This research paper presents an investigation of aquifer structure using a combination of gravity and seismic analyses, calibrated by hydrogeological data. This work illustrates how crucial it is to study geological structures and fault network as preliminary work to understand water and pollutant flow systems and aquifer vulnerability, especially with the increased frequency of drought events and climate change pressures. A Plio-Quaternary coastal northeastern aquifer in Tunisia was chosen as the study case. First, a hydrogeological approach was performed using water wells, and piezometers data shows an important fluctuation in the piezometric level and a notable depression in the piezometric surface observed in the southern part of the study area. Secondly, gravity data were analyzed and calibrated by a seismic profile. The results demonstrate the presence of shallow NE-SW faults less than 300 m under the region's principal wadis as well as deeper faults of varying depths (from 400 m to 2600 m) that influence the basin structure, aquifer geometry, and resulting water flow. The combination of those approaches revealed that the variation of the aquifer thickness, piezometric surface depression zones, and groundwater flow is mainly controlled by the shallow and deep geological structures and their tectonic reactivation.
{"title":"Structure of the Plio-Quaternary Coastal Aquifer (Mediterranean basin, Tunisia): Insights from Gravity and Seismic Analysis","authors":"Sana Ayari, Nesrine Ghouili, H. Gabtni, L. Zouhri","doi":"10.1144/qjegh2023-084","DOIUrl":"https://doi.org/10.1144/qjegh2023-084","url":null,"abstract":"This research paper presents an investigation of aquifer structure using a combination of gravity and seismic analyses, calibrated by hydrogeological data. This work illustrates how crucial it is to study geological structures and fault network as preliminary work to understand water and pollutant flow systems and aquifer vulnerability, especially with the increased frequency of drought events and climate change pressures. A Plio-Quaternary coastal northeastern aquifer in Tunisia was chosen as the study case.\u0000 First, a hydrogeological approach was performed using water wells, and piezometers data shows an important fluctuation in the piezometric level and a notable depression in the piezometric surface observed in the southern part of the study area.\u0000 Secondly, gravity data were analyzed and calibrated by a seismic profile. The results demonstrate the presence of shallow NE-SW faults less than 300 m under the region's principal wadis as well as deeper faults of varying depths (from 400 m to 2600 m) that influence the basin structure, aquifer geometry, and resulting water flow.\u0000 The combination of those approaches revealed that the variation of the aquifer thickness, piezometric surface depression zones, and groundwater flow is mainly controlled by the shallow and deep geological structures and their tectonic reactivation.","PeriodicalId":20937,"journal":{"name":"Quarterly Journal of Engineering Geology and Hydrogeology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2024-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139860771","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Because of the characteristics of water-swelling and drying shrinkage, the mechanical performances of expansive clay in semi-arid areas deteriorate with the change in humidity and temperature. So investigating the moisture migration in expansive clays is of great significance. Herein, scanning electron microscopy test and water migration tests of unsaturated soil were carried out to address the water variation law and microscopic mechanism in the unsaturated expansive clay. It is found that small and medium-sized pores (2-10μm) are dominated, and these pores are conducive to the rise of water in the soil. The soil with high water content exhibits a flocculent structure, characterized by a small fractal dimension and a high relative hydraulic conductivity. Conversely, the soil with low water content displays a dispersed structure, featuring a large fractal dimension and a low relative hydraulic conductivity. The water migration tests under constant temperature(5, 20, and 40°C) and variable temperature (15-25°C) show that the migration amount at 5°C and 20°C was about 25%-40%, 40%-60% of that at 40°C, respectively. The amount of water migration under constant temperature was obviously lower than that under variable temperature. The research results have provided technical support for effective control of soil change.
