ALBERT

Description: 〈p〉〈em〉Landuse play a role in the determination of main’s social, economic, and cultural progress. In general, the idea of land use is connected to the local physical environment. Landuse reflect a complex correlation between natural historical and socio-economic factors. Besides, size of holding and caste structure determine the changing of land use on the agricultural crops. Such as undulating terrain and hilly poor land determine the process of farming and as-well-as sometime at the capacity of farmers. The present study characteristics of changing pattern of land use in the Sagar district. Slightly more-than half (52.64%) of the total geographical area is net sown in 2021. This proportion is higher than the 48.93% statewide average. An additional 2.29% of the total area is made up of fallow areas. As a consequence, around 75% of the land had farmed. The forest land (24.46%) is quite similar to the average distribution. Around 1.69% of the area is designated as barren and uncultivable due to physical limitations. For a number of reasons, other uncultivated land accounts for about 10.65% of the total area. Land use patterns are influenced by cropping practices and intensity of farming as well as human social and economic position, institutional makeup, and technology advancements. The terrain of its land is ridged on a big chunk of it. Therefore, regional balances of natural processes within them are crucial prerequisites for the rising population's access to food security and its ability to get the most out of the resources at hand.〈/em〉〈/p〉

Description: 〈p〉〈em〉The ruling aspect of the present investigation is to study the textural characters as well as to understand the grain size relationship and distributionby engaging granulometric analysis, along the Pennar estuary, South east coast of India. An aggregate of 36 Surface sediment samples were retrieved and a comprehensive study of textural parameters and various size distribution of sediments were analysed at six various stations in six different micro – environments viz., dune, backshore, berm, upper foreshore (UFS), middle foreshore (MFS) and lower foreshore (LFS).  These were further subjected to statistical treatment viz., Mean size (Mz), Skewness (Sk), Standard deviation (σ〈strong〉〈sub〉I〈/sub〉〈/strong〉), and Kurtosis (K〈sub〉G〈/sub〉). The procured results indicates that the sediment samples were coarse to fine grained, very negatively skewed to positively skewed, very well to moderately sorted, and platy tovery leptokurtic in nature and also indicates two mixed environments at some stations. Scatter plots were help to understand the mode of deposition, geological significance and transportation of grains along the coast. Scatter plots also divulges that the sediments along the coast were mainly associated with fluvial process. C-M diagrams demonstrate the type of transportation and deposition of the beach sediments. Ebbing and flooding shows prominent role in changing the characteristics of grains in the Pennar estuary, especially in the estuarine mouth and adjoining river areas.〈/em〉〈/p〉

Description: 〈p〉〈em〉〈span〉Currently, wind and solar power generation systems have many drawbacks. Wind and solar power generation Full use of new energy will break the barrier to growth. Location for wind/solar hybrid power plant the primary problem is how to choose scientifically. This article selects six wind/solar hybrid power plants and implements them as a case study and evaluates these six areas via VIKOR by weighting the indicators through the MCDM method. Conclusions Related research findings and better valid, this demonstrates the feasibility and effectiveness of the method. This macro-site selection plants may provide some theoretical basis. In this statistical methods in the literature and established by statistical analysis. Tamil Nadu, Rajasthan, Maharashtra, Gujarat, Andhra Pradesh, Karnataka taken this alternative in this method and evaluation parameters are Total investment, Wind direction, Wind speed and speed change, sunshine stabilization, wind power density, energy saving, Environmental factors. Gujarat is on 2nd rank, Rajasthan is on the 1st rank, Tamil Nadu is on the 3rd rank, Indian Karnataka is on the 4th rank, Maharashtra is on the 5th rank and finally Andhra Pradesh is on the 6th rank.〈/span〉〈/em〉〈/p〉

Description: 〈p〉〈em〉Flood hazard mapping, which uses model and satellite remote sensing data, is extremely useful for flood monitoring and risk management. The flood inundation extent and flooding depth on Majuli Island and its surrounding area in Assam, India, were simulated using MIKE FLOOD, a coupled 1D-2D hydrodynamic model. MIKE FLOOD is a platform that integrates the MIKE Hydro River (1D) and MIKE 21 FM (2D) models into a dynamically coupled single modeling framework. The study employed daily discharge and water level data from several gauging stations operated by the Centre Water Commission (CWC), Global Flood Monitoring System (GFMS), and Water Resource Department (WRD) of Assam. First, the MIKE Hydro River (1D) model was calibrated using discharge and water level data from 2016 to 2018 and validated for the period of 2019-2021. The MIKE Hydro River (1D) model's calibration and validation results were evaluated using a numerous of performance metrics. From ALOS PALSAR DEM data / SRTM DEM data, a fine mesh and bathymetry of Majuli Island with a spatial resolution of 10m has been created and provided as an input to the MIKE 21 FM (2D, Flow Model). The MIKE Hydro River (1D) and MIKE 21 FM (2D) models were then linked to the MIKE FLOOD model for simulating two-dimensional flood inundations in the study area through lateral linkages. Flood inundation has been simulated for the year 2020, and the model's maximum flood inundation extent has been compared to the actual flooded area retrieved from Sentinel-1 C-Band satellite data. The R〈sup〉2〈/sup〉 in the study area was ranging between 0.86 and 0.97, but the WBL in the MIKE Hydro River model was less than 1.23. On the opposite hand, the MIKE FLOOD's total accuracy is 93.6 percent according to the confusion matrix. According to the most recent model simulation, flooding will occur between July 19 and July 21, 2020, with the greatest and lowest flood depths being 2.38 and 0.786 m, respectively〈/em〉〈em〉. In addition, the MIKE FLOOD model may be used for flood control in the future, and this research will aid policymakers in the field of water management in achieving successful mitigation measures.〈/em〉〈/p〉

Description: 〈p〉〈em〉A simulation tool of a sky wave over-the-horizon radar performance and detection process includes many stages based on different models, which creates a synthetic searching scenario as a first step followed by a digital signal processing to detect and locate a potential target. Its accuracy will depend on the quality of the input and adequacy degree of the model assumptions. A sensitivity analysis of this simulation tool is carried out analyzing outputs’ variation as a consequence of changes in input factors. The architecture of this tool allow easy implementation and the study of input variables impact on detection and location results that can be useful towards dimensioning features and elements of a real radar〈/em〉〈/p〉

Description: 〈p〉〈em〉This work provides an overview of the use of remote sensing and Geographic Information System (GIS) techniques for mineral exploration. The integration and analysis of various data types, including geological, geochemical, geophysical, and remote sensing data, using remote sensing and GIS tools allow for the creation of comprehensive maps and models of mineral deposits. The advantages of remote sensing and GIS in mineral exploration include more effective targeting of exploration activities, assessment of environmental and social impacts of mining activities, and creation of predictive models of mineral deposits. However, limitations to their use include the quality and resolution of input data, the expertise of the user, and availability and accessibility of data. As technology continues to improve and the availability of data increases, the use of remote sensing and GIS is likely to become even more important for the efficient and sustainable exploration and development of mineral resources.〈/em〉〈/p〉

Description: 〈p〉〈em〉Himachal Pradesh state is very vulnerable to flash floods, landslides, and riverbank erosion. Efforts have been made to develop a tool that can predict these disasters before the event, so that the authorities can take the protection measures. A web-enable 〈/em〉〈em〉vulnerability assessment tool has been developed for identification of vulnerable reaches for flood, riverbank erosion, and landslide in Himachal Pradesh. 〈/em〉〈em〉Historical excessive rainfall events, flash floods events and its causes, largest instrumented earthquake events have been reviewed and analyzed in detail. A flash flood risk index for rainfall-induced events occurring during the monsoon, glacial lake outburst flood (GLOF) risk index to monitor glacial lakes, and landslide risk index have been developed. 〈/em〉〈em〉River model (HecRAS,1D) model has developed for 〈/em〉〈em〉inflow forecasting system and 〈/em〉〈em〉early warning system; flood model (TUFLOW/SOBEK, 2D) has developed to identify the flood prone areas; river morphological model (Delft, 3D) has developed to find out the morphological active areas; historical satellite imageries between 1973-2023 have been analyzed by using 〈/em〉〈em〉artificial intelligence technology〈/em〉〈em〉 to identify the riverbank erosion areas, landslide active area; these imageries have also analyzed for snowmelt forecasting and GLOF study. 〈/em〉〈em〉Multi criteria analysis model has been developed for identification of vulnerable reaches.〈/em〉〈em〉 These all five activities have been integrated in the web-enable real-time vulnerability assessment tool of Himachal Pradesh. This tool can be identified of vulnerable reaches for riverbank erosion, flood, and landslide in real-time meaner, and can predict the flash floods. The tool is available at: https://www.hpVulnerableReach-kupa.com. This tool is very useful for authorities, communities, and stakeholders, who take the protection measures during the disaster. There is still a need for some improvement, this tool can be upgraded at large scale, which can be done with the help of concern department or can be done with more accurate data as well when funds will available.〈/em〉〈/p〉

Description: 〈p〉〈em〉Urban sprawl is increasing rapidly with the increased rate of rural to urban migration and with the tremendous population growth. Due to rural-urban migration and continuous population growth; urban centers tend to expand outwards to lodge the ever-increasing population pressure. Urban sprawl has to be considered in spatio-temporal terms to understand the phenomena of urban growth, land use and land transformation.  Urban sprawl is momentous to the quality of life of urban dwellers as well as quantity of rural land lost and land degradation; key issues of agricultural as well as environmental perspectives. Himalayan state of Uttarakhand is witnessing steady and continuous urban growth. Urban sprawl in Ranikhet tehsil has resulted in loss of productive agricultural land of the surrounding rural areas, open green spaces, loss of surface water bodies, and depletion of groundwater too. Problems of dwellings, slums, and unhygienic livings are also growing rapidly with the rapid urban sprawl. There is regular competition between urban and rural areas for land needed for growth and development.  The present study finds out that the built-up areas of different towns of Ranikhet tehsil have been increased from 4.92km〈sup〉2〈/sup〉 in 2000 to 6.19km〈sup〉2〈/sup〉 in 2010 which has further been increased to 7.70km〈sup〉2〈/sup〉 in 2020 witnesses a continuous struggle for space in Ranikhet tehsil.〈/em〉〈/p〉

Description: 〈p〉〈em〉A simulation tool of a sky wave over-the-horizon radar performance and detection process includes many stages based on different models, which creates a synthetic searching scenario as a first step followed by a digital signal processing to detect and locate a potential target. Its accuracy will depend on the quality of the input and adequacy degree of the model assumptions. A sensitivity analysis of this simulation tool is carried out analyzing outputs’ variation as a consequence of changes in input factors. The architecture of this tool allow easy implementation and the study of input variables impact on detection and location results that can be useful towards dimensioning features and elements of a real radar〈/em〉〈/p〉

Description: 〈p〉〈em〉This work provides an overview of the use of remote sensing and Geographic Information System (GIS) techniques for mineral exploration. The integration and analysis of various data types, including geological, geochemical, geophysical, and remote sensing data, using remote sensing and GIS tools allow for the creation of comprehensive maps and models of mineral deposits. The advantages of remote sensing and GIS in mineral exploration include more effective targeting of exploration activities, assessment of environmental and social impacts of mining activities, and creation of predictive models of mineral deposits. However, limitations to their use include the quality and resolution of input data, the expertise of the user, and availability and accessibility of data. As technology continues to improve and the availability of data increases, the use of remote sensing and GIS is likely to become even more important for the efficient and sustainable exploration and development of mineral resources.〈/em〉〈/p〉

Description: 〈p〉〈em〉Himachal Pradesh state is very vulnerable to flash floods, landslides, and riverbank erosion. Efforts have been made to develop a tool that can predict these disasters before the event, so that the authorities can take the protection measures. A web-enable 〈/em〉〈em〉vulnerability assessment tool has been developed for identification of vulnerable reaches for flood, riverbank erosion, and landslide in Himachal Pradesh. 〈/em〉〈em〉Historical excessive rainfall events, flash floods events and its causes, largest instrumented earthquake events have been reviewed and analyzed in detail. A flash flood risk index for rainfall-induced events occurring during the monsoon, glacial lake outburst flood (GLOF) risk index to monitor glacial lakes, and landslide risk index have been developed. 〈/em〉〈em〉River model (HecRAS,1D) model has developed for 〈/em〉〈em〉inflow forecasting system and 〈/em〉〈em〉early warning system; flood model (TUFLOW/SOBEK, 2D) has developed to identify the flood prone areas; river morphological model (Delft, 3D) has developed to find out the morphological active areas; historical satellite imageries between 1973-2023 have been analyzed by using 〈/em〉〈em〉artificial intelligence technology〈/em〉〈em〉 to identify the riverbank erosion areas, landslide active area; these imageries have also analyzed for snowmelt forecasting and GLOF study. 〈/em〉〈em〉Multi criteria analysis model has been developed for identification of vulnerable reaches.〈/em〉〈em〉 These all five activities have been integrated in the web-enable real-time vulnerability assessment tool of Himachal Pradesh. This tool can be identified of vulnerable reaches for riverbank erosion, flood, and landslide in real-time meaner, and can predict the flash floods. The tool is available at: https://www.hpVulnerableReach-kupa.com. This tool is very useful for authorities, communities, and stakeholders, who take the protection measures during the disaster. There is still a need for some improvement, this tool can be upgraded at large scale, which can be done with the help of concern department or can be done with more accurate data as well when funds will available.〈/em〉〈/p〉

