Robust Conceptual Model Research Articles

The John Mitchell Lecture 2022: thinking conceptually about groundwater problems

Many excavations and tunnels experience problems and instability caused by uncontrolled groundwater inflows or groundwater pressures that influence stability and soil behaviour. A range of groundwater control measures can be used to overcome these problems and create stable and workably dry conditions below groundwater level. A key challenge for designers is that the performance of the various different techniques is strongly influenced by the hydrogeological conditions at a site. Furthermore, the available ground investigation data may have data gaps or considerable uncertainty regarding key parameters such as hydraulic conductivity or hydraulic boundary conditions. This means that, when working with real-world data sets, there are some groundwater problems where analysis involves so many assumptions and uncertainties that the design outcomes are of little practical value. This paper will discuss how thinking conceptually about groundwater problems can be of great benefit when developing of groundwater control schemes, and that a robust conceptual model helps reduce the risk of designs being developed using inappropriate techniques. Historic examples from the 19 th Century and early 20 th century (before sophisticated methods of groundwater analysis were available) are described, where developing a conceptual understanding of groundwater conditions was vital in developing practical engineering solutions.

Digital nomads: a systematic literature review and future research agenda

Purpose This study aims to address the need for robust conceptual foundations in the digital nomadism discourse through a systematic literature review (SLR). It delves into digital nomadism within sustainable tourism, providing valuable insights to foster community development. Design/methodology/approach This study uses a rigorous eight-step process that combines an SLR and a system dynamics approach. In the SLR phase, the authors use the theory, context, characteristics and methodology framework to identify key variables for a dynamic model of sustainable tourism through digital nomadism, following detailed search and selection criteria based on PRISMA guidelines. The second phase uses causal loop diagrams (CLDs) from the literature review to visualize relationships and inform future research directions. The CLD model is validated through literature-based and stakeholder interaction processes, focusing on the social, economic and environmental dimensions, resulting in the development of a robust conceptual model. Findings This study identified 28 theories, including agency–structure theory, travel career ladder theory, stakeholder theory and grounded theory, among others. Semi-structured interviews were the primary research method. Major themes explored encompass community interactions, work lifestyles, cultural aspects, financial considerations, infrastructure and policy. The proposed conceptual model aims to scrutinize relationships across economic, environmental and social dimensions, providing a foundation for investigating and promoting sustainable tourism. Research limitations/implications Policy implications involve refining taxation policies to maintain tax bases, promoting collaborative economic models and enforcing environmental regulations. Additionally, integrating community planning infrastructure and implementing demographic strategies to manage potential population shifts are crucial. Policies supporting education, skill transfer, health and well-being initiatives contribute significantly to fostering sustainable tourism practices and enhancing community vitality. Originality/value To the best of authors’ knowledge, this study is the first in the digital nomadism space to propose a conceptual model for sustainable tourism adoption.

De-risking green energy from mine waters by developing a robust hydrogeological conceptual model of the UK Geoenergy Observatory in Glasgow

Mine-water geothermal resources have potential to provide low-carbon heating and cooling in many areas; however, this potential has not been fully realised due to technical, economic and policy challenges. The UK Geoenergy Observatory (UKGEOS) in Glasgow was developed to provide an at-scale research facility designed to help de-risk mine-water geothermal usage. The limited knowledge of the hydrogeological systems altered by former mining activities is a key determinant of the long-term sustainability of water and heat abstraction/reinjection. This work presents a hydrogeological conceptual model developed using groundwater monitoring data obtained during the construction of the Observatory between 2020 and 2022, results from initial pumping tests performed in 2020, and results of hydrochemistry analysis from 25 sampling rounds collected between 2019 and 2022. The analysis of the data provides evidence of the dominant role of mine workings in controlling groundwater flow, with high intra-mine connectivity; increased fracturing in sandstones above mine workings; and limited inter-mine connectivity. Groundwater recharge is meteoric, mean residence times are >50 years, and there is a general upwards circulation from the deeper mine levels to the superficial deposits and the River Clyde. Faults play a significant role in limiting the extent of the highly transmissive mine workings, but there remains uncertainty surrounding the role of the faults in connecting different mine workings and their hydraulic behaviour in nonmined units. The conceptual model, that will be refined as new data become available, will be used to help guide monitoring and sampling programs and plan research activities in the Observatory.

