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Floodplains are unique environments that provide a dynamic link between terrestrial and aquatic systems. Intensification of human activity – particularly agriculture and urbanisation – has resulted in the degradation of floodplains worldwide. Restoration and sustainable management of floodplains requires holistic assessment and compromise between stakeholders to successfully balance environmental, economic, and social benefits. Yet, understanding these complex systems sufficiently to provide evidence-based recommendations is a challenge. We present the lessons learned from establishing an interdisciplinary research-based framework on the agricultural floodplain of Lake Saint Pierre, Québec, Canada, whose mandate was to a) understand and define key environmental, agricultural, and socioeconomic attributes of the landscape, b) quantify the trade-offs and synergies between these attributes across different agricultural practices, regions, and land uses, and c) explore novel agri-environmental management practices to assess their role in sustainable floodplain management. Within this manuscript, we explore the benefits that such an approach offers in evaluating sustainable floodplain land use. We found that an interdisciplinary research-based approach demonstrated important benefits such as knowledge transfer, more efficient use of resources (e.g., personnel, funding), and a flexible yet robust research framework. A framework of individual research projects connected to broader interdisciplinary themes allowed a more holistic synthesis of the floodplain systems and assessment of agri-environmental practices. By implicitly considering spatial and social scales, we conceptualised not just how redistribution of the land use types can meet sustainable management objectives, but also explored how compromises within existing uses can optimise socio-economic, agricultural and environmental dimensions and move towards a sustainable multifunctional landscape. [ABSTRACT FROM AUTHOR]

Hydrological drought and river disconnectivity worsen from dams and human activities. This research investigates how dam constructions exacerbate hydrological drought and river disconnectivity in Apalachicola River system. Data from two hydrological stations (1928-2022), a hydrographic survey, high-resolution LiDAR, and a triangular irregular network (TIN) were used to identify three connectivity flow (141.5 m3/s, 169.8 m3/s, and 226.4 m3/s) categories, each impacting floodplain differently. A relative elevation model (REM) was also developed for floodplain connectivity assessment. Findings show a significant increase in the frequency, duration, and magnitude of connectivity low flow events from pre-dam to post-dam periods, especially at the 169.8 m³/s connectivity flow threshold. A 20th percentile variable threshold shows increasing hydrological drought. Drought increases have led to decreased connectivity between tributaries and the main river system, and an increase in the moderately disconnected floodplain area from 37.1% to 46.0%. Adaptive management strategies are needed to address drought-induced floodplain disconnectivity [ABSTRACT FROM AUTHOR]

The maternal roosting behavior of migratory, tree‐dwelling bat species remains poorly understood. From 2016 to 2020 we radio‐tagged 53 adult female silver‐haired bats (Lasionycteris noctivagans) and tracked them to their day roosts to evaluate roosting habits in a cottonwood (Populus) forest in the floodplain of the Bitterroot River in western Montana. We investigated roost tree characteristics of maternity colonies such as canopy closure, tree size, and decay stage, as well as the daily roost fidelity of tagged bats. Additionally, we marked 55 bats with passive integrated transponder (PIT) tags to assess interannual fidelity to summer habitat. We tracked bats to 94 unique roost trees. Based on previous studies, we expected silver‐haired bat maternity colonies to roost in tall, large diameter trees. We modeled roosting probability as a function of tree height, day of year, and the interaction of these terms. We found bats preferred taller trees earlier in the year, but overall roosting probability decreased throughout the season and tree height had lesser influence on roosting probability later in the year. Bats used tall trees with high canopy closure in early stages of decay during periods of pregnancy and lactation, while the effect of these tree attributes lessened later in the season, perhaps after lactation when energetic constraints were reduced for adult females to prepare for migration by entering torpor during the day. Bats used an average of 5.2 roost trees during the young rearing period and remained in the same roost for an average of 1.5 consecutive days. While daily roost fidelity was low, we documented interannual fidelity to summer habitat from nine individuals. We found silver‐haired bat roosting preferences vary with time, are tree‐specific, and policies targeting conservation of the species should manage flood regimes to promote cottonwood establishment, height growth, and a mosaic of riparian habitats. [ABSTRACT FROM AUTHOR]

