River Flow Research Articles

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The cover image is based on the Research Article Collateral benefits: River flow normalization for endangered fish enabled riparian rejuvenation by Stewart B. Rood et al., https://doi.org/10.1002/rra.4255.image

Arrival of crocodilians to São Tomé Island, Gulf of Guinea, Western Africa, highlights the role of sea currents to the natural colonization of islands

Abstract Historical and recent arrivals of crocodilians to the Gulf of Guinean Oceanic Island of São Tomé have intrigued naturalists for several centuries. Here we present the revision of the historical records, and present data regarding the recent arrival of a single specimen in 2021. After being killed by the local authorities, the specimen was preserved and studied both through morphological and molecular methods. Our findings suggest that the specimen was a sub-adult Nile crocodile, Crocodylus niloticus Laurenti, 1768, which most likely drifted from the Congo or Ogooué river mouths in West Africa by the oceanic current acting on the Gulf of Guinea. The story of this individual highlights the dispersion paths that have contributed by the past biological colonization of São Tomé Island.

Detecting Margalefidinium polykrikoides through high-frequency imagery: Example of a bloom formation, environmental conditions, and phytoplankton community composition changes

In August 2018, the harmful algae species Margalefidinium polykrikoides bloomed to levels previously unobserved in the open waters of Narragansett Bay, Rhode Island, in a transient but intense bloom. Detected by an Imaging FlowCytobot providing hourly data, it is characterized by a time span of less than a week and patchiness with sub-daily oscillations in concentration. The highest concentrations are recorded at lower salinity and higher temperature, suggesting the bloom may have developed in the upper bay and was transported south. The proportion of chains increased during the height of the bloom, and many of the images contained 4-cells per chain. The development of the bloom was favored by optimal temperature and salinity conditions as well as increased nitrogen coincident with greater precipitation and river flow. The period preceding bloom formation also saw a sharp decrease in the dominating large chain-forming diatom Eucampia sp. and highly abundant Skeletonema spp., thus reducing competition over resources for the slow-growing M. polykrikoides. The height of the bloom was reached during the lowest tidal range of the month when the turbulence and water displacement were lower. This time series highlights an out-of-the-ordinary bloom's environmental and biological conditions and the importance of frequent sampling during known favorable conditions.

Combining terrestrial lidar with single line transects to investigate geomorphic change: A case study on the Upper Verde River, Arizona

The Upper Verde River in northern Arizona, USA is a vital resource for the wildlife and humans that rely on its waters. We characterize the riparian corridor topography using terrestrial laser scanner (TLS) data from 2021 to 2022. We also quantify geomorphic changes associated with human and climate-driven alterations in river flow and vegetation changes by combining the contemporary lidar surveys with legacy measurements from single line geomorphology transects measured by the United States Forest Service (USFS) in 2009. Seventeen plots along the Upper Verde River were surveyed with the TLS and the data were coregistered within individual plots with a Root Mean Square Error of <0.03 m among scan positions. Digital Elevation Models (DEM) were derived for each plot from the TLS data at 10 cm resolution and compared to the 2009 USFS cross-section data to quantify elevation changes. In areas with statistically significant change, we detected maximum changes in elevation due to erosion and deposition of −0.37 m and + 0.97 m, respectively. Topographic changes over the 13-year period were predominately aggradation and associated with sediment deposition, which we hypothesize might have resulted from altered river flow and vegetation encroachment. This study also demonstrates a quantitative and statistical methodology to fuse traditional single line cross-section data with contemporary lidar data to quantify geomorphic change. The novel approach demonstrated here is broadly applicable to natural resource managers for integrating and contextualizing legacy topographic data for understanding past, present, and future landscape and habitat changes.

Comprehensive performance analysis of training functions in flow prediction model using artificial neural network

Higher Himalayan catchments are often poorly monitored for hydrological activities involving flood flow prediction for the safety of riverside communities and the successful operation of hydropower projects. This study aimed to estimate the comparative performance of artificial neural network (ANN) based flow prediction models using 10 years of daily river flow data of Kaligandaki catchment at Kotagaun, Nepal, which is a snow-fed catchment in the Himalayan region. The flow prediction models were trained and tested at a hydrological station using the previous 3 days’ river flow data to predict the 1-day ahead flow data. Eight different training functions were employed in an ANN model for comprehensive statistical assessment of accuracy and precision of each training function. The most significant and validated result obtained in this study is the comprehensive comparison of various training functions’ performance, and identification of the most efficient training function for the study case. Among the training functions investigated, the Levenberg-Marquardt backpropagation function exhibits the best performance for the model having Nash-Sutcliffe efficiency, root mean square error and mean absolute error values of 0.866, 209.578 and 75.422, respectively. This study provides a fundamental basis for accurate flow prediction of topographically challenged catchments where hydrological monitoring and data collection may be limited. In particular, this model will help to improve early warning system, hydrological planning, and the safety of riverside communities in the Himalayan region.