Optimising groundwater recharge to counteract seawater intrusion through an inverse modelling approach and identifying efficient recharge structure locations

In semi-arid coastal urban regions, groundwater faces challenges from seawater intrusion due to reduced recharge and increased extraction. This study employs advanced numerical modeling to comprehensively assess seawater intrusion along the South Chennai coast from 2018 to 2022. The inverse modelling approach utilizes observed data, such as groundwater heads or concentrations, to estimate aquifer properties, like hydraulic conductivity, by minimizing the disparity between model predictions and actual measurements to identify the best-fit parameter values. This inverse method forecasts the necessary recharge rate to address seawater intrusion by increasing groundwater head and decreasing chloride concentrations. The estimation of recharge incorporates variables such as rainfall, soil infiltration capacity, land use, and the vital groundwater draft calculated based on per capita consumption and population. The study uses FEFLOW software to develop a robust conceptual model, simulating groundwater flow and chloride transport. The inverse modeling approach resulted in critical recharge adjustments, enhancing rates by 40%–60% in specific regions. The predictive scenarios, integrating proposed recharge structures, show promising results, notably with a 50% reduction in chloride concentration during the post-monsoon season compared to the pre-monsoon period in wells 8 and 3. A notable decrease in chloride concentration of over 90% was observed during May 2025 in well no: 15 due to its proximity to the Adayar River. These fluctuations are influenced by seasonal variations resulting from climatic changes in South India, with intense rainfall accompanying northeast monsoon winds playing a significant role. Increased recharge rates and strategically placed structures along the Buckingham Canal provide significant relief in the most impacted northern coastal area, acting as effective barriers. These interventions successfully reduce chloride concentration, providing a sustainable and effective solution to mitigate the persistent challenge of seawater intrusion.

Access to early diagnosis for attention-deficit/hyperactivity disorder among children and adolescents in Mexico City at specialized mental health services

BackgroundIn Mexico, this pioneering research was undertaken to assess the accessibility of timely diagnosis of Dyads [Children and adolescents with Attention Deficit Hyperactivity Disorder (ADHD) and their primary caregivers] at specialized mental health services. The study was conducted in two phases. The first phase involved designing an “Access Pathway” aimed to identify barriers and facilitators for ADHD diagnosis; several barriers, with only the teacher being identified as a facilitator. In the second phase, the study aimed to determine the time taken for dyads, to obtain a timely diagnosis at each stage of the Access Pathway. As well as identify any disparities based on gender and socioeconomic factors that might affect the age at which children can access a timely diagnosis.MethodIn a retrospective cohort study, 177 dyads participated. To collect data, the Acceda Survey was used, based on the robust Conceptual Model Levesque, 2013. The survey consisted of 48 questions that were both dichotomous and polytomous allowing the creation of an Access Pathway that included five stages: the age of perception, the age of search, the age of first contact with a mental health professional, the age of arrival at the host hospital, and the age of diagnosis. The data was meticulously analyzed using a comprehensive descriptive approach and a nonparametric multivariate approach by sex, followed by post-hoc Mann-Whitney’s U tests. Demographic factors were evaluated using univariable and multivariable Cox regression analyses.Results71% of dyads experienced a late, significantly late, or highly late diagnosis of ADHD. Girls were detected one year later than boys. Both boys and girls took a year to seek specialized mental health care and an additional year to receive a formal specialized diagnosis. Children with more siblings had longer delays in diagnosis, while caregivers with formal employment were found to help obtain timely diagnoses.ConclusionsOur findings suggest starting the Access Pathway where signs and symptoms of ADHD are detected, particularly at school, to prevent children from suffering consequences. Mental health school-based service models have been successfully tested in other latitudes, making them a viable option to shorten the time to obtain a timely diagnosis.