{"title":"Study on water migration and microstructure of unsaturated expansive clays","authors":"Qiuyan Liu, Mingwu Wang","doi":"10.1144/qjegh2023-067","DOIUrl":"https://doi.org/10.1144/qjegh2023-067","url":null,"abstract":"Because of the characteristics of water-swelling and drying shrinkage, the mechanical performances of expansive clay in semi-arid areas deteriorate with the change in humidity and temperature. So investigating the moisture migration in expansive clays is of great significance. Herein, scanning electron microscopy test and water migration tests of unsaturated soil were carried out to address the water variation law and microscopic mechanism in the unsaturated expansive clay. It is found that small and medium-sized pores (2-10μm) are dominated, and these pores are conducive to the rise of water in the soil. The soil with high water content exhibits a flocculent structure, characterized by a small fractal dimension and a high relative hydraulic conductivity. Conversely, the soil with low water content displays a dispersed structure, featuring a large fractal dimension and a low relative hydraulic conductivity. The water migration tests under constant temperature(5, 20, and 40°C) and variable temperature (15-25°C) show that the migration amount at 5°C and 20°C was about 25%-40%, 40%-60% of that at 40°C, respectively. The amount of water migration under constant temperature was obviously lower than that under variable temperature. The research results have provided technical support for effective control of soil change.","PeriodicalId":20937,"journal":{"name":"Quarterly Journal of Engineering Geology and Hydrogeology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139683541","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Editorial 2024","authors":"Cherith Moses, Colin Serridge","doi":"10.1144/qjegh2024-012","DOIUrl":"https://doi.org/10.1144/qjegh2024-012","url":null,"abstract":"","PeriodicalId":20937,"journal":{"name":"Quarterly Journal of Engineering Geology and Hydrogeology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139811085","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Editorial 2024","authors":"Cherith Moses, Colin Serridge","doi":"10.1144/qjegh2024-012","DOIUrl":"https://doi.org/10.1144/qjegh2024-012","url":null,"abstract":"","PeriodicalId":20937,"journal":{"name":"Quarterly Journal of Engineering Geology and Hydrogeology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139870963","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study explores the impact of external pressure and high-temperature erosion on the physical and mechanical properties of granite, the geothermal well storage medium, during geothermal exploitation. Objectives include evaluating the effects of repeated heating and cooling cycles at different temperatures on porosity, permeability, and mechanical performance, with a focus on confining pressure's influence on permeability. Results indicate that under water-cooling and ambient conditions, porosity and permeability increase with cycle repetition, while compressive strength and elastic modulus decrease. Notably, Group B's (water-cooled) mechanical performance surpasses Group A (room temperature cooling) when porosity is below 1.5%. However, with increasing porosity due to thermal cycling, Group B's granite becomes inferior to Group A. CT scans reveal a post-cycling granite pore structure dominated by horizontal cracks, with primary uniaxial compression damage in the vertical direction. Thermal cycling reduces crack paths and load-bearing capacity, diminishing granite's mechanical performance. This study offers insights into subtle interactions between cooling methods and porosity during geothermal energy exploitation. It provides valuable guidance for optimizing geothermal energy use and mitigating potential adverse impacts on rock integrity, laying a foundation for further research and practical applications in geothermal energy exploitation.
本研究探讨了在地热开采过程中，外部压力和高温侵蚀对地热井存储介质花岗岩的物理和机械性能的影响。研究目标包括评估在不同温度下反复加热和冷却循环对孔隙度、渗透率和机械性能的影响，重点是封闭压力对渗透率的影响。结果表明，在水冷和常温条件下，孔隙度和渗透率会随着循环次数的增加而增加，而抗压强度和弹性模量则会降低。值得注意的是，当孔隙率低于 1.5% 时，B 组（水冷）的机械性能超过了 A 组（室温冷却）。CT 扫描显示，循环后的花岗岩孔隙结构以水平裂缝为主，垂直方向主要是单轴压缩破坏。热循环减少了裂缝路径和承载能力，降低了花岗岩的机械性能。这项研究深入揭示了地热能源开采过程中冷却方法与孔隙度之间微妙的相互作用。它为优化地热能利用和减轻对岩石完整性的潜在不利影响提供了宝贵的指导，为地热能开发的进一步研究和实际应用奠定了基础。
{"title":"Analysis of physical and mechanical properties of granite under different cooling methods under high temperatures thermal cycles","authors":"Haonan Li, Li Yu, Yue Wu, Weihao Wang, Xinyuan Zhang, Yongchuan Zhao","doi":"10.1144/qjegh2023-110","DOIUrl":"https://doi.org/10.1144/qjegh2023-110","url":null,"abstract":"This study explores the impact of external pressure and high-temperature erosion on the physical and mechanical properties of granite, the geothermal well storage medium, during geothermal exploitation. Objectives include evaluating the effects of repeated heating and cooling cycles at different temperatures on porosity, permeability, and mechanical performance, with a focus on confining pressure's influence on permeability. Results indicate that under water-cooling and ambient conditions, porosity and permeability increase with cycle repetition, while compressive strength and elastic modulus decrease. Notably, Group B's (water-cooled) mechanical performance surpasses Group A (room temperature cooling) when porosity is below 1.5%. However, with increasing porosity due to thermal cycling, Group B's granite becomes inferior to Group A. CT scans reveal a post-cycling granite pore structure dominated by horizontal cracks, with primary uniaxial compression damage in the vertical direction. Thermal cycling reduces crack paths and load-bearing capacity, diminishing granite's mechanical performance. This study offers insights into subtle interactions between cooling methods and porosity during geothermal energy exploitation. It provides valuable guidance for optimizing geothermal energy use and mitigating