Water, Volume 15, Issue 15 (August-1 2023) – 182 articles

In this study, a quasi-stumps group structure was proposed and placed upstream of the bridge piers to mitigate the scour of the waterflow on the riverbed. Both experiment and numerical simulations using FLOW 3D were employed to study the protective effect of this structure. The numerical results were in good agreement with the experimental findings. It was found that the quasi-stumps group can effectively reduce the flow velocities around the bridge piers, thereby promoting the deposition of suspended sediment. As a result, there was no erosion around the piers, and instead, siltation was formed, which contributed to the stability of the piers. The deposition height around the piers increased as the L (the horizontal distance between the quasi-stumps group and the piers) decreased and both the P (the height of the quasi-stumps group) and S (the ratio of the area of a single leaf on the quasi-stumps group to the cross-sectional area of a single pier) increased. As the L, P, and S increased, the quantity of suspended sediment deposition over the entire riverbed increased. The optimal combination of the quasi-stumps group’s protective effect was determined to be L = D (pier diameter), P = H (water depth), and S = 0.148. Full article

This Special Issue includes 12 research papers on the development of various materials for adsorbing different contaminants in water, such as Sb, Cr(VI), Cu(II), Zn(II), fluorine, phenol, dyes (indigo carmine, Congo red, methylene blue, and crystal violet), and drugs (dlevofloxacin, captopril, and diclofenac, and paracetamol). The commercial, natural, and synthetic materials used as adsorbents comprise commercial activated carbon, natural clay and montmorillonite, biosorbent based on sugarcane bagasse or algal, graphene oxide, graphene oxide-based magnetic nanomaterial, mesoporous Zr-G-C₃N₄ nanomaterial, nitrogen-doped core–shell mesoporous carbonaceous nano-sphere, magnetic Fe-C-N composite, polyaniline-immobilized ZnO nanorod, and hydroxy-iron/acid–base-modified sepiolite composite. Various operational conditions are evaluated under batch adsorption experiments, such as pH, NaCl, solid/liquid ratio, stirring speed, contact time, solution temperature, initial adsorbate concentration. The re-usability of laden materials is evaluated through adsorption–desorption cycles. Adsorption kinetics, isotherm, thermodynamics, and mechanisms are studied and discussed. Machine learning processes and statistical physics models are also applied in the field of adsorption science and technology. Full article

Peroxymonosulfate (PMS) activation has gained increasing attention for its water remediation. In this work, carbon nanotube-supported FeCo₂O₄ nanoparticles (FeCo₂O₄/CNT) were prepared and showed tremendous potential as a catalyst for PMS activation. The synergistic effect between FeCo₂O₄ and CNT in FeCo₂O₄/CNT promotes its better catalytic performance than individual CNT or FeCo₂O₄. The synthesized FeCo₂O₄/CNT could reach 100% phenol removal with a k value of 0.30 min⁻¹ within 15 min ([PMS] = 0.3 g L⁻¹, [FeCo₂O₄/CNT] = 0.3 g L⁻¹). FeCo₂O₄/CNT can adapt well to a wide pH range (4–9) and a complex water component (with inorganic ions or organic matter). Moreover, the catalytic mechanism investigation suggested that both radical and non-radical pathways are accountable for the efficient removal of phenol. Full article

Typhoon intensity forecast is an important issue. The objective of this study is to construct a 5-day 12-hourly typhoon intensity forecast model based on the adaptive neuro-fuzzy inference systems (ANFIS) to improve the typhoon intensity forecast in the Northwest Pacific. It analyzed the improvement of the ANFIS typhoon intensity forecast model by comparing it with the MLR model when only the atmospheric factor or both atmospheric and oceanic factors are considered. This study collected the SHIPS (Statistical Hurricane Intensity Prediction Scheme) developmental data of typhoons in the Northwest Pacific before landing from 2000 to 2012. The input factors of the ANFIS model were simplified by the stepwise regression procedure (SRP). Subtractive clustering (SC) was used to determine the number of ANFIS rules and to reduce model complexity. Model Index (MI) was taken as the clustering standard of SC to determine the network architecture of the ANFIS typhoon intensity forecast model. The simulated results show that the MI could effectively determine the radius of influence of SC. The typhoon intensity forecast was significantly improved after oceanic environmental factors were added. The improvement of RMSE of ANFIS was the highest at 84 h; the improvement of ANFIS on the underestimated ratio was primarily positive. The Typhoon Songda case study shows that the maximum bias of ANFIS is greatly improved, at 60 h of the lead time, and the improvement percentage of maximum bias is the highest (39%). Overall, the ANFIS model could effectively improve the MLR model in typhoon intensity forecast. Full article