Description: 〈p〉〈em〉Urban sprawl is increasing rapidly with the increased rate of rural to urban migration and with the tremendous population growth. Due to rural-urban migration and continuous population growth; urban centers tend to expand outwards to lodge the ever-increasing population pressure. Urban sprawl has to be considered in spatio-temporal terms to understand the phenomena of urban growth, land use and land transformation.  Urban sprawl is momentous to the quality of life of urban dwellers as well as quantity of rural land lost and land degradation; key issues of agricultural as well as environmental perspectives. Himalayan state of Uttarakhand is witnessing steady and continuous urban growth. Urban sprawl in Ranikhet tehsil has resulted in loss of productive agricultural land of the surrounding rural areas, open green spaces, loss of surface water bodies, and depletion of groundwater too. Problems of dwellings, slums, and unhygienic livings are also growing rapidly with the rapid urban sprawl. There is regular competition between urban and rural areas for land needed for growth and development.  The present study finds out that the built-up areas of different towns of Ranikhet tehsil have been increased from 4.92km〈sup〉2〈/sup〉 in 2000 to 6.19km〈sup〉2〈/sup〉 in 2010 which has further been increased to 7.70km〈sup〉2〈/sup〉 in 2020 witnesses a continuous struggle for space in Ranikhet tehsil.〈/em〉〈/p〉

Description: 〈p〉〈em〉Flood hazard mapping, which uses model and satellite remote sensing data, is extremely useful for flood monitoring and risk management. The flood inundation extent and flooding depth on Majuli Island and its surrounding area in Assam, India, were simulated using MIKE FLOOD, a coupled 1D-2D hydrodynamic model. MIKE FLOOD is a platform that integrates the MIKE Hydro River (1D) and MIKE 21 FM (2D) models into a dynamically coupled single modeling framework. The study employed daily discharge and water level data from several gauging stations operated by the Centre Water Commission (CWC), Global Flood Monitoring System (GFMS), and Water Resource Department (WRD) of Assam. First, the MIKE Hydro River (1D) model was calibrated using discharge and water level data from 2016 to 2018 and validated for the period of 2019-2021. The MIKE Hydro River (1D) model's calibration and validation results were evaluated using a numerous of performance metrics. From ALOS PALSAR DEM data / SRTM DEM data, a fine mesh and bathymetry of Majuli Island with a spatial resolution of 10m has been created and provided as an input to the MIKE 21 FM (2D, Flow Model). The MIKE Hydro River (1D) and MIKE 21 FM (2D) models were then linked to the MIKE FLOOD model for simulating two-dimensional flood inundations in the study area through lateral linkages. Flood inundation has been simulated for the year 2020, and the model's maximum flood inundation extent has been compared to the actual flooded area retrieved from Sentinel-1 C-Band satellite data. The R〈sup〉2〈/sup〉 in the study area was ranging between 0.86 and 0.97, but the WBL in the MIKE Hydro River model was less than 1.23. On the opposite hand, the MIKE FLOOD's total accuracy is 93.6 percent according to the confusion matrix. According to the most recent model simulation, flooding will occur between July 19 and July 21, 2020, with the greatest and lowest flood depths being 2.38 and 0.786 m, respectively〈/em〉〈em〉. In addition, the MIKE FLOOD model may be used for flood control in the future, and this research will aid policymakers in the field of water management in achieving successful mitigation measures.〈/em〉〈/p〉

Description: 〈p〉〈em〉〈span〉This study delves into the management of electronic waste (e-waste) stemming from the disposal of personal electronic items and mobile phones, primarily in response to the remarkable surge in the utilization of these devices within the Hassan city populace in recent years. The principal objectives revolved around investigating the existing disposal methods for electronic devices including mobile phones and collecting fundamental data concerning their disposal practices within the geographical confines of Hassan city of Karnataka State. Additionally, an endeavor was undertaken to gauge the level of awareness among respondents regarding the potential hazards posed by e-waste. It was observed that a significant proportion of the Hassan population typically retains especially electronic devices is cell phones, once these devices become outdated and obsolete. Among the prevalent disposal methods, the most widespread approach involves selling these gadgets to scrap dealers or junk shops, whereas recycling practices remain relatively underutilized. Notably, a mere minority of individuals engage in recycling activities. An intriguing revelation emerged, with 65% of respondents expressing concern about the adverse repercussions of improper e-waste disposal on human health and the environment. Astonishingly, all respondents admitted to having no knowledge of the fate of their discarded electronic devices. Based on the findings gleaned from this survey, it is strongly recommended that a comprehensive review be conducted on the overarching management of e-waste stemming from this electronic waste including mobile phones, gadgets in the Hassan city of Karnataka State. The purpose of these surveys and data collection endeavors is to approximate the volume of e-waste generated through the disposal of these devices. This information is envisioned to assist stakeholders and government agencies in formulating effective and efficient legislation and policies for the proficient management of e-waste〈/span〉〈/em〉〈/p〉

Description: 〈p〉〈em〉Indian Railroads is one of the largest railroad systems in the World. The Indian railway system has grown significantly over the years, as seen by the massive construction of its railroads; nonetheless, some accidents are caused by fractures in the railway track. Splits may occur because of the track's expansion or contraction brought on by seasonal variations. This study proposes a crack monitoring vehicle that employs an ultrasonic sensor to detect fractures on railway tracks and uses an Arduino Uno to facilitate the GSM and GPS module to send an SMS to the testing station, thereby mitigating the problems caused by these cracks. This intelligent system works like a remote monitoring system which gives an alert to stop the passage of trains in that path. The proposed model involves the use of Arduino, ultrasonic sensor, buzzer, GSM module, and GPS module.〈/em〉〈/p〉

Description: 〈p〉〈em〉Road safety is a critical concern in the modern world, where advancements in technology have made our lives easier but have also given rise to increased traffic hazards and road accidents. The "Car Accident Detector and Informer" project is an innovative system aimed at enhancing road safety by accurately detecting and informing about car accidents in real-time. This project integrates advanced sensors, microcontroller technology, and communication protocols to create an efficient accident detection and notification system. Utilizing GPS and GSM technology for precise location tracking and instant notifications, this system has the potential to reduce emergency response times, save lives, and minimize property damage. This research paper presents a detailed overview of the project, including its objectives, working principles, components, advantages, disadvantages, and prospects.〈/em〉〈/p〉

Description: 〈p〉〈em〉Spatiotemporal data analytics is a dynamic field that seeks to extract valuable information from data that integrates both spatial and temporal dimensions. This article explores the importance of this emerging field and its applications in a variety of fields, including environmental science, public health, and urban planning. Spatiotemporal data analysis addresses important research questions, such as determining event probabilities, understanding change patterns, identifying associations between events, and predicting events Future. However, this comes with many challenges, including managing large datasets, ensuring data quality, dealing with spatial and temporal autocorrelation, and more. To address these challenges, proposed solutions include data reduction and sampling, dimensionality reduction, data compression, use of spatial and temporal indexes, parallel and distributed processing, data filtering and pre- processing. Furthermore, strategies to handle spatial and temporal autocorrelation include exploratory data analysis, using spatial weight matrices, including spatially lagged variables, and regression models. spatial attribution, cluster analysis, etc for spatial autocorrelation and for temporal autocorrelation, solutions include time series analysis, differencing, ARIMA models, lagged variables, time series decomposition, exponential smoothing, state space modelling, machine learning, cross-validation, and regularization techniques. These approaches provide valuable insights to address the complexity of spatio-temporal data analysis and unlock its potential in various fields.〈/em〉〈/p〉

Description: 〈p〉〈em〉Diamond drilling, a core drilling technique employing diamond-encrusted drill bits, has emerged as a critical method for extracting cylindrical rock samples from diverse geological formations. This article provides an extensive overview of diamond drilling, encompassing its equipment, applications, challenges, and its pivotal role in geological exploration, mining, and construction projects. The versatility of diamond drilling is evident in its adaptability to various rock types, spanning the gamut from soft sedimentary strata to formidable crystalline structures. In mining, it serves as an indispensable tool for assessing the quality, depth, and size of mineral deposits. Likewise, in construction and civil engineering, diamond drilling aids in ascertaining geological conditions for safe and stable foundation design. Environmental considerations are paramount in contemporary drilling practices, with containment measures for drilling fluids to mitigate ecological impacts. Safety precautions are rigorously adhered to, ensuring the well-being of workers and the integrity of drilling operations. Furthermore, core samples extracted through diamond drilling are instrumental in geological investigations. These samples, meticulously analyzed, yield insights into rock composition, mineral content, and geological structures. They inform decisions in resource exploration, mine planning, and construction project management. This review underscores the invaluable contributions of diamond drilling to our understanding of the Earth's subsurface, emphasizing its adaptability, environmental consciousness, and safety. By examining the critical aspects of this technique, this article illuminates the profound impact of diamond drilling on various industries and the scientific community, positioning it as an indispensable tool for unlocking the secrets hidden beneath the Earth's surface.〈/em〉〈/p〉

Description: 〈p〉〈em〉The COVID-19 pandemic has underscored the necessity for digital infrastructure and accessibility, particularly in the education sector. This paper investigates the benefits and effectiveness of utilizing Green Cloud Computing (GCC) techniques for the dissemination of educational library data in remote regions of India during this critical period. The GCC model, known for its energy efficiency and reduced environmental impact, is proposed as a robust, scalable, and eco-friendly solution for providing remote educational access. The research utilizes a mixed-methods approach, incorporating both quantitative assessments of data reach and usage, and qualitative surveys to understand user experiences. The study reveals that GCC techniques can significantly improve educational resource distribution, thereby mitigating the educational disparities further exacerbated by the pandemic. These findings reinforce the potential of GCC techniques as a sustainable and inclusive technology in reshaping the educational landscape in remote regions.〈/em〉〈/p〉

Description: 〈p〉〈em〉One of the most crucial global issues of our era is climate change, whose consequences are presently being felt all over the world. As climate change keeps on forgoing, it's important that governments, organizations, and businesses take visionary actions for adapting and protecting themselves from calamities.〈/em〉〈em〉 This paper summarizes the application of Remote Sensing (RS) and 〈/em〉〈em〉Geographic Information System (〈/em〉〈em〉GIS) in observing impact of climate change on drought, soil moisture, land degradation, food security, EHIs’ characterization and blue carbon science and review of AI based climate solutions. The〈/em〉〈em〉 〈/em〉〈em〉integration of advanced machine learning algorithms,〈/em〉〈em〉 〈/em〉〈em〉real-time data analysis, and other cutting-edge technologies could lead to even more effective climate change〈/em〉〈em〉 〈/em〉〈em〉adaptation strategies. AI-activated climate change adaptation strategies have the prospective to significantly〈/em〉〈em〉 〈/em〉〈em〉improve the resilience of infrastructure communities, and businesses to the changing climate.〈/em〉〈strong〉〈/strong〉〈/p〉

Description: 〈p〉〈em〉Urban transportation systems face significant challenges due to rapid population growth and development. This study delves into the enhancement of road safety in Navi Mumbai by employing Geographic Information System (GIS) and Remote Sensing (RS) techniques. The escalating rate of vehicular accidents in Navi Mumbai presents a pressing concern. This research investigates accident data and traffic patterns, identifying vulnerable areas prone to accidents and congestion. By conducting spatial analysis using GIS and RS, the study aims to uncover accident hotspots and traffic congestion zones, offering insights into underlying road safety issues. The research methodology involves a multi-stage process. Initial data collection from various sources, including police reports, live traffic data, and satellite imagery, forms the foundation. Geographic coordinates extracted and processed through GIS applications aid in plotting accident locations and creating density maps. Additionally, on-site investigations at strategically chosen locations provide invaluable insights into local conditions, traffic patterns, and contributing factors to congestion and accidents. The findings are presenting tailored solutions for each area, ranging from optimized traffic signal timings to infrastructural improvements. The findings of this study present actionable insights aimed at improving road safety and traffic management in Navi Mumbai. Recommendations encompassing signal optimizations, infrastructure enhancements, and community engagement strategies offer a holistic approach to mitigate traffic congestion and reduce accidents. The collaborative effort with relevant authorities, as highlighted in the study, serves as a crucial step towards implementing these recommendations for meaningful change. This research not only identifies critical areas for intervention but also serves as a model for leveraging GIS and RS techniques to enhance the road safety in urban areas, paving the way for safer and efficient transportation networks in the future.〈/em〉〈/p〉