Salinity Fronts in the South Atlantic

Monthly climatology data for salinity fronts in the South Atlantic have been created from satellite SMOS sea surface salinity (SSS) measurements taken from 2011–2019, processed at the Barcelona Expert Center of Remote Sensing (BEC), and provided as high-resolution (1/20°) daily SSS data. The SSS fronts have been identified with narrow zones of enhanced horizontal gradient magnitude (GM) of SSS, computed using the Belkin–O’Reilly algorithm (BOA). The SSS gradient fields generated by the BOA have been log-transformed to facilitate feature recognition. The log-transformation of SSS gradients markedly improved the visual contrast of gradient maps, which in turn allowed new features to be revealed and previously known features to be documented with a monthly temporal resolution and a mesoscale (~100 km) spatial resolution. Monthly climatologies were generated and analyzed for large-scale open-ocean SSS fronts and for low-salinity regions maintained by the Rio de la Plata discharge, Magellan Strait outflow, Congo River discharge, and Benguela Upwelling. A 2000 km-long triangular area between Africa and Brazil was found to be filled with regular quasi-meridional mesoscale striations that form a giant ripple field with a 100 km wave length. South of the Tropical Front, within the subtropical high-salinity pool, a trans-ocean quasi-zonal narrow linear belt of meridional SSS maximum (Smax) was documented. The meridional Smax belt shifts north–south seasonally while retaining its well-defined linear morphology, which is suggestive of a yet unidentified mechanism that maintains this feature. The Subtropical Frontal Zone (STFZ) consists of two tenuously connected fronts, western and eastern. The Brazil Current Front (BCF) extends SE between 40 and 45°S to join the subantarctic front (SAF). The STFZ trends NW–SE across the South Atlantic, seemingly merging with the SAF/BCF south of Africa to form a single front between 40 and 45°S. In the SW Atlantic, the Rio de la Plata plume migrates seasonally, expanding northward in winter (June–July) from 39°S into the South Brazilian Bight, up to Cabo Frio (23°S) and beyond. The inner Plata front moves in and out seasonally. Farther south, the Magellan Strait outflow expands northward in winter (June–July) from 53°S up to 39–40°S to nearly join the Plata outflow. In the SE Atlantic, the Congo River plume spreads radially from the river mouth, with the spreading direction varying seasonally. The plume is often bordered from the south by a quasi-zonal front along 6°S. The diluted Congo River water spreads southward seasonally down to the Angola–Benguela Front at 16°S. The Benguela Upwelling is delineated by a meridional front, which extends north alongshore up to 20°S, where the low-salinity Benguela Upwelling water forms a salinity front, which is separate from the thermal Angola–Benguela Front at 16°S. The high-salinity tropical water (“Angola water”) forms a wedge between the low-salinity waters of the Congo River outflow and Benguela Upwelling. This high-salinity wedge is bordered by salinity fronts that migrate north–south seasonally.

Identifikasi Jenis Zooplankton di Sepanjang Perairan Sungai Jangkok Kota Mataram

Zooplankton is animal plankton, which plays a role as primary consumers in aquatic ecosystems and as a link in the aquatic food chain. The Jangkok River is one of the large rivers on Lombok Island. This river flows from the western slopes of Mount Rinjani through the Narmada area of ​​West Lombok Regency to downstream at Ampenan Beach. Many river flows provide functions and benefits for the continuity of life of the surrounding community. This research aims to identify zooplankton in the waters of the Jangkok River, Mataram City. This type of research is exploratory descriptive. Research procedures include taking zooplankton water samples horizontally and vertically. Data collection techniques use observation and documentation techniques. The data analysis technique uses the zooplankton abundance index. The research results show that there are 4 types of Zooplankton consisting of 4 species that have been discovered including Harpacticoid copepod, Parathemisto abyssorum, Cyclops bicuspidatus and Diaptomus sp.