Desert vegetation in the outer transition zone of an arid oasis serves as a protective barrier against wind and sand, safeguarding the oasis ecosystem. However, intensive agricultural water usage within the oasis has led to water depletion, posing a threat to the survival and growth of desert vegetation, as well as the associated increase in wind and sand phenomena. To ensure the sustainable distribution of water resources and maintain the stability of the oasis peripheral ecosystem, this study aimed to investigate the relationship between the ecological water demand of desert vegetation and its effectiveness in preventing wind erosion. Through a combination of field sample tests, field pit tests, and data analysis, this research focused on Haloxlon ammodendron, the most prevalent species on the oasis periphery, to explore the intricate relationship between its ecological water demand and resistance to wind erosion. The results showed that medium-vegetation-coverage soils exhibited a higher soil moisture content (7.02%) compared to high-vegetation-coverage soils (1.57%) and low-vegetation-coverage soils (3.41%). As the soil water content decreased, the growth rate of H. ammodendron’s plant height, new branches, and crown width decelerated. The ecological water requirement of H. ammodendron during its growth period was 70.95 mm under medium-vegetation-coverage conditions, exhibiting a significant increase of 14.6% and 12.3% compared to high- and low-vegetation-coverage conditions, respectively. Meanwhile, H. ammodendron exhibits remarkable wind erosion prevention effects in moderate coverage conditions, resulting in a significant reduction in surface sand collection and sand transport by 53.15% and 51.29%, respectively, compared to low vegetation coverage; however, no significant difference was observed when compared to high vegetation coverage. The SEM model results revealed that soil water content had an indirect effect on sand transport (R² = 0.90) and sand collection (R² = 0.96) through three pathways of action, namely: volatile water content–crown growth rate–wind speed–sediment discharge; volatile water content–plant height growth rate–vegetation coverage–wind speed–sediment discharge; and volatile water content–plant height growth rate–vegetation coverage–sediment accumulation. This study provides valuable insights for the scientific formulation and implementation of strategies aimed at protecting desert vegetation. Full article

As a widely employed method for in situ remediation of groundwater contamination, the pump-and-treat (PAT) system involves the management of water recirculation between the extraction and injection wells. The recirculation zone (RZ) of an extraction-injection well pair in a confined aquifer has been well known. However, PAT systems are more frequently used in unconfined aquifers with a natural regional flow and may not only include one injection well. We develop comparable analytical models for an unconfined aquifer treated by two different system settings, including an extraction well and one injection well (1e/1i system) or two injection wells (1e/2i system). The role of regional groundwater flow is highlighted. Analytical solutions of RZs and recirculation ratios are obtained using complex potential functions, with a new treatment of the jump of the stream function at a branch cut. Results indicate that the shape of RZs and the recirculation ratio nonlinearly depend on several dimensionless parameters linked to the pumping rate and direction of regional flow. Compared to the 1e/1i system, the two injection wells in the 1e/2i system may reduce the integrity of RZs and decrease the recirculation ratio; however, they lead to a higher allowable pumping rate in satisfying the limitations of the water table in wells. This study suggests a useful methodology for analyzing PAT systems with multiple injection wells and provides new insights into RZs between extraction and injection wells. Full article