Description: 〈p〉〈em〉The urgency to transition to renewable energy sources is underscored by the environmental crises stemming from our reliance on non-renewable fuels. This study focuses on assessing wind energy potential in Odisha, India, utilizing satellite data and Geographic Information System (GIS) technologies. The research addresses the critical need for strategic planning and site selection before investing in renewable energy infrastructure. By employing a model that integrates various free satellite datasets and leverages fundamental physical principles, the study calculates wind power density (WPD) at a height of 90 meters above the surface for both onshore and offshore locations. The methodology involves acquiring and processing datasets such as temperature, wind speed, digital elevation model (DEM), pressure, air density, and land use/land cover (LULC) classifications. The model applies equations derived from physical laws to determine key parameters necessary for calculating WPD. Specifically, temperature and pressure data are used to estimate air density, while surface roughness is assigned based on LULC classes with windspeed at 10m to extrapolate wind speed at 90 meters above ground level. The method can be used at any hub height. Results reveal significant wind energy potential in Odisha, particularly along the coastal regions. Jagatsinghpur and Puri emerge as areas with high WPD onshore, while the offshore exclusive economic zone (EEZ) of Odisha exhibits substantial wind energy resources. The model outputs provide valuable insights for various studies related to renewable energy and facilitate informed decision-making in site selection analyses. Furthermore, the study emphasizes the simplicity and effectiveness of the developed model,〈/em〉〈br〉〈em〉making it a practical tool for assessing wind energy potential in other regions as well. Overall, this research contributes to the global effort towards transitioning to sustainable energy sources and combating climate change. By highlighting the renewable energy potential of Odisha, it underscores the importance of harnessing wind energy as a viable pathway towards a cleaner, greener future.〈/em〉〈/p〉

Description: 〈p〉The research strives to enhance digital surveying methodologies for precise and detailed land mapping, utilizing advanced instruments like terrestrial scanners, SLAM scanners, total stations, DGPS, and drones. The survey conducted at Ratnagiri Hill in Udaipur aims to scrutinize and compare the merits and drawbacks of each surveying method. The study outlines a systematic process encompassing data collection, processing, output generation, and validation of survey techniques. It highlights the adaptability of these methods across various〈br〉domains, such as building conservation, restoration, and mapping of typically inaccessible areas, emphasizing their potential for time and resource savings. The research underscores the effectiveness of a one-time data collection process for subsequent work, laying the groundwork for the advancement of digital surveying technologies. When integrated with the Total station and DGPS survey, the combination of terrestrial scanners, drones, and SLAM scanners achieves a vertical accuracy of around 32 mm.〈/p〉

Description: Summary Distributed Acoustic Sensing (DAS) networks promise to revolutionize observational seismology by providing cost-effective, highly dense spatial sampling of the seismic wavefield, especially by utilizing pre-deployed telecomm fiber in urban settings for which dense seismic network deployments are difficult to construct. However, each DAS channel is sensitive only to one projection of the horizontal strain tensor and therefore gives an incomplete picture of the horizontal seismic wavefield, limiting our ability to make a holistic analysis of instrument response. This analysis has therefore been largely restricted to pointwise comparisons where a fortuitious coincidence of reference three-component seismometers and co-located DAS cable allows. We evaluate DAS instrument response by comparing DAS measurements from the PoroTomo experiment with strain-rate wavefield reconstructed from the nodal seismic array deployed in the same experiment, allowing us to treat the entire DAS array in a systematic fashion irrespective of cable geometry relative to the location of nodes. We found that, while the phase differences are in general small, the amplitude differences between predicted and observed DAS strain-rates average a factor of 2 across the array and correlate with near-surface geology, suggesting that careful assessment of DAS deployments is essential for applications that require reliable assessments of amplitude. We further discuss strategies for empirical gain corrections and optimal placement of point sensor deployments to generate the best combined sensitivity with an already deployed DAS cable, from a wavefield reconstruction perspective.

Description: Food webs are central entities mediating processes and external pressures in marine ecosystems. They are essential to understand and predict ecosystem dynamics and provision of ecosystem services. Paradoxically, utilization of food web knowledge in marine environmental conservation and resource management is limited. To better understand the use of knowledge and barriers to incorporation in management, we assess its application related to the management of eutrophication, chemical contamination, fish stocks, and non-indigenous species. We focus on the Baltic, a severely impacted, but also intensely studied and actively managed semi-enclosed sea. Our assessment shows food web processes playing a central role in all four areas, but application varies strongly, from formalized integration in management decisions, to support in selecting indicators and setting threshold values, to informal knowledge explaining ecosystem dynamics and management performance. Barriers for integration are complexity of involved ecological processes and that management frameworks are not designed to handle such information. We provide a categorization of the multi-faceted uses of food web knowledge and benefits of future incorporation in management, especially moving towards ecosystem-based approaches as guiding principle in present marine policies and directives. We close with perspectives on research needs to support this move considering global and regional change.

Description: In 2020, the developing COVID-19 pandemic disrupted fisheries surveys to an unprecedented extent. Many surveys were cancelled, including those for walleye pollock (Gadus chalcogrammus) in the eastern Bering Sea (EBS), the largest fishery in the United States. To partially mitigate the loss of survey information, we deployed three uncrewed surface vehicles (USVs) equipped with echosounders to extend the ship-based acoustic-trawl time series of pollock abundance. Trawling was not possible from USVs, so an empirical relationship between pollock backscatter and biomass established from previous surveys was developed to convert USV backscatter observations into pollock abundance. The EBS is well suited for this approach since pollock dominate midwater fishes in the survey area. Acoustic data from the USVs were combined with historical surveys to provide a consistent fishery-independent index in 2020. This application demonstrates the unique capabilities of USVs and how they could be rapidly deployed to collect information on pollock abundance and distribution when a ship-based survey was not feasible. We note the limitations of this approach (e.g. higher uncertainty relative to previous ship-based surveys), but found the USV survey to be useful in informing the stock assessment in a situation where ship-based surveys were not possible.

Description: Ecological interactions among marine zooplankton are poorly described because conventional sampling gears, such as plankton nets and traps, obscure the physical and biological environment that individuals experience. With in situ imagery, however, it is possible to resolve these interactions and potentially convert snapshot distributions into process-oriented oceanographic and ecological understanding. We describe a variety of imagery-detected ecological interactions with high spatial resolution in the northern Gulf of Mexico shelf waters (20–35 m bottom depth), providing new evidence of parasitism, predation, and life stage spatial structuring for different zooplankton groups. Chaetognaths were infected with an anteriorly attached, parasitic polychaete (1.1% of 33 824 individuals), and these infected chaetognaths were more common further offshore, south of a nearshore patch where unparasitized individuals reached concentrations of ∼90 m–3. Predation by Liriope spp. hydromedusae tended to occur in the shallowest 10–15 m, and doliolids formed distinct patches of different life stages, indicating that the environment is replete with sharp transitions among various ecological processes. Similar patterns in other marine ecosystems likely exist, and we encourage hybrid (machine/human expertise) approaches that broaden the scope for analysis of plankton images, which are rich sources of new ecological information and hypotheses yet to be examined quantitatively.

Description: Coastal erosion has become an issue globally. As the sea level continues to rise due to global warming, projections are that erosion would increase. To address the issue sustainably, relevant scientific information such as sediment transport and shoreline dynamics is required at local scales. Over the years, erosion at the eastern coast of Ghana has been mainly evaluated using low-resolution imagery due to the challenges in retrieving high-resolution data in the nearshore region. An unmanned aerial vehicle (UAV) approach was used to assess beach evolution on a seasonal and short-term basis between May 2018 and December 2019. Using the UAV approach, shoreline changes, sediment volume changes, and profile elevation parameters were extracted for the Dzita beach of Ghana. Shoreline changes indicated the dominance of erosion during the first and third phases (May 2018–December 2018 and June 2019–December 2019, respectively) at a rate of −7.23 ± 0.23 and −4.85 ± 0.23 m/yr, whereas the second phase (January 2019–June 2019) showed accretion of +8.44 ± 0.23 m/yr. Beach profiles from the first, second, and third phases had steep and gentle slopes, respectively. From these observations, it was recommended that soft engineering approaches such as beach nourishment should be implemented to protect the shoreline and strict prevention of nearshore sand mining and gravel mining. It is also possible that the beach could go through a cycle of changes. Further studies using this same approach should be done as well as probing into other parameters such as nearshore bathymetry to have a better understanding of beach dynamics as envisaged.

Description: Exploitation is one of the major drivers of change in marine ecosystems. Following discovery in 1775, South Georgia saw sequential overexploitation of living resources, including seals, whales, and fish. Although exploitation is now tightly regulated, the ecosystem is still recovering. Marbled rockcod, Notothenia rossii (Richardson 1844), was the first fish species to be commercially exploited and high catches between 1967 and 1972 resulted in dramatic stock decline. Here, we use 30 years of trawl survey data to provide the first evidence of a sustained increase in the N. rossii population starting two decades after the prohibition of targeted fishing in 1985. The way species respond to change is mediated in part by trophic relationships with other organisms. We present the first multi-year, spatially-resolved comparison of adult N. rossii diet at South Georgia, highlighting a variable diet with less reliance on Antarctic krill than previously thought. Life history factors and possible heavy predation on early life stages might have delayed their recovery while diet plasticity potentially supported recent population growth. Due to the dynamic ecosystem at South Georgia and questions over catch reports from the period of heaviest exploitation, it is unlikely the current ecosystem could support a recovery to estimated pre-exploitation levels.

Description: The connectivity of complex carbonate reservoirs has an essential impact on the exploration and development of these reservoirs. From geologic genesis, the connectivity of complex carbonate reservoirs is mainly controlled by faults and dissolution. Therefore, accurate identification of faults and karst caves is the key to studying reservoir connectivity. The Ordovician carbonate reservoir in the Hudson Oilfield of the Tarim Basin is used for our reservoir connectivity analysis study. First, we calculate the coherence and curvature attributes, respectively, and then merge the two attributes using a neural network algorithm. Finally, we use the ant-tracking method to track the faults for the merged data. The results show that the approach substantially enhances deterministic faults that can be seen directly on the seismic data, and subtle faults can also be identified. For reservoir identification, we use the diffraction imaging method to describe the karst reservoir in this study area. The results show that diffraction imaging can identify small-scale caves that cannot be well recognized on the seismic reflection data. Furthermore, the caves connected on the diffraction seismic data are isolated from each other on the seismic reflection data, making the connection between caves clearer. Based on the results of the fault and cave identification, we analyze the reservoir connectivity of the study area using the oil pressure and daily production data, which indicates that the north–northwest and near-north–south faults probably play a role in the connection of the reservoirs, whereas the northeast–east faults tend to block the connection of the reservoirs.

Description: The Middle to Upper Eocene series are characterized by multiple hiatuses related to erosion, nondeposition, or condensed series in the Cap Bon and Gulf of Hammamet provinces. We have performed an integrated study taking advantage of surface and subsurface geology, faunal content, borehole logs, electrical well logs, vertical seismic profiles, and surface seismic sections. Calibrated seismic profiles together with borehole data analysis reveal unconformities with deep erosion, pinch outs, normal faulting, and basin inversion that are dated Campanian, intra-Lutetian, and Priabonian compressive phases; these events were also described at the regional scale in Tunisia. Tectonics, sea-level fluctuations, and climate changes closely controlled the depositional process during the Middle to Upper Eocene time. The depositional environment ranges from internal to outer platform separated by an inherited paleo high. We determine eight third-order sequences characterizing the interaction among tectonic pulsations, sea-level changes, and the developed accommodation space within the Middle to Upper Eocene interval. We correlate the obtained results of the Cap Bon-Gulf of Hammamet provinces with the published global charts of sea-level changes, and we find a good correspondence across third-order cycles. Model-based 3D inversion proved to be a solution to model the lateral and vertical lithologic distribution of the Middle to Upper Eocene series.