50 Years Of Hanbar Concrete Units In Australia And New-Zealand: Lessons Learned From Physical Modelling Studies And Recently Built Structures

During the last 50 years, numerous breakwaters along the eastern coast of Australia, and more recently in New Zealand, have undergone construction, repairs, or upgrades using Hanbar concrete armour units. These units are distinct to Australasia, and there is limited information about their properties in standard coastal engineering literature. This paper first provides a survey and timeline of all known projects using Hanbars. An overview of the Hanbar concrete unit features and manufacturing method is then provided. The paper presents a summary of results of previous modelling studies of Hanbar applications to specific breakwaters, as well as recent research programs completed at WRL, and provides placement density guidelines as well as recommended damage coefficient (Hudson Kd) for design. The paper concludes with a brief overview of two recent case studies which have successfully capitalized on the economical, robustness and manufacturing simplicity of the Hanbar concrete units. The first case study is on the Opotiki Harbour Development (“OHD”) in New Zealand. The OHD scheme comprises twin 400 m long training wall breakwaters to train a dynamic river mouth. A multi-stage approach to physical modelling was adopted by conducting 2D modelling of key sections of the training wall trunks, quasi-3D modelling of the breakwater head, and full 3D modelling of complete structures. The second case study presents the results of a field trial investigating the potential for high-density geopolymer concrete (GPC) coastal armour units. This resulted in the casting and placing of thirteen 16 t GPC Hanbar units (SG 2.6) on the Port Kembla northern breakwater in NSW. The trial proved the viability of production of geopolymer armour units, and allowed long-term monitoring of the integrity of the concrete in the aggressive marine environment.

Landscape modelling of the Yalong River catchment during the uplift of Southeast Tibet

Southeast Tibet is characterized by low-relief surfaces at high-elevation, showing very little exhumation during the India–Asia collision, as well as deeply incised rivers valleys. Understanding how these low-relief surfaces adjacent to the plateau's edge survived from regressive fluvial erosion is still an enigma, which is key to understanding the formation of the plateau. In the Three Rivers Region around the Eastern Himalayan Syntaxis, the squeezing of the Salween, Mekong and Yangtze rivers’ drainage basins in their middlestream, where numerous thrusts parallel to the river channels are observed, has been invoked as the key factor driving the river evolution. More to the east, in the Great Bends Region, no such squeezing of the drainage basins has been observed; the Yalong and Yangtze rivers flow perpendicularly across northeast-trending thrust belts, generating huge (>100 km) river course bends with steep channel slopes. These faults have significantly contributed to construct the high plateau margin, including the Yalong Thrust Belt (YTB), active during the Eocene (∼35–25 Ma) and reactivated in the Miocene (15–12 Ma). By applying state-of-the-art landscape modelling (FastScape) to the Yalong River catchment, with simplified rock uplift scenario deduced from fault activities, we show that strong monsoonal precipitation on the plateau (∼1 m/yr), even during only a short period such as the Mid–Miocene Climatic Optimum (17–14 Ma), produces wide rivers and destroys the plateau edge. In contrast, modelling the orographic effect with weak net precipitation (∼0.2 m/yr) above ∼2700 or 4000 m, preserves the plateau edge and reproduces the slope of the Yalong River, but with a width larger than in nature. To reproduce both the slope and narrowness of the Yalong gorge just upstream of the YTB, a combination of a rapid Miocene rock uplift leading to a regional surface uplift, which creates a significant orographic effect and preserves interfluve low-relief surfaces close to the plateau edge, and a water inflow in upstream, which deeply incises downstream river valleys, is necessary. Such an amount of upstream water is collected from the flat and expansive headwater, inherited from the inland endorheic zone of the plateau interior, on which the hillslope processes dominate the landscape evolution.