Geochemical evolution along regional groundwater flow in a semi-arid closed basin using a multi-tracing approach

Groundwater is the main source for domestic drinking water supply, irrigation, and industrial activities in Zacatecas in central Mexico, a good example for numerous semiarid regions worldwide, however, there is insufficient information about characterization and evolution of the baseline water quality to create hydrogeological conceptual models, fundamentals for the future planning of new sources of groundwater supply for the population, especially under ongoing global climate change conditions. By a multi-method analysis that included geological, geophysical, hydrochemical and isotopic tools this investigation allowed the identification of: a) local flows, represented by shallow groundwater and shallow wells, hosted over basin fill sediments with low average temperatures (≈ 23.3 °C), variation in water types related to anthropogenic activities, low trace elements concentrations, δ18O and δ2H signatures indicating surface water and tritium being present in this system, b) intermediate flows (25 °C), identified in wells with depths of 100 to 200 m, water circulating through the basin fill sediments and the sequence of volcanic rocks characterized by intermediate concentrations of trace elements, and groundwater ages calculated for this system vary from 1,000 to 6,000 years, c) regional flows in volcanic rocks, characterized by groundwater from wells with depths of more than 200 m, high temperatures (up to 31.5 °C) and elevated concentrations of trace elements. The δ18O and δ2H signals are more homogenous and the 14C residence times for this flow system are greater than 8,000 years, and d) regional flows in Cretaceous rocks, with depths greater than 400 m, the highest temperatures (≈ 43.7 °C) and intermediate concentrations of trace elements. The δ18O and δ2H signals are homogenous and δ13C can widely be associated with carbonate shales. The hydrogeochemical evolution has been documented along a 62 km flow line to develop a robust conceptual model, reflecting the water–rock interaction in the system. Physicochemical parameters, as well as major and trace element concentrations, reflect a distinct evolution according to the flow paths and their increase is generally proportional to the residence time. Likewise, processes of dissolution of feldspars and some clay minerals from initial weathering in the basin fill sediments, as well as devitrification of the glassy matrix in the volcanic rocks are taking place in the evolution of the system.The results obtained through the analysis of water–rock interaction in this research can be applied to other semi-arid regions with geogenically impacted aquifers, due to the geological and climatic similarity with numerous volcano-sedimentary basins around the world.

A Conceptual Model for Inclusive Technology: Advancing Disability Inclusion through Artificial Intelligence

Artificial intelligence (AI) has ushered in transformative changes, championing inclusion and accessibility for individuals with disabilities. This article delves into the remarkable AI-driven solutions that have revolutionized their lives across various domains. From assistive technologies such as voice recognition and AI-powered smart glasses catering to diverse needs, to healthcare benefiting from early disease detection algorithms and wearable devices that monitor vital signs and alert caregivers in emergencies, AI has steered in significant enhancements. Moreover, AI-driven prosthetics and exoskeletons have substantially improved mobility for those with limb impairments. The realm of education has not been left untouched, with AI tools creating inclusive learning environments that adapt to individual learning styles, paving the way for academic success among students with disabilities. However, the boundless potential of AI also presents ethical concerns and challenges. Issues like safeguarding data privacy, mitigating algorithmic bias, and bridging the digital divide must be thoughtfully addressed to fully harness AI’s potential in empowering individuals with disabilities. To complement these achievements, a robust conceptual model for AI disability inclusion serves as the theoretical framework, guiding the development of tailored AI solutions. By striking a harmonious balance between innovation and ethics, AI has the power to significantly enhance the overall quality of life for individuals with disabilities across a spectrum of vital areas.