Sedimentation traps were used to assess the annual surface renewal dynamics of the low floodplain of the Oka River (a major tributary of the Volga River in central European Russia). Trap-mats and platforms made of crushed bricks were installed in positions near the meandering and relatively straight riverbed, in different sedimentation environments. Stationary research in 2014–2020 covered a section of the bottom of the Oka River valley with a length of more than 400 km along the main channel. The graphical-analytical processing of field data using Ferret's Triangles and sedimentation diagrams showed that transport and deposition of suspended sediment dominated in the accumulation of 87% of alluvium samples. The formation of ripples was not recorded, which was lithologically reflected in the horizontal layering of the new sediment. The determination of the granulometric composition of the removed sediment and their thickness on the traps showed the absence of statistically significant differences according to the Kruskal–Wallis test between the data samples from the trap-mats and trap-platforms. The reference to the daily calendar of synoptic mechanisms according to the classification of Dzerdzeevsky contributed to the identification of meteorological prerequisites for the variation of the hydrograph curve of the Oka River in its middle reaches. Prolonged floods caused by the premature arrival of spring lead to massive deposition of silt and clay particles even on sandbanks. On the other hand, short (15–35 d) March floods and abnormal high water in June, caused by Atlantic cyclone intrusions, can stabilize sand accumulation on the riverine floodplain. The thickest sediment layers on the traps were obtained in 2018 after a very cold March and a powerful April flood, and the overall distribution of alluvium thickness and its particle size distribution also depends on the morphology of the riverine relief. The siltation is caused by the accumulation of silts; the most finely dispersed sediment was deposited in those facies environments for which siltation was also characteristic in historical times. [ABSTRACT FROM AUTHOR]

Riverine floodplains are ecologically remarkable systems that have historically faced strong anthropogenic pressures. The aim of this study was to examine whether the phytoplankton functional approach by Reynolds is a useful tool for disentangling anthropogenic pressure from the impact of natural flooding on a riverine floodplain lake. Lake Sakadaš, part of the large conserved river–floodplain system along the Danube River (Kopački Rit, Croatia), was used as a case study. Historical data on phytoplankton dynamics from the 1970s, when the lake was exposed to direct inflows of agricultural wastewater, were compared with current data from a time when the lake was a strongly protected area. Analysis of the phytoplankton community, based on functional groups and their beta diversities, revealed clear variation between the observed periods. The heavy bloom of species from only one functional group with extremely high biomass indicated a highly impacted environment in the past. Recent data suggest that, with the cessation of direct pollution, near-natural hydrological conditions with flooding as a fundamental environmental driving factor, support algal assemblages characteristic of a naturally eutrophic lake. Assessing multiple pressures on floodplain lakes and disentangling their specific impacts on ecological statuses are crucial for defining the protection and sustainable management of these particularly sensitive and endangered freshwater systems. [ABSTRACT FROM AUTHOR]

Highlights: A LightGBM-based water level prediction model was developed for floodplain lakes. The RMSE values of the model's one-day-ahead prediction range from 0.09 to 0.10 m. The rank of the driving factors of Poyang Lake water level change was identified. Timely and accurate prediction of water levels is crucial for managing floodplain lakes with important ecosystem services, especially for flood prevention. Floodplain lakes are hydrologically complex and incredibly variable systems. Their water levels respond nonlinearly to external disturbances, complicating their prediction. Machine learning methods, especially the ensemble learning strategy, provide an excellent choice for solving such nonlinear problems. Based on the Light Gradient Boosting Machine (LightGBM) method, a water level prediction model was developed for Poyang Lake, the largest freshwater lake in China, featuring seasonal flooding and drying under strong river-lake interaction. Daily lake water levels at typical stations and discharge of the Yangtze River and the five main inflowing rivers from 2003 to 2019 were collected for training and testing the proposed model. Combinations of input variables are important for the model performance. The past information of water levels in Poyang Lake can improve the prediction accuracy significantly. Compared with the predictions without considering past water level information, the root mean square error values of the model considering past water levels have decreased from 0.49 to 0.62 m to 0.09–0.10 m for one-day ahead prediction. Therefore, the proposed model with optimized input variables can be an effective tool for the water level prediction of floodplain lakes. Note that the prediction accuracy decreases with the extension of the prediction period. Importance rank analysis shows that the water levels at different typical stations of Poyang Lake have diverse responses to the Yangtze River and the main five inflowing rivers, providing new insights into river-lake interaction. It also implied that the lake regulation should be deliberately conducted for such a large lake with a complex flow regime. [ABSTRACT FROM AUTHOR]

