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Search Results (3,186)

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17 pages, 28900 KiB  
Article
Research on the Audit Rules for National Mountain Flood Disaster Survey and Evaluation Results of Key Towns and Villages
by Min Xie, Shuwen Qi, Yanhong Dou and Xiaolei Zhang
Water 2025, 17(6), 773; https://doi.org/10.3390/w17060773 - 7 Mar 2025
Viewed by 41
Abstract
In recent years, there have been frequent extreme weather events that defy traditional understanding. Specifically, mountain flood disasters can cause significant loss of life due to their sudden onset and destructive power. The 7.21 flood event in Xingyang, Zhengzhou, China, recorded a maximum [...] Read more.
In recent years, there have been frequent extreme weather events that defy traditional understanding. Specifically, mountain flood disasters can cause significant loss of life due to their sudden onset and destructive power. The 7.21 flood event in Xingyang, Zhengzhou, China, recorded a maximum 6 h precipitation of 240.5 mm in the Suo River basin, corresponding to a 500-year return period, and causing fatalities and substantial damage. The central government of China has launched supplementary mountain flood disaster surveys and evaluations involving key towns and villages, following an initial round of surveys in riverside villages, to improve foresight and response capabilities for mountain flood disaster risks under extreme conditions. This paper introduces the contents of the national mountain flood disaster surveys and evaluations of key towns and villages, elaborating on the principles, content, and rules for auditing the national survey and evaluation results. This paper innovatively proposes professional audit criteria, such as early warning indicators, monitoring facility correlations, and hazard zoning, based on a formal audit of the data quality. The implementation of professional audit criteria improved the data accuracy by 85% and reduced false alarms by 40%, enhancing the overall effectiveness of mountain flood disaster prevention. The analysis of the audit results suggests that the audit rules for the survey and evaluation results of key towns are scientific, reasonable, and effective, achieving the expected goals of data quality control. This approach can effectively enhance the practical value of the survey and evaluation outcomes for key towns, laying a solid data foundation for transforming flood disaster prevention from merely “existing” to “optimal”. Full article
(This article belongs to the Special Issue Recent Advances in Flood Risk Assessment and Management)
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<p>Schematic diagram of main contents of survey and evaluation of key towns and villages.</p>
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<p>Schematic diagram of audit contents of survey and evaluation results for key towns and villages.</p>
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<p>Comparison of early warning indicators and flood control capacity for key towns in mountainous regions, below a 100-year return period.</p>
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<p>Schematic illustration of a case for implementing professional audit rules into hazard zone classification. (<b>a</b>) Hazard zone crossing before and after modifications. (<b>b</b>) Comparison between conditions before and after modification of no-transfer routes and settlements in hazard zones. (<b>c</b>) Comparison of conditions before and after modification of hazard zones and settlements without connection to diversionary routes.</p>
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<p>Effects of implementing the monitoring facility association audit rules. (<b>a</b>) shows the rain measuring station in Sanya City. (<b>b</b>) shows the implementation effect of the new professional audit rules that take into account the monitoring of facility linkages.</p>
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<p>Effects of implementing the monitoring facility association audit rules. (<b>a</b>) shows the rain measuring station in Sanya City. (<b>b</b>) shows the implementation effect of the new professional audit rules that take into account the monitoring of facility linkages.</p>
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25 pages, 11574 KiB  
Article
Research on GRU-LSTM-Based Early Warning Method for Electric Vehicle Lithium-Ion Battery Voltage Fault Classification
by Liang Zhang, Qizhi Wu, Longfei Wang, Ling Lyu, Linru Jiang and Yu Shi
Energies 2025, 18(6), 1315; https://doi.org/10.3390/en18061315 - 7 Mar 2025
Viewed by 100
Abstract
Battery cell voltage is an important evaluation index for electric vehicle condition estimation and one of the main monitoring parameters of the battery management system, and accurate voltage prediction is crucial for electric vehicle battery failure warning. Therefore, this paper proposes a novel [...] Read more.
Battery cell voltage is an important evaluation index for electric vehicle condition estimation and one of the main monitoring parameters of the battery management system, and accurate voltage prediction is crucial for electric vehicle battery failure warning. Therefore, this paper proposes a novel hybrid gated recurrent unit and long short-term memory (GRU-LSTM) neural network to predict electric vehicle lithium-ion battery cell voltage. Firstly, Pearson coefficient correlation analysis is carried out to determine the input parameters of the neural network by analyzing the influence factors of the voltage parameters, and the hyperparameters of the neural network are determined through cross-validation to construct the lithium-ion battery single-unit voltage prediction model based on GRU-LSTM. Secondly, the voltage prediction accuracy and robustness of the GRU-LSTM model are verified by training the historical data of real vehicles in spring, summer, fall, and winter, combined with four different error indicators. Finally, the feasibility of the proposed method is verified by designing hierarchical warning rules based on the prediction data to realize the accurate warning of multiple voltage anomalies. Full article
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<p>Electric vehicle battery voltage fault warning flow chart.</p>
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<p>LSTM network architecture unit.</p>
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<p>GRU network architecture.</p>
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<p>GRU-LSTM hybrid model structure.</p>
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<p>Flowchart of the GRU-LSTM prediction model.</p>
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<p>Electric vehicle battery-related parameter curve.</p>
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<p>Pearson correlation coefficient between influencing factors.</p>
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<p>Training under different hidden layer nodes and iteration times.</p>
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<p>Training of different batch sizes at different learning rates.</p>
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<p>Battery voltage fitting during driving and charging periods.</p>
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<p>Prediction results and absolute errors of three algorithms.</p>
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<p>The R<sup>2</sup> values of the results predicted by the three algorithms.</p>
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<p>Battery voltage prediction effect in different seasons.</p>
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<p>Absolute value of battery voltage prediction error for different seasons.</p>
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<p>Battery voltage prediction error metrics for four seasons.</p>
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<p>The real voltage and predicted voltage curve of vehicle battery are studied.</p>
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<p>Change in voltage difference in a single battery.</p>
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<p>Standard deviation comparison between the true value and the predicted value.</p>
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<p>Dynamic early-warning effect of maximum/minimum cell voltage.</p>
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44 pages, 3834 KiB  
Review
Sustainable Management of Major Fungal Phytopathogens in Sorghum (Sorghum bicolor L.) for Food Security: A Comprehensive Review
by Maqsood Ahmed Khaskheli, Mir Muhammad Nizamani, Entaj Tarafder, Diptosh Das, Shaista Nosheen, Ghulam Muhae-Ud-Din, Raheel Ahmed Khaskheli, Ming-Jian Ren, Yong Wang and San-Wei Yang
J. Fungi 2025, 11(3), 207; https://doi.org/10.3390/jof11030207 - 6 Mar 2025
Viewed by 155
Abstract
Sorghum (Sorghum bicolor L.) is a globally important energy and food crop that is becoming increasingly integral to food security and the environment. However, its production is significantly hampered by various fungal phytopathogens that affect its yield and quality. This review aimed [...] Read more.
Sorghum (Sorghum bicolor L.) is a globally important energy and food crop that is becoming increasingly integral to food security and the environment. However, its production is significantly hampered by various fungal phytopathogens that affect its yield and quality. This review aimed to provide a comprehensive overview of the major fungal phytopathogens affecting sorghum, their impact, current management strategies, and potential future directions. The major diseases covered include anthracnose, grain mold complex, charcoal rot, downy mildew, and rust, with an emphasis on their pathogenesis, symptomatology, and overall economic, social, and environmental impacts. From the initial use of fungicides to the shift to biocontrol, crop rotation, intercropping, and modern tactics of breeding resistant cultivars against mentioned diseases are discussed. In addition, this review explores the future of disease management, with a particular focus on the role of technology, including digital agriculture, predictive modeling, remote sensing, and IoT devices, in early warning, detection, and disease management. It also provide key policy recommendations to support farmers and advance research on disease management, thus emphasizing the need for increased investment in research, strengthening extension services, facilitating access to necessary inputs, and implementing effective regulatory policies. The review concluded that although fungal phytopathogens pose significant challenges, a combined effort of technology, research, innovative disease management, and effective policies can significantly mitigate these issues, enhance the resilience of sorghum production to facilitate global food security issues. Full article
(This article belongs to the Special Issue Crop Fungal Diseases Management)
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<p>Timeline of research and review articles on sorghum that were published from 2000 to April 2024. Mining of this analysis to describe the total number of publications was published within the literature domain. The Web of Science database was searched using related keywords, and we found that 851 reports on crop rotation, 525 on environmental impacts, 63 on fungal disease management, 53 on biological control, 39 on predictive modeling, 33 on disease-resistant varieties, 22 on fungicide development, and 12 on digital agriculture management were published.</p>
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<p>The symptoms of grain mold complex disease of sorghum and the intricate network of fungal hyphae enveloping grain particles. This complex symbiosis illustrates the interplay between fungi and grains in agricultural ecosystems.</p>
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<p>Charcoal rot disease symptoms on sorghum plants showcase characteristic discoloration and fungal growth in the stem tissues.</p>
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<p>Downy mildew symptoms on sorghum leaves, characterized by yellowing and fuzzy grayish patches, caused by the fungal pathogen <span class="html-italic">Peronosclerospora sorghi</span>.</p>
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<p>Rust disease on sorghum leaves. Orange pustules indicative of fungal infection are visible, accompanied by yellowing and necrosis of leaf tissue.</p>
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21 pages, 11630 KiB  
Article
Assessment of the Maize Crop Water Stress Index (CWSI) Using Drone-Acquired Data Across Different Phenological Stages
by Mpho Kapari, Mbulisi Sibanda, James Magidi, Tafadzwanashe Mabhaudhi, Sylvester Mpandeli and Luxon Nhamo
Drones 2025, 9(3), 192; https://doi.org/10.3390/drones9030192 - 6 Mar 2025
Viewed by 77
Abstract
The temperature-based crop water stress index (CWSI) is the most robust metric among precise techniques that assess the severity of crop water stress, particularly in susceptible crops like maize. This study used a unmanned aerial vehicle (UAV) to remotely collect data, to use [...] Read more.