Strategic Policies to Support the Independence and Interaction of Older Adults: A Leadership Model That Is Inclusive of Local Businesses

This study employs qualitative analysis techniques for text mining, and its primary focus is on interview data collected from 105 elderly residents living in Mihama City, Fukui Prefecture. The overarching goal of this research is to uncover valuable insights into the specific needs and requirements of the elderly population in this region. Through text mining, several key elements have surfaced, shedding light on important aspects of the elderly residents’ lives. These findings underscore the significance of spaces designed to facilitate social interaction, as well as the indispensable role that policy support plays in ensuring the mobility and accessibility of the elderly within the community. Leveraging advanced cluster analysis techniques, a robust conceptual model has emerged. This model offers a comprehensive perspective on the myriad factors that are vital for nurturing an environment in which elderly individuals can not only exist but thrive in contentment and security. One of the significant contributions of this research is the proposal of a holistic leadership model. This model does not merely advocate for policy implementation; it also strongly emphasizes fostering collaboration with the local business sectors. The foundation of this model is built on the principles of continuous engagement with and listening to the evolving needs of the elderly population, rigorous policy implementation, periodic review, and an ongoing commitment to making iterative improvements. The findings of this study underscore the immense importance of actively involving various stakeholders and local businesses in the city planning process. The ultimate objective is to create an environment finely tuned to optimize the overall well-being of older adults, ensuring that they can enjoy a fulfilling and secure lifestyle within the community.

Hydrogeological characterization of the Silala River catchment

AbstractThis article reviews hydrogeological studies carried out between 2016 and 2018 in the Silala River basin, a catchment shared by Chile and Bolivia. These were conducted in the context of the Case Concerning the Status and Use of the Waters of the Silala River, submitted to the International Court of Justice in 2016, and contributed to multidisciplinary science to demonstrate that this system is an international watercourse. In 2016, the hydrogeological understanding of the Silala River basin was poor. The studies reviewed here filled many knowledge gaps, providing a solid hydrogeological baseline, and establishing new monitoring infrastructure to collect relevant aquifer data. The most important hydrogeological units were identified as the fluvial deposits, alluvial deposits, and the Cabana ignimbrite. The latter is highly heterogeneous, weathered and fractured, and exhibits a high permeability. It is the most important unit in terms of productivity, and is the major regional aquifer providing spring flows to Bolivian wetlands and groundwater flow across the international border. The studies provided a preliminary understanding of the main aquifers in Chile and their properties, which underpinned the development of a robust hydrogeological conceptual model of the system, reviewed elsewhere in this special issue. Subsequent refinements are also summarized. This work confirmed that both surface water and groundwater flows from Bolivia to Chile, and thus confirms the status of the Silala River as an international watercourse and provided the basis for a basin‐scale groundwater numerical model, used to investigate the impact of wetland channelization on surface water/groundwater partitioning.This article is categorized under: Science of Water > Hydrological Processes

Sources of antimony contamination and its migration into water systems of Xikuangshan, China: Evidence from hydrogeochemical and stable isotope (H, O, S, and Sr) signatures

The Xikuangshan (XKS) mine was selected for a comprehensive Sb-related hydrogeochemical study because of its significant Sb contamination in water systems. Hydrochemical data, specifically multi-isotope (H, O, S, and Sr) data, were conducted to elucidate the primary sources and migration processes of Sb responsible for water system contamination. At the XKS Sb mine, water is near-neutral to alkaline and is characterized by high concentrations of SO42− and Sb. Sb occurs as Sb(OH)6− (the dominant species) in these oxidized waters. The hydrochemistry is mainly controlled by carbonate dissolution and silicate weathering. δ2HH2O and δ18OH2O values indicate that the infiltration recharge of mine water and mining activities regulate the migration of Sb in groundwater. δ34SSO4 and δ18OSO4 values indicate that dissolved SO42− and Sb primarily come from stibnite oxidation, bacterial SO42− reduction has either not occurred or is extremely weak, and the reductive dissolution of Fe (III) hydroxides does not significantly affect Sb migration in water. The 87Sr/86Sr ratios further indicate that the discharge of solid mine wastes leaching and smelting water is a crucial source of Sb contamination in groundwater. In addition, the relationship between δ34SSO4 and δ87Sr values suggests the complexity of the contamination source and migration of Sb in water. Finally, a robust conceptual hydrogeochemical model was developed using isotopic tools in combination with detailed hydrogeological and hydrochemistry characterization to describe the contamination source and migration of Sb in water systems at the XKS Sb mine.