Description: Data transformation, regional-residual separation, trend analysis, and analytic signal (AS) depth estimation were applied to aeromagnetic data covering the Anambra Basin, which is a major depocenter in the Benue Trough, southeast Nigeria, with the primary objectives of accentuating the attributes of magnetic sources and determining if sufficient sediment thickness exists for hydrocarbon generation, maturation, and expulsion. The application of data transformation techniques (such as map projection, merging, and reduction-to-pole) and regional-residual ensured the computation of a crustal magnetic field that would be suitable for magnetic analyses. Results indicate that the magnetic basement in the basin forms an undulating surface overlain by sediments with an average thickness ranging between 4 and 7.5 km, whereas the maximum thickness reaches 8 km in some areas. This depth range suggests a promising prospect for source-facies maturation and expulsion. We expect that areas in the study area with these appreciable sediment thicknesses, good preservation of graben fill, and suitable areal closures or fault structures would be favorable for hydrocarbon prospectivity.

Description: As industrialized fishing activities have moved into deeper water, the recognition of Vulnerable Marine Ecosystems (VMEs) has become important for the protection of the deep-sea. Our limited knowledge on the past and present distribution of VMEs hinders our ability to manage bottom fisheries effectively. This study investigated whether accounting for bottom fishing intensity (derived from Vessel Monitoring System records) as a predictor in habitat suitability models can (1) improve predictions of, and (2) provide estimates for a pre-fishing baseline for the distribution and biomass of a VME indicator taxon. Random Forest models were applied to presence/absence and biomass of Geodia sponges and environmental variables with and without bottom fishing intensity. The models including fishing were further used to predict distribution and biomass of Geodia to a pre-fishing scenario. Inclusion of fishing pressure as a predictive term significantly improved model performance for both sponge presence and biomass. This study has demonstrated a way to produce a more accurate picture of the current distribution of VMEs in the study area. The pre-fishing scenario predictions also identified areas of suitable Geodia habitat that are currently impacted by fishing, suggesting that sponge habitat and biomass have been impacted by bottom trawling activities.

Description: While the importance of early life survival and growth variations for population dynamics is well documented, there is still a relatively limited understanding of how survival and growth is affected by the species’ spatial distribution. Using Barents Sea spatial bottom survey data (1994–2018), we study the spatiotemporal variability of the juvenile Atlantic cod (Gadus morhua) growth and survival. We used indices of the spatial distribution of juvenile cod at age-1 to study the role of distribution for the change in abundance and mean body size through their second winter of life (from age-1 to age-2). Over the 24 years analysed, we found that the location where the age-1 cod are in the Barents Sea matters for their growth and survival. We found that year-classes growing up in the western Barents Sea have higher mortality but faster growth than year-classes distributed farther east. Our results indicate that the biotic and abiotic conditions encountered at the settlement location may influence the spatial survival and growth of age-1 cod and subsequently the population dynamics. Our results underscore the importance of distribution for survival and growth early in life and by providing this essential information has implications for stock assessment and spatial fisheries management.

Description: We have characterized the petrophysical and geomechanical properties of the Late Cretaceous Turonian and Cenomanian carbonate reservoirs from the southeast Constantine Basin, northern Algeria. In general, Turonian carbonates exhibit a wide range of porosities (2%–15%) and permeabilities (0.001–10 mD), whereas the Cenomanian reservoir appears to be very tight (

Description: Compaction effects can obscure the impedance separation between hydrocarbon-bearing and fully brine-saturated sandstones. We have improved their discrimination by removing depth-related trends from inverted seismic impedance. Although the ratio of compressional- to shear-wave velocity versus seismic compressional-wave impedance crossplots shows differences among pay, brine sand, and shale trends, using absolute inverted impedances only imperfectly distinguishes hydrocarbon sands from brine sands due to outliers. In a given locality, statistical comparison of well log and seismic-derived impedances enables us to obtain a shale impedance model for a lithology baseline to detrend the impedance from the effects of burial and overburden. This has the effect of unmasking anomalies associated with hydrocarbon-bearing sands and serves as a reliable fluid discriminator. For an offshore Gulf of Mexico data set on the flank of a salt dome, with pay occurring over a wide range of depths, we identify hydrocarbon-bearing sands with a greater success rate after detrending the absolute seismic impedance.

Description: Summary The Bayesian slip inversion offers a powerful tool for modeling the earthquake source mechanism. It can provide a fully probabilistic result and thus permits us to quantitively assess the inversion uncertainty. The Bayesian problem is usually solved with Monte Carlo methods, but they are computationally expensive and are inapplicable for high-dimensional and large-scale problems. Variational inference is an alternative solver to the Bayesian problem. It turns Bayesian inference into an optimization task and thus enjoys better computational performances. In this study, we introduce a general variational inference algorithm, automatic differentiation variational inference (ADVI), to the Bayesian slip inversion and compare it with the classic Metropolis-Hastings (MH) sampling method. The synthetic test shows that the two methods generate nearly identical mean slip distributions and standard deviation maps. In the real case study, the two methods produce highly consistent mean slip distributions, but the ADVI-derived standard deviation map differs from that produced by the MH method, possibly because of the limitation of the Gaussian approximation in the ADVI method. In both cases, ADVI can give comparable results to the MH method but with a significantly lower computational cost. Our results show that ADVI is a promising and competitive method for the Bayesian slip inversion.

Description: The best petrophysical models are based on direct measurements from the core. Unfortunately, core is not available in many cases, either for economic, logistical, or historical reasons. In this study, we needed to construct a detailed Field Development Plan (FDP) for the small, marginal B-9 field in the Western Offshore Basin, India, which did not merit core acquisition. The objective is to propose a workflow for building a petrophysical model with limited data sets instead of a typical FDP workflow. After analyzing the assumptions, limitations, and uncertainties involved in the petrophysical model, we used advanced petrophysical logs to reduce uncertainty and create a robust petrophysical model. We carried out a log-based petrophysical study to determine the volume of shale, porosity, saturation, and permeability. The advanced petrophysical logs including spectroscopy, nuclear magnetic resonance (NMR), formation pressures, and well testing data are used to calibrate the petrophysical model. Spectroscopy data are used to calibrate the mineralogical volumes and grain density, whereas the porosity is calibrated from NMR data. We calibrated log-derived permeability results with NMR permeability and mobility from well test data. We used heterogeneous rock analysis on petrophysical outputs to carry out petrophysical rock typing (PRT). This has helped in establishing the porosity-permeability relationship and saturation-height model for each PRT. In the absence of irreducible water saturation ([Formula: see text]) information from the core, NMR-derived [Formula: see text] is calculated and then used to calibrate the saturation model. Log-derived permeability and saturation are estimated, which agrees well with the available testing data. This provided a robust petrophysical model that served as a basis for geologic static and reservoir dynamic models. The gas-down-to and water-up-to methods are used to establish the contacts. The resulting saturation height model agreed well with the saturations derived from the log, which gave us confidence in our dynamic model.

Description: Assessment of zooplankton abundance, distribution, community composition, and temporal variability is critical to understanding the effects of climate variability and change on lower trophic level production and availability for consumption by larger consumers. Zooplankton sampling is performed across the Canadian continental shelf system by Fisheries and Oceans Canada's Atlantic Zone Monitoring Programme (AZMP). Sampling includes semi-monthly to monthly collection of zooplankton using vertical net tows (VNTs) deployed from near-bottom to surface at stations on the central Scotian Shelf (Stn 2, 150 m depth) and Newfoundland Shelf (Stn 27, 175 m depth), and by Continuous Plankton Recorders (CPRs) in the near-surface layers along routes over the Scotian and Newfoundland shelves (0–10 m depth). Here, we compare abundance metrics for 11 copepod taxa collected using both gear types in both regions between 1999 and 2015. Seasonal cycles of VNT and CPR abundance were similar for near-surface residents. VNT: CPR abundance ratios varied year-round for vertical migrants, as ontogenetic migrants shifted their vertical distribution, and as diel migrants changed their migratory behaviour. For some taxa, differences in annual average VNT: CPR abundance ratios between regions suggest differences in vertical distribution, while for others differences in inter-annual variability for VNT and CPR abundances suggest differences in the dynamics of the near- and sub-surface components of the populations.

Description: Summary We present a technique for lithofacies classification of well-log data using an active semi-supervised algorithm. This method considers both the input of domain experts and the distribution characteristics of well-log properties. It aims to obtain lithofacies that are more geologically meaningful and seismically interpretable than the conventional clustering methods. We impose guidance from experts (e.g., geologist, petrophysicist and seismic interpreter) as pairwise constraints. The acquired constraints were incorporated into facies classification in two ways: modification of the objective function and optimization of the classification subspace. An iterative expectation-maximization (EM) algorithm was used to minimize the objective function. We applied the method to a set of well logs from the Glitne field, North Sea, where six lithofacies had been defined initially. Classification results illustrated that facies predicted with the semi-supervised approach achieved good matches with true labels. Comparisons among different methods (semi-supervised method, quadratic determinant analysis and expectation-maximization with Gaussian mixture model algorithm) also demonstrated that the proposed method significantly outperformed the others. We also tested a scenario with five facies, where we combined silty shale and shale into one group due to significant overlap in the elastic domain. Results demonstrated that the semi-supervised approach produced facies that were more consistent with expert intention, and they were more geologically interpretable. The techniques and results illustrated here could be performed in different types of reservoir facies classification, and the facies classified using semi-supervised algorithm honors the input of the users and data characteristics.

Description: Summary In an attempt to overcome the difficulties of the full waveform inversion (FWI), several alternative objective functions have been proposed over the last few years. Many of them are based on the assumption that the residuals (differences between modelled and observed seismic data) follow specific probability distributions when, in fact, the true probability distribution is unknown. This leads FWI to converge to an incorrect probability distribution if the assumed probability distribution is different from the real one and, consequently it may lead the FWI to achieve biased models of the subsurface. In this work, we propose an objective function which does not force the residuals to follow a specific probability distribution. Instead, we propose to use the non-parametric kernel density estimation technique (KDE) (which imposes the least possible assumptions about the residuals) to explore the probability distribution that may be more suitable. As evidenced by the results obtained in a synthetic model and in a typical P-wave velocity model of the Brazilian pre-salt fields, the proposed FWI reveals a greater potential to overcome more adverse situations (such as cycle-skipping) and also a lower sensitivity to noise in the observed data than conventional L2 and L1-norm objective functions and thus making it possible to obtain more accurate models of the subsurface. This greater potential is also illustrated by the smoother and less sinuous shape of the proposed objective function with fewer local minima compared with the conventional objective functions.

Description: Summary We have studied the active and recent tectonics of New Guinea, using earthquake source modelling, analysis of gravity anomalies, seismic reflection profiles, and thermal and mechanical models. Our aim is to investigate the behaviour and evolution of a young continental deformation belt, and to explore the effects of lateral variations in foreland rheology on the deformation. We find that along-strike gradients in the lithosphere thickness of the southern foreland have resulted in correlated changes in seismogenic thickness, likely due to the effects on the temperature structure of the crust. The resulting variation in the strength of the foreland means that in the east, the foreland is broken through on thrust faults, whereas in the west it is relatively intact. The lack of correlation between the elevation of the mountain belt and the seismogenic thickness of the foreland is likely to be due to the time taken to thicken the crust in the mountains following changes in the rheology of the underthrusting foreland, as the thinned passive margin of northern Australia is consumed. The along-strike variation in whether the force exerted between the mountains and the lowlands is able to break the foreland crust enables us to estimate the effective coefficient of friction on foreland faults to be in the range of 0.01-0.28. We use force-balance calculations to show that the recent tectonic re-organisation in western New Guinea is likely to be due to the development of increasing curvature in the Banda Arc, and that the impingement of continental material on the subduction zone may explain the unusually low force it exerts on western New Guinea.

Description: The origin of the eclogites that reside in cratonic mantle roots has long been debated. In the classic Roberts Victor kimberlite locality in South Africa, the strongly contrasting textural and geochemical features of two types of eclogites have led to different genetic models. We studied a new suite of 63 eclogite xenoliths from the former Roberts Victor Mine. In addition to major- and trace-element compositions for all new samples, we determined 18O/16O for garnet from 34 eclogites. Based on geochemical and textural characteristics we identify a large suite of Type I eclogites (n = 53) consistent with previous interpretations that these rocks originate from metamorphosed basaltic-picritic lavas or gabbroic cumulates from oceanic crust, crystallised from melts of depleted MORB mantle. We identify a smaller set of Type II eclogites (n = 10) based on geochemical and textural similarity to eclogites in published literature. We infer their range to very low δ18O values combined with their varied, often very low Zr/Hf ratios and LREE-depleted nature to indicate a protolith origin via low-pressure clinopyroxene-bearing oceanic cumulates formed from melts that were more depleted in incompatible elements than N-MORB. These compositions are indicative of derivation from a residual mantle source that experienced preferential extraction of incompatible elements and fractionation of Zr-Hf during previous melting.