The temperature-based crop water stress index (CWSI) is the most robust metric among precise techniques that assess the severity of crop water stress, particularly in susceptible crops like maize. This study used a unmanned aerial vehicle (UAV) to remotely collect data, to use in combination with the random forest regression algorithm to detect the maize CWSI in smallholder croplands. This study sought to predict a foliar temperature-derived maize CWSI as a proxy for crop water stress using UAV-acquired spectral variables together with random forest regression throughout the vegetative and reproductive growth stages. The CWSI was derived after computing the non-water-stress baseline (NWSB) and non-transpiration baseline (NTB) using the field-measured canopy temperature, air temperature, and humidity data during the vegetative growth stages (V5, V10, and V14) and the reproductive growth stage (R1 stage). The results showed that the CWSI (CWSI < 0.3) could be estimated to an R2 of 0.86, RMSE of 0.12, and MAE of 0.10 for the 5th vegetative stage; an R2 of 0.85, RMSE of 0.03, and MAE of 0.02 for the 10th vegetative stage; an R2 of 0.85, RMSE of 0.05, and MAE of 0.04 for the 14th vegetative stage; and an R2 of 0.82, RMSE of 0.09, and MAE of 0.08 for the 1st reproductive stage. The Red, RedEdge, NIR, and TIR UAV-bands and their associated indices (CCCI, MTCI, GNDVI, NDRE, Red, TIR) were the most influential variables across all the growth stages. The vegetative V10 stage exhibited the most optimal prediction accuracies (RMSE = 0.03, MAE = 0.02), with the Red band being the most influential predictor variable. Unmanned aerial vehicles are essential for collecting data on the small and fragmented croplands predominant in southern Africa. The procedure facilitates determining crop water stress at different phenological stages to develop timeous response interventions, acting as an early warning system for crops. Full article
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<p>Location of the Swayimane study area, study site, and smallholder maize field.</p>
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<p>Flowchart showing the data collection (blue), data preparation RF analysis (orange), and data analysis (green).</p>
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<p>(<b>a</b>) An automated in-field meteorological tower in the maize field, (<b>b</b>) meteorological tower-mounted infrared radiometers (IRRs), and (<b>c</b>) a CR1000 data logger, an Em50 datalogger, and a 12 V battery.</p>
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<p>(<b>a</b>) UAV system, DJI Matrice 300, (<b>b</b>) MicaSense Altum camera, (<b>c</b>) DJI M-300 flight plan, and (<b>d</b>) MicaSense Altum calibration reflectance panel.</p>
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<p>Non-water-stressed baselines used to calculate the CWSI for maize growth stages.</p>
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<p>The variation in the CWSI for maize over different DOYs in 2021.</p>
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<p>Linear relationships between the actual and predicted CWSI for maize crop’s vegetative stages (<b>ai</b>) V5, (<b>bi</b>) V10, and (<b>ci</b>) V14 and (<b>di</b>) reproductive stages (R1), as well as the corresponding variables’ importance (<b>ai</b>–<b>dii</b>).</p>
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<p>The maize CWSI over the smallholder field for vegetative stages (<b>a</b>–<b>c</b>) and reproductive stages (<b>d</b>).</p>
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22 pages, 11281 KiB  
Article
A Multivariate Spatiotemporal Feature Fusion Network for Wind Turbine Gearbox Condition Monitoring
by Shixian Dai, Shuang Han, Xinjian Bai, Zijian Kang and Yongqian Liu
Energies 2025, 18(5), 1273; https://doi.org/10.3390/en18051273 - 5 Mar 2025
Viewed by 110
Abstract
SCADA data, due to their easy accessibility and low cost, have been widely applied in wind turbine gearbox condition monitoring. However, the high-dimensional and nonlinear nature of the collected data, along with the insufficient spatiotemporal feature capabilities of existing methods and the lack [...] Read more.
SCADA data, due to their easy accessibility and low cost, have been widely applied in wind turbine gearbox condition monitoring. However, the high-dimensional and nonlinear nature of the collected data, along with the insufficient spatiotemporal feature capabilities of existing methods and the lack of consideration of the physical mechanisms of wind turbine operation, limit the accuracy of monitoring models. In this paper, a multivariate spatiotemporal feature fusion network is proposed for wind turbine gearbox condition monitoring. First, by analyzing the operational mechanism of wind turbines and the correlation between sensor data, the time series data are transformed into graph data. Then, graph convolutional networks and temporal convolutional networks are used to extract spatial and temporal features, respectively. Next, long short-term memory networks are employed to fuse the extracted temporal and spatial features, further capturing long-term spatiotemporal dependencies. Finally, the proposed method is validated using real data from two wind turbines. Experimental results show that the proposed method reduces the RMSE by 29.67% and 17.61% compared to the best-performing models. Moreover, the proposed method provides early warning signals 188.6 h and 133.67 h in advance, achieving stable and efficient early anomaly detection for wind turbines. Full article
(This article belongs to the Section A3: Wind, Wave and Tidal Energy)
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<p>Flow chart of wind turbine gearbox condition monitoring.</p>
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<p>Framework of MSFFN.</p>
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<p>Subsequence and graph construction.</p>
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<p>Flow chart of the graph convolutional network.</p>
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<p>Dilated causal convolution diagram.</p>
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<p>TCN residual block.</p>
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<p>The architecture of the LSTM network and its unit structure.</p>
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<p>SCADA variable correlation coefficient heatmap.</p>
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<p>Adjacency matrix diagram. (<b>a</b>) Static graph adjacency matrix. (<b>b</b>) Dynamic graph adjacency matrix.</p>
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<p>Gearbox oil temperature prediction results for different models of the Unit 26 WT.</p>
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<p>Localized enlarged view of gearbox oil temperature predictions for different models of the Unit 26 WT.</p>
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<p>Residual plot of gearbox oil temperature for Unit 26.</p>
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<p>Residual plot of gearbox oil temperature for Unit 26.</p>
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<p>Gearbox oil temperature prediction results for different models of the Unit 3 WT.</p>
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<p>Localized enlarged view of gearbox oil temperature predictions for different models of the Unit 3 WT.</p>
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<p>Residual plot of gearbox oil temperature for Unit 3.</p>
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<p>Residual plot of gearbox oil temperature for Unit 3.</p>
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29 pages, 48363 KiB  
Article
Comparison of Artificial Intelligence Algorithms and Remote Sensing for Modeling Pine Bark Beetle Susceptibility in Honduras
by Omar Orellana, Marco Sandoval, Erick Zagal, Marcela Hidalgo, Jonathan Suazo-Hernández, Leandro Paulino and Efrain Duarte
Remote Sens. 2025, 17(5), 912; https://doi.org/10.3390/rs17050912 - 5 Mar 2025
Viewed by 169
Abstract
The pine bark beetle is a devastating forest pest, causing significant forest losses worldwide, including 25% of pine forests in Honduras. This study focuses on Dendroctonus frontalis and Ips spp., which have affected four of the seven native pine species in Honduras: Pinus [...] Read more.