Evolution of behavioral research on E‐waste management: Conceptual frameworks and future research directions

AbstractThe rapid growth of e‐waste or waste electrical and electronic equipment (WEEE) has garnered significant attention from scholars, particularly in the behavioral domain. This study aims to conduct a comprehensive bibliometric analysis and content analysis to provide a systematic review of WEEE‐behavioral research. Firstly, a bibliometric analysis was performed using Biblioshiny (R packages) on a sample of 293 articles from Scopus and WOS databases. This part addresses the research question: A) How has the WEEE‐behavioral domain evolved over time in terms of key journals, institutions, countries, trending topics, and research streams? Secondly, a content analysis was conducted on 41 relevant articles that were able to address the following research questions: B) What are the main theories utilized and their implications in WEEE‐behavioral research? and C) what are the potential directions for future research? The findings reveal two distinct research categories, namely circular economic behavior and behavioral spillovers, with seven underlying and emerging clusters followed by corresponding research streams. Additionally, the theory of planned behavior (TPB) emerged as the core theory that was extensively utilized and expanded upon. Consequently, this study contributes to 1) understanding the evolution of the WEEE‐behavioral domain, 2) proposing an integrated theoretical framework, 3) identifying the primary research streams and their interconnections, and 4) suggesting avenues for future research, supported by a robust conceptual model for hypothesis generation.

Recommendation matters: how does your social capital engage you in eWOM?

PurposeThe purpose of this study is to contribute to the existing knowledge on two aspects. First, the authors introduce a conceptual model based on the social capital theory (SCT) to understand the mechanisms through which social capital factors affect consumers’ electronic word-of-mouth (eWOM) engagement and purchase intentions via social network sites (SNSs). Second, the present study empirically tests and validates the proposed relationships that delineate social capital dimensions as crucial precursors of eWOM engagement and purchase intention in the specific SNS context, namely, Facebook, Instagram and Twitter.Design/methodology/approachThe authors applied both exploratory and descriptive design based on a triangulation approach. The authors adapted an in-depth interview method in the first part to better specify our constructs and hypotheses. At the quantitative part, the authors conducted the survey method on 1,169 consumers as central part of the research for empirical testing and validating our conceptual model. The authors applied structural equation modeling analysis by using AMOS 22.0.FindingsOverall, the results of this study indicate that social capital-based drivers have a significant role underlying the eWOM engagement of consumers, while engagement in eWOM has a further effect on their purchase intentions. In this study, social network culture appears as the most dominant social driver of consumers’ engagement in eWOM, followed by tie strength and interpersonal trust.Research limitations/implicationsThis study extends prior research on drivers of eWOM. An integrated conceptual model under SCT is proposed and tested to verify the dimensional interrelationships and effects on consumers’ eWOM engagement and purchase intentions. Second, this work advances the understanding of eWOM behavior in a novel context, social networks. Cross-cultural comparison of our results in other regions of Turkey or different countries might enable generalizability, which is one of the limitations of the study.Practical implicationsThis study highlights that consumers are incorporating recommendations into their social networking behavior. The findings of this study show that before constructing their social media strategies, marketers should first investigate the congruence between the cultural environment of the SNS in which they connect with their customers and the positioning of their products.Social implicationsThis study suggests implications about privacy guidelines for SNS regulation setters. Policymakers should understand when and how consumers’ profile and social tie information should be disclosed and accessed through their eWOM behaviors and try to develop trustful regulations.Originality/valueThis study serves as the first attempt to demonstrate that social capital drivers affect consumers’ purchase intentions through their eWOM engagement by its robust conceptual model. No integrated model under SCT has ever been proposed and tested on consumers’ eWOM engagement via SNSs.

Towards a New Conceptual Framework of Student Activism in South Africa

While the phenomenon of student activism is not new in South Africa, it has escalated recently and has taken on new forms. The literature expounds the emergence of a new modality of student activism in the form of protest movements employing social media as mobilisation tools. While such activism traditionally manifested itself in student representation in university governance structures and student demonstrations, protest movements and social media have emerged as its modern manifestation in South Africa. This article systematically analyses extant theories and conceptual frameworks to assess their relevance to these new modalities. After closely analysing key conceptual frameworks including Stakeholder Theory, the Ideal-type Regime of Governance Model and the Activist Leadership Model, it demonstrates their limitations for describing the emerging trends of student activism in South Africa, the paper proposes a new and robust conceptual model called Unbounded Student Activism.