potential adverse impacts on rock integrity, laying a foundation for further research and practical applications in geothermal energy exploitation.","PeriodicalId":20937,"journal":{"name":"Quarterly Journal of Engineering Geology and Hydrogeology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2024-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139607214","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In radioactive waste repositories and tunnel engineering, the near-field groundwater environment is extremely complex, and changes in multiple chemical components are bound to disrupt the long-term stability of soft rock and soil, thus inducing a series of environmental and engineering geological problems. This article selects argillaceous slate as the research object and prepares different types of aqueous chemical solutions. It then conducts lateral constraint expansion tests, XRD tests, nuclear magnetic resonance tests, and SEM electron microscopy scanning tests. First, the expansion characteristics and evolution mechanism of argillaceous slate in a hydrochemical environment are revealed at the multiscale level. Then, the internal relationship between the macroscopic expansion of argillaceous slate and the microscopic and mesoscopic structures is explored. Finally, based on the experimental data and gray theory, a nonequal step GM (1, N) gray prediction model is constructed. The results indicate that (1) the water‒rock physicochemical reactions mainly affect the microstructure evolution of the argillaceous slate expansion process through pore changes, mineral dissolution, and ion exchange; (2) there is a certain correlation between the microstructure parameters and the expansion rate, and it was found that pore volume and clay mineral content are the main factors affecting the expansion of soft rocks; and (3) the model verification results show that the nonequal-step GM(1, N) gray prediction model established in this study can effectively predict the expansion trend of soft rocks in different hydrochemical environments. The research findings can provide a reference for the study of the expansion mechanism of soft rocks in complex hydrochemical environments and the disposal of expansion problems.
{"title":"Swelling evolution mechanism of argillaceous slate in a hydrochemical environment","authors":"Qingjun Zuo, Xuefeng He, Youyin Wu, Qinglin Yi, Sheng Zhu, Yiliang Liu, Jian Jiang","doi":"10.1144/qjegh2023-114","DOIUrl":"https://doi.org/10.1144/qjegh2023-114","url":null,"abstract":"In radioactive waste repositories and tunnel engineering, the near-field groundwater environment is extremely complex, and changes in multiple chemical components are bound to disrupt the long-term stability of soft rock and soil, thus inducing a series of environmental and engineering geological problems. This article selects argillaceous slate as the research object and prepares different types of aqueous chemical solutions. It then conducts lateral constraint expansion tests, XRD tests, nuclear magnetic resonance tests, and SEM electron microscopy scanning tests. First, the expansion characteristics and evolution mechanism of argillaceous slate in a hydrochemical environment are revealed at the multiscale level. Then, the internal relationship between the macroscopic expansion of argillaceous slate and the microscopic and mesoscopic structures is explored. Finally, based on the experimental data and gray theory, a nonequal step GM (1, N) gray prediction model is constructed. The results indicate that (1) the water‒rock physicochemical reactions mainly affect the microstructure evolution of the argillaceous slate expansion process through pore changes, mineral dissolution, and ion exchange; (2) there is a certain correlation between the microstructure parameters and the expansion rate, and it was found that pore volume and clay mineral content are the main factors affecting the expansion of soft rocks; and (3) the model verification results show that the nonequal-step GM(1, N) gray prediction model established in this study can effectively predict the expansion trend of soft rocks in different hydrochemical environments. The research findings can provide a reference for the study of the expansion mechanism of soft rocks in complex hydrochemical environments and the disposal of expansion problems.","PeriodicalId":20937,"journal":{"name":"Quarterly Journal of Engineering Geology and Hydrogeology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2024-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139606185","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bahadir Öztürk, Volkan İşbuğa, Esra Bilgiç, Alper Baba
The bearing capacity of the soil is a critical factor in the design of foundations for civil engineering structures. The bearing capacity depends on soil properties as well as the location of the water table. The rise in groundwater level can be dramatic, especially in highly urbanized regions, and it can affect the bearing capacity of foundations. In this study, groundwater level fluctuation in a highly urbanized region in İzmir, the third largest city in Türkiye, was monitored over a one-year period, and its effect on the reduction of bearing capacity, which is not considered in foundation design and construction, were investigated. For this purpose, four observation wells equipped with groundwater data loggers were used to determine the variations in groundwater level within a year. Using the Terzaghi approach to calculate the bearing capacity, normalized bearing capacity plots for various foundation width/depth (B/D f ) ratios were generated for all four observation wells. The remarkable bearing capacity changes of 10.94%, 8.21%, 7.62% and 9.29% were observed for OW-1, OW-3, OW-6, and OW-9, respectively. The study showed that the change in groundwater level in the region caused by urbanization poses a potential risk to the sustainability of the previously constructed foundations.