Distribution and Abundance of Microplastics in Underground Rivers in the South Malang Karst Area: First Evidence in Indonesia

Introduction: The presence of microplastics in the environment increases the diversity of types of pollutants in waters, including clean water sources on the surface and underground. Karst areas have unique hydrological characteristics, with cracks and fissures between the rocks that can be potential routes for the transport and accumulation of microplastics in underground river flows. In this study, we want to know the distribution and abundance of microplastics in underground rivers in the karst area of South Malang, Indonesia. Methods: Samples were collected purposively from underground river of Lowo, Banyu and Sengik. Microplastics were prepared using a diluted solvent of 30% H2SO4 and 30% H2O2. The sediment sample was dried and then filtered twice using 300-mesh size nylon filters until microplastic particles accumulated. Results and Discussion: Microplastics were detected in all water samples, with an average abundance ranging from 1.8 to 2.3 particles per liter. Fibers were the dominant microplastic type, followed by fragments and films, while the color distribution includes blue, white, red, yellow, black, green, pink, and brown. Conclusion: Microplastic contamination has been found in underground river flows in the karst area of South Malang, Indonesia. Karst soil, traditionally viewed as a natural filter, is not impervious to plastic pollution. This suggests significantly higher surface contamination than previously assumed. Therefore, reducing surface pollution is essential to safeguard the precious quality of underground aquifers and protect public health above.

Pollution Characteristics and Risk Assessment of Heavy Metals in the Sediments of the Inflow Rivers of Dianchi Lake, China.

To explore the contamination status and identify the source of the heavy metals in the sediments in the major inflow rivers of Dianchi Lake in China, sediment samples were collected and analyzed. Specifically, the distribution, source, water quality, and health risk assessment of the heavy metals were analyzed using correlation analysis (CA), principal component analysis (PCA), the heavy metal contamination factor (Cf), the pollution load index (PLI), and the potential ecological risk index (PERI). Additionally, the chemical fractions were analyzed for mobility characteristics. The results indicate that the average concentration of the heavy metals in the sediment ranked in the descending order of Zn > Cr > Cu > Pb > As > Ni > Cd > Hg, and most of the elements existed in less-mobile forms. The Cfwas in the order of Hg > Zn > Cd > As > Pb > Cr > Ni; the accumulation of Hg, Zn, Cd, and As was obvious. Although the spatial variability of the heavy metal contents was pronounced, the synthetical evaluation index of the PLI and PERI both reached a high pollution level. The PCA and CA results indicate that industrial, transportation, and agricultural emissions were the dominant factors causing heavy metal pollution. These results provide important data for improving water resource management efficiency and heavy metal pollution prevention in Dianchi Lake.

Effect of Acid Fluid on Deep Eocene Sweet Spot Reservoir of Steep Slope Zone in Lufeng Sag, Pearl River Mouth Basin, South China Sea

The Paleogene system of the Zhuyi Depression exhibits a pronounced mechanical compaction background. Despite this compaction, remarkable secondary porosity is observed in deep clastic rocks due to dissolution processes, with well-developed hydrocarbon reservoirs persisting in deeper strata. We conducted a comprehensive study utilising various analytical techniques to gain insights into the dissolution and transformation mechanisms of deep clastic rock reservoirs in the steep slope zone of the Lufeng Sag. The study encompassed the collection and analysis of the rock thin sections, XRD whole-rock mineralogy, and petrophysical properties from seven wells drilled into the Eocene. Our findings reveal that the nature of the parent rock, tuffaceous content, dominant sedimentary facies, and the thickness of individual sand bodies are crucial factors that influence the development of high-quality reservoirs under intense compaction conditions. Moreover, the sustained modification and efficient expulsion of organic–inorganic acidic fluids play a main role in forming secondary dissolution porosity zones within the En-4 Member of the LF X transition zone. Notably, it has been established that the front edge of the fan delta, the front of the thin layer, and the near margin of the thick layer of the braided river delta represent favorable zones for developing deep sweet-spot reservoirs. Furthermore, we have identified the LF X and LF Y areas as favourable exploration zones and established an Eocene petroleum-accumulation model. These insights will significantly aid in predicting high-quality dissolution reservoirs and facilitate deep oil and gas exploration efforts in the steep slope zone of the Zhuyi Depression.

Analysis of heavy metals in Ictalurus punctatus (channel catfish), Perca flavescens (yellow perch), and Aplodinotus grunniens (freshwater drum) in a Coastal Lake Michigan Watershed