Determination of vadose zone and saturated zone nitrate lag times using long-term groundwater monitoring data and statistical machine learning

Abstract. In this study, we explored the use of statistical machine learning and long-term groundwater nitrate monitoring data to estimate vadose zone and saturated zone lag times in an irrigated alluvial agricultural setting. Unlike most previous statistical machine learning studies that sought to predict groundwater nitrate concentrations within aquifers, the focus of this study was to leverage available groundwater nitrate concentrations and other environmental variables to determine mean regional vertical velocities (transport rates) of water and solutes in the vadose zone and saturated zone (3.50 and 3.75 m yr−1, respectively). The statistical machine learning results are consistent with two primary recharge processes in this western Nebraska aquifer, namely (1) diffuse recharge from irrigation and precipitation across the landscape and (2) focused recharge from leaking irrigation conveyance canals. The vadose zone mean velocity yielded a mean recharge rate (0.46 m yr−1) consistent with previous estimates from groundwater age dating in shallow wells (0.38 m yr−1). The saturated zone mean velocity yielded a recharge rate (1.31 m yr−1) that was more consistent with focused recharge from leaky irrigation canals, as indicated by previous results of groundwater age dating in intermediate-depth wells (1.22 m yr−1). Collectively, the statistical machine learning model results are consistent with previous observations of relatively high water fluxes and short transit times for water and nitrate in the primarily oxic aquifer. Partial dependence plots from the model indicate a sharp threshold in which high groundwater nitrate concentrations are mostly associated with total travel times of 7 years or less, possibly reflecting some combination of recent management practices and a tendency for nitrate concentrations to be higher in diffuse infiltration recharge than in canal leakage water. Limitations to the machine learning approach include the non-uniqueness of different transport rate combinations when comparing model performance and highlight the need to corroborate statistical model results with a robust conceptual model and complementary information such as groundwater age.

Deciphering groundwater flow-paths in fault-controlled semiarid mountain front zones (Central Chile)

The Mountain-Block Recharge (MBR), also referred to as the hidden recharge, consists of groundwater inflows from the mountain block into adjacent alluvial aquifers. This is a significant recharge process in arid environments, but frequently discarded since it is imperceptible from the ground surface. In fault-controlled Mountain Front Zones (MFZs), the hydrogeological limit between the mountain-block and adjacent alluvial basins is complex and, consequently, the groundwater flow-paths reflect that setting. To cope with the typical low density of boreholes in MFZs hindering a proper assessment of MBR, a combined geoelectrical-gravity approach was proposed to decipher groundwater flow-paths in fault-controlled MFZs. The study took place in the semiarid Western Andean Front separating the Central Depression from the Principal Cordillera at the Aconcagua Basin (Central Chile). Our results, corroborated by field observations and compared with worldwide literature, indicate that: (i) The limit between the two domains consists of N-S-oriented faults with clay-rich core (several tens of meters width low electrical-resistivity subvertical bands) that impede the diffuse MBR. The “hidden recharge” along the Western Andean Front occurs through (ii) focused MBR processes by (ii.a) open and discrete basement faults (mass defect and springs) oblique to the MFZ that cross-cut the N-S-oriented faults, and (ii.b) high-hydraulic transmissivity alluvial corridors in canyons. Alluvial corridors host narrow unconfined mountain aquifers, which are recharged by indirect infiltration along ephemeral streams and focused inflows from oblique basement faults. This study also revealed seepage from irrigation canals highlighting their key role in the recharge of alluvial aquifers in the Central Depression. The proposed combined geophysical approach successfully incorporated (hydro)geological features and geophysical forward/inverse modelling into a robust hydrogeological conceptual model to decipher groundwater flow-paths in fault-controlled MFZs, even in the absence of direct observation points.