Based on stationary and expeditionary hydrological data and information about the water management complex and volumes of water use, we have calculated for the first time the minimum permissible, average, and optimal hydrographs (in monthly increments) of the influx of Ural waters from Russia to the West Kazakhstan and Atyrau regions, which would not limit the functioning of the main participants of the Kazakhstan water management complex, would not deteriorate the quality of life of the population and existence conditions for aquatic and near-water biocenoses, and would preserve the river as a hydrographic object. The resulting hydrographs summarize (1) the values of current and future water consumption in the cities of Uralsk and Atyrau and numerous rural settlements, as well as water intake by irrigation and water supply canals, including the Kushum Canal; (2) the needs of river navigation for controlling depths and continuous navigation from May to October; (3) the environmental flow necessary for the reproduction of sturgeon fish species and the preservation of the bioproductivity and biodiversity of floodplain ecosystems. The latter element required nonstandard solutions, including those based on the existing domestic approaches to determining critical and optimal values (with respect to floodplain–channel ecosystems) values. Another and completely new result of this research is analysis of the long-term dynamics of maximum and minimum levels in the lower reaches of the Ural River and the frequency, duration, and depth of floodplain flooding. [ABSTRACT FROM AUTHOR]

Context: Floodplain inundation creates a diversity of aquatic habitats that diverge in their physical, chemical and biological characteristics through space and time, influencing site-scale ecological processes, with implications for local and landscape-scale ecosystem functioning. Aims: In this study, we characterise conditions of pools on the floodplain and pools in the main channel of the Fitzroy River, north-western Australia. Methods: We used linear models to investigate the spatial and temporal dynamics of top–down and bottom–up forces acting on phytoplankton and zooplankton. Key results: Floodplain pools showed considerable heterogeneity compared with the main channel and were shallow and turbid with high nutrient loads, whereas main-channel pools were deep, clear and nutrient-limited. Phytoplankton and zooplankton biomass (mass per unit volume) were considerably greater and more variable in floodplain pools than in the main channel, where both were largely absent. On the floodplain, bottom–up processes drove water-column productivity (e.g. nutrients to phytoplankton to zooplankton) to a degree not observed in the main channel, providing a valuable resource pathway supporting consumer populations locally and catchment wide. We detected no top–down effects in floodplain pools and no top–down or bottom–up effects in the main channel. Conclusion: Maintaining flows that inundate the floodplain and promote habitat heterogeneity in the Fitzroy River is crucial for preserving local and landscape-scale ecosystem functioning. Implications: Water managers should take into account the important contribution of floodplain pools to the wider riverine ecosystem and ensure these habitats are not unduely affected by water resource development. Seasonal flooding promotes habitat diversity that influences biodiversity and ecological processes in river–floodplain ecosystems. We demonstrated that environmental conditions in floodplain pools on the Fitzroy River (WA) vary substantially compared with the main channel, providing an important habitat for organisms that contribute to landscape-scale ecosystem function. Floodplain pools fill a unique role in the wider river–floodplain ecosystem and should be protected from negative effects of water development. [ABSTRACT FROM AUTHOR]