The pine bark beetle is a devastating forest pest, causing significant forest losses worldwide, including 25% of pine forests in Honduras. This study focuses on Dendroctonus frontalis and Ips spp., which have affected four of the seven native pine species in Honduras: Pinus oocarpa, P. caribaea, P. maximinoi, and P. tecunumanii. Artificial intelligence (AI) is an essential tool for developing susceptibility models. However, gaps remain in the evaluation and comparison of these algorithms when modeling susceptibility to bark beetle outbreaks in tropical conifer forests using Google Earth Engine (GEE). The objective of this study was to compare the effectiveness of three algorithms—random forest (RF), gradient boosting (GB), and maximum entropy (ME)—in constructing susceptibility models for pine bark beetles. Data from 5601 pest occurrence sites (2019–2023), 4000 absence samples, and a set of environmental covariates were used, with 70% for training and 30% for validation. Accuracies above 92% were obtained for RF and GB, and 85% for ME, along with robustness in the area under the curve (AUC) of up to 0.98. The models revealed seasonal variations in pest susceptibility. Overall, RF and GB outperformed ME, highlighting their effectiveness for implementation as adaptive approaches in a more effective forest monitoring system. Full article
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Graphical abstract
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<p>Methodological framework for modeling pine bark beetle susceptibility. The diagram illustrates the methodological workflow where processing scripts and remote sensing data in GEE are utilized to derive environmental covariates. These are combined with training samples obtained from historical pest records and random absence sites. The resulting combination is subjected to Pearson correlation analysis and kernel density estimation (KDE), along with a hyperparameter selection process in R (4.2.2 version) and Python (version 3.11.11 in colab). Subsequently, modeling scripts in GEE generate both annual and monthly susceptibility maps, enabling the analysis of covariate importance and model validation. Finally, the results are integrated into a statistical report and documentation.</p>
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<p>General location map of coniferous forests in Honduras. Layer derived from the 2018 Forest and Land Cover Map of Honduras [<a href="#B65-remotesensing-17-00912" class="html-bibr">65</a>]. (<b>a</b>) Country, (<b>b</b>) regional, and (<b>c</b>) global scales.</p>
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<p>Pearson correlation between the covariates and the occurrence of bark beetles. Blue colors indicate an inverse correlation, while red colors indicate a direct correlation. Color intensity reflects the level of correlation (from −1 to 1).</p>
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<p>Density patterns of the environmental covariates were based on the training data of the models. Occ = occurrence; 0 = pest absence; 1 = pest presence.</p>
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<p>Annual susceptibility modeling maps for pine bark beetle infestation and historically plagued area: (<b>a</b>) RF model, (<b>b</b>) GB model, (<b>c</b>) ME model, (<b>d</b>) plagued area between 2014 and 2016.</p>
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<p>Monthly susceptibility modeling maps for pine bark beetle infestation by algorithm type. The scale ranges from 0 (green), representing low susceptibility values, to 1 (red), representing high susceptibility values.</p>
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<p>Importance of environmental covariates (%) for each evaluated algorithm.</p>
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<p>AUC for the annual susceptibility models of (<b>a</b>) RF, (<b>b</b>) GB, and (<b>c</b>) ME.</p>
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<p>Monthly trend of model accuracy by algorithm type.</p>
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<p>Training samples for estimation models: sites with bark beetle pest outbreaks (2019–2023) and randomly generated non-infested sites in pine forests of Honduras.</p>
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<p>Map of the average annual precipitation distribution in the pine ecosystem in Honduras.</p>
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<p>Monthly behavior of precipitation and evapotranspiration in the pine ecosystem.</p>
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<p>Map of the average annual temperature distribution in the pine ecosystem in Honduras.</p>
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<p>Monthly temperature behavior in the pine ecosystem: average (blue line) and maximum (red line).</p>
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<p>Monthly distribution of bark beetle outbreaks and damaged area (ha) from 2019 to 2023 in Honduras.</p>
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19 pages, 6902 KiB  
Article
Predictive Modeling of Cyanobacterial Blooms and Diurnal Variation Analysis Based on GOCI
by Chichang Luo, Xiang Wang, Yuan Chen, Hongde Luo, Heng Dong and Sicong He
Water 2025, 17(5), 749; https://doi.org/10.3390/w17050749 - 4 Mar 2025
Viewed by 206
Abstract
Algal bloom is a major ecological and environmental problem caused by abnormal algal reproduction in water, and it poses a serious threat to the aquatic ecosystem, drinking water safety, and public health. Because of the high dynamic and spatiotemporal heterogeneity of bloom outbreaks, [...] Read more.
Algal bloom is a major ecological and environmental problem caused by abnormal algal reproduction in water, and it poses a serious threat to the aquatic ecosystem, drinking water safety, and public health. Because of the high dynamic and spatiotemporal heterogeneity of bloom outbreaks, the process often presents significant changes in a short time. Therefore, it has important scientific research value and practical application significance to construct an accurate and effective bloom warning model. This study constructs an integrated model combining sequence features, attention mechanisms, and random forest using machine learning algorithms for bloom prediction, based on watercolor geostationary satellite observations and meteorological data from GOCI in South Korea. In the process, high spatial resolution Sentinel-2 satellite data is also utilized for sample extraction. With a 10-m resolution, Sentinel-2 provides more precise spatial information compared to the 500-m resolution of GOCI, which significantly enhances the accuracy of the model, especially in monitoring local water body changes. The experimental results demonstrate that the model exhibits excellent accuracy and stability in the spatiotemporal prediction of water blooms. The average AUC value is 0.88, the F1 score is 0.72, and the accuracy is 0.79 when identifying the dynamic change of water bloom on the hourly scale. At the same time, this study summarized four typical diurnal change modes of effluent bloom, including dispersal mode, persistent outbreak mode, dispersal-regression mode, and subsidence mode, revealing the main characteristics of diurnal dynamic change of bloom. The research results provided strong technical support for water environment monitoring and water quality safety management and showed a good application prospect. Full article
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<p>Geographical location of Taihu Lake.</p>
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<p>Technical Roadmap.</p>
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<p>Fivefold cross-validation results for different models.</p>
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<p>Average ROC curves for different models.</p>
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<p>Performance Comparison of Different Models. (<b>a1</b>–<b>a4</b>) represent the prediction results of the RF, LSTM, LSTM-RF, and SAERF models on 21 May 2019. (<b>b1</b>–<b>b4</b>) represent the predictions of these four models on 15 August 2020. (<b>c1</b>–<b>c4</b>) represent the predictions of the four models on 4 September 2020. (<b>d1</b>–<b>d4</b>) represent the predictions of the four models on 17 March 2019. (<b>A</b>) corresponds to the GOCI image from 21 May 2019, (<b>B</b>) corresponds to the GOCI image from 15 August 2020, (<b>C</b>) corresponds to the GOCI image from 4 September 2020, and (<b>D</b>) corresponds to the GOCI image from 17 March 2019.</p>
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<p>Diurnal dynamic change model of lake bloom. (<b>a1</b>–<b>a6</b>) represent the model′s prediction results from 10:00 to 15:00 (UTC+8). (<b>A1</b>–<b>A6</b>) represent the COCI image changes under the Dispersal state. (<b>b1</b>–<b>b6</b>) represent the model′s prediction results from 10:00 to 15:00 (UTC+8). (<b>B1</b>–<b>B6</b>) represent the COCI image changes under the Persistent Outbreak state.(<b>c1</b>–<b>c6</b>) represent the model′s prediction results from 10:00 to 15:00 (UTC+8). (<b>C1</b>–<b>C6</b>) represent the COCI image changes under the Dispersal-Regression state. (<b>d1</b>–<b>d6</b>) represent the model′s prediction results from 10:00 to 15:00 (UTC+8). (<b>D1</b>–<b>D6</b>) represent the COCI image changes under the Subsidence state.</p>
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<p>Characteristic importance score of each variable.</p>
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<p>Comparison of bloom evolution on hourly and daily scales. (<b>A1</b>–<b>A3</b>) represent the changes in the GOCI images on 10 November 2020, during the morning, noon, and afternoon. (<b>B1</b>,<b>B2</b>) represent the changes in the COCI images on 10 November 2020, and 11 November 2020.</p>
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<p>Mean temperature curve and bloom image.</p>
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15 pages, 1824 KiB  
Article
SPN-Based Dynamic Risk Modeling of Fire Incidents in a Smart City
by Menghan Hui, Feng Ni, Wencheng Liu, Jiang Liu, Niannian Chen and Xingjun Zhou
Appl. Sci. 2025, 15(5), 2701; https://doi.org/10.3390/app15052701 - 3 Mar 2025
Viewed by 158
Abstract
Smart cities are confronted with a variety of disaster threats. Among them, natural fires pose a serious threat to human lives, the environment, and asset security. In view of the fact that existing research mostly focuses on the analysis of accident precursors, this [...] Read more.
Smart cities are confronted with a variety of disaster threats. Among them, natural fires pose a serious threat to human lives, the environment, and asset security. In view of the fact that existing research mostly focuses on the analysis of accident precursors, this paper proposes a dynamic risk-modeling method based on Stochastic Petri Nets (SPN) and Bayesian theory to deeply explore the evolution mechanism of urban natural fires. The SPN model is constructed through natural language processing techniques, which discretize the accident evolution process. Then, the Bayesian theory is introduced to dynamically update the model parameters, enabling the accurate assessment of key event nodes. The research results show that this method can effectively identify high-risk nodes in the evolution of fires. Their dynamic probabilities increase significantly over time, and key transition nodes have a remarkable impact on the emergency response efficiency. This method can increase the fire prevention and control efficiency by approximately 30% and reduce potential losses by more than 20%. The dynamic update mechanism significantly improves the accuracy of risk prediction by integrating real-time observation data and provides quantitative support for emergency decision making. It is recommended that urban management departments focus on strengthening the maintenance of facilities in high-risk areas (such as fire alarm systems and emergency passages), optimize cross-departmental cooperation processes, and build an intelligent monitoring and early-warning system to shorten the emergency response time. This study provides a new theoretical tool for urban fire risk management. In the future, it can be extended to other types of disasters to enhance the universality of the model. Full article
(This article belongs to the Section Computing and Artificial Intelligence)
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<p>Dynamic risk modelling.</p>
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<p>(<b>a</b>) BPMN model for urban fires, (<b>b</b>) SPN model for urban fires.</p>
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<p>Markov chain for urban fire emergency response processes.</p>
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<p>Probability of occurrence of core repository dynamics.</p>
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16 pages, 58877 KiB  
Article
A Two-Level Early Warning System on Urban Floods Caused by Rainstorm
by Qian Gu, Fuxin Chai, Wenbin Zang, Hongping Zhang, Xiaoli Hao and Huimin Xu
Sustainability 2025, 17(5), 2147; https://doi.org/10.3390/su17052147 - 1 Mar 2025
Viewed by 461
Abstract
In recent years, the combined effects of rapid urbanization and climate change have led to frequent floods in urban areas. Rainstorm flood risk warning systems play a crucial role in urban flood prevention and mitigation. However, there has been limited research in China [...] Read more.