Multiple-step numerical modeling to assist aquifer characterization: a case study from the south of Brazil

Management of coastal groundwater must take account of the complex hydrological processes and uncertainties associated with this environment. Regular evaluation of mechanisms, parameters and boundary conditions is required to understand groundwater flow and to develop a robust conceptual model. In certain conditions, as in tropical regions, due to the high intensity and variability of natural drivers (precipitation, evapotranspiration), a comprehensive hydrogeological characterization may be needed. Data on transient recharge, tide-driven fluctuations of groundwater receptors (seas, rivers) and the activation status of drainage networks may need to be updated recurrently, as they likely influence groundwater balance. Numerical models are applied at various phases of a hydrogeological investigation to elucidate preliminary conceptual models and to guide the field characterization. Those models provide a quantitative framework for synthesizing field information and verifying mechanisms readily contributing to a cost-effective decision-making process. This article presents a systematic hydrogeological characterization of a coastal basin in a tropical region of southern Brazil that is affected by intensive precipitation and ocean tides; precipitation is the main process driving groundwater flow, although head variations at the boundaries affect a spatiotemporal distribution of the water table. A set of numerical experiments is deployed to test the understanding of natural processes and to assist additional field campaigns. The hierarchy of hydrogeological processes is evaluated over different scales, to eliminate less sensitive mechanisms. By presenting the detailed setup information on model development, the applications are demonstrated and limitations are discussed in light of the available field data and specific research objectives.

Reservoir architecture and heterogeneity distribution in floodplain sandstones: Key features in outcrop, core and wireline logs

AbstractExploration and production from formations deposited in low‐gradient fluvial systems is typically associated with a high degree of uncertainty; a reflection of the inherent characteristics of these environments, notably the dominance of non‐reservoir floodplain fines, rapid lateral facies variations and associated heterogeneities at different scales. However, for a field development to be successful it becomes crucial to know the location, geometry, dimensions and connectivity of the most permeable facies, related to the main channel and the associated proximal overbank deposits (crevasse‐splay complexes). With the aim of addressing this problem, a multi‐disciplinary study is presented, combining outcrop data, high‐resolution sedimentological descriptions and advanced visualization techniques based on Digital Outcrop Models. This is compared with subsurface data from behind the outcrop (core, gamma ray and borehole image logs). The Mudstone–Sandstone Unit of the Triassic Red Beds of Iberian Meseta formation in south‐central Spain was selected for the present study. The unit is characterized by the lateral and vertical stacking of four architectural elements: (i) channelized sandstone bodies; (ii) asymmetrical sigmoidal‐shaped sandstone bodies; (iii) lobe‐shaped to sheet‐like sandstone bodies; and (iv) sheet‐like mudstones. These elements represent meandering channel, crevasse‐channel‐splay and floodplain sub‐environments, comprising a distal, low‐gradient meandering fluvial system. Together with well‐documented outcrop and core facies, calibrated log responses are also presented for the channel bodies (bell‐shape Gamma Ray profile, random azimuths and low to high dip angles), the crevasse‐splay bodies (funnel‐shape Gamma Ray profile, unidirectional azimuths and low dip angles) and the floodplain deposits (serrated Gamma Ray profile, unidirectional azimuths and very low dip angles). The full integration of outcrop and subsurface datasets has enabled generation of a robust conceptual model with predictive potential when establishing the three‐dimensional stacking of facies, distribution of heterogeneities, and the connectivity between reservoir rock geobodies of primary (channel) and secondary (crevasse complex) interest in this type of fluvial reservoir.