Malan loess is an eolian sediment in arid and semi-arid areas. It is of great significance to study the pore structure of Malan loess for its evolution, strength, and mechanical properties. In order to quantitatively characterize the absolute permeability tensor of Malan loess and to simulate the seepage process of Malan loess, this study calculated the specific yield of intact Malan loess with a homemade seepage experimental device and recorded the water flow process on the surface of Malan loess during the seepage process. Modern computed tomography was used to scan the intact Malan loess samples from Jiuzhoutai, Lanzhou (western part of the Loess Plateau, China); the specific yield of the intact loess was used as the parameter value for the threshold segmentation of the scanned image for the 3D reconstruction of the connected pore space, the solver program in AVIZO software was used to solve the absolute permeability tensor of Malan loess using the volume averaging method combined with the CT scan to reconstruct the 3D pore space, and the simulation of the seepage process was carried out. The simulation results showed that Malan loess is a highly anisotropic loess; the absolute permeability in the vertical direction is 9.02 times and 3.86 times higher than the permeability in the horizontal direction. The pore spaces are well connected in the vertical direction (forming a near-vertical arrangement of pipes) and weakly connected in the horizontal direction. In the seepage simulation, it was found that the water flows first along the vertically oriented channels and then fills the horizontally oriented pores; the absolute permeability coefficient was calculated to be 0.3482 μm². The indoor seepage experiment was consistent with the simulation experiment, which verifies the reliability of the calculated model. Full article

Daily average springtime air temperatures from four weather stations distributed along north–south and nearly east–west directions within or on the divide of the Sagavanirktok River watershed in Arctic Alaska were studied and compared with discharge measurements and field observations made from 2015 to 2021 during breakup. The results indicate that under widespread air temperature events, during El Niño, rapid and dynamic breakup can occur (promoting sediment transport along the stream), while during La Niña, slow and thermal breakup can be expected. Due to these climate pattern effects, open channel conditions (i.e., ice-free channels) are reached earlier (18 May 2015) during El Niño and later (7 June 2021) during La Niña. Full article

High-speed fluid flows over roughened surfaces occur in many engineering applications; one important application involves high velocity water flows in pipelines with roughened interior walls where the wall roughness affects head loss estimates necessary for engineering design purposes. The present analysis provides an analytical solution of the fluid physics underlying the induced static pressure profile resulting from high Froude number supercritical velocity through duct with random wall roughness. The analytic solution of the hyperbolic governing small perturbation velocity potential equation subject to high Froude number flows brings forward characteristic wave solutions that determine the static pressure profile in a duct with random height wall roughness. While current engineering practice utilizes semi-empirical engineering equations employing test data to determine the friction factor, velocity and static pressure profiles and head loss for different roughness types in different sized ducts as a function of Reynolds number (as summarized in a later section of the paper), the present analysis provides a new analytical method to determine the fluid physics involved in the static pressure change induced by wall random roughness in ducts subject to high Froude number supercritical flows. Full article

Extreme precipitation poses significant threats to economic development and social security. In order to tackle this formidable issue, the Chinese government has invested substantial investments to promote the “sponge city” project. However, extreme precipitation in Zhengzhou on 21 July 2021 proved that this effort fell far short of its goal, highlighting the difficulty in relying solely on the government to respond to severe disasters. Collaborations between the public and the government have become essential for effectively managing extreme precipitation risk. However, bridging the gap between the public and the government remains a challenging task in China. Interestingly, an Online Collaborative Document (OCD) emerged without any financial investment from the government yet went on to save countless lives. The key lies in that the OCD greatly promoted the cooperation between spontaneous volunteering and official response. This study aims to explain how an OCD encourages effective collaboration between spontaneous volunteering and official responses in tackling extreme precipitation risk. This study employs the method of the case study about the extreme precipitation and analyzes the directed survey on the spontaneous volunteers, grassroots government officials, and affected individuals who used the OCD. Additionally, a variety of data collection techniques, including focus groups and one-on-one interviews, are used to examine the relevant information. This study explores how the OCD eliminated the paradox of collaboration between spontaneous volunteering and the official response thereby fostering coordination between them. Full article