In recent years, the combined effects of rapid urbanization and climate change have led to frequent floods in urban areas. Rainstorm flood risk warning systems play a crucial role in urban flood prevention and mitigation. However, there has been limited research in China on nationwide urban flood risk warning systems based on rainfall predictions. This study constructs a two-level early warning system (EWS) at the national and urban levels using a two-dimensional hydrological–hydrodynamic model considering infiltration and urban drainage standards. A methodology for urban rainstorm flood risk warnings is proposed, leveraging short-term and high-resolution rainfall forecast data to provide flood risk warnings for 231 cities in central and eastern China. Taking Beijing as an example, a refined rainstorm flood warning technique targeting city, district, and street scales is developed. We validated the methodology with monitoring data from the “7.31” rainstorm event in 2023 in Beijing, demonstrating its applicability. It is expected that the findings of this study will serve as a valuable reference for the urban rainstorm flood risk warning system in China. Full article
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<p>Study area and city locations. Map lines delineate study areas and do not necessarily depict accepted national boundaries.</p>
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<p>Flow chart of EWS.</p>
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<p>Elevation data and land use data. Map lines delineate study areas and do not necessarily depict accepted national boundaries.</p>
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<p>Schematic diagram of built-up areas in selected cities.</p>
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<p>Model Area, Surface Elevation, and Land Use Data.</p>
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<p>Rainfall for 28 July 2023. Map lines delineate study areas and do not necessarily depict accepted national boundaries.</p>
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<p>National urban flood risk warning map for 28 July 2023. Map lines delineate study areas and do not necessarily depict accepted national boundaries.</p>
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<p>Field images of urban flooding in partially successful forecasted cities on 28 July 2023.</p>
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<p>Schemes follow the same formatting. Warning results from 29 July to 1 August 2023. Map lines delineate study areas and do not necessarily depict accepted national boundaries.</p>
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<p>Schemes follow the same formatting. Warning results from 29 July to 1 August 2023. Map lines delineate study areas and do not necessarily depict accepted national boundaries.</p>
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<p>Simulated maximum inundation depth map of the modeling area.</p>
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<p>Difference distribution map between actual and simulated water depths at inundation points.</p>
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<p>Maximum inundation depth map for each district.</p>
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<p>Flood risk warning map for streets in Dongcheng District.</p>
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23 pages, 4130 KiB  
Article
Machine Learning-Based Early Warning of Algal Blooms: A Case Study of Key Environmental Factors in the Anzhaoxin River Basin
by Yuyin Ao, Juntao Fan, Fen Guo, Mingyue Li, Aopu Li, Yue Shi and Jian Wei
Water 2025, 17(5), 725; https://doi.org/10.3390/w17050725 - 1 Mar 2025
Viewed by 286
Abstract
Algal blooms are a major risk to aquatic ecosystem health and potable water safety. Traditional statistical models often fail to accurately predict algal bloom dynamics due to their complexity. Machine learning, adept at managing high-dimensional and non-linear data, provides a superior predictive approach [...] Read more.
Algal blooms are a major risk to aquatic ecosystem health and potable water safety. Traditional statistical models often fail to accurately predict algal bloom dynamics due to their complexity. Machine learning, adept at managing high-dimensional and non-linear data, provides a superior predictive approach to this challenge. In this study, we employed support vector machine (SVM), random forest (RF), and backpropagation neural network (BPNN) models to predict the severity of algal blooms in the Anzhaoxin River Basin based on an algal density-based grading standard. The SVM model demonstrated the highest accuracy with training and test set accuracies of 0.96 and 0.92, highlighting its superiority in small-sample learning. The Shapley Additive Explanations (SHAP) technique was utilized to evaluate the contribution of environmental variables in various predictive models. The results show that TP is the most significant environmental factor affecting the algal bloom outbreak in Anzhaoxin River, and the phosphorus management strategy is more suitable for the management of the artificial water body in northeast China. This study contributes to exploring the potential application of machine learning models in diagnosing and predicting riverine ecological issues, providing valuable insights and support for the protection and management of aquatic ecosystems in the Anzhaoxin River Basin. Full article
(This article belongs to the Special Issue Microalgae Control and Utilization: Challenges and Perspectives)
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<p>Map of the study area incorporating the main channel of the Anzhaoxin River and several larger lakes at the time of sample collection in 2022–2023. The 23 sampling sites and different types of land use in the basin are indicated, and the location of the study area relative to the national boundary of China is shown in the inset.</p>
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<p>Spatial–temporal distribution of phytoplankton abundance in the Anzhaoxin River Basin, where “up”, “mid”, and “down” represent the upper, middle, and lower reaches of the river.</p>
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<p>Changes in phytoplankton community diversity indices in the Anzhaoxin River Basin. (<b>a</b>) Shannon-Wiener diversity index (H′); (<b>b</b>) Pielou evenness index (J). “up”, “mid”, and “down” represent the upper, middle, and lower reaches of the river.</p>
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<p>Dominant species and dominance of phytoplankton in different seasons in the Anzhaoxin River Basin. Bac: <span class="html-italic">Bacillariophyta</span>. Eug: <span class="html-italic">Euglenophyta</span>. Cya: <span class="html-italic">Cyanophyta</span>. Chl: <span class="html-italic">Chlorophyta</span>. sp1–sp19 represent different species of algae. sp1: <span class="html-italic">Cyclotella catenate</span>; sp2: <span class="html-italic">Nitzschia sp</span>.; sp3: <span class="html-italic">Fragilaria capucina</span>; sp4: <span class="html-italic">Synedra acus</span>; sp5: <span class="html-italic">Cyclotella meneghiniana</span>; sp6: <span class="html-italic">Euglena gracilis</span>; sp7: <span class="html-italic">Aphanocapsa delicatissima</span>; sp8: <span class="html-italic">Microcystis flos-aquae</span>; sp9: <span class="html-italic">Anabaena spiroides</span>; sp10: <span class="html-italic">Scenedesmus sp</span>.; sp11: <span class="html-italic">Chlamydomonas debaryana</span>; sp12: <span class="html-italic">Chlorella vulgaris</span>; sp13: <span class="html-italic">Coelastrum sp.</span>; sp14: <span class="html-italic">Oocystis sp</span>.; sp15: <span class="html-italic">Oocystis borgei</span>; sp16: <span class="html-italic">Pediastrum boryanum</span>; sp17: <span class="html-italic">Monoraphidium arcuatum</span>; sp18: <span class="html-italic">Scenedesmus dimorphus</span>; sp19: <span class="html-italic">Scenedesmus quadricauda</span>.</p>
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<p>The ROC curves of the training and testing datasets for each model, as well as the confusion matrices for predicting phytoplankton abundance in the testing dataset. (<b>a1</b>) ROC curve of SVM; (<b>a2</b>) confusion matrix of SVM; (<b>b1</b>) ROC curve of RF; (<b>b2</b>) confusion matrix of RF; (<b>c1</b>) ROC curve of BPNN; (<b>c2</b>) confusion matrix of BPNN.</p>
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<p>The accuracy change curves of SVM and RF independently trained 20 times. (<b>a</b>) SVM; (<b>b</b>) RF.</p>
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<p>The accuracy and loss function variation curves during the training process of BPNN. (<b>a</b>) Variation in accuracy with training epochs. (<b>b</b>) Variation in loss function with training epochs.</p>
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<p>Accuracy comparisons of SVM, RF, and BPNN using test sets contaminated with Gaussian noise.</p>
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<p>The importance of various features in different models. (<b>a</b>) SVM; (<b>b</b>) RF; (<b>c</b>) BPNN. The SHAP value indicates the significance of a feature, with positive or negative values representing the direction of the feature’s impact on the algal blooms.</p>
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26 pages, 10461 KiB  
Article
Modeling ANN-Based Estimations of Probabilistic-Based Failure Soil Depths for Rainfall-Induced Shallow Landslides Due to Uncertainties in Rainfall Factors
by Shiang-Jen Wu, Syue-Rou Chen and Cheng-Der Wang
Geosciences 2025, 15(3), 88; https://doi.org/10.3390/geosciences15030088 - 1 Mar 2025
Viewed by 83
Abstract
In this study, an ANN-derived innovative model was developed for estimating the failure soil depths of rainfall-induced shallow landslide events, named the SM_EFD_LS model. The proposed SM_EFD_LS model was created using the modified ANN model via the genetic algorithm calibration approach (GA-SA) with [...] Read more.