Hydrogeochemical, isotopic and geophysical characterization of saline lake systems in semiarid regions: The Salada de Chiprana Lake, Northeastern Spain

Most of the athalassic saline and hypersaline lakes are located in arid and semiarid regions where water availability drives the hydrological dynamics of the lake itself and the associated ecosystems. This is the case of the Salada de Chiprana Lake, in the Ebro River basin (Spain). It is the only athalassic permanent hypersaline lake in Western Europe, and where rare and endangered bacterial mats exist. This work presents a robust hydrogeological conceptual model for the lake system. The model evaluates the contribution of groundwater discharge to the whole water budget and explains the hydrological behaviour of the lake system. The lake behaves as a flow-through system rather than a closed basin. About 40% of total water outflow from the lake occurs as groundwater, whereas evaporation accounts for the remaining 60%. The surface water inflows are variable, but the groundwater contribution seems almost constant, amounting to 13% of the average total water inflow and contributing 1.9% of salt income. The high water salinity of the lake is controlled by evaporation, by saline water inflows from irrigation return flows, and the by groundwater outflows. The role of groundwater should be taken into account when drafting the water and land planning, once the conditions for the conservation of the algal mats are defined. A major contribution of this study is the water balance in the Salada de Chiprana Lake, which is consistent with a robust hydrogeological conceptual model defined upon scarce hydrogeological, hydrochemical and isotopic data in the local context as conditioned by the regional behaviour. The water balance is a key tool to help to correctly manage this unique athalassic saline lake, and the approach used here can be extrapolated to other similar ecosystems around the world.

The Last Planner® System and Building Information Modeling in Construction Execution: From an Integrative Review to a Conceptual Model for Integration

Many researchers have stated that lean and building information modeling (BIM) have positive synergies. This integrative literature review aims at exploring this body of knowledge within the scope of combinations of BIM and the Last Planner® System, as an important Lean construction method, in the phase of construction execution. The research motivation is to find out whether a comprehensive understanding of how to take advantage of these synergies exists. Eventually, the question arises of how to condense this understanding—if existing—into a robust conceptual model for integration. As a theoretical backbone, we will make use of the original BIM-Lean interaction matrix. The hypothesis is that new BIM functionalities have been evolved since the first formulation of this interaction matrix almost 10 years ago. These new BIM functionalities cause new interactions with existing lean principles. We will focus on interactions that refer directly or indirectly to production planning and control and use them to find the most relevant literature for this review. Within the content analysis, as a part of this review, we focus on existing conceptual models and frameworks for integration of BIM and the Last Planner® System and reveal their shortcomings. Eventually, we will propose a new conceptual model.

Multi-tracer and hydrogeophysical investigation of the hydraulic connectivity between coal seam gas formations, shallow groundwater and stream network in a faulted sedimentary basin

Characterization of geological fault networks in sedimentary basins targeted for coal seam gas development typically use deep-penetrating seismic data. Such methods can reveal the presence of numerous fault zones at depths greater than 100 m but not necessarily show if these extend to the surface or provide a significant degree of hydraulic connectivity between deep and shallower geological formations. Our combined multi-tracer and hydrogeophysical study used transient electromagnetic surveys to image the subsurface in a sedimentary coal seam gas basin (Gloucester Basin, NSW, Australia) and indicated that deep faults (greater than 200 m) from seismic analysis may extend to within metres of the ground surface. Analysis of environmental tracers in surface water and groundwater samples near fault traces showed the presence of hotspots of deeper groundwater from the coal seams discharging into the stream network via the alluvial aquifer. The isotopic composition of methane was extremely variable in groundwater (δ13C-CH4 from –81.6 to –29.2‰ V-PDB) and surface water (δ 13C-CH4 from –56.0 to –19.9‰ V-PDB), suggesting several sources of methane being recycled in the connected alluvial aquifer and stream network. A 4He hotspot (1.67 × 10−6 cm3 STP g−1) in the alluvial aquifer close to a fault line showed high methane (463 µg L−1) with a thermogenic signature (δ 13C-CH4 of −62.4‰ and δ2H-CH4 of −174.7‰). The Gloucester Basin, which has experienced multiple episodes of complex restructuring, displays high dilation tendency of fractures close to fault damage zones with fracture orientations parallel to the orientation of maximum horizontal stress. As a result, there is increased permeability for wells close to the fault damage zone and with increasing depth. These findings resulted in a robust hydrogeological conceptual model of a faulted basin, which can be used in a monitoring and modelling framework for improved evaluation of risk associated with unconventional gas developments.