{"title":"Effect of the Urbanization on Groundwater Resources Hydrodynamic and Bearing Capacity – a Case Study: Bayraklı Region, İzmir, Türkiye","authors":"Bahadir Öztürk, Volkan İşbuğa, Esra Bilgiç, Alper Baba","doi":"10.1144/qjegh2023-092","DOIUrl":"https://doi.org/10.1144/qjegh2023-092","url":null,"abstract":"\u0000 The bearing capacity of the soil is a critical factor in the design of foundations for civil engineering structures. The bearing capacity depends on soil properties as well as the location of the water table. The rise in groundwater level can be dramatic, especially in highly urbanized regions, and it can affect the bearing capacity of foundations. In this study, groundwater level fluctuation in a highly urbanized region in İzmir, the third largest city in Türkiye, was monitored over a one-year period, and its effect on the reduction of bearing capacity, which is not considered in foundation design and construction, were investigated. For this purpose, four observation wells equipped with groundwater data loggers were used to determine the variations in groundwater level within a year. Using the Terzaghi approach to calculate the bearing capacity, normalized bearing capacity plots for various foundation width/depth (B/D\u0000 f\u0000 ) ratios were generated for all four observation wells. The remarkable bearing capacity changes of 10.94%, 8.21%, 7.62% and 9.29% were observed for OW-1, OW-3, OW-6, and OW-9, respectively. The study showed that the change in groundwater level in the region caused by urbanization poses a potential risk to the sustainability of the previously constructed foundations.\u0000","PeriodicalId":20937,"journal":{"name":"Quarterly Journal of Engineering Geology and Hydrogeology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2024-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139614392","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Recharge is considered a key parameter in groundwater modelsfor sustainable management of aquifers, which is influenced by factors such as land use, soil, and weather. The present study was conducted to couple WetSpass-M and MODFLOW models in the Neyshabur-Rokh basin. To this aim, the simulated recharge by the WetSpass-M model was applied as an input of MODFLOW to assess the groundwater balance. The hydrodynamic coefficients were determined by calibrating the model and the model sensitivity to the hydraulic conductivity coefficient, specific yield, and recharge were evaluated. The results indicated that the annual average of surface runoff, actual evapotranspiration, interception, and recharge during 1991-2017 equaled 18, 36, 7.6, and 42.6% of the average annual precipitation in the basin, respectively. The accurate alignment of simulated and observed water levels, along with the achievement of suitable evaluation criteria values in both steady and transient states, demonstrates the WetSpass-M model's precision in estimating recharge and successfully integrating the two models. The groundwater balance assessment revealed a significant deficit in the aquifer, with the model demonstrating greater sensitivity to the hydraulic conductivity coefficient provides valuable insights for the sustainable management of the Neyshabur aquifer. Thematic collection: This article is part of the Monitoring the aquifers collection available at: https://www.lyellcollection.org/topic/collections/monitoring-the-aquifers
{"title":"Coupling of WetSpass-M and MODFLOW Models for Groundwater Flow Assessment","authors":"S. Dowlatabadi, Mahdi Amirabadizadeh, Mahdi Zarei","doi":"10.1144/qjegh2023-138","DOIUrl":"https://doi.org/10.1144/qjegh2023-138","url":null,"abstract":"Recharge is considered a key parameter in groundwater modelsfor sustainable management of aquifers, which is influenced by factors such as land use, soil, and weather. The present study was conducted to couple WetSpass-M and MODFLOW models in the Neyshabur-Rokh basin. To this aim, the simulated recharge by the WetSpass-M model was applied as an input of MODFLOW to assess the groundwater balance. The hydrodynamic coefficients were determined by calibrating the model and the model sensitivity to the hydraulic conductivity coefficient, specific yield, and recharge were evaluated. The results indicated that the annual average of surface runoff, actual evapotranspiration, interception, and recharge during 1991-2017 equaled 18, 36, 7.6, and 42.6% of the average annual precipitation in the basin, respectively. The accurate alignment of simulated and observed water levels, along with the achievement of suitable evaluation criteria values in both steady and transient states, demonstrates the WetSpass-M model's precision in estimating recharge and successfully integrating the two models. The groundwater balance assessment revealed a significant deficit in the aquifer, with the model demonstrating greater sensitivity to the hydraulic conductivity coefficient provides valuable insights for the sustainable management of the Neyshabur aquifer.