In this study, an ANN-derived innovative model was developed for estimating the failure soil depths of rainfall-induced shallow landslide events, named the SM_EFD_LS model. The proposed SM_EFD_LS model was created using the modified ANN model via the genetic algorithm calibration approach (GA-SA) with multiple transfer functions (MTFs) (ANN_GA-SA_MTF) with a significant number of failure soil depths and corresponding rainfall factors. Ten shallow landslide-susceptible spots in the Jhuokou watershed in southern Taiwan were selected as the study area. The associated 1000 simulations of rainfall-induced shallow landslide events were used in the model’s development and validation. The model validation results indicate that the validated failure soil depths are mainly located within the resulting 60% confidence intervals from the proposed SM_EFD_LS model. Moreover, the estimated failure depths resemble the validated ones, with acceptable averages of the absolute error (RMSE) and relative error (MRE) (11 cm and 0.06) and a high model reliability index of 1.2. In the future, the resulting probabilistic-based failure soil depths obtained using the proposed SM_EFD_LS model could be introduced with the desired reliability needed for early landslide warning and prevention systems. Full article
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<p>The schematic framework for developing the proposed SM_EFD_LS model.</p>
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<p>Locations of the study area and grids based on Taiwan Datum 1997 (TWD97) [<a href="#B4-geosciences-15-00088" class="html-bibr">4</a>].</p>
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<p>The 1000 simulations of the failure soil characteristics of 10 study grids within the study area [<a href="#B4-geosciences-15-00088" class="html-bibr">4</a>].</p>
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<p>The 1000 simulations of the failure soil characteristics of 10 study grids within the study area [<a href="#B4-geosciences-15-00088" class="html-bibr">4</a>].</p>
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<p>Correlation coefficients between failure depths and rainfall-related factors for the study grids.</p>
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<p>Average correlation coefficients between failure depths and rainfall-related factors.</p>
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<p>Validated failure soil depths and corresponding rainfall factors for the study grids.</p>
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<p>Failure depth quantiles estimated using the proposed SM_EFD_LS model for various validation events.</p>
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<p>Comparison of the validated failure soil depths with the resulting 60% confidence intervals obtained using the proposed SM_EFD_LS model.</p>
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<p>Comparison between the validated failure depths (FDEP_VAL) and estimated depths (FDEP_EST) using the proposed SM_EFD_LS model for various validation events.</p>
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<p>Performance indices of the estimated failure depths using the proposed SM_EFD_LS model for various validation events.</p>
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<p>Performance indices of the estimated failure depths using the proposed SM_EFD_LS model for various validation events.</p>
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<p>Quantification of probabilistic-based failure depths (FDEP_EST) at the study sites of interest using the proposed SM_EFD_LS model.</p>
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15 pages, 1225 KiB  
Article
Assessing Breast Cancer Awareness Among Women in Al Baha, Saudi Arabia: A Cross-Sectional Study Using the Breast Cancer Awareness Measure (BCAM)
by Mohammad A. Albanghali, Rawan K. Alnemari, Rhaff B. Al Ghamdi, Fatma Alzahraa M. Gomaa, Taif A. Alzahrani, Alya S. Al Ghamdi, Batol M. Albanghali, Yasser M. Kofiah, Eltayeb M. Alhassan and Basim A. Othman
Med. Sci. 2025, 13(1), 24; https://doi.org/10.3390/medsci13010024 - 1 Mar 2025
Viewed by 216
Abstract
Introduction: Breast cancer (BC) awareness and preventive practices are critical for the early detection and effective management of the disease. This study aimed to assess the level of BC awareness among women residing in Al Baha, Saudi Arabia. Methods: A cross-sectional study was [...] Read more.
Introduction: Breast cancer (BC) awareness and preventive practices are critical for the early detection and effective management of the disease. This study aimed to assess the level of BC awareness among women residing in Al Baha, Saudi Arabia. Methods: A cross-sectional study was conducted using the Breast Cancer Awareness Measure (BCAM) survey tool to evaluate BC awareness among female residents of Al Baha between June and July 2023. The sample was obtained through the snowball sampling technique. Results: A total of 1007 women participated in the study, with a mean age of 29 ± 10.9 years. Overall awareness of BC warning signs and risk factors was low, with 45% of participants demonstrating poor awareness. Significant positive associations were found between BC awareness and factors such as level of education (p = 0.020), employment status (p = 0.023), field of study for students (p < 0.0001), and average monthly family income (p = 0.001). Furthermore, 75% of participants rarely or never practiced breast self-examination, and only 37% of those invited to the Ministry of Health’s screening program had attended. Conclusions: The results highlight a significant lack of awareness and knowledge about BC among women in Al Baha. These findings underscore the urgent need for targeted educational initiatives and awareness campaigns to address this knowledge gap and promote preventive practices. Full article
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<p>Pooled awareness scores based on various sociodemographic characteristics of participants. <sup>o</sup>: indicates extreme values. <span class="html-italic">p</span>-value estimated using the Kruskal–Wallis test.</p>
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<p>Pooled awareness scores based on various sociodemographic characteristics of participants. <sup>o</sup>: indicates extreme values. <span class="html-italic">p</span>-value estimated using the Kruskal–Wallis test.</p>
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14 pages, 759 KiB  
Article
Estimating Dengue Outbreak Thresholds in West Africa: A Comprehensive Analysis of Climatic Influences in Burkina Faso, 2018–2024
by John Otokoye Otshudiema, Watton R. Diao, Sonia Marie Wend-Kuuni Ouedraogo, Alain Ngoy Kapete, Laurent Moyenga, Emmanuel Chanda, Tieble Traore, Otim Patrick Ramadan and Alimuddin Zumla
Trop. Med. Infect. Dis. 2025, 10(3), 66; https://doi.org/10.3390/tropicalmed10030066 - 28 Feb 2025
Viewed by 327
Abstract
Background: Dengue, transmitted by Aedes spp. mosquitoes, poses significant public health challenges in Burkina Faso. This study investigated outbreak thresholds, utilizing historical data since 2018 to explore the climatic impacts on dengue transmission and address knowledge gaps. Methodology: This retrospective ecological study utilized [...] Read more.
Background: Dengue, transmitted by Aedes spp. mosquitoes, poses significant public health challenges in Burkina Faso. This study investigated outbreak thresholds, utilizing historical data since 2018 to explore the climatic impacts on dengue transmission and address knowledge gaps. Methodology: This retrospective ecological study utilized historical and contemporary data from Burkina Faso’s Public Health Ministry (2018–2024) to model dengue outbreak thresholds. A combination of epidemic channel analysis, joinpoint regression, climate–disease relationship analysis, and negative binomial regression was employed to provide comprehensive insights into the factors driving dengue outbreaks. Principal Findings: The incidence of probable dengue cases remained stable, mostly below 5 cases per 100,000 people, except for a sharp surge in week 40 of 2023, peaking at 38 cases per 100,000. This surge was brief, normalizing by week 47, but coincided with a marked increase in mortality, reaching 90 deaths in week 45. Joinpoint regression identified key thresholds, an alert at 2.1 cases per 100,000 by week 41 and an intervention threshold at 19.1 cases by week 44, providing a framework for timely public health responses. Climatic factors significantly influenced dengue transmission, with higher temperatures (RR = 2.764) linked to increased incidence, while higher precipitation (RR = 0.551) was associated with lower case numbers, likely due to disrupted mosquito breeding conditions. Additionally, intermediate precipitation levels showed a complex relationship with higher incidence rates. Conclusions: This study established evidence-based epidemiological thresholds for dengue outbreak detection in Burkina Faso (2018–2024), demonstrating temperature as a primary transmission driver while precipitation showed inverse relationships. Analysis of the 2023 outbreak identified a critical five-week intervention window (weeks 40–45), providing a framework for climate-sensitive early warning systems. These findings advance the understanding of dengue dynamics in West Africa, though future research should integrate geographical and socioeconomic variables to enhance predictive modeling and outbreak preparedness. Full article
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<p>Probable dengue cases per 100,000 people in Burkina Faso from 2020 to 2024 by week.</p>
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<p>Relationship between average annual mean surface temperature and cases of dengue, Burkina Faso (2018 to 2022).</p>
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<p>Relationship between average precipitation and cases of dengue, Burkina Faso (2018 to 2022).</p>
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39 pages, 12565 KiB  
Article
Integrating Land Use/Land Cover and Climate Change Projections to Assess Future Hydrological Responses: A CMIP6-Based Multi-Scenario Approach in the Omo–Gibe River Basin, Ethiopia
by Paulos Lukas, Assefa M. Melesse and Tadesse Tujuba Kenea
Climate 2025, 13(3), 51; https://doi.org/10.3390/cli13030051 - 28 Feb 2025
Viewed by 313
Abstract
It is imperative to assess and comprehend the hydrological processes of the river basin in light of the potential effects of land use/land cover and climate changes. The study’s main objective was to evaluate hydrologic response of water balance components to the projected [...] Read more.