Taking the 14,030 panel of Zhaogu No. 2 coal mine as its research object, this paper studies the evolution characteristics of the developing height, propagation track and caving arch shape of water-flowing fractures under the influence of thick alluvium by utilizing a physical experiment, theoretical analysis and field investigation. The results show that the height and limit span of the water-flowing fracture zone experience four stages, which include the initial stage, slow-increasing stage, sudden-increasing stage and stable-increasing stage. With the increase in the mining influence range, the shape of the water-flowing fracture in overburden under the influence of thick alluvium is gradually formed. The water in the thick alluvium and the water in the upper phreatic aquifer of the bedrock penetrate each other to form a concentrated danger zone, and the expansion track of the mining water-flowing fracture connects the hydraulic connection between the upper concentrated danger zone of overburden and the panel of No. 2’s first coal seam. A large amount of water mixed with sandstone flows into the fracture surface of the bedrock’s broken rock block through the water-flowing fracture, leading to the instability of the load-bearing structure composed of the thick alluvium caving arch and the towering roof beam, which illustrates the whole process of water–sand inrush accidents in thin bedrock stope with deep thick alluvium. Full article

The shortage of water resources is a long-standing constraint on the development of the Chinese economy and society. In this paper, the climate change occurring in Hulan River Basin is analyzed using the data collected at Wangkui Meteorological Station from 1960 to 2020. The overall temperature in the basin shows an upward trend, with a cumulative increase of 1.6 °C, as does the precipitation, which reaches 566.2 mm. In contrast, there is a downward trend shown by wind speed, with a cumulative decrease of 1.313 m/s. GIS remote sensing technology is applied to build a SWAT distributed hydrological model for the purpose of conducting runoff simulation in Hulan River Basin, and SWAT-CUP software is used to correct and analyze the simulation results. The parameters of snow melt are set to improve the accuracy of the model. The runoff data collected from Lanxi Hydrological Station from 2008 to 2020 are used to verify the model. The results show that the efficiency coefficient (NES) and correlation coefficient (R²) are 0.75 and 0.84, respectively, in the validation period from 2010 to 2013, while they are 0.77 and 0.93, respectively, in the correction period from 2014 to 2016, meeting the criteria of model evaluation. It can be seen from results noted above that SWAT is applicable in Hulan River Basin, providing a certain reference for the management of hydrological and water resources available in this region and for the construction of a distributed hydrological model of rivers in those high-latitude cold regions. Full article

In the milieu of escalating flood occurrences, the concept of community resilience has garnered considerable attention. A series of studies recommend a river restoration approach to encourage the participation of all relevant stakeholders to manage floods to improve community resilience. However, existing studies have not sufficiently unraveled the intricate interplay of drivers shaping such participation. Therefore, using the Moat System Restoration Project in Tianchang City as the empirical conduit, this study elucidates the relationship between the drivers that drive stakeholder participation in river restoration in the context of improving community resilience. The Theory of Planned Behavior was employed to extend additional independent variables such as stakeholder attitudes, priorities, risk perception, trust in government decisions, knowledge, motivation, and intentions. A sample of 473 local residents involved in the Moat System Restoration Project was evaluated by Structural Equation Modelling. The empirical results revealed the salient influence of stakeholder attitudes, knowledge, and priorities on their behavior and risk perception where harnessing perceptions of priority has the potential to significantly improve community resilience. Notably, the study dispelled the presumed influence of trust on risk perception, a revelation that deviates from some existing literature. The findings further demonstrate a strong association between stakeholder motivation and both risk perception and intentions, a relationship underappreciated in previous studies. Theoretically, this study unearths the intricate dynamics of stakeholder participation in river restoration projects, thereby extending the Theory of Planned Behavior to the sphere of stakeholder participation, which adds a critical dimension to the understanding of flood management and community resilience. Practically, this study provides a valuable lens for practitioners as it illuminates pathways to foster stakeholder participation in river restoration initiatives, guiding the development of strategies to foster stakeholder participation in similar projects. Full article