Studies on metals in Great Lakes fish have focused typically on mercury (Hg), with less attention on other contaminants. Few studies exist on fish from drowned river mouths supplying the Great Lakes. This paper reports on metals in 3 common species, Ictalurus punctatus (channel catfish), Perca flavescens (yellow perch), and Aplodinotus grunniens (freshwater drum, a.k.a. sheep head) sampled from a coastal lake in West Michigan, USA. 135 fish were taken with pole and line methods from 6 different locations from July 2019–July 2021. Flank tissues were processed and analyzed by ICP-OES techniques for antimony (Sb), arsenic (As), barium (Ba), cadmium (Cd), cerium (Ce), chromium (Cr), copper (Cu), iron (Fe), lead (Pb), magnesium (Mg), manganese (Mn), nickel (Ni), selenium (Se), and zinc (Zn). Eight metals detected at quantifiable levels were Ba, Cr, Cu, Fe, Mg, Mn, Se, and Zn. Mg levels were the highest for all sites and all fish, with averages ranging from 300-1400 ppm (mg/kg of wet tissue). Zn concentrations ranged 11–21 ppm, Fe 4–14 ppm, Se 1–5 ppm, Mn about 0.4–1 ppm, and Cu below 1 ppm. Cr was only quantifiable in 34 % of the fish at <1 ppm, and Ba was detectable in 20 % of the fish, from approximately 0.1 to 4 ppm. Results were examined for statistically-significant differences between species and sites. Comparison of 3 species from one site showed sheep head had lower levels of all metals, except Fe, which were indistinguishable from perch. Cu was higher in catfish than perch, and Mn and Ba concentrations were lower in sheep head by 10× and 100×, respectively, when compared to other species. Zn, Mg, Fe, and Mn concentrations were different in perch from different sites; and, sheep head contained different concentrations of Se, Zn, Fe, Mn, Cr, Cu, and Ba between sites.

ХАРАКТЕРИСТИКА ПРИЛИВНЫХ ОСУШЕК В МЕЗОПРИЛИВНЫХ ЭСТУАРИЯХ РЕК БЕЛОГО МОРЯ НА ПРИМЕРЕ УСТЬЯ РЕКИ ПИЛЬЕМА В ОНЕЖСКОМ ЗАЛИВЕ

The biogeochemical characteristics of tidal drying in the estuary of the small Pilema River in the Onega Bay of the White Sea are considered based on observations made in October 2023. Here, mesotidal conditions are observed with a mean tidal range of 2.4 m at the entrance to the river mouth. Along the eastern shore of the estuary, anomalously high suspended sediment loads (356–692 mg/L) were observed due to stormy weather, but the estuarine section of the river, which is closed to developed wind disturbance, had relatively low suspended sediment loads (6–21 mg/L). The upper tidal drying zone was characterized by low values of benthic abundance, biomass and biodiversity, low projective cover of the bottom by algae, and insignificant concentrations of heavy metals such as cadmium, copper, lead and zinc. This situation is mainly due to active lithodynamic processes observed in this zone.

CHARACTERIZATION OF MICROPLASTICS IN MARINE SEDIMENTS FROM THE GULF OF TEHUANTEPEC, MEXICAN PACIFIC

Microplastics (MPs), a universal pollutant is widely distributed in sediments, which attracted the environmental researchers worldwide. MPs are harmful may adsorb toxic compounds present in the environment, which can be ingested by benthic organisms and easily transfer to humans. We investigated the distribution of MPs and its types in beach sediments from the Tehuantepec River mouth, Gulf of Tehuantepec, Mexican Pacific coast. MPs are categorized by their size, shape, color, and polymer types. 73 % of MPs detected are &lt; 5 mm in size. Fiber and colorless are mostly dominated in all samples. The fibers are weathered and degraded with adhered particles on their surfaces. The polymer types detected are polyacrylamide (PAM) and poly(methyl acrylate) (PMA), which are rarely reported in Mexico beach sediments. The prevalence of colorless MPs at the Gulf of Tehuantepec beach needs further attention.

Structural characteristics and development model of fluid diapirs within the structural transition zone, northern South China Sea