It is imperative to assess and comprehend the hydrological processes of the river basin in light of the potential effects of land use/land cover and climate changes. The study’s main objective was to evaluate hydrologic response of water balance components to the projected land use/land cover (LULC) and climate changes in the Omo–Gibe River Basin, Ethiopia. The study employed historical precipitation, maximum and minimum temperature data from meteorological stations, projected LULC change from module for land use simulation and evaluation (MOLUSCE) output, and climate change scenarios from coupled model intercomparison project phase 6 (CMIP6) global climate models (GCMs). Landsat thematic mapper (TM) (2007) enhanced thematic mapper plus (ETM+) (2016), and operational land imager (OLI) (2023) image data were utilized for LULC change analysis and used as input in MOLUSCE simulation to predict future LULC changes for 2047, 2073, and 2100. The predictive capacity of the model was evaluated using performance evaluation metrics such as Nash–Sutcliffe Efficiency (NSE), the coefficient of determination (R2), and percent bias (PBIAS). The bias correction and downscaling of CMIP6 GCMs was performed via CMhyd. According to the present study’s findings, rainfall will drop by up to 24% in the 2020s, 2050s, and 2080s while evapotranspiration will increase by 21%. The findings of this study indicate that in the 2020s, 2050s, and 2080s time periods, the average annual Tmax will increase by 5.1, 7.3, and 8.7%, respectively under the SSP126 scenario, by 5.2, 10.5, and 14.9%, respectively under the SSP245 scenario, by 4.7, 11.3, and 20.7%, respectively, under the SSP585 scenario while Tmin will increase by 8.7, 13.1, and 14.6%, respectively, under the SSP126 scenario, by 1.5, 18.2, and 27%, respectively, under the SSP245 scenario, and by 4.7, 30.7, and 48.2%, respectively, under the SSP585 scenario. Future changes in the annual average Tmax, Tmin, and precipitation could have a significant effect on surface and subsurface hydrology, reservoir sedimentation, hydroelectric power generation, and agricultural production in the OGRB. Considering the significant and long-term effects of climate and LULC changes on surface runoff, evapotranspiration, and groundwater recharge in the Omo–Gibe River Basin, the following recommendations are essential for efficient water resource management and ecological preservation. National, regional, and local governments, as well as non-governmental organizations, should develop and implement a robust water resources management plan, promote afforestation and reforestation programs, install high-quality hydrological and meteorological data collection mechanisms, and strengthen monitoring and early warning systems in the Omo–Gibe River Basin. Full article
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<p>The study area map comprises meteorological stations, streamflow gauging stations, and stream networks.</p>
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<p>The general flowchart of the study comprises data input, preprocessing and processing, and outputs.</p>
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<p>Historical and projected LULC patterns of 2007, 2016, 2023, 2047, 2073, and 2100 in the Omo–Gibe River Basin.</p>
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<p>CMIP6 GCM selection procedure.</p>
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<p>Mean annual maximum temperature for the baseline (1985–2014), SSP126, SSP245, and SSP585 scenarios (2023–2100) considering the 95% confidence level in the OGRB.</p>
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<p>Mean annual minimum temperature for the baseline (1985–2014), SSP126, SSP245, and SSP585 scenarios (2023–2100) considering the 95% level of confidence in the OGRB.</p>
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<p>Mean annual minimum temperature for the baseline (1985–2014), SSP126, SSP245, and SSP585 scenarios (2023–2100) considering the 95% level of confidence in the OGRB.</p>
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<p>Anomalies of mean annual Tmax and Tmin for five CMIP6 models (<b>a</b>,<b>b</b>), and model ensemble mean for Tmax (<b>c</b>) and for Tmin (<b>d</b>) for the base historical period (1985–2014).</p>
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<p>Mean annual precipitation for the observed (1985–2022), SSP126, SSP245, and SSP585 scenarios (2023–2100) from five CMIP6 ensemble GCMs considering the 95% confidence level.</p>
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<p>Mean annual precipitation for the observed (1985–2022), SSP126, SSP245, and SSP585 scenarios (2023–2100) from five CMIP6 ensemble GCMs considering the 95% confidence level.</p>
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<p>Mean annual precipitation for the observed (1985–2022), SSP126, SSP245, and SSP585 scenarios (2023–2100) from five CMIP6 ensemble GCMs considering the 95% confidence level.</p>
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<p>Mean annual precipitation anomalies of five CMIP6 models (<b>a</b>) and model ensemble mean (<b>b</b>) for the base historical period (1985–2014).</p>
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<p>Mean annual precipitation anomalies of five CMIP6 models (<b>a</b>) and model ensemble mean (<b>b</b>) for the base historical period (1985–2014).</p>
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<p>Streamflow changes (<b>a</b>–<b>h</b>) in the observed and simulated data for the calibration (1995–2012) and validation periods (2013–2019).</p>
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<p>Streamflow changes (<b>a</b>–<b>h</b>) in the observed and simulated data for the calibration (1995–2012) and validation periods (2013–2019).</p>
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<p>Streamflow changes (<b>a</b>–<b>h</b>) in the observed and simulated data for the calibration (1995–2012) and validation periods (2013–2019).</p>
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<p>Effects of LULC changes on surface runoff during the 2020s (<b>left</b>), 2050s (<b>middle</b>), and 2080s (<b>right</b>) in the OGRB.</p>
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<p>Effects of LULC changes on evapotranspiration during the 2020s (<b>left</b>), 2050s, and 2080s in the OGRB.</p>
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<p>Effects of LULC changes on groundwater recharge during the 2020s, 2050s, and 2080s in the OGRB.</p>
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<p>Effects of climate change on surface runoff (mm) in the 2020s, 2050s, and 2080s from five CMIP6 GCMs under SSP126, SSP245, and SSP585 in the OGRB.</p>
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<p>Effects of climate change on evapotranspiration (mm) in the 2020s, 2050s, and 2080s from five CMIP6 GCMs under SSP126, SSP245, and SSP585 in the OGRB.</p>
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<p>Effects of climate change on groundwater recharge (mm) in the 2020s, 2050s, and 2080s from five CMIP6 GCMs under SSP126, SSP245, and SSP585 in the OGRB.</p>
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<p>Effects of LULC and climate changes on surface runoff (mm) in the 2020s, 2050s, and 2080s from five CMIP6 GCMs under SSP126, SSP245, and SSP585 in the OGRB.</p>
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<p>Effects of LULC and climate changes on evapotranspiration (mm) in the 2020s, 2050s, and 2080s from five CMIP6 GCMs under SSP126, SSP245, and SSP585 in the OGRB.</p>
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<p>Effects of LULC and climate changes on groundwater recharge (mm) in the 2020s, 2050s, and 2080s from five CMIP6 GCMs under SSP126, SSP245, and SSP585 in the OGRB.</p>
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21 pages, 3300 KiB  
Article
Growth of Oxygen Minimum Zones May Indicate Approach of Global Anoxia
by Yazeed Alhassan and Sergei Petrovskii
Mathematics 2025, 13(5), 806; https://doi.org/10.3390/math13050806 - 28 Feb 2025
Viewed by 115
Abstract
The dynamics of large-scale components of the Earth climate system (tipping elements), particularly the identification of their possible critical transitions and the proximity to the corresponding tipping points, has been attracting considerable attention recently. In this paper, we focus on one specific tipping [...] Read more.