The Pomeranian lakes in Northern Poland and the nearby coastal waters of the Baltic Sea belong to optically complex water bodies characterised by high eutrophication levels. These water types require a local approach when developing bio-optical algorithms that combine the inherent and the apparent properties of seawater. Well-established local algorithms are of great value for understanding and addressing rapid changes in water quality related mostly to human activities in coastal and near-shore zones, as well as in optically similar lakes. Our research analyses the possibility of using the multi-parameter algorithms of absorption a(λ), backscattering b_b(λ) and remote sensing reflectance R_rs(λ), originally developed for the coastal waters of the Southern Baltic Sea, for three selected Pomeranian lakes. Our multi-parameter algorithms are based on the input concentrations of the biogeochemical components measured in the lake waters, i.e., chlorophyll a (Chl a), suspended particulate matter (SPM), inorganic suspended particulate matter (SPM_inorg), the sum of the surface concentrations of accessory pigments (ΣC) and coloured dissolved organic matter with a wavelength of 400 nm (a_CDOM(400)). R_rs(λ) and a(λ) output values were compared with independent measurements of these parameters conducted in the lake waters at 20 sampling stations. Our algorithm output values of b_b(λ) were compared to the values obtained based on the algorithm provided by Ficek, previously developed and validated for Pomeranian lakes, at the same stations. The statistical analyses conducted afterwards showed that the multi-parameter algorithms of R_rs(λ) and a(λ) for the Southern Baltic Sea are sufficient to be used for the stations investigated in the aforementioned three lakes. Specifically, the correlations between the b_b(λ) values obtained based on the Ficek algorithm and the b_b(λ) values obtained using our multi-parameter algorithm reveal a statistical error rate of less than 20%. Full article

Unsaturated zones are critical for water and material exchange between groundwater and surface ecosystems. Understanding the migration patterns of soil water and salts in these zones can offer theoretical support for maintaining the equilibrium between groundwater and surface ecosystems in Northwestern China’s salinized regions. This study explores the correlation between soil particle composition and soil water and salt distribution at a test site in the lower reaches of the Shiyang River basin. It analyzes the way in which water and salt patterns vary with different soil structures over various timescales. The results indicate that lithological profiles with similar structures but varying fine particle contents exhibit distinct water–salt variation patterns. Higher fine particle content leads to increased water and total dissolved solid content, but a decreased infiltration rate. When the middle layer has the highest fine content, soil evaporation is partially inhibited. The more complex the lithologic structure, the less effective irrigation is in leaching salt. However, when the lithologic structure remains constant, fine particle content has minimal impact on salt leaching. Full article

Sandspits are important natural defences against the effects of storm events in estuarine regions, and their temporal and spatial dynamics are related to river flow, wave energy, and wind action. Understanding the impact of extreme wave events on the morphodynamics of these structures for current conditions and future projections is of paramount importance to promote coastal and navigation safety. In this work, a numerical analysis of the impact of a storm on the sandspit of the Douro estuary (NW Portugal) was carried out considering several mean sea level conditions induced by climate change. The selected numerical models were SWAN, for hydrodynamics, and XBeach, for hydrodynamic and morphodynamic assessments. The extreme event selected for this study was based on the meteo-oceanic conditions recorded during Hurricane Christina (January 2014), which caused significant damage on the western Portuguese coast. The analysis focused on the short-term (two days) impact of the storm on the morphodynamics of the sandspit in terms of its erosion and accretion patterns. The obtained results demonstrate that the mean sea level rise will induce some increase in the erosion/accretion volumes on the seaward side of the sandspit. Overtopping of the detached breakwater and the possibility of wave overtopping of the sandspit crest were observed for the highest simulated mean sea levels. Full article

Blue–green infrastructures (BGI) play an important role in addressing contemporary challenges posed by urbanization, climate change, and demographic shifts. This study focuses on the parameterization of BGI within hydrological models, specifically emphasizing the Low Impact Development (LID) module of the Storm Water Management Model (SWMM), supplemented by the SWMM-UrbanEVA evapotranspiration model. Employing a systematic approach, a transferable framework is developed to categorize BGI types, leading to a comprehensive parameterization toolset. This toolset includes parameter estimates for predefined BGI types, encompassing both natural and technical systems with a specific emphasis on plant-specific parameterization. The justification of these parameter estimates is supported by an extensive literature review. Sensitivity analyses reveal the influence of plant-specific parameters, such as the crop factor (K_C), and soil storage capacity, on water balance and peak runoff. Additionally, this study presents practical guidelines to enhance the comprehension of model behavior and ensure the highest possible quality in model parameterization. While further research on validity and transferability of the toolset is required, the findings of this study provide useful support for the differentiated representation and analysis of hydrological processes in urban environments. As a result, this study serves as a valuable resource for researchers, practitioners, and decision makers, facilitating the implementation of sustainable water management practices in urban settings. Full article