Fluid diapirs are widespread in the northern South China Sea (SCS), are significant indicators of the existence and distribution of hydrocarbons and natural gas hydrates and are of great petroleum geological significance. Based on high‐precision 3D seismic and drilling data, this paper analyses the tectonic features and genetic mechanism of a fluid diapir zone in the northern SCS and a development model of fluid diapirs is proposed herein. Studies have revealed that the northern SCS large‐scale fluid diapir zone is located within a concealed structural transition zone, which is consistent with the spatial distribution location and direction of a concealed structural transition zone and that the formation of a fluid diapir zone is strongly influenced by the structural transition zone. Fluid diapirs are large continuously spreading bright reflection zones in shallow surface layers and are downwards converging high‐variance ribbons in middle and shallow layers, all of which are spreading in a NW–NNW orientation on the plane. The profile shows a conical or mushroom‐shaped shape that converges from shallow to deep, with a height of approximately 7 km and is characterized by a compound gas chimney fuzzy zone. The main body of the concealed structural transition zone is a slope structure and is flanked by large‐scale NW–NNW‐oriented fault systems. Minor en echelon spreading NW–NNW‐oriented faults and fractures are developed within the structural transition zone and are soft linkages that match well with the distribution direction and location of the fluid diapirs. On the profile, the overall display is a composite flower‐like structure dispersed from deep to shallow, which belongs to a large strike‐slip fault zone with a tectonic transformation effect. A comprehensive analysis suggests that the formation and development of the structural transition zone are mainly controlled by pre‐existing structures in the basement and that minor faults, fractures and slope zones within the structural transition zone serve as dominant pathways for the migration of deep overpressure fluids and gas hydrates. Consequently, the concealed structural transition zone provides favourable conditions for fluid diapirs to develop. Moreover, the stratigraphic overpressure systems mainly caused by gas generation provided the main driving force for the formation of fluid diapirs. Obviously, the development location, distribution direction, formation and evolution of the northern SCS fluid diapirs are jointly controlled by internal minor faults and fractures of the Eocene‐Miocene structural transition zone and the overpressure of the rifting period after the Pliocene. The main development period of the northern SCS large‐scale fluid diapirs was the second phase of the Dongsha Movement. During the exploration of gas hydrates and hydrocarbons in the Pearl River Mouth Basin, it is essential to consider the mutually restricting relationships between fluid diapir structures and gas hydrates and hydrocarbons.

Deep dive into predictive excellence: Transformer's impact on groundwater level prediction

Groundwater, an essential water resource in Taiwan, is closely linked to land subsidence in the Zhuoshui River basin due to excessive exploitation. Therefore, there is a critical need for robust monitoring and predictive tools to facilitate effective management of water resources. Despite the success of Transformer neural networks in natural language processing, their potential in environmental research remains underexplored. This study explores the feasibility of employing a Transformer-based deep neural network to simultaneously predict groundwater levels at eight strategically positioned monitoring stations in the distal fan of the Zhuoshui River basin in central Taiwan. Utilizing a 20-year dataset with 10-day intervals, we compare the Transformer model with benchmarks established separately by the Convolutional Neural Network (CNN), the Long Short-Term Memory neural network (LSTM), and the Feedforward Neural Network (FFNN). Results reveal the Transformer's superior performance in predicting groundwater levels 10 and 20 days in advance. This achievement is attributed to Transformer's self-attention mechanism capable of capturing relationships between factors like rainfall and river flow, enhancing accuracy in predicting trends and peak values. This groundbreaking study underscores the Transformer model's efficacy in groundwater level prediction, emphasizing its significance for sustainable water resource management amid climate change. The findings open new avenues for environmental research and water resource management, not only in Taiwan but also globally.

Use of one-dimensional CNN for input data size reduction in LSTM for improved computational efficiency and accuracy in hourly rainfall-runoff modeling

A deep learning architecture, denoted as CNNsLSTM, is proposed for hourly rainfall–runoff modeling in this study. The architecture involves a serial coupling of the one-dimensional convolutional neural network (1D-CNN) and the long short-term memory (LSTM) network. In the proposed framework, multiple layers of the CNN component process long-term hourly meteorological time series data, while the LSTM component handles short-term meteorological time series data and utilizes the extracted features from the 1D-CNN. In order to demonstrate the effectiveness of the proposed approach, it was implemented for hourly rainfall–runoff modeling in the Ishikari River watershed, Japan. A meteorological dataset, including precipitation, air temperature, evapotranspiration, longwave radiation, and shortwave radiation, was utilized as input. The results of the proposed approach (CNNsLSTM) were compared with those of previously proposed deep learning approaches used in hydrologic modeling, such as 1D-CNN, LSTM with only hourly inputs (LSTMwHour), a parallel architecture of 1D-CNN and LSTM (CNNpLSTM), and the LSTM architecture, which uses both daily and hourly input data (LSTMwDpH). Meteorological and runoff datasets were separated into training, validation, and test periods to train the deep learning model without overfitting, and evaluate the model with an independent dataset. The proposed approach clearly improved estimation accuracy compared to previously utilized deep learning approaches in rainfall = runoff modeling. In comparison with the observed flows, the median values of the Nash–Sutcliffe efficiency for the test period were 0.455–0.469 for 1D-CNN, 0.639–0.656 for CNNpLSTM, 0.745 for LSTMwHour, 0.831 for LSTMwDpH, and 0.865–0.873 for the proposed CNNsLSTM. Furthermore, the proposed CNNsLSTM reduced the median root mean square error (RMSE) of 1D-CNN by 50.2%–51.4%, CNNpLSTM by 37.4%–40.8%, LSTMwHour by 27.3%–29.5%, and LSTMwDpH by 10.6%–13.4%. Particularly, the proposed CNNsLSTM improved the estimations for high flows (≧75th percentile) and peak flows (≧95th percentile). The computational speed of LSTMwDpH is the fastest among the five architectures. Although the computation speed of CNNsLSTM is slower than LSTMwDpH's, it is still 6.9–7.9 times faster than that of LSTMwHour. Therefore, the proposed CNNsLSTM would be an effective approach for flood management and hydraulic structure design, mainly under climate change conditions that require estimating hourly river flows using meteorological datasets.