The dynamics of large-scale components of the Earth climate system (tipping elements), particularly the identification of their possible critical transitions and the proximity to the corresponding tipping points, has been attracting considerable attention recently. In this paper, we focus on one specific tipping element, namely ocean anoxia. It has been shown previously that a sufficiently large, ‘over-critical’ increase in the average water temperature can disrupt oxygen production by phytoplankton photosynthesis, hence crossing the tipping point, which would lead to global anoxia. Here, using a conceptual mathematical model of the plankton–oxygen dynamics, we show that this tipping point of global oxygen depletion is going to be preceded by an additional, second tipping point when the Oxygen Minimum Zones (OMZs) start growing. The OMZ growth can, therefore, be regarded as a spatially explicit early warning signal of the global oxygen catastrophe. Interestingly, there is growing empirical evidence that the OMZs have indeed been growing in different parts of the ocean over the last few decades. Thus, this observed OMZ growth may indicate that the second tipping point has already been crossed, and hence, the first tipping point of global ocean anoxia may now be very close. Full article
(This article belongs to the Section E3: Mathematical Biology)
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<p>Oxygen Minimum Zones in the Atlantic, Pacific, and eastern equatorial Indian oceans. The oxygen concentration (ranging between 10 and 230 μmol·kg<sup>−1</sup>) is shown at 400 m depth. Labels A to F mark the areas where additional data on the structure of the vertical oxygen profile are available (see [<a href="#B24-mathematics-13-00806" class="html-bibr">24</a>] for details); remarkably, all of them demonstrate the tendency of the OMZ to increase in size. Note the large spatial extent of areas with particularly low oxygen concentration, as shown by the deep blue and magenta colours. Adapted from [<a href="#B24-mathematics-13-00806" class="html-bibr">24</a>].</p>
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<p>(<b>a</b>) The isoclines of an oxygen–phytoplankton system. The black curve shows the first (oxygen) isocline, and the red curve shows the second (phytoplankton) isoclines obtained for different values of parameter <span class="html-italic">A</span>: from left to right, for <math display="inline"><semantics> <mrow> <mi>A</mi> <mo>=</mo> <mn>3</mn> <mo>,</mo> <mspace width="3.33333pt"/> <mn>3.5</mn> </mrow> </semantics></math>, and 4. (<b>b</b>) The values of <span class="html-italic">c</span> in the steady states <math display="inline"><semantics> <msubsup> <mi>S</mi> <mn>2</mn> <mn>1</mn> </msubsup> </semantics></math> (bottom value) and <math display="inline"><semantics> <msubsup> <mi>S</mi> <mn>2</mn> <mn>2</mn> </msubsup> </semantics></math> (top value) for different values of the parameter <span class="html-italic">A</span> for a fixed value <math display="inline"><semantics> <mrow> <mi>B</mi> <mo>=</mo> <mn>1.8</mn> </mrow> </semantics></math>. Other parameters are <math display="inline"><semantics> <mrow> <mi>σ</mi> <mo>=</mo> <mn>0.1</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>δ</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <msub> <mi>c</mi> <mn>1</mn> </msub> <mo>=</mo> <mn>0.7</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <msub> <mi>c</mi> <mn>2</mn> </msub> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math>, and <math display="inline"><semantics> <mrow> <mi>m</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math>.</p>
Full article ">Figure 3
<p>(<b>a</b>) The isoclines of an oxygen–phytoplankton system. The black curve shows the first (oxygen) isocline, and the red curves show the second (phytoplankton) isocline for different values of parameter <span class="html-italic">B</span>: from top to bottom, for <math display="inline"><semantics> <mrow> <mi>B</mi> <mo>=</mo> <mn>1.8</mn> <mo>,</mo> <mn>1.2</mn> </mrow> </semantics></math>, and <math display="inline"><semantics> <mrow> <mn>0.6</mn> </mrow> </semantics></math>. (<b>b</b>) The values of <span class="html-italic">c</span> in the steady states <math display="inline"><semantics> <msubsup> <mi>S</mi> <mn>2</mn> <mn>1</mn> </msubsup> </semantics></math> (bottom value) and <math display="inline"><semantics> <msubsup> <mi>S</mi> <mn>2</mn> <mn>2</mn> </msubsup> </semantics></math> (top value) for different values of the parameter <span class="html-italic">B</span> for a fixed value <math display="inline"><semantics> <mrow> <mi>A</mi> <mo>=</mo> <mn>25</mn> </mrow> </semantics></math>. Other parameters are <math display="inline"><semantics> <mrow> <mi>σ</mi> <mo>=</mo> <mn>0.1</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>δ</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <msub> <mi>c</mi> <mn>1</mn> </msub> <mo>=</mo> <mn>0.7</mn> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <msub> <mi>c</mi> <mn>2</mn> </msub> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math>, and <math display="inline"><semantics> <mrow> <mi>m</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math>.</p>
Full article ">Figure 4
<p>The structure of the phase plane <math display="inline"><semantics> <mrow> <mo>(</mo> <mi>c</mi> <mo>,</mo> <mi>u</mi> <mo>)</mo> </mrow> </semantics></math>. The black dots show the steady states obtained as the intersections between the oxygen isocline (red curve) and the phytoplankton isocline (black curve). The red arrows visualise the phase flow of the system, as determined by the vectors <math display="inline"><semantics> <mrow> <mo>(</mo> <mi>d</mi> <mi>c</mi> <mo>/</mo> <mi>d</mi> <mi>t</mi> <mo>,</mo> <mi>d</mi> <mi>u</mi> <mo>/</mo> <mi>d</mi> <mi>t</mi> <mo>)</mo> </mrow> </semantics></math>.</p>
Full article ">Figure 5
<p>A sketch of the modelling presumptions. The blue curve shows a typical spatial distribution of oxygen across an Oxygen Minimum Zone where the anoxic water inside is separated from well-oxygenated waters outside by the oxycline (a narrow spatial domain of large gradient in the oxygen concentration). The thick black curve shows a typical solution of the reaction–diffusion system (<a href="#FD9-mathematics-13-00806" class="html-disp-formula">9</a>) and (<a href="#FD10-mathematics-13-00806" class="html-disp-formula">10</a>). Arrows show possible directions of the travelling wave propagation, which can be different depending on the system’s parameters.</p>
Full article ">Figure 6
<p>Solution of the system (<a href="#FD9-mathematics-13-00806" class="html-disp-formula">9</a>) and (<a href="#FD10-mathematics-13-00806" class="html-disp-formula">10</a>) shown at different times, left to right for <math display="inline"><semantics> <mrow> <mi>t</mi> <mo>=</mo> <mrow> <mn>500</mn> <mo>,</mo> <mn>1000</mn> <mo>,</mo> <mn>1500</mn> </mrow> </mrow> </semantics></math> and 2000, respectively; blue line for oxygen, red line for phytoplankton. (<b>a</b>) <math display="inline"><semantics> <mrow> <mi>A</mi> <mo>=</mo> <mn>1</mn> </mrow> </semantics></math>, (<b>b</b>) <math display="inline"><semantics> <mrow> <mi>A</mi> <mo>=</mo> <mn>1.1</mn> </mrow> </semantics></math>. Other parameters are given in the text.</p>
Full article ">Figure 7
<p>Profiles of the oxygen spatial distribution at different times (red line for <math display="inline"><semantics> <mrow> <mi>t</mi> <mo>=</mo> <mn>500</mn> </mrow> </semantics></math>, black line for <math display="inline"><semantics> <mrow> <mi>t</mi> <mo>=</mo> <mn>1000</mn> </mrow> </semantics></math>) obtained for different values of parameter <span class="html-italic">A</span>: (<b>a</b>) for <math display="inline"><semantics> <mrow> <mi>A</mi> <mo>=</mo> <mn>0.941</mn> </mrow> </semantics></math>; (<b>b</b>) for <math display="inline"><semantics> <mrow> <mi>A</mi> <mo>=</mo> <mn>0.98</mn> </mrow> </semantics></math>.</p>
Full article ">Figure 8
<p>Speed of the travelling front for different values of <span class="html-italic">A</span> obtained for the following: (<b>a</b>) <math display="inline"><semantics> <mrow> <mi>B</mi> <mo>=</mo> <mn>1.8</mn> </mrow> </semantics></math>; (<b>b</b>) <math display="inline"><semantics> <mrow> <mi>B</mi> <mo>=</mo> <mn>1.6</mn> </mrow> </semantics></math>. Here, Domain I corresponds to <math display="inline"><semantics> <mrow> <mi>A</mi> <mo>&lt;</mo> <msubsup> <mi>A</mi> <mrow> <mi>c</mi> <mi>r</mi> </mrow> <mrow> <mo>(</mo> <mn>1</mn> <mo>)</mo> </mrow> </msubsup> </mrow> </semantics></math>, where the corresponding nonspatial system possesses only the trivial ‘extinction’ steady state but not any positive steady state. Domain II corresponds to the range <math display="inline"><semantics> <mrow> <mi>A</mi> <mo>&gt;</mo> <msubsup> <mi>A</mi> <mrow> <mi>c</mi> <mi>r</mi> </mrow> <mrow> <mo>(</mo> <mn>1</mn> <mo>)</mo> </mrow> </msubsup> </mrow> </semantics></math> where, additionally to the trivial equilibrium, the nonspatial system possesses two positive steady states (cf. <a href="#mathematics-13-00806-f002" class="html-fig">Figure 2</a>b and <a href="#mathematics-13-00806-f004" class="html-fig">Figure 4</a>). The travelling wave solution exists for parameters from Domaion II but does not exist for parameters from Domain I. The large black dot shows the second critical value <math display="inline"><semantics> <msubsup> <mi>A</mi> <mrow> <mi>c</mi> <mi>r</mi> </mrow> <mrow> <mo>(</mo> <mn>2</mn> <mo>)</mo> </mrow> </msubsup> </semantics></math> for which the travelling front changes the direction of its propagation. The OMZ grows for <math display="inline"><semantics> <mrow> <mi>A</mi> <mo>&gt;</mo> <msubsup> <mi>A</mi> <mrow> <mi>c</mi> <mi>r</mi> </mrow> <mrow> <mo>(</mo> <mn>2</mn> <mo>)</mo> </mrow> </msubsup> </mrow> </semantics></math> but shrinks for <math display="inline"><semantics> <mrow> <msubsup> <mi>A</mi> <mrow> <mi>c</mi> <mi>r</mi> </mrow> <mrow> <mo>(</mo> <mn>1</mn> <mo>)</mo> </mrow> </msubsup> <mo>&lt;</mo> <mi>A</mi> <mo>&lt;</mo> <msubsup> <mi>A</mi> <mrow> <mi>c</mi> <mi>r</mi> </mrow> <mrow> <mo>(</mo> <mn>2</mn> <mo>)</mo> </mrow> </msubsup> </mrow> </semantics></math>.</p>