The Belá River is a specific submountain river running through the Liptov Basin in the Slovak Carpathians. Its transformation from a braided to a braided-wandering system and degradation including incision of the river system has been observed since the middle of the 20th century. These processes have created a complex system of floodplains with development stages. For their identification, the Relative Elevation Model normalizing absolute floodplain elevation to the river channel changes has been established. Three models have been prepared, from the channel bottom and water level elevation gauge by GPS, and the water level elevation by LiDAR. Based on the resulting models, the floodplain was identified and delineated to an active or potentially active floodplain, to an inaccessible floodplain spread behind artificial structures, and to a perched floodplain beyond the reach of the river. Spatial statistics, including "Hot spot analysis" and "Cluster and outlier analysis" have been used to identify recent river floodplain formation from 1949 to 2018, caused by simplification and incision of the Belá River. The unique aspect and contribution of the research lies in implementing and comparing the Relative Elevation Models and linking them to floodplain age. [ABSTRACT FROM AUTHOR]

The loss of lateral hydrological connectivity (LLHC) in freshwater ecosystems is increasingly threatening biodiversity; however, studies reporting this situation are limited, especially those assessing multi‐measure biodiversity features at large spatial scales.Here, and using one the most threatened taxonomic groups in freshwater ecosystems, we examined the possible influence of LLHC on the species diversity, density, and biomass of mussel assemblages and the genetic diversity and structure of Nodularia douglasiae (a common and widespread native species) in the Yangtze River floodplain.Results showed that the species diversity of freshwater mussels (α and β diversity) significantly differed between the connected and the disconnected areas, with higher α diversity and lower β diversity in the connected areas. At the same time, relative abundance, density, biomass, and genetic diversity of freshwater mussels were higher in the connected areas. High genetic differentiation and low gene flow were found among the 18 analysed N. douglasiae populations, indicating that LLHC is affecting genetic structure of this particular freshwater mussel species.Overall, results indicated that river–lake connectivity is affecting freshwater mussel biodiversity. In addition, this study highlights that multi‐measure biodiversity features provide distinct information about biodiversity dynamics, and are essential to evaluate the effects of floodplain disconnection. We advocate that an integrative approach to floodplain management embracing species and genetic diversity is needed for effective biodiversity conservation in large river ecosystems. [ABSTRACT FROM AUTHOR]

Catchment‐scale sediment storage is conceptualized as increasing in magnitude downstream, although reach‐scale controls may override this trend. We use empirical data from a literature review and two numerical models to quantitatively estimate sediment storage across the Colorado River Basin, USA. We use assumed alluvial thickness with floodplains delineated in the GFPLAIN model from 30 m digital elevation models. We use the SWAT+ model based on model‐estimated (i) groundwater storage and (ii) sediment storage. Existing studies indicate that sediment stored in floodplains and on low terraces is ~0.3–6 m thick. A first‐order approximation of volumetric storage capacity for natural floodplains is ~105 m3 per km. Sediment storage volumes of floodplains are ~108–1011 m3 over river lengths of 101–103 m. For the modeling estimates, we evaluated sediment storage by stream order and by elevation band within the Upper and Lower Colorado River Basins. Comparisons among the outputs cause us to place more confidence in the GFPLAIN and SWAT+ aquifer volume estimates. Each method includes substantial uncertainty and constitutes a first‐order approximation. Results suggest using 21 and 130 billion cubic meters as approximate lower and upper bounds for total sediment storage in the Upper Basin and 314 and 482 billion cubic meters as approximate lower and upper bounds for the Lower Basin. The largest proportion of sediment is stored in the montane and steppe zones in the Upper Basin and in the Sonoran zone in the Lower Basin. [ABSTRACT FROM AUTHOR]