Crack detection is an important component of dam safety monitoring. Detection methods based on deep convolutional neural networks (DCNNs) are widely used for their high efficiency and safety. Most existing DCNNs with high accuracy are too complex for users to deploy for real-time detection. However, compressing models face the dilemma of sacrificing detection accuracy. To solve this dilemma, an improved residual neural network (ResNet)-based algorithm for concrete dam crack detection using dynamic knowledge distillation is proposed in this paper in order to obtain higher accuracy for small models. To see how well distillation works, preliminary experiments were carried out on mini-ImageNet. ResNet18 was trained by adding additional tasks to match soft targets generated by ResNet50 under dynamic high temperatures. Furthermore, these pre-trained teacher and student models were transferred to experiments on concrete crack detection. The results showed that the accuracy of the improved algorithm was up to 99.85%, an increase of 4.92%. Full article

Under the background of drastic global climate change, the evolution law of groundwater resources in the northeastern margin of the Tibetan Plateau presents new characteristics, and the groundwater is gradually becoming more complicated, diversified and disordered. In this study, cross-correlation analysis, wavelet analysis and cross-wavelet transform were used to explore the response mechanism and time delay effect of groundwater, exploitation amount, rainfall and surface runoff in the northeastern margin of the Tibetan Plateau. The results show that the groundwater depth increased with the increase in the exploitation amount and decreased with the increase in the rainfall-to-exploitation ration and the surface runoff-to-exploitation ratio from 1980 to 2020. On the annual scale, groundwater, rainfall and surface runoff had a strong cohesiveness period of 12a. On the monthly scale, groundwater lagged behind rainfall and surface runoff for 3 months and 2 months, respectively. The above conclusions provide a scientific theoretical basis for deepening the characteristics of groundwater endowment, the evolution law of water cycle elements and the theory of the hydrological cycle in the northeastern margin of the Tibetan Plateau. Full article

The aim of this study was to synthesize N, P codoped CQDs modifying TiO₂/g-C₃N₄ nanorod array (i.e., N, P-CQD/TCN NA) photoanodes for the degradation of 1,4-dioxane (1,4-D) and to explore the possibility of the photoelectrocatalytic (PEC) process in wastewater treatment. With the characterization of N, P-CQD/TCN NA anodes, 1,4-D degradation and pesticide wastewater was tested in the PEC cell, respectively. Under a bias voltage of 1.2 V and visible light, the current density of the N, P-CQD/TCN NAs was much higher than that of the CQD/TCN NAs (0.15 vs. 0.11 mA/cm²). The removal of 1,4-D reached 97% in the PEC cell within 6 h. The high performance of the N, P-CQD/TCN NA anodes could be attributed to the efficient charge separation, narrowed energy gap, and high upconverted PL properties. The C4 and C6 positions of 1,4-D were the preferential sites for the nucleophilic attack to form intermediates. The COD removal in the pesticide wastewater was kept stable at ~80% in a five-cycle operation using the PEC cell with the N, P-CQD/TCN NA photoelectric anodes. The results from this study should provide a promising way to develop novel photoelectric catalysts and to expand PEC application in wastewater treatment. Full article

The aim of this study is to investigate the patterns and trends of drought occurrence in the northern part of Poland on the example of the Łeba river basin in the years 1956–2015. The study of meteorological drought was conducted on the basis of the Standardized Precipitation Index (SPI) on the scale of 1, 3, 6, 9, and 12 months. Annual precipitation totals did not show significant changes in the analyzed period, except for the station in Wejherowo, which is characterized by a significant increasing trend. The analysis of the long term of the variability average annual air temperature showed its statistically significant increase in the analyzed area at the rate of about 0.2 °C per decade. During the analyzed period, 14 to 84 meteorological droughts were identified, with durations ranging from 200 to 300 months. As the period of accumulating values of SPI, the number of droughts decreased, while their total duration increased. Most droughts were mild in nature, while extreme droughts accounted for between 5.2% and 10.7% of the duration. Drought intensification was shown only for SPI-1 in February and March in Wierzchucino station. On the other hand, a decreasing trend in SPI values was noted during longer periods of accumulation (SPI-6, 9, and 12). Full article