Description: Summary Finite-difference (FD) modeling of seismic waves in the vicinity of dipping interfaces gives rise to artifacts. Examples are phase and amplitude errors, as well as staircase diffractions. Such errors can be reduced in two general ways. In the first approach, the interface can be anti-aliased (i.e., with an anti-aliased step-function, or a lowpass filter). Alternatively, the interface may be replaced with an equivalent medium (i.e., using Schoenberg & Muir (SM) calculus or orthorhombic averaging). We test these strategies in acoustic, elastic isotropic, and elastic anisotropic settings. Computed FD solutions are compared to analytical solutions. We find that in acoustic media, anti-aliasing methods lead to the smallest errors. Conversely, in elastic media, the SM calculus provides the best accuracy. The downside of the SM calculus is that it requires an anisotropic FD solver even to model an interface between two isotropic materials. As a result, the computational cost increases compared to when using isotropic FD solvers. However, since coarser grid spacings can be used to represent the dipping interfaces, the two effects (an expensive FD solver on a coarser FD grid) equal out. Hence, the SM calculus can provide an efficient means to reduce errors, also in elastic isotropic media.

Description: Summary Objective assessment of seismic hazard and understanding of the Himalayan arc's tectonics requires detailed information on the crustal structure and geometry of the underthrusting Indian Plate beneath the Himalaya. Here, we present high-resolution three-dimensional P- wave velocity (Vp) and P-to-S wave velocity ratio (Vp/Vs) images of the Kumaun-Garhwal Himalaya, a proposed potential region for the future great earthquake. We generate these images by inverting arrival times of 515 local earthquakes recorded by 41 broadband stations during November 2006-June 2008. The tomographic images show a heterogeneous structure in the upper-mid crust. These images, along with available geophysical and geological information, indicate the presence of quartz-rich felsic rocks in the uppermost crust; and the occurrence of saline-rich aqueous fluid/partial melt in the upper-mid crust. We propose that the Main Himalayan Thrust (MHT), having a flat-ramp-flat geometry, lies at the base of these fluid zones. The small and moderate-to-strong magnitude earthquakes are mainly confined to the fluid-rich zones along the MHT and quartz-rich rocks in the upper crust. Such an interpretation implies that the earthquake occurrence in the Kumaun-Garhwal Himalaya is largely controlled by the geometry of the MHT and crustal lithology.

Description: Summary On 2020 December 29, the Mw 6.4 Petrinja earthquake hit the Kupa Valley region and set a record for the largest earthquake in northwestern (NW) Croatia. The coseismic surface displacements are well obtained on three pairs of interferometric synthetic aperture radar (InSAR) images from Sentinel-1 satellites. The interferograms exhibit coseismic ground deformation with a maximum line-of-sight (LOS) displacement of 0.4 m. Based on the coseismic deformation field, we investigate both the fault geometry and the coseismic slip distribution. The results show a dextral event with a peak slip of 3.50 m at a depth of 3.47 km. The shallow depth and unusually large coseismic slip correspond to obvious ground deformation and serious damage in the epicentral zone. The 2020 earthquake highlights an unmapped, steeply dipping strike-slip fault, which possibly enabled a potential ‘curve cut-off’ process on the bending segment of the Pokupsko fault in the context of ∼N-S compression in NW Croatia. The large coseismic slip and high stress drop associated with the Mw 6.4 Petrinja earthquake are likely products of the geometrically complex fault zones and immature seismotectonic environment in NW Croatia.

Description: Seismic amplitude-variation-with-offset (AVO) inversion from prestack seismic data plays a significant role in estimating elastic parameters and characterizing reservoir properties. In general, sparse regularization is widely used to solve ill-posed inverse problems by reducing the solution space of subsurface parameters, which makes seismic AVO inversion more stable. However, the traditional sparse constraint inversion only focuses on the vector sparsity of reflectivity, instead of the structural sparse characteristics of the estimated parameters. Consequently, various elastic parameters demonstrate different formation structural features in the same location of stratum. In this study, we have developed a novel approach that combines the structural sparsity and the vector sparsity of the model reflectivity to establish the posterior probability density distribution and solve the objective function of the model parameters. Based on the relationship among multiple elastic parameters, we divide the model parameters to be inverted into several groups according to intrinsic structural sparse characteristics of elastic parameters. In this case, all of the model parameters at the same sampling point are classified into the identical group, which ensures that different estimated parameters indicate the same characteristic in terms of stratigraphic structure. From the perspective of Bayesian inference, we use the modified Cauchy probability density function (PDF) to characterize the group sparsity and describe the relationship among model parameters in the same group by Gaussian PDF. Furthermore, we estimate the optimum solution corresponding to the maximum a posteriori probability under Bayesian inference. Synthetic experiments on a Marmousi model prove that the estimated P-velocity, S-velocity, and density are consistent with those of the real models, and the application of field data confirms the availability and feasibility of group sparse inversion.

Description: Summary We deployed a seismic network near the source region of the 2017 Mw 6.5 Jiuzhaigou earthquake to monitor aftershock activity and to investigate the local fault structure. An aftershock deployment of Array of small Arrays (AsA) and a Geometric Mean Envelop (GME) algorithm are adopted to enhance detection performance. We also adopt a set of association, relocation, and matched-filter techniques to obtain a detailed regional catalog. 16,742 events are detected and relocated, including 1,279 aftershocks following the Mw 4.8 aftershock. We develop a joint inversion algorithm utilizing locations of event clusters and focal mechanisms to determine the geometry of planar faults. Six segments were finally determined, in which three segments are related to the Huya fault reflecting a change in fault dip direction near the mainshock hypocenter, while the other segments reflect branches showing orthogonal and conjugate geometries with the Huya fault. Aftershocks were active on branching faults between the Huya and Minjiang faults indicating that the mainshock may have ruptured both major faults. We also resolve a fault portion with ‘weak strength’ near the mainshock hypocenter, which is characterized by limited co-seismic slips, concentrated afterslip, low aftershock activities, high b-value, and high sensitivity to stress changes. These phenomena can be explained by fault frictional properties at conditional stable sliding status, which may be related to the localized high pore-fluid pressure produced by the fluid intrusion.

Description: Nephrops (Nephrops norvegicus) is an economically valuable target species in the North Sea. Although individual Nephrops populations are scattered, the crustacean is managed regionally by the European Union (EU). The spatial competition for fisheries in the North Sea is growing especially due to expanding offshore wind farms (OWF) and newly implemented marine protected areas (MPA). Moreover, the Brexit affects the availability of EU fishing quotas and adds to the overall uncertainty EU fishers face. We compare landings and catches to scientifically advised quantities and perform an overlap analysis of fishing grounds with current and future OWFs and MPAs. Furthermore, we explore the German Nephrops fleet using high-resolution spatial fishing effort and catch data. Our results confirm earlier studies showing that Nephrops stocks have been fished above scientific advice. Present OWFs and MPAs marginally overlap with Nephrops fishing grounds, whereas German fishing grounds are covered up to 45% in future scenarios. Co-use strategies with OWFs could mitigate the loss of fishing opportunities. Decreased cod quotas due to Brexit and worse stock conditions, lowers Germany's capability to swap Nephrops quotas with the UK. We support the call for a new management strategy of individual Nephrops populations and the promotion of selective fishing gears.

Description: Qualitative Network Models (QNMs), Fuzzy Cognitive Maps (FCMs), and Bayesian Belief Networks (BBNs) have been proposed as methods to formalize conceptual models of social–ecological systems and project system responses to management interventions or environmental change. To explore how these different methods might influence conclusions about system dynamics, we assembled conceptual models representing three different coastal systems, adapted them to the network approaches, and evaluated outcomes under scenarios representing increased fishing effort and environmental warming. The sign of projected change was the same across the three network models for 31–60% of system variables on average. Pairwise agreement between network models was higher, ranging from 33 to 92%; average levels of similarity were comparable between network pairs. Agreement measures based on both the sign and strength of change were substantially worse for all model comparisons. These general patterns were similar across systems and scenarios. Different outcomes between models led to different inferences regarding trade-offs under the scenarios. We recommend deployment of all three methods, when feasible, to better characterize structural uncertainty and leverage insights gained under one framework to inform the others. Improvements in precision will require model refinement through data integration and model validation.

Description: Summary Constitutive theory for viscoelasticity has broad application to solid mantle or ice deformations driven by tides, surface mass variations, and post-seismic flow. Geophysical models using higher order viscoelasticity can better accommodate geodetic observations than lower-order theory, typically provided by tensor versions of Maxwell, 4-parameter Burgers or standard linear (Zener) rheology. We derive, for the first time, a mathematical description of a compressible version of the extended Burgers material (EBM) model paradigm which has a distribution function of relaxation spectra. The latter model is often used for parameterizing high temperature background transient responses in the rock physics and mechanics laboratory setting and have demonstrated application to low frequency seismic wave attenuation. A new generalization of this practical anelastic model is presented and applied to the glacial isostatic adjustment momentum equations, thus providing useful guidance for generating initial-value boundary problem-solving software for quite general coding strategies. The solutions for the vertical motion response to a suddenly imposed surface load reveal a short-term transience of substantial amplitude.

Description: Summary Stoneley modes are a special subset of normal modes whose energy is confined along the core-mantle boundary. As such, they offer a unique glimpse into Earth structure at the base of the mantle. They are often observed through coupling with mantle modes due to rotation, ellipticity and lateral heterogeneity, though they can be detected without such coupling. In this study, we explore the relative sensitivities of seismic spectra of two low-frequency Stoneley modes to several factors, taking as reference the fully coupled computation up to 3 mHz in model S20RTS. The factors considered are (i) theoretical, by exploring the extent to which various coupling approximations can accurately reproduce reference spectra; and (ii) model-based, by exploring how various Earth parameters such as core-mantle boundary topography, attenuation, and S-wave and P-wave structures, and the seismic source solution may influence the spectra. We find that mode-pair coupling is insufficiently accurate, but coupling modes within a range of ±0.1 mHz produces acceptable spectra, compared to full coupling. This has important implications for splitting function measurements, which are computed under the assumption of isolated modes or at best, mode-pair or group coupling. We find that uncertainties in the P-wave velocity mantle model dominate compared to other model parameters. In addition, we also test several hypothetical models of mantle density structure against real data. These tests indicate that, with the low-frequency Stoneley mode spectral data considered here, it is difficult to make any firm statement on whether the large-low-shear-velocity-provinces are denser or lighter than their surroundings. We conclude that better constraints on long wavelength elastic mantle structure, particularly P-wave velocity, need to be obtained, before making further statements on deep mantle density heterogeneity. In particular, a dense anomaly confined to a thin layer at the base of the mantle (less than ∼100-200 km) may not be resolvable using the two Stoneley modes tested here, while the ability of higher frequency Stoneley modes to resolve it requires further investigations.

Description: Mitigating bycatch of non-target fish species is a common objective in fisheries management that may be supported by the gathering of data from fishery observer programs and quantitative analysis of bycatch risk factors. We build three GLM models based on Chinese tuna longline fishery observer data in terms of analysis of total bycatch rate (TB rate), total bycatch ratio (TB ratio), and species-specific bycatch rate, respectively. The positive log-linear models assumed a Gaussian observation error model and a linear combination of categorical independent variables, including area, year, month, depth, and bycatch species. Results show that distributions of TB rate and TB ratio followed different trends and a latitudinal decrease was observed from both the northern and southern hemisphere of the equator. Comprehensively, the Pacific is a better place to fish compared to the Indian and Atlantic Oceans in terms of relatively lower TB rate and TB ratio. Fishing in open oceans can somehow avoid a high TB ratio than fishing in coastal waters. As a result, we recommend area 2SW, 2SE, 2 NW, 14SW, 14SE, and 14 NW as appropriate fishing ground for Albacore (Thunnus alalunga) while area 11N,  11S, 18SW, and 18SE to be appropriate fishing ground for fishing bigeye tuna (Thunnus obesus). Setting fishing gears deeper than 500 m would also help to get a low TB rate and TB ratio.