Floodplains are essential ecosystems that provide a variety of economic, hydrologic, and ecologic services. Within floodplains, surface water‐groundwater exchange plays an important role in facilitating biogeochemical processes and can have a strong influence on stream hydrology through infiltration or discharge of water. These functions can be difficult to assess due to the heterogeneity of floodplains and monitoring constraints, so numerical models are useful tools to estimate fluxes, especially at large spatial extents. In this study, we use the SWAT+ (Soil and Water Assessment Tool) ecohydrological model to quantify magnitudes and spatiotemporal patterns of floodplain surface water‐groundwater exchange in a mountainous watershed using an updated version of the gwflow module that directly calculates floodplain‐aquifer exchange rates during periods of floodplain inundation. The gwflow module is a spatially distributed groundwater modelling subroutine within the SWAT+ code that uses a gridded network and physically based equations to predict groundwater storage, groundwater head, and groundwater fluxes. We used SWAT+ to model the 7516 km2 Colorado River headwaters watershed and streamflow data from USGS gages for calibration and testing. Models that included floodplain‐groundwater interactions outperformed those without such interactions and provided valuable information about floodplain exchange rates and volumes. Our analyses on the location of floodplain fluxes in the watershed also show that wider areas of floodplains, "beads" (e.g., like beads on a necklace), exchanged a higher net and per area volume of water, as well as higher rates of exchange, compared to narrower areas, "strings." Study results show that floodplain channel‐groundwater exchange is a valuable process to include in hydrologic models, and model outputs could inform land conservation practises by indicating priority locations, such as beads, where substantial hydrologic exchange occurs. [ABSTRACT FROM AUTHOR]

Floods stand out as one of the most devastating environmental threats worldwide resulting in the tragic loss of human lives and significant damage to our essential infrastructure. This study focuses on creating floodplain maps for the two important reaches of Swat River in the Khyber Pakhtunkhwa Province of Pakistan, namely, Kalam–Khwazakhela and Khwazakhela–Chakdara reaches. The Advanced Land Observing Satellite Phased Array Type L-band Synthetic Aperture Radar (ALOS PALSAR) 12.5 m Digital Elevation Model (DEM) data has been used for this purpose. Furthermore, the sensitivity of the flood model was assessed for the Flood 2022 event, considering simulated flood depth, extent, and velocity in relation to various terrains derived from the 12.5-m ALOS PALSAR data. To estimate extreme flows for different return periods (2, 5, 10, 25, 50, and 100 years), the Log Normal (LN), Log Pearson III (LP3), and Generalized Extreme Value (GEV) distributions were employed for the frequency analysis. The GEV distribution turned out to be the best fit for modeling the Swat River for both the Chakdara and Khwazakhela gauge stations. To predict flood levels for the peak floods identified through frequency analysis and for the specific return periods the Hydrologic Engineering Center's River Analysis System (HEC-RAS) 2D simulations were performed. Subsequently the outcomes of this model were used to create floodplain maps using Geographic Information System Professional (ArcGIS Pro) software customized for various return periods. The analysis revealed a linear increase in flood inundation area with longer return periods. The floodplain maps developed hold significant importance for the governing authorities of the Swat region. These maps serve as essential tools for implementing proactive measures against potential infrastructure damage, thereby protecting against economic losses and enhancing public safety. This research effectively combines hydrological modeling and geospatial technology offering practical solutions for managing flood risks. It serves as a valuable guide for making well-informed decisions and promoting sustainable development in flood-prone areas. [ABSTRACT FROM AUTHOR]

Floodplains are unique environments that provide a dynamic link between terrestrial and aquatic systems. Intensification of human activity – particularly agriculture and urbanisation – has resulted in the degradation of floodplains worldwide. Restoration and sustainable management of floodplains requires holistic assessment and compromise between stakeholders to successfully balance environmental, economic, and social benefits. Yet, understanding these complex systems sufficiently to provide evidence-based recommendations is a challenge. We present the lessons learned from establishing an interdisciplinary research-based framework on the agricultural floodplain of Lake Saint Pierre, Québec, Canada, whose mandate was to a) understand and define key environmental, agricultural, and socioeconomic attributes of the landscape, b) quantify the trade-offs and synergies between these attributes across different agricultural practices, regions, and land uses, and c) explore novel agri-environmental management practices to assess their role in sustainable floodplain management. Within this manuscript, we explore the benefits that such an approach offers in evaluating sustainable floodplain land use. We found that an interdisciplinary research-based approach demonstrated important benefits such as knowledge transfer, more efficient use of resources (e.g., personnel, funding), and a flexible yet robust research framework. A framework of individual research projects connected to broader interdisciplinary themes allowed a more holistic synthesis of the floodplain systems and assessment of agri-environmental practices. By implicitly considering spatial and social scales, we conceptualised not just how redistribution of the land use types can meet sustainable management objectives, but also explored how compromises within existing uses can optimise socio-economic, agricultural and environmental dimensions and move towards a sustainable multifunctional landscape.