Analyzing microbial communities and metabolic functions in estuaries affected by human activity to uncover bioelectrochemical system potential

In the context of bioelectrochemical systems (BES), a profound understanding of the taxonomic composition within indigenous microbial communities is crucial. Their metabolic versatility assumes a foundational role in dictating the functionality of BES, yielding diverse applications for bioenergy production and bioremediation in anthropogenically impacted estuaries. Employing high-throughput sequencing of the V3-V4 region of 16S rRNA and predictive metagenomic analyses of three different estuaries samples (eutrophicated urban reservoir, mud volcano impacted river, and its river mouth), this study delves into the intricate interplay between these communities and their metabolic functions in response to human-induced perturbations, with a specific focus on their applicability to BES. Our findings illuminate remarkable distinctions among the three samples, manifesting in variations in microbial composition and functional metabolic pathways within the respective ecosystems. The mud volcano-affected river, characterized by the highest microbial diversity, exhibited the most diverse array of functional metabolic processes, prominently dominated by chemoheterotrophy (67.43%). In contrast, the river mouth displayed a distinct penchant for autotrophy (33.33%). The eutrophicated urban reservoir showcased a balanced coexistence of chemoheterotrophy (41.18%) and autotrophy (35.29%). Regarding metabolic potential for BES application, most of metabolism potential were associated with anodic activity, while cathodic activity was restricted to autotrophy and its relatives. The results suggested that the microbial communities anthropogenically impacted estuaries were potentially used for anodic and cathodic reactions in BES as electrogens to generate bioelectricity and reduce of pollutants.

Suspended particulate matter response to extreme forcings in the Bay of Seine

The latest Intergovernmental Panel on Climate Change report of 2023 alerts about an increase in the occurrence and intensity of extreme hydro-meteorological events such as storms and extreme river flows, i.e. drought and floods. Investigating the occurrence of these extreme events in the past 15 years and their impacts on sediment dynamics will provide crucial knowledge for anticipating future trajectories of coastal ecosystems. Time series from in situ observations are analyzed to identify extreme events of river flows and waves and examine their impact on Suspended Particulate Matter (SPM) dynamics in a highly turbid coastal area equipped with a high frequency in situ monitoring station at the interface between the Seine Estuary and the Bay of Seine (northern coast of France). Extreme river flow and wave orbital velocity events are investigated because high river discharge contributes to deliver large amounts of SPM concentration to the bay and strong wave action within the bay can lead to erosion and resuspension of bottom sediments. An original detection method is proposed, based on high frequency in situ observations combined with satellite and model data from 2006 to 2022. Extreme forcings are examined through their specific characteristics (high intensity, long duration, season of occurrence, succession of events), their impact on SPM concentration in the coastal environment and the comparison to mean seasonal dynamics. A positive relationship exists between SPM concentration and high SPM spatial extent and forcing intensity. Extremes are more intense in winter for both forcings and generate larger SPM concentration anomalies. However, extreme events during late spring/summer, periods or mean low forcing intensity, are demonstrated to generate SPM concentration anomalies up to 4 times larger than the monthly mean value, hence possibly strongly impacting the system during these atypical periods. This is particularly important as analyzing the distribution of extreme river flow events over the last 60 years indicated an increase in their occurrence and more important the progressive occurrence of high intensity extreme events during spring/summer periods.