to the difficulty of conducting traditional hydrologic studies in mined landscapes. We used electrical resistivity imaging (ERI) to visualize the subsurface geologic structure and hydrologic flow paths within a valley fill. ERI is a noninvasive geophysical technique that maps spatiotemporal changes in resistivity of the subsurface. We paired ERI with artificial rainfall experiments to track infiltrated water as it moved through the valley fill. Results indicate that ERI can be used to ...

Environmental Earth Sciences, May 1, 2016