The occurrence of pharmaceutically active compounds (PhACs), nutrients, and an artificial sweetener acesulfame in wastewater, and subsequent removal in an engineered system comprising aerobic wetland, anaerobic wetland, and steel slag cells, were investigated. The PhACs evaluated in this study covered a range of octanol–water partition coefficients (log K_ow = 0.07–2.45) and acid dissociation constants (pK_a = 1.7–13.9) and included carbamazepine, caffeine, sulfamethoxazole, ibuprofen, and naproxen. The mean flow rate in the system was 0.89 m³ day⁻¹ (0.02 to 4.27 m³ day⁻¹), representing a hydraulic retention time of 5 days. The removal efficiencies of PO₄-P, NH₃-N, and cBOD₅ in the treatment system were >99, 82, and 98%. The removal efficiencies for the PhACs and acesulfame were classified into four groups, including those that were (a) efficiently removed (caffeine by >75%); (b) moderately removed (ibuprofen by 50–75%); (c) poorly removed (sulfamethoxazole and naproxen by 25–50%); and (d) recalcitrant (carbamazepine and acesulfame by <25%). Variability in concentrations and treatment efficiencies was observed in different sampling events, which may be due to variations in input concentrations or changes in the flow rate. The addition of a steel slag cell increased the overall removal efficiency of the studied compounds, except for carbamazepine. Full article

For a semi-infinite aquifer controlled by a river channel boundary, when the Laplace transform is used to solve a one-dimensional unsteady seepage model of phreatic water while considering the influence of the vertical water exchange intensity ε with the change in the river channel water level f(t), a complicated and tedious integral transformation process is required. By replacing f(t) with an operator, this study first derived the analytic formula of the ε term based on the properties of the Laplace transform without the direct participation of f(t) in the transformation. By using f(t) in the form of several types of linear functions, the Laplace transform and inverse transform laws were summarized. The analytical solution to the problem was easily obtained by applying the “integral property” of the transformation to the linear function term with time t. The relative error between the numerical solution and the analytical solution of the example was less than 0.2%, which verified the rationality of the model linearization method and the reliability of the analytical solution. For different boundary conditions, the process of establishing and applying the inflection point method and the curve-fitting method for calculating the model parameters by using dynamic monitoring data for phreatic water is presented with examples. Full article

In recent years, human impact on the Earth’s ecological environment has become increasingly visible, with serious negative consequences. One of the most important pollutants are heavy metals which can easily bind to sediments. Due to their toxic behavior, persistence, lack of biodegradability and bioaccumulation, they are considered key river pollutants that need to be controlled. This study examined two rivers: the Liwiec and Muchawka rivers located in south-eastern Poland. The mouth of the Liwiec River is the Bug River, which is partly the border between Poland and Belarus. In turn, the mouth of the Muchawka River is the Liwiec River. The objectives of the study were the following: (1) To complete a qualitative analysis of heavy metals (Cd, Pb, Cu, Ni, Zn) in the waters and bottom sediments of the Liwiec and Muchawka rivers; (2) To assess the degree of heavy metal contamination; (3) To identify the sources of contamination. The analysis included samples of surface water and bottom sediments collected (16 water and 16 bottom sediment samples were taken from the Muchawka River and 32 water and 32 bottom sediment samples were taken from the Liwiec River) in June and September 2022. The variability of characteristics, such as temperature, precipitation and humidity, contributes to seasonal changes in the distribution characteristics and sources of heavy metals. The study showed that only a small part of the heavy metals entering rivers are present in the water depth in the dissolved state, and most of them enrich the sediment, resulting in much higher concentrations of heavy metals in the sediment than in the water column. The differences in the distribution of some elements in water and sediment are due to the fact that surface sediments retain long-term records. Therefore, sediment can be considered a potential source of heavy metals in the aquatic environment. In general, the content of heavy metals determined in bottom sediments was not high but indicative of anthropogenic human activity. There is a possibility of re-release of heavy metals from the sediment into the water when hydrodynamic conditions or environmental factors (pH, redox potential, etc.) change, which could lead to secondary water pollution. The data obtained will be of great importance to both researchers studying river systems and the population living in the area. Full article