\u0000 \u0000 Thematic collection:\u0000 This article is part of the Monitoring the aquifers collection available at:\u0000 https://www.lyellcollection.org/topic/collections/monitoring-the-aquifers\u0000","PeriodicalId":20937,"journal":{"name":"Quarterly Journal of Engineering Geology and Hydrogeology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2024-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139617276","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Steven F. Thornton, Michael J. Spence, S. Bottrell, K. H. Spence
A plume-scale mass balance is developed to assess the natural attenuation (NA) of dissolved organic contaminants in fractured, dual porosity aquifers. This methodology can be used to evaluate contaminant distribution within the aquifer, plume source term, contaminant biodegradation and plume status. The approach is illustrated for a site on the UK Upper Chalk aquifer impacted by petroleum fuel containing MTBE and TAME. Variability in site investigation data and uncertainty in the mass balance was assessed using probabilistic analysis. The analysis shows that BTEX compounds are biodegraded primarily by denitrification and sulphate reduction in the aquifer, with an equivalent plume-scale first-order biodegradation rate of 0.49 year -1 . Other biodegradation processes are less important. Sorption contributes to hydrocarbon attenuation in the aquifer but is less important for MTBE and TAME. Uncertainty in the plume source term and site hydrogeological parameters had the greatest effect on the mass balance. The probabilistic analysis enabled the most likely long-term composition of the plume source term to be deduced and provided a site-specific estimate of contaminant mass flux for the prediction of plume development. The mass balance methodology provides a novel approach to improve NA assessments for petroleum hydrocarbons and other organic contaminants in these aquifer settings. Thematic collection: This article is part of the Monitoring the aquifers collection available at: https://www.lyellcollection.org/topic/collections/monitoring-the-aquifers Supplementary material: https://doi.org/10.6084/m9.figshare.c.7016429
本研究开发了一种羽流尺度质量平衡方法，用于评估断裂双孔含水层中溶解有机污染物的自然衰减（NA）。该方法可用于评估污染物在含水层中的分布、羽流源项、污染物生物降解和羽流状态。该方法针对英国上白垩统含水层中受含 MTBE 和 TAME 的石油燃料影响的地点进行了说明。利用概率分析评估了现场调查数据的可变性和质量平衡的不确定性。分析表明，含水层中的 BTEX 化合物主要通过反硝化作用和硫酸盐还原作用进行生物降解，等效的羽状尺度一阶生物降解率为 0.49 年-1。其他生物降解过程的重要性较低。吸附作用对含水层中碳氢化合物的衰减有影响，但对 MTBE 和 TAME 的影响较小。羽流源项和现场水文地质参数的不确定性对质量平衡的影响最大。通过概率分析，可以推断出羽流源项最可能的长期组成，并为预测羽流发展提供了特定场地的污染物质量通量估算。质量平衡方法为改进这些含水层环境中石油碳氢化合物和其他有机污染物的 NA 评估提供了一种新方法。 专题集锦：本文是含水层监测文集的一部分，可从以下网址获取： https://www.lyellcollection.org/topic/collections/monitoring-the-aquifers 补充材料：https://doi.org/10.6084/m9.figshare.c.7016429
{"title":"Natural attenuation of dissolved petroleum fuel constituents in a fractured Chalk aquifer: Contaminant mass balance with probabilistic analysis","authors":"Steven F. Thornton, Michael J. Spence, S. Bottrell, K. H. Spence","doi":"10.1144/qjegh2023-116","DOIUrl":"https://doi.org/10.1144/qjegh2023-116","url":null,"abstract":"\u0000 A plume-scale mass balance is developed to assess the natural attenuation (NA) of dissolved organic contaminants in fractured, dual porosity aquifers. This methodology can be used to evaluate contaminant distribution within the aquifer, plume source term, contaminant biodegradation and plume status. The approach is illustrated for a site on the UK Upper Chalk aquifer impacted by petroleum fuel containing MTBE and TAME. Variability in site investigation data and uncertainty in the mass balance was assessed using probabilistic analysis. The analysis shows that BTEX compounds are biodegraded primarily by denitrification and sulphate reduction in the aquifer, with an equivalent plume-scale first-order biodegradation rate of 0.49 year\u0000 -1\u0000 . Other biodegradation processes are less important. Sorption contributes to hydrocarbon attenuation in the aquifer but is less important for MTBE and TAME. Uncertainty in the plume source term and site hydrogeological parameters had the greatest effect on the mass balance. The probabilistic analysis enabled the most likely long-term composition of the plume source term to be deduced and provided a site-specific estimate of contaminant mass flux for the prediction of plume development. The mass balance methodology provides a novel approach to improve NA assessments for petroleum hydrocarbons and other organic contaminants in these aquifer settings.