Full article ">Figure 9
<p>The travelling front speed in the parameter plane <math display="inline"><semantics> <mrow> <mo>(</mo> <mi>A</mi> <mo>,</mo> <mi>B</mi> <mo>)</mo> </mrow> </semantics></math>. In Domain I, no travelling waves exist and any initial distribution of oxygen converges to zero uniformly in space. In Domain II (between the two thick red curves), any initial OMZ shrinks via the travelling fronts (i.e., its boundaries) propagating towards each other. In Domain III, an initial OMZ grows via the travelling fronts (the OMZ’s boundaries) that propagate away from each other. The lower red curve corresponds to the first tipping point <math display="inline"><semantics> <msubsup> <mi>A</mi> <mrow> <mi>c</mi> <mi>r</mi> </mrow> <mrow> <mo>(</mo> <mn>1</mn> <mo>)</mo> </mrow> </msubsup> </semantics></math> (now as a function of <span class="html-italic">B</span>), and the upper red curve corresponds to the second tipping point <math display="inline"><semantics> <msubsup> <mi>A</mi> <mrow> <mi>c</mi> <mi>r</mi> </mrow> <mrow> <mo>(</mo> <mn>2</mn> <mo>)</mo> </mrow> </msubsup> </semantics></math>.</p>
Full article ">Figure 10
<p>Distribution of dissolved oxygen over space simulated using Equations (<a href="#FD13-mathematics-13-00806" class="html-disp-formula">13</a>) and (<a href="#FD14-mathematics-13-00806" class="html-disp-formula">14</a>) for <math display="inline"><semantics> <mrow> <mi>A</mi> <mo>=</mo> <mn>1.1</mn> </mrow> </semantics></math> (other parameters are given in the text), with the initial conditions (<a href="#FD15-mathematics-13-00806" class="html-disp-formula">15</a>) and (<a href="#FD16-mathematics-13-00806" class="html-disp-formula">16</a>) <span class="html-italic">d</span> = 100. This is shown with the following: (<b>a</b>) <math display="inline"><semantics> <mrow> <mi>t</mi> <mo>=</mo> <mn>500</mn> </mrow> </semantics></math>; (<b>b</b>) <math display="inline"><semantics> <mrow> <mi>t</mi> <mo>=</mo> <mn>2000</mn> </mrow> </semantics></math>.</p>
Full article ">Figure 11
<p>Distribution of dissolved oxygen over space simulated for <math display="inline"><semantics> <mrow> <mi>A</mi> <mo>=</mo> <mn>0.941</mn> </mrow> </semantics></math>. This is shown with the following: (<b>a</b>) <math display="inline"><semantics> <mrow> <mi>t</mi> <mo>=</mo> <mn>500</mn> </mrow> </semantics></math>; (<b>b</b>) <math display="inline"><semantics> <mrow> <mi>t</mi> <mo>=</mo> <mn>1000</mn> </mrow> </semantics></math>. Here, <math display="inline"><semantics> <mrow> <mi>d</mi> <mo>=</mo> <mn>350</mn> </mrow> </semantics></math>. Other parameters are given in the text.</p>
Full article ">Figure 12
<p>Speed of the travelling front (the OMZ boundary) in the 2D case obtained for different values of <span class="html-italic">A</span> and fixed <math display="inline"><semantics> <mrow> <mi>B</mi> <mo>=</mo> <mn>1.8</mn> </mrow> </semantics></math> (other parameter values are given in the text). The vertical black line corresponds to the first critical value <math display="inline"><semantics> <msubsup> <mi>A</mi> <mrow> <mi>c</mi> <mi>r</mi> </mrow> <mrow> <mo>(</mo> <mn>1</mn> <mo>)</mo> </mrow> </msubsup> </semantics></math>, and the large black dot shows the second critical value <math display="inline"><semantics> <msubsup> <mi>A</mi> <mrow> <mi>c</mi> <mi>r</mi> </mrow> <mrow> <mo>(</mo> <mn>2</mn> <mo>)</mo> </mrow> </msubsup> </semantics></math>. In Domain I, the corresponding nonspatial system possesses only the trivial steady state, so that the travelling fronts do not exist and the oxygen depletion and plankton extinction occur uniformly over space. In Domain II, the OMZ boundary propagates in space as a travelling front. The front propagates towards the area with low oxygen concentration (hence the OMZ is shrinking) for <math display="inline"><semantics> <mrow> <mi>A</mi> <mo>&gt;</mo> <msubsup> <mi>A</mi> <mrow> <mi>c</mi> <mi>r</mi> </mrow> <mrow> <mo>(</mo> <mn>2</mn> <mo>)</mo> </mrow> </msubsup> </mrow> </semantics></math>, and the front propagates towards the area with high oxygen concentration (the OMZ is growing) for <math display="inline"><semantics> <mrow> <msubsup> <mi>A</mi> <mrow> <mi>c</mi> <mi>r</mi> </mrow> <mrow> <mo>(</mo> <mn>1</mn> <mo>)</mo> </mrow> </msubsup> <mo>&lt;</mo> <mi>A</mi> <mo>&lt;</mo> <msubsup> <mi>A</mi> <mrow> <mi>c</mi> <mi>r</mi> </mrow> <mrow> <mo>(</mo> <mn>2</mn> <mo>)</mo> </mrow> </msubsup> </mrow> </semantics></math>.</p>
Full article ">Figure 13
<p>A sketch of the main findings of the paper. The thick black curve shows a hypothetical dependence of the phytoplankton’s net oxygen production rate <span class="html-italic">A</span> on the average water temperature <span class="html-italic">T</span>, which is known to be a decreasing function and can even drop to zero for a sufficiently large increase <math display="inline"><semantics> <mrow> <mo>Δ</mo> <msup> <mrow> <mi>T</mi> </mrow> <mo>∗</mo> </msup> </mrow> </semantics></math> in the water temperature (roughly estimated as 6 °C, cf. [<a href="#B68-mathematics-13-00806" class="html-bibr">68</a>]). However, global anoxia may occur for a much smaller temperature increase as soon as <math display="inline"><semantics> <mrow> <mi>A</mi> <mo>(</mo> <mi>T</mi> <mo>)</mo> </mrow> </semantics></math> crosses the first tipping point <math display="inline"><semantics> <msubsup> <mi>A</mi> <mrow> <mi>c</mi> <mi>r</mi> </mrow> <mrow> <mo>(</mo> <mn>1</mn> <mo>)</mo> </mrow> </msubsup> </semantics></math>. This is preceded by the second tipping point <math display="inline"><semantics> <msubsup> <mi>A</mi> <mrow> <mi>c</mi> <mi>r</mi> </mrow> <mrow> <mo>(</mo> <mn>2</mn> <mo>)</mo> </mrow> </msubsup> </semantics></math> when the OMZ starts growing. The arrow indicates the direction of change. The existing empirical evidence of the OMZ growth seems to suggest (cf. the question mark) that the ocean has already passed the second tipping point.</p>
Full article ">Figure A1
<p>Steady state values of oxygen (<b>a</b>) and phytoplankton (<b>b</b>) at equilibrium <math display="inline"><semantics> <msubsup> <mi>S</mi> <mn>2</mn> <mn>1</mn> </msubsup> </semantics></math> shown as functions of <span class="html-italic">A</span> and <span class="html-italic">B</span>.</p>
Full article ">Figure A2
<p>The eigenvalues of the oxygen–phytoplankton system at equilibrium <math display="inline"><semantics> <msubsup> <mi>S</mi> <mn>2</mn> <mn>1</mn> </msubsup> </semantics></math> in the given range of parameters <span class="html-italic">A</span> and <span class="html-italic">B</span>.</p>
Full article ">Figure A3
<p>The eigenvalues dependence on <span class="html-italic">A</span> in the positive oxygen–phytoplankton state <math display="inline"><semantics> <msubsup> <mi>S</mi> <mn>2</mn> <mn>1</mn> </msubsup> </semantics></math> shown for <math display="inline"><semantics> <mrow> <mi>B</mi> <mo>=</mo> <mn>1.8</mn> </mrow> </semantics></math> (<b>a</b>) and <math display="inline"><semantics> <mrow> <mi>B</mi> <mo>=</mo> <mn>0.8</mn> </mrow> </semantics></math> (<b>b</b>).</p>
Full article ">Figure A4
<p>Steady state values of oxygen (<b>a</b>) and plankton (<b>b</b>) at the equilibrium <math display="inline"><semantics> <msubsup> <mi>S</mi> <mn>2</mn> <mn>2</mn> </msubsup> </semantics></math> shown vs. <span class="html-italic">A</span> and <span class="html-italic">B</span>.</p>
Full article ">Figure A5
<p>Eigenvalues of the oxygen–phytoplankton system at the equilibrium <math display="inline"><semantics> <msubsup> <mi>S</mi> <mn>2</mn> <mn>2</mn> </msubsup> </semantics></math> over a given range of parameters <span class="html-italic">A</span> and <span class="html-italic">B</span>.</p>
Full article ">Figure A6
<p>Dependence of the eigenvalues on parameter <span class="html-italic">A</span> at the steady state <math display="inline"><semantics> <msubsup> <mi>S</mi> <mn>2</mn> <mn>2</mn> </msubsup> </semantics></math> shown for <math display="inline"><semantics> <mrow> <mi>B</mi> <mo>=</mo> <mn>1.8</mn> </mrow> </semantics></math> (<b>a</b>) and <math display="inline"><semantics> <mrow> <mi>B</mi> <mo>=</mo> <mn>0.8</mn> </mrow> </semantics></math> (<b>b</b>).</p>
Full article ">
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