Description: Summary The M=8.1, April 1st, 2014 Iquique earthquake, which broke part of the northern Chile seismic gap, was preceded by a strong foreshock sequence starting early January 2014. The reported analysis of the continuous records of the nearby GPS stations from the IPOC North Chili array lead to contradictory results concerning the existence and location of slow slip events (SSE) on the interplate contact. Resolving this controversy is an important issue, as although many SSEs are reported in subduction zones, only a few were found to be precursory to large earthquakes. Here we show that the records of a long base tiltmeter installed near Iquique, when corrected for coseismic steps, long term drift, tidal signals, and oceanic and atmospheric loading, show significant residual signals. These can be modelled with a sequence of four SSEs located close to Iquique. Their signature was already reported on some GPS stations, but their source was then characterized with a very low resolution in time and space, leading to contradicting models. With the tilt records, we can rule out the previously proposed models with a single large SSE closer to the mainshock. Combining tilt with GPS records greatly improves the resolution of GPS alone, and one could locate their sources 100 to 180 km south-southeast to the mainshock epicenter, with moment magnitudes between 5.8 and 6.2, at the edge of the main aftershock asperities. These moderate SSEs thus did not directly trigger the mainshock, but contributed to trigger the main foreshock and the main aftershock. Only the sensitivity and resolution of the tiltmeter, added to the GPS records, allowed us to describe with unprecedented accuracy this precursory process as a cascade of cross-triggered, short term aseismic slip events and earthquakes on the interplate contact. This three months of precursory activation appears to be the final acceleration burst of a weaker, longer term SSE which started mid-2013, already reported, with a moment release history which we could quantify. From the methodological point of view, our study takes advantage of an interesting complementarity of tilt and GPS measurements, due to their different dependence in distance to the source of strain, which turns out to be very efficient for resolving location and moment of strain sources, even when both instruments are close to each other. It finally demonstrates the efficient removal of sequences of small or even undetected coseismic steps from high resolution tilt record signal in order to retrieve the purely aseismic signal, a presently impossible task for high time resolution GPS records due to low signal to noise.

Description: Summary This article proposes the use of geostatistical techniques to estimate dispersion curves between other known ones. To do it, we introduce two novel methodologies: the stacking method and the group-velocity mapping method. We obtain our set of group-velocity fundamental mode dispersion curves from seismic noise correlation. Consequently, we first assign their attribution point at the mid-distance between the stations used for the dispersion curves calculation. The stacking method uses the range of the omnidirectional semivariogram of a regionalized variable that quantifies the similarity between dispersion curves to stack them according to their spatial correlation. We test this technique with dispersion curves obtained in Mexico City and get a range of ∼400 m for the omnidirectional semivariogram. We also calculate directional semivariograms and observe a maximum range (∼500 m) in the NW-SE direction, agreeing with the city's spatial distribution of natural periods. On the other hand, the group-velocity mapping method uses the ordinary kriging estimator in the group velocities for all the ranges of periods to generate maps and then dispersion curves. Estimated dispersion curves retrieved from both, the stacking and the group-velocity mapping method, were compared with those obtained with the fast marching tomographic method. We also establish analogies between getting group-velocity maps with the tomographic method and with the group-velocity mapping method. Finally, we observe that the range of the omnidirectional semivariogram used in the stacking method may be related to the tomographic method resolution.

Description: Summary The numerical simulation of seismic wave propagation in realistic heterogeneous media, as sedimentary basins, is a key element of seismic hazard estimation. Many numerical methods in two dimensions are based on unstructured triangular meshes and explicit time schemes. However, the presence of thin layers and tangential stratigraphic contacts in sedimentary basins entails poorly shaped mesh elements: some triangle heights are extremely small compared to the edge lengths, which requires small time steps in the simulations and thus leads to prohibitive computation times. We compare manual and automatic geological model simplification techniques to modify problematic areas of the domain, so as to improve the quality of the triangulated mesh. We modify the shape and the connectivity between rock units in the basin, with the objective to reduce the computation time without significantly changing the physical response of the geological medium. These simplification techniques are applied in an investigation of site effects in the lower Var valley, a densely urbanized area located near the city of Nice (South-East of France). Numerical simulations of plane wave propagation in a heterogeneous 2D profile are carried out with a discontinuous Galerkin finite element method. Five simplified meshes are generated and the impacts of the simplifications are analyzed in comparison to the reference model. We compare the time solutions and the transfer functions obtained on the surface of the basin. The results show that the simplification procedures, in particular automatic modifications of the model, yield a significant performance gain, with a ratio higher than 55, while having a negligible impact on the ground motion response.

Description: The state-space assessment model (SAM) is extended by allowing a functional relationship between observation variance and the corresponding prediction. An estimated relationship between observation variance and predicted value for each individual observation allows the model to assign smaller (or larger) variance to predicted larger log-observations. This relation is different from the usual assumption of constant variance of log-observations within age groups. The prediction–variance link is implemented and compared to the usual constant variance assumption for the official assessments of North East Arctic cod and haddock. For both of these stocks, the prediction–variance link is found to give a significant improvement.

Description: A powerful aspect of single particle cryogenic electron microscopy (cryo-EM) is its ability to determine high-resolution structures from samples containing heterogeneous mixtures of the same macromolecule in different conformational or compositional states. Beyond determining structures at higher resolutions, one outstanding question is if macromolecules with only subtle conformation differences, such as the same protein bound with different ligands in the same binding pocket, can be separated reliably, and if information concerning binding kinetics can be derived from the particle distributions of different conformations obtained in classification. In this study, we address these questions by assessing the classification of synthetic heterogeneous datasets of TRPV1 generated by combining different homogeneous experimental datasets. Our results indicate that classification can isolate highly homogeneous subsets of particle for calculating high-resolution structures containing individual ligands, but with limitations.

Description: Fluid-rock interaction has profound effects on the dynamics of the lithosphere. This Perspectives article describes the catalytic effects of water on the kinetics of mineral reactions and on the strength of rocks in terms of coupled dissolution and precipitation mechanisms on a macro- and nano-scale. The length scale of coupling between the dissolution and precipitation steps depends on the fluid composition at the mineral-fluid interface and also on differential stress. Stress-induced mass transport, dependent on the generation of porosity by mineral reactions, results in dissolution-precipitation creep as the principal mechanism of rock deformation in the lithosphere. The heterogeneous distribution of fluid infiltration into dry, strong rocks in the deep crust leads to weak rocks within strong, stressed host rock and the possibility of significant local variations in pressure. Fluid-rock interaction mechanisms are discussed in terms of recrystallisation reactions whereby mass transport and the most favourable nucleation sites determine the distribution and texture of the resultant assemblages. Metamorphic differentiation is a natural consequence of dissolution-precipitation mechanisms under deviatoric stress and similar mechanisms may apply to general pattern formation in rocks.

Description: Summary Seismic wave scattering dispersion and attenuation can be significant in cracked reservoirs. Many scattering models have been proposed, and the fractal (self-similar) features of the medium need to be further incorporated and analyzed. We solve the P-wave scattering caused by fluid-saturated aligned cracks of finite thickness embedded in fractal media. The model is based on crack displacement discontinuities by using the Foldy approximation and representation theorem. The frequency dependence of velocity and attenuation are analyzed as a function of the incidence angle and the crack and fluid properties. The results show that the crack density, thickness and radius can have a significant influence on the wave properties, as well as the fluid bulk modulus and saturation. The model requires three parameters to describe self-similar cracked media, and can be relevant in seismology, oil exploration and non-destructive testing of materials.

Description: We have carried out a geomechanical study of three wells, one each in the Niobrara A, Niobrara C, and Codell Sandstone to investigate how the state of stress and stress variations with depth affect vertical hydraulic fracture growth and shear stimulation of preexisting fractures. We determine that the higher magnitudes of measured least principal stress values in the Niobrara A and C shales are the result of viscoplastic stress relaxation. Using a density log and a vertical transverse isotropy velocity model developed to accurately locate the microseismic events, we theoretically calculated a continuous profile of the magnitude of the least principal stress with depth. This stress profile explains the apparent vertical hydraulic fracture growth as inferred from the well-constrained depths of the associated microseismic events. Finally, we determine that because of the upward propagation of hydraulic fractures from the Niobrara C to the Niobrara A, the latter formation experienced considerably more shear stimulation, which may contribute to the greater production of oil and gas from that formation.

Description: This article investigates the local economic cost of hosting refugees. Using administrative data in France, we show that the opening of small housing centers for refugees decreases the economic activity in hosting municipalities. We demonstrate that this downturn is related to a decline in the population by around 2% due to fewer people moving to hosting municipalities. We show that this avoidance behavior of natives results from prejudices, and is unlikely to be driven by a labor market supply shock from the arrival of refugees. We also estimate the aggregate cost of hosting refugees.

Description: A pressing challenge for climate-vulnerable fisheries is how to manage now for present and future climate change. In contrast to climate forecasting approaches, we track integrated signals of change for example populations in a climatically forced region and use stochastic dynamic programming to compare the performance of a range of management-ready policies over all possible future states. Our main results highlight: (i) that biomass-linked harvest control rules (HCRs) can partially compensate for changing production, even if the HCR is time invariant; and (ii) that the form of utility (e.g. risk neutral or risk averse) can result in remarkably different optimal decision paths. Performance over future horizons degrades marginally from dynamic HCRs to static HCRs (except at low productivity where differences are more pronounced) but markedly when the biomass level is ignored altogether, as is the case in many managed fish populations globally. Understanding the processes whereby climate affects productivity is important for interpreting past data, but forecasts are not needed for tactical decision making now. Instead, we argue that the priorities for managing fish stocks influenced by climate change are to: measure the current productivity, assess the current abundance of the stock, and respond with a dynamic HCR.

Description: The fishery for Northern Atlantic cod (Gadus morhua) off Newfoundland and Labrador, Eastern Canada, presents the most spectacular case of an exploited stock crashed in a few decades by an industrial bottom trawl fishery under a seemingly sophisticated management regime after half a millennium of sustainable fishing. The fishery, which had generated annual catches of 100000 to 200000 tonnes from the beginning of the 16th century to the 1950s,  peaked in 1968 at 810000 tonnes, followed by a devastating collapse and closure 24 years later. Since then, stock recovery may have been hindered by premature openings, with vessels targeting the remains of the cod population. Previous research paid little attention towards using multicentury time series to inform sustainable catches and recovery plans. Here, we show that a simple stock assessment model can be used to model the cod population trajectory for the entire period from 1508 to 2019 for which catch estimates are available. The model suggests that if fishing effort and mortality had been stabilized in the 1980s,  precautionary annual yields of about 200000 tonnes could have been sustained. Our analysis demonstrates the value of incorporating prior knowledge to counteract shifting baseline effects on reference points and contemporary perceptions of historical stock status.

Description: The choice of an initial model for seismic waveform inversion is important. In matured exploration areas with adequate well control, we can generate a suitable initial model using well information. However, in new areas where well control is sparse or unavailable, such an initial model is compromised and/or biased by the regions with more well controls. Even in matured exploration areas, if we use time-lapse seismic data to predict dynamic reservoir properties, an initial model that we obtain from the existing preproduction wells could be incorrect. In this work, we outline a new methodology and workflow for a nonlinear prestack isotropic elastic waveform inversion. We call this method a data-driven inversion, meaning that we derive the initial model entirely from the seismic data without using any well information. By assuming a locally horizontal stratification for every common midpoint and starting from the interval P-wave velocity, estimated entirely from seismic data, our method generates pseudowells by running a two-pass 1D isotropic elastic prestack-waveform inversion that uses the reflectivity method for forward modeling and the genetic algorithm for optimization. We then use the estimated pseudowells to build the initial model for seismic inversion. By applying this methodology to real seismic data from two different geologic settings, we determine the usefulness of our method. We believe that our new method is potentially applicable for subsurface characterization in areas where well information is sparse or unavailable. Additional research is, however, necessary to improve the computational efficiency of the methodology.

Description: Since 1996, the European Union has required that fishery products of 35 fish species or groups of species, including crustaceans and cephalopods, be graded before being landed on the basis of commercial size-categories. A multi-stage sampling scheme to estimate catch-at-length and catch-at-age compositions of total annual landings has been conducted in Portuguese waters since 2009. All species and their size-categories are sampled concurrently from random trips within representatively selected site-days annually. In an effort to improve cost-efficiency of the biological catch sampling of commercial landings in Portugal, a size- category sampling scheme was tested during 2017, taking advantage of the stratification of horse mackerel landings, induced by the mandatory grading of landings by size-category. The total number of site-days (primary sampling units), fish boxes sampled, and specimens of horse mackerel sampled for length and age across strata during the pilot study were 30%, 57%, and 12% of the sampling carried out under the standard concurrent scheme, respectively. The assignment of horse mackerel length to the six commercial size-categories was highly consistent across site-days. Our study shows that the concurrent sampling, where trips are subsampled within site-days, could miss some size-categories by chance, resulting in poor estimates of catch-at-length especially for small fish present at the market during a site-day. The size-category sampling scheme ensured subsamples of fish from all size-categories within a site-day, and achieved data on catch-at-age that are fit-for purpose at 24% of the total cost for the standard concurrent sampling. The effect of sampling designs and sample sizes on horse mackerel stock assessment outputs showed that the onshore biological sampling to estimate catch-at-age compositions for stock assessment is optimized with the size-category sampling scheme. Pilot field experiments should be carried out for selected species that evidence consistent size grading among commercial categories.