\u0000 \u0000 \u0000 Thematic collection:\u0000 This article is part of the Monitoring the aquifers collection available at:\u0000 https://www.lyellcollection.org/topic/collections/monitoring-the-aquifers\u0000 \u0000 \u0000 Supplementary material:\u0000 https://doi.org/10.6084/m9.figshare.c.7016429\u0000","PeriodicalId":20937,"journal":{"name":"Quarterly Journal of Engineering Geology and Hydrogeology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2024-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139531489","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A rainfall-induced debris flow occurred on 30 September 2022 closing the A87 trunk (strategic) road on the Isle of Skye for around two hours. Ground-based and aerial drone inspections were used to describe the event and a comprehensive rainfall analysis undertaken. It is concluded that the event was triggered by overland water flow from the slopes above the source zone as a result of high rainfall. The resulting translational slide transitioned into a debris flow that reached a pre-existing channel where entrained superficial deposits were deposited, adding to pre-existing levee structures before reaching the road. The rainfall that led to the debris flow was high intensity-low duration; the rainfall analysis encompasses annual, monthly, daily, hourly and 15-minute data, each aiding understanding of the climate of the area and/or the event rainfall. Comparison is made with a rainfall event the following month which was of a greater magnitude but of longer duration and lower intensity. The hazard at this location is a concern but the risk is emphasised by the proximity of the road to the steep slopes above and the lack of a viable detour. Thematic collection: This article is part of the Geo-resilience and infrastructure collection available at: https://www.lyellcollection.org/topic/collections/geo-resilience-and-infrastructure
{"title":"Debris flow at Luib on the A87 strategic road: Isle of Skye, Scotland","authors":"M. G. Winter, T. Waaser","doi":"10.1144/qjegh2023-111","DOIUrl":"https://doi.org/10.1144/qjegh2023-111","url":null,"abstract":"A rainfall-induced debris flow occurred on 30 September 2022 closing the A87 trunk (strategic) road on the Isle of Skye for around two hours. Ground-based and aerial drone inspections were used to describe the event and a comprehensive rainfall analysis undertaken. It is concluded that the event was triggered by overland water flow from the slopes above the source zone as a result of high rainfall. The resulting translational slide transitioned into a debris flow that reached a pre-existing channel where entrained superficial deposits were deposited, adding to pre-existing levee structures before reaching the road. The rainfall that led to the debris flow was high intensity-low duration; the rainfall analysis encompasses annual, monthly, daily, hourly and 15-minute data, each aiding understanding of the climate of the area and/or the event rainfall. Comparison is made with a rainfall event the following month which was of a greater magnitude but of longer duration and lower intensity. The hazard at this location is a concern but the risk is emphasised by the proximity of the road to the steep slopes above and the lack of a viable detour.\u0000 \u0000 Thematic collection:\u0000 This article is part of the Geo-resilience and infrastructure collection available at:\u0000 https://www.lyellcollection.org/topic/collections/geo-resilience-and-infrastructure\u0000","PeriodicalId":20937,"journal":{"name":"Quarterly Journal of Engineering Geology and Hydrogeology","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2024-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139626351","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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