Large-scale photovoltaic power plants located in highland mountainous areas are vulnerable to landslides due to extreme rainfall, posing a significant threat to the normal operation of photovoltaic power plants. However, limited research has been conducted on landslide risk assessment specifically tailored to large photovoltaic power plants, with most studies focusing on static assessments that lack long-term sustainability in risk assessment and prediction. In this paper, a dynamic study on landslide risk at a large photovoltaic power plant project under extreme rainfall conditions is conducted. Firstly, the factors in landslide susceptibility assessment based on typical landslide characteristics in the study area are selected and an assessment index database using mapping units to extract the relevant factors is established. Subsequently, the ANP-FBN model is employed to evaluate the landslide susceptibility of large photovoltaic power plant sites. Furthermore, an assessment index system for landslide hazard vulnerability is developed by considering population, economic, and material vulnerabilities, and the AHP method is adapted to assess landslides vulnerability in the study area. Finally, the landslide rainfall threshold with the susceptibility and vulnerability assessment results are coupled to achieve a dynamic assessment of landslide hazard risk at large photovoltaic power plant sites under extreme rainfall conditions. The findings highlight that the central valley and the eastern steep slope of the study area are the primary “high” and “very high” risk areas. Moreover, with the increase in rainfall duration, the risk level of landslide hazards in the study area also rises. Full article

The issue of microplastic (MP) pollution is one of the most pressing environmental problems faced today and for the future. Plastics are ubiquitous due to their exponential use and mismanagement, resulting in the accumulation of fragments across the world. Hence, the problem of MP pollution is aggravated when these plastic items disintegrate into smaller particles due to different physical, chemical, and environmental factors. The consumption of these MP pollutants by wildlife is a worldwide concern and a potentially crucial risk for all ecosystems. Consequently, MPs have caused a wide variety of problems for both public health and wildlife concerning vital life processes—specifically reproduction, which is critical to species’ survival in an ecosystem. Despite MPs’ detrimental effects on wildlife reproduction, it remains unclear how MPs can affect the hypothalamic–pituitary–gonadal (HPG) axis. This review highlights the significant reproductive toxicity of MPs in wildlife, with potentially devastating consequences for human health. The findings emphasize the urgency of developing effective solutions for mitigating the adverse effects of MP pollution on the reproductive systems of wildlife and preserving the integrity of aquatic and terrestrial habitats. Full article

Hydrological drought poses a major global challenge, exacerbated by climate change and increasing water demand, leading to water scarcity, environmental degradation, and socioeconomic impacts. Thereby, there is a need for comprehensive methods to assess and predict hydrological droughts. The methodology part was based on the calculation of hydrological drought risk components—hazard and vulnerability—according to the equal weight scale of each variable. The spatial distribution of point values was performed by the inverse distance weighting interpolation method. To calculate indices, the spatial layer overlapping of variables was performed using the Raster Calculator tool. Statistical tools were used to estimate drought risk in river catchments. As a result, three main maps were prepared: The hydrological drought hazard index, the hydrological drought vulnerability index, and the hydrological drought risk. These maps highlight regional variations in drought hazards, vulnerability, and risk. Hazard and risk index values are higher in the northern part of Lithuania and lower in the south. The central region exhibits the highest percentage of areas at high and very high risk; the western region shows less risk due to a maritime climate; and the Southeastern region demonstrates the lowest susceptibility to hydrological drought due to physical-geographical factors. Full article

A substantial portion of the water supply and sanitation (WatSan) infrastructure in the rural areas of developing countries is currently not operating. This failure is due to the inappropriate implementation of WatSan technologies and the lack of decision-making resources. This study explores the application of several machine learning classification algorithms to predict the optimal WatSan system effectively. The proposed classification methods are Logistic Regression, Random Forest, Support Vector Machine, CatBoost, and Neural Network. The practicality of these classification methods was tested using a dataset comprising 774 water technology options. Several experiments were conducted to obtain the highest possible classification accuracy of the capacity requirement level (CRL) in terms of accuracy and F1 score classification metrics. Our findings suggest that CatBoost, with the addition of the synthetic minority oversampling technique (SMOTE), outperforms the other algorithms in classifying WatSan technology options. Full article