Description: Many applications in seismology involve the modeling of seismic-wave traveltimes in anisotropic media. We have developed homotopy solutions of the acoustic eikonal equation for P-wave traveltimes in attenuating transversely isotropic media with a vertical symmetry axis. Instead of the commonly used perturbation theory, we use the homotopy analysis method to express the traveltimes by a Taylor series expansion over powers of an embedding parameter. For the derivation, we first perform homotopy analysis of the eikonal equation and derive the linearized ordinary differential equations for the coefficients of the Taylor series expansion. Then, we obtain the homotopy solutions for the traveltimes by solving the linearized ordinary differential equations. Results of our investigation with approximate formulas demonstrate that the analytical expressions are efficient methods for the computation of traveltimes from the eikonal equation. In addition, these formulas are also effective methods for benchmarking approximate numerical solutions in strongly attenuating anisotropic media.

Description: The Triassic-Jurassic deep sandstone reservoirs in onshore Denmark are known geothermal targets that can be exploited for sustainable and green energy for the next several decades. The economic development of such resources requires accurate characterization of the sandstone reservoir properties, namely, volume of clay, porosity, and permeability. The classic approach to achieving such objectives has been to integrate well-log and prestack seismic data with geologic information to obtain facies and reservoir property predictions in a Bayesian framework. Using this prestack inversion approach, we can obtain superior spatial and temporal variations within the target formation. We then examined whether unsupervised facies classification in the target units can provide additional information. We evaluated several machine learning techniques and found that generative topographic mapping further subdivided intervals mapped by the Bayesian framework into additional subunits.

Description: Pockmarks, as depression morphology related to fluid escape on the seafloor, are revealed by 3D seismic data on the northwestern South China Sea (SCS) margin. The pockmarks can be classified into two groups based on their various shapes in plan view: the circular group and the elongating group. These pockmarks in the study area could be defined as mega-pockmarks because their maximum diameters can reach to 7.5 km. They commonly develop more than one crater, which are called the central crater and the secondary crater. The seismic data illuminated their complicated internal architectures in the subsurface, as well as their evolution periods, such as the initiation stage, mature stage, and abandonment stage. According to the buried structures and their genesis mechanism, mega-pockmarks could be classified into linear faults-associated pockmarks and volcano-associated pockmarks. The linear fault-associated pockmarks root on the top Middle Miocene, where the linear faults are distributed. The linear faults on the top of fluid reservoir in Middle Miocene act as conduits for fluid seepage. The fluid seepage is driven by the break of balance between the hydrostatic and pore pressure. When the fluid seepage initiates, they will migrate along the linear faults, making the linear feature of pockmarks on the seafloor. Thermogenic gas from deep intervals and biogenic gas from shallow intervals may be fluid sources for the genesis of pockmarks. However, the volcanic activities control the genesis and evolution of volcano-associated pockmarks. Volcano-associated pockmarks root on the craters of volcanoes. The volcanoes underneath the pockmarks provide volcanic hydrothermal solutions, such as phreatomagmatic eruptions through the volcanic craters. The confined fluid seepages make the pockmarks exhibit a more circular shape on the seafloor. Long-term, multiepisode fluid expulsions generate the complicated internal architecture that leads to multicratered mega-pockmarks on the northwestern margin of SCS.

Description: In a shale gas reservoir, pore characterization is an important factor used to determine gas storage capacity. However, the nanometer (nm)-scale pore system in shale is difficult to explore by traditional optical, scanning electron microscopy, or even nuclear magnetic resonance well logging. We have investigated the pore structure and storage capacity of the Marcellus Shale through integration of petrophysical analysis from laboratory and well-logging data and nitrogen adsorption. The isotherm of Marcellus Shale is a composite isotherm, which has features of type I, type II, and type IV isotherms with type H4 of the hysteresis loop, suggesting slit-like pores developed in the Marcellus Shale. Quantitative analysis of pore volumes from the nitrogen adsorption indicates that density porosity may be more properly used to approximate the shale porosity and estimate the shale gas volume. In addition, the specific surface area, micropore, and mesopore volumes have a positive relationship with the kerogen volume and total organic content (TOC). By using the Langmuir and Brunauer-Emmet-Teller models, the simulated result indicates that the higher adsorbed quantity of the Marcellus Shale could be the result of the increase of micropore volume contributed, by the increase of kerogen or TOC content. The proposed equations rapidly compute TOC, a key parameter to predict gas storage capacity in overmature shale such as the Marcellus Shale.

Description: Reservoir damage is considered one of the major challenges in the oil and gas industry. Many studies have been conducted to understand formation damage mechanisms in borehole wells, but few studies have been conducted to analyze the data to detect the source, causes, and mitigations for each well where damage has occurred. I have investigated and quantified the reasons and mitigation of reservoir damage problems in the middle Miocene reservoir within the El Morgan oil field at the southern central Gulf of Suez, Egypt. I used integrated production, reservoir, and geologic data sets and their history during different operations to assess the reservoir damage in El Morgan-XX well. The collected data include the reservoir rock type, fluid, production, core analysis, rock mineralogy, geology, water chemistry, drilling fluids, perforations depth intervals, workover operations, and stimulation history. The integration of different sets of data gave a robust analysis of reservoir damage causes and helps to suggest suitable remediation. Based on these results, I conclude the following: (1) Workover fluid has been confirmed as the primary damage source, (2) the reservoir damage mechanisms could be generated by multisources including solids and filtrate invasions, fluid/rock interaction (deflocculating of kaolinite clay), water blockage, salinity chock, and the high sulfate content of the invaded fluid, and (3) multidata integration leads to appropriate reservoir damage analysis and effective design of the stimulation treatment. Furthermore, minimizing fluid invasion into the reservoir section by managing the overbalance during drilling and workover operations could be very helpful. Fluid types and solids should be considered when designing the stimulation treatment and compatibility tests should be performed. Long periods of completion fluid in boreholes are not recommended, particularly if the completion fluid pressure and reservoir pressure are out of balance, as well as the presence of sensitive formation minerals.

Description: Mississippian carbonate and silica-rich reservoirs of northern and central Oklahoma formed along a regionally extensive carbonate ramp to basin transect. The stratigraphy, lithology, and porosity characteristics of the Mississippian Meramec and Osage series significantly vary as older ramp carbonates prograde southward and transition into younger calcareous and quartz-rich silt deposits of the Anadarko Basin. Lithofacies identified within the northern carbonate-dominated portion of the system commonly include altered chert, skeletal grainstones, peloidal packstones-grainstones, bioturbated wackestones-packstones, bioturbated mudstones-wackestones, glauconitic sandstones, and siliceous shale. Lithofacies within the southern siliciclastic-dominated portion of the system include structureless to bioturbated sandstones, siltstones, and laminated mudstones, each with varying degrees of carbonate content. We have grouped these core-based lithofacies into dominant lithologies/rock types, which tie to well-log properties. Electrofacies classification methods including the artificial neural network (ANN) and k-means clustering predict lithologies in noncored wells. ANN yielded the highest overall prediction accuracy of 85% for lithologies. Core, well log, and lithology log data establish the regional stratigraphic framework. The Mississippian interval of interest subdivides into 16 stratigraphic zones. A depositional-dip-oriented cross section and the associated reservoir models illustrate the proximal to distal and stratigraphic variability of the lithology and porosity. Lithology trends moving from north to south, from older to younger strata, reveal a carbonate-dominated succession capped by diagenetically altered chert northward shifting into a siliciclastic-dominated interval, which increases in clay content southward. Northward, prospective conventional reservoirs developed near cycle tops within diagenetically replaced cherts and cherty limestones associated with subaerial exposure and sea-level fluctuations. Southward, higher total porosity associates with increased clay content linked to the suppression of calcite cement, forming prospective unconventional targets near the bases of depositional cycles.

Description: Marine predatory fish face unpredictable prey environments, ranging from abundance to scarcity of food. Dimensioning their assimilative system to accommodate gorging and fasting is therefore a central life history choice. Assimilative capacity experiments typically operate with sustained feeding to satiation, and therefore ignore the fluctuations in natural feeding opportunities. A more relevant description of the adaptive response is the episodic capacity associated with binge feeding (hyperphagia). We develop the theoretical foundation to define episodic and sustained capacity and its allometry. Extensive empirical evidence on marine piscivorous fish at higher latitudes confirms that the episodic capacity scales almost linearly with predator body mass (exponent approximately 0.95), producing an increasing factorial hyperphagic scope (exponent approximately 0.20). Our synthesis overturns the reigning steady state perspective on assimilative capacity. The fish can utilize an episodic capacity, typically twice the size of the sustained capacity, resulting in local dynamics of functional responses with profound implications for scaling-up to ecosystem level.

Description: Lateral changes in velocity about faults can give rise to fault shadow (FS) zones on time-migrated data volumes, which can result in structural interpretation artifacts in the fault trap reservoir. To address this issue, we have adopted a new reconstruction method of FS distortion structures based on a deep learning fully connected network (FCN). We use the 3D stratigraphic dip attributes to quantitatively delineate the extent of the FS zone. Then, we train a model to construct a nonlinear trend surface based on the structures of the stratigraphic reflectors that fall outside of the shadow zone. Finally, we use this nonlinear trend surface to compensate for the distorted structure within the FS zone. We calibrate our method using synthetic data and find that the method can accurately recover structural data within the FS distortion zone. We then test the effectiveness of our workflow by applying it to recover real FS distortion structures in the Pearl River Mouth Basin of the South China Sea. The results confirm that our method significantly reduces drilling depth errors in the FS zone. Compared to the traditional polynomial fitting method, the multilayer, multiparameter, and flexible nonlinear activation function of FCN is more capable of reconstructing nonlinear geologic structures in the FS zone. We find the FCN-based geologic reconstruction method to be efficient and effective for exploring potential structures in the FS zone and thereby in avoiding the risks of structural failure.

Description: Spawning timing in fish is generally cyclical in temperate regions in order to increase the probability of matching larval occurrence with ideal environmental conditions. The capelin stock in Northwest Atlantic Fisheries Organization Divisions 2J3KL collapsed in 1990–1991 and has not recovered. This collapse was concomitant with collapses in groundfish stocks and cold oceanographic conditions. Using citizen science data, newspaper archives, grey and primary literature, and monitoring data, a century of capelin beach spawning times were compiled. Capelin beach spawning has been persistently 3 weeks later since the stock collapse. To identify potential predictors of capelin spawning timing, an exploratory analysis was conducted using environmental and biological variables and a period factor that categorized a year as either pre-collapse (1990 and earlier) or post-collapse (post-1990) in a step-wise multiple regression model. Spawning timing was predicted to be delayed in the post-collapse period when there were negative anomalies in the Newfoundland and Labrador Climate Index and summer (June–August) North Atlantic Oscillation, and when there was a decrease in mean length of the spawning population. The production of weak year-classes is predicted when spawning is delayed, suggesting that late spawning is severely inhibiting the recovery of the stock.

Description: In this article, we make use of large-scale municipal border changes in Germany to provide the first evidence on the effect of local border changes on the distribution of activity in space. To allow for a comparison of economic activity within unique geographical units over time, we use geo-coded light data as well as local land-use data. Applying a difference-in-differences approach, we find evidence that municipalities absorbing their merger partners and hosting the new administrative center experience a significant increase in local activity, while the municipalities that are being absorbed and are losing the administrative center experience a decrease in such activity. The difference between the gains in activity from absorbing municipalities and the losses from absorbed ones is positive. These previously undocumented results point to the importance of distance to the administrative center as a determinant of the spatial distribution of economic activity.