Understanding the relative importance of the factors that drive global patterns of biodiversity is among the major topics of ecological and biogeographic research. In freshwater bodies, spatial, temporal, abiotic, and biotic factors are important structurers of these ecosystems and can trigger distinct responses according to the facet of biodiversity considered. The objective was to evaluate how different facets of β-diversity (taxonomic, functional, and phylogenetic) based on data from the planktonic ciliate community of a Neotropical floodplain, are influenced by temporal, spatial, abiotic, and biotic factors. The research was conducted in the upper Paraná River floodplain between the years 2010 and 2020 in different water bodies. All predictors showed significant importance on the facets of β-diversity, except the abiotic predictors on species composition data, for the taxonomic facet. The functional and phylogenetic facets were mostly influenced by abiotic, biotic, and spatial factors. For temporal predictors, results showed influence on taxonomic (structure and composition data) and functional (structure data) facets. Also, a fraction of shared explanation between the temporal and abiotic components was observed for the distinct facets. Significant declines in β-diversity in continental ecosystems have been evidenced, especially those with drastic implications for ecosystemic services. Therefore, the preservation of a high level of diversity in water bodies, also involving phylogenetic and functional facets, should be a priority in conservation plans and goals, to ensure the maintenance of important ecological processes involving ciliates. [ABSTRACT FROM AUTHOR]

Abstract The long-term interaction between the environment and humans has significantly shaped contemporary landscapes worldwide. As a heritage landscape, the polder is essential for understanding the impact of the past human activities on contemporary landscape on low-lying area of land. In this case study, we reconstructed the regional spatial distribution of the polders in the early twentieth century and examined their coherence over the past century using historical maps and other materials in the Jianghan Plain. The results revealed several key findings: (1) In the early twentieth century, there were 1571 polders covering an area of 11,826.1 km2 with a perimeter of 17,035.9 km. (2) These polders exhibited a J-shaped distribution, with few large-scale polders despite their substantial areas. (3) The shape of these polders reflected an ability to balance human needs and the natural environment. (4) Considerable regional differences in these polders were attributed to centuries-old interactions between humans and the environment. (5) The remnants of these early twentieth century polders have had a lasting influence on the contemporary landscape, particularly in rural areas. This case study underscores how taking into account a broader historical perspective can enhance our understanding of present-day landscapes and, more importantly, the role that past human actions have played in shaping them.

Abstract Between 2013 and 2017, we carried out nine field missions in the Lago Grande de Curuai floodplain, located in Pará state – North of Brazil – to collect samples for monitoring surface water quality. This site separated from the river by a narrow bank is composed of a network of channels and shallow lakes, a morphology shared by the floodplains of the lower Amazon. A multiparameter probe was used in situ to measure electrical conductivity, temperature, pH, dissolved oxygen, chlorophyll, turbidity, depth and a Secchi disk to estimate transparency. Water grab samples were analysed for suspended material, alkalinity, humic acid, phosphorus, nitrogen, carbon and chlorophyll. Sampling stations were distributed over the seven larger lakes in the floodplain and sampled at different periods of the hydrological cycle. The number of samples varied with the floodplain water level, with a minimum of 25 samples for each field visit. This data set is a collection of water quality data to assist in the limnological or biogeochemical studies of surface waters in Amazonian floodplain lakes, and the product of successive French‐Brazilian projects: (1) the Clim‐FABIAM ‘Climate changes and Floodplain lake biodiversity in the Amazon Basin: how to cope and help the ecological and economic sustainability’ funded by the French Foundation for biodiversity research (FRB), (2) the project Bloom‐ALERT –‘Environmental sensitivity and population health vulnerability to cyanobacteria in the Amazon: towards shared indicators’ funded by the French‐Brazilian research program GUYAMAZON 2014, and the project (3) ‘Ecossistemas das várzeas e biodiversidade: Impactos das mudanças ambientais e climáticas considerando cenários de desenvolvimento sustentáveis’ (Project number 490634/2013‐3) funded by the Brazilian National scientific Research Council CNPq.