Description: The extensive development of unconventional reservoirs using horizontal drilling and multistage hydraulic fracturing has generated large volumes of reservoir characterization and production data. The analysis of this abundant data using statistical methods and advanced machine-learning (ML) techniques can provide data-driven insights into well performance. Most predictive modeling studies have focused on the impact that different well completion and stimulation strategies have on well production but have not fully exploited the available in situ rock property data to determine its role in reservoir productivity. We have used machine-learning techniques to rank rock mechanical properties, microseismic attributes, and stimulation parameters in the order of their significance for predicting natural gas production from an unconventional reservoir. The data for this study came from a hydraulically fractured well in the Marcellus Shale in Monongalia County, West Virginia. The data classes included measurements aggregated by well completion stage that included (1) gas production, (2) well-log-derived measurements including bulk density, elastic moduli, shear impedance, compressional impedance, brittleness, and gamma measurements, (3) microseismic attributes, (4) long-period long-duration (LPLD) event counts, (5) fracture counts, and (6) stimulation parameters that included the fluid injection volume and average pumping pressure. To identify observable proxies for the drivers of gas production, we evaluated five commonly used ML approaches including multivariate adaptive regression spline, Gaussian mixture model, random forest, gradient boosting, and neural network. We selected five variables including LPLD event count, seismogenic b-value, hydraulic diffusivity, cumulative moment, and fluid volume as the features most likely to impact gas productivity at the stage level in the study area. The data-driven selection of these parameters for their importance in determining gas production can help reservoir engineers design more effective hydraulic-fracture treatments in the Marcellus Shale and other similar unconventional reservoirs. Plain language summary: We use machine-learning methods and data-driven selection of reservoir parameters to rank and better understand their importance in determining gas production, which can help reservoir engineers design more effective hydraulic-fracture treatments in the Marcellus Shale and other similar unconventional reservoirs.

Description: In the Wattenberg Field, the Reservoir Characterization Project at the Colorado School of Mines and Occidental Petroleum Corporation (Oxy) (formerly the Anadarko Petroleum Corporation) collected time-lapse seismic data for characterization of changes in the reservoir caused by hydraulic fracturing and production in the Niobrara Formation and Codell Sandstone member of the Carlile Formation. We have acquired three multicomponent seismic surveys to understand the dynamic reservoir changes caused by hydraulic fracturing and production of 11 horizontal wells within a 1 mi2 section (the Wishbone Section). The time-lapse seismic survey acquisition occurred immediately after the wells were drilled, another survey after stimulation, and a third survey after two years of production. In addition, we integrate core, petrophysical properties, fault and fracture characteristics, as well as P-wave seismic data to illustrate reservoir properties prior to simulation and production. Core analysis indicates extensive amounts of bioturbation in zones of high total organic content (TOC). Petrophysical analysis of logs and core samples indicates that chalk intervals have high amounts of TOC (〉2%) and the lowest amount of clay in the reservoir interval. Core petrophysical characterization included X-ray diffraction analysis, mercury intrusion capillary pressure, N2 gas adsorption, and field emission scanning electron microscopy. Reservoir fractures follow four regional orientations, and chalk facies contain higher fracture density than marl facies. Integration of these data assist in enhanced well targeting and reservoir simulation.

Description: Enhanced hydrocarbon recovery is essential for continued economic development of unconventional reservoirs. We have focused on dynamic characterization of the Niobrara and Codell Formations in Wattenberg Field through the development and analysis of a full integrated reservoir model. We determine the effectiveness of the hydraulic fracturing and production with two seismic monitor surveys, surface microseismic, completion data, and production data. The two monitor surveys were recorded after stimulation and again after two years of production. Identification of reservoir deformation due to hydraulic fracturing and production improves reservoir models by mapping nonstimulated and nonproducing zones. Monitoring these time-variant changes improves the prediction capability of reservoir models, which in turn leads to improved well and stage placement. We quantify dynamic reservoir changes with time-lapse P-wave seismic data using prestack inversion and velocity-independent layer stripping for velocity and attenuation changes within the Niobrara and Codell reservoirs. A 3D geomechanical model and production data are history matched, and a simulation is run for two years of production. Results are integrated with time-lapse seismic data to illustrate the effects of hydraulic fracturing and production. Our analyses illustrate that chalk facies have significantly higher hydraulic fracture efficiency and production performance than marl facies. In addition, structural and hydraulic complexity associated with faults generate spatial variability in a well’s total production.

Description: The prediction of natural fracture networks and their geomechanical properties remains a challenge for unconventional reservoir characterization. Because natural fractures are highly heterogeneous and of subseismic scale, integrating petrophysical data (i.e., cores and well logs) with seismic data is important for building a reliable natural fracture model. Therefore, I have developed an integrated and stochastic approach for discrete fracture network modeling with field data experimentation. In the method, I first perform a seismic attribute analysis to highlight the discontinuity in the seismic data. Then, I extrapolate the well-log data that include localized but high-confidence information. By using the fracture intensity model including seismic and well logs, I build the final natural fracture model that can be used as a background model for the subsequent geomechanical analysis such as simulation of hydraulic fractures propagation. As a result, our workflow combining multiscale data in a stochastic approach constructs a reliable natural fracture model. I validate the constructed fracture distribution by its good agreement with the well-log data.

Description: Four controlled-source audio-frequency magnetotelluric (CSAMT) profiles were conducted in early 2011 to investigate the distribution rules of oil shale in the Tongchuan area of the southern Ordos Basin. After terrain correction, we high-pass filtered the resulting images to prepare the 2D CSAMT apparent resistivity profiles for further analysis. Specifically, we have correlated the high-pass-filtered apparent resistivity anomalies to the distribution of oil shale seen in three available wells. The results reveal a close relationship between the oil shale distribution and the anomalously high-apparent-resistivity belt-like anomalies in the Tongchuan area. Our analysis indicates two prospective areas with different depths for oil shale within the study area.

Description: Ecosystem-based Fisheries Management is a holistic management approach that integrates the dynamics of an entire ecosystem, including societal dimensions. However, this approach seldom lives up to its promise because economic and social objectives are rarely specified. To fill this gap, we explored how an ecosystem model could better integrate economic and social objectives, using the coral reef ecosystem around Hawai`i as a case study. After meeting with stakeholders and conducting a literature review of policy/strategy documents, we identified societal and ecological objectives and associated performance indicators for which data existed. We developed a social–ecological system conceptual framework to illustrate the relationships between ecological and social state components. This framework was the foundation for the development of the final social–ecological system model which we simulated using an Ecopath with Ecosim model. We simulated four gear/species restrictions for the reef-based fishery, two fishing scenarios associated with the opening of hypothetical no-take Marine Protected Areas for the deepwater-based fishery, and a Constant Effort (No Action) scenario. Despite limitations in the model, our approach shows that when social and economic objectives and social–ecological relationships are defined, we can quantify the trade-offs among the identified societal objectives to support managers in choosing among alternative interventions.

Description: Two end-to-end ecosystem models, NORWECOM.E2E and NoBa Atlantis, have been used to explore a selection of indicators from the Barents Sea Management plans (BSMP). The indicators included in the BSMP are a combination of simple (e.g. temperature, biomass, and abundance) and complex (e.g. trophic level and biomass of functional groups). The abiotic indicators are found to serve more as a tool to report on climate trends rather than being ecological indicators. It is shown that the selected indicators give a good overview of the ecosystem state, but that overarching management targets and lack of connection between indicators and management actions makes it questionable if the indicator system is suitable for direct use in management as such. The lack of socio-economic and economic indicators prevents a holistic view of the system, and an inclusion of these in future management plans is recommended. The evaluated indicators perform well as an assessment of the ecosystem, but consistency and representativeness are extremely dependent on the time and in what area they are sampled. This conclusion strongly supports the inclusion of an observing system simulation experiment in management plans, to make sure that the observations represent the properties that the indicators need.

Description: Gas-bearing prediction of tight sandstone reservoirs is significant but challenging due to the relationship between the gas-bearing property and its seismic response being nonlinear and complex. Although machine learning (ML) methods provide potential for solving the issue, the major challenge of ML applications to gas-bearing prediction is that of generating accurate and interpretable intelligent models with limited training sets. The k nearest neighbor ( kNN) method is a supervised ML method classifying an unlabeled sample according to its k neighboring labeled samples. We have introduced a kNN-based gas-bearing prediction method. The method can automatically extract a gas-sensitive attribute called the gas-indication local waveform similarity attribute (GLWSA) combining prestack seismic gathers with interpreted gas-bearing curves. GLWSA uses the local waveform similarity among the predicting samples and the gas-bearing training samples to indicate the existence of an exploitable gas reservoir. GLWSA has simple principles and an explicit geophysical meaning. We use a numerical model and field data to test the effectiveness of our method. The result demonstrates that GLWSA is good at characterizing the reservoir morphology and location qualitatively. When the method applies to the field data, we evaluate the performance with a blind well. The prediction result is consistent with the geologic law of the work area and indicates more details compared to the root-mean-square attribute.

Description: The Shaximiao Formation in the Zhongjiang Gas Field of the Sichuan Basin was initially a high-productivity gas field with the bright spot channel as the vital exploration target. With further development, gas wells were obtained in some nonbright spot areas, which caused interpreters to pay great attention to the channels with nonbright spot abnormal amplitudes. We have developed a method to delineate nonbright spot channels from the complicated sand-mudstone contact relationship. First, we classified sandstone into types I, IIa, IIb, and III, depending on the responses of the amplitude variation with offset from the drilled data, to produce a forward model. We the explain why the hidden channel cannot be identified using the full-angle stack seismic data based on this model. Afterward, we put forward a difference, between the synthetic seismogram responses of bright and nonbright channels, in creating seismic-to-well ties for nonbright channels. This difference from bright channels is that the synthetic data’s wave peak is not corresponding to the peak of the real seismic data. The wave trough has the same situation. Finally, we used far-angle stack seismic data to calculate coherent energy and instantaneous spectral attributes (the latter produced for red-green-blue blending) to identify the hidden channel. We observed that parts of the channel are more clearly visible in the far-angle stack than in the full-angle stack data. In the latter situation, we cannot describe the geometric shape of the channel elaborately. The Shaximiao Formation example is a relatively effective analog for nonbright spot plays compared with elsewhere.

Description: Hydraulic fracturing (HF) and horizontal drilling are essential to the development of shale gas and oil. Production depends on the stimulation success. During fracture initiation, propagation, and closure, cracks emit acoustic waves; these can be monitored in real time as microseismics in the field and as acoustic emissions (AEs) in the laboratory. AEs are the laboratory equivalent of field-scale microseismics and contain detailed information about HF fracture mechanics. The number of acoustic events correlates with the number of induced fractures and hence the stimulation volume. Three HF protocols under dry conditions were carried out on Tennessee sandstone: (1) a constant injection rate, (2) a precyclic injection, and (3) a variable-rate injection test. All three tests were performed under the same principal stress conditions: vertical stress of 10.3 MPa (1500 psi), minimum horizontal stress of 3.5 MPa (500 psi), and maximum horizontal stress of 20.7 MPa (3000 psi). In total, 16 piezoelectric transducers were mounted around a cylindrical sample to record the AEs. We have performed postsignal processing to extract AE event attributes, including the amplitudes, signal-to-noise ratio, arrival time, event location (with the velocity-anisotropy input), and frequency analyses. The AE events associated with the constant-rate injection test possessed the lowest frequencies (150–270 kHz). The variable-rate test AE events possessed higher frequencies (160–310 kHz), whereas the precyclic injection had events with the highest frequencies, peaking at 330 kHz. Acoustic events before failure had lower amplitudes, but higher frequency compared to those recorded postbreakdown, suggesting different failure modes. Precyclic injection induced the greatest number of locatable events before and after failure.

Description: Bottom trawlers are engaged in multi-species fisheries and fish for profit. In quota-regulated fisheries, intra- and inter-temporal substitutions of fishing effort is regarded as a key mechanisms that influences the profitability of the fishing portfolio. The feeding and spawning migration patterns of the available fish species in the fishing portfolio alter the bio-economic conditions of the different fishing areas. In addition, the spatial heterogeneity among different fishing areas in terms of the fuel costs and travel distance, accessibility to other fishing fleets, and sea ice extent affects the relative attractiveness of the fishing areas and further complicates the decisions underlying the effort allocation, such as when and where to fish what and how much to fish to maximize the profit. In this regard, the aim of this article is to identify the key drivers of intra- and inter-temporal effort allocation in a multi-species trawl fishery consisting of 61 Norwegian trawl vessels targeting cod, saithe, and haddock, the aim being to maximize the fishing profit within the quota constraints. We adopted a two-step Heckman estimator that incorporates the relative attractiveness of three heavily trawled areas, the southern and northern parts of the west coast of Norway and the high sea areas of the Arctic. The relative attractiveness is specified by the fish availability, measured using the catch per unit of effort, prices of the target species, fuel cost, intensity of the coastal fleet's participation in winter fishery, and seasonal sea ice extent in the Barents Sea during the period 2011–2016. Our results show that region-specific attributes and spatial margins have a profound impact on the intra-temporal and inter-temporal allocation of fishing effort to maximize the seasonal profit. Furthermore, we found evidence of economically rational behaviour of the Norwegian trawlers in constantly reallocating their fishing effort in response to the changes in the relative attractiveness of the selected fishing areas over the course of a fishing year.