Reliable indicators of success are needed to monitor the process of reclaiming disturbed land in order to understand the achievement of reclamation objectives. The formation of coherent dynamics of vegetation and soil development is ultimately a crucial condition for the success of reclaiming territory disturbed by surface mining and the possibility of using reclaimed land in agricultural production. The study revealed a relationship between the phytoindicator of vegetation hemeroby and the physical properties of technosols to prove its application as a measure of the restoration of the disturbed ecosystem in the reclamation process. The plant communities were classified into beta-, alpha-euhemerobic, polyhemerobic and metahemerobic levels of anthropogenic transformation. The technosols varied in the proportion of hemeroby levels of plant communities. The hemeroby level was consistent with the physical properties of technosols. A decrease in hemeroby level resulted in increased soil electrical conductivity, decreased soil penetration resistance and altered soil aggregate structure. The hemeroby of plant communities is a dependable phytoindicator of ecosystem restoration during reclamation.

Tropical wetlands account for ∼20% of the global total methane (CH4) emissions, but uncertainties remain in emission estimation due to the inaccurate representation of wetland spatiotemporal variations. Based on the latest satellite observational inundation data, we constructed a model to map the long‐term time series of wetland extents over the Sudd floodplain, which has recently been identified as an important source of wetland CH4 emissions. Our analysis reveals an annual, total wetland extent of 5.73 ± 2.05 × 104 km2 for 2003–2022, with a notable accelerated expansion rate of 1.19 × 104 km2 yr−1 during 2019–2022 driven by anomalous upstream precipitation patterns. We found that current wetland products generally report smaller wetland areas, resulting in a systematic underestimation of wetland CH4 emissions from the Sudd wetland. Our study highlights the pivotal role of comprehensively characterizing the seasonal and interannual dynamics of wetland extent to accurately estimate CH4 emissions from tropical floodplains. Plain Language Summary: Methane (CH4) plays an important role in global warming. About one‐fifth of global CH4 emissions come from tropical wetlands, with the Sudd wetland in tropical Africa presenting as a hotspot for CH4 emissions. In this study, we generate a monthly wetland map series based on the latest satellite observation for the Sudd wetland. Our results show that wetland area dynamics present large seasonal and interannual variabilities. However, current widely used wetland products tend to indicate smaller sizes and variations of wetlands, which might lead to the underestimation of wetland CH4 emissions. We point out that refined maps of tropical wetlands can help reduce the uncertainties of CH4 emission estimations. Key Points: Extended monthly inundation maps across the Sudd wetland for 2003–2022Rapid growth of the Sudd wetland extent for 2019–2022 driven by upstream precipitationUnderestimation of methane emissions from the Sudd wetland due to the inadequate characterization of wetland extent [ABSTRACT FROM AUTHOR]

The long-term interaction between the environment and humans has significantly shaped contemporary landscapes worldwide. As a heritage landscape, the polder is essential for understanding the impact of the past human activities on contemporary landscape on low-lying area of land. In this case study, we reconstructed the regional spatial distribution of the polders in the early twentieth century and examined their coherence over the past century using historical maps and other materials in the Jianghan Plain. The results revealed several key findings: (1) In the early twentieth century, there were 1571 polders covering an area of 11,826.1 km2 with a perimeter of 17,035.9 km. (2) These polders exhibited a J-shaped distribution, with few large-scale polders despite their substantial areas. (3) The shape of these polders reflected an ability to balance human needs and the natural environment. (4) Considerable regional differences in these polders were attributed to centuries-old interactions between humans and the environment. (5) The remnants of these early twentieth century polders have had a lasting influence on the contemporary landscape, particularly in rural areas. This case study underscores how taking into account a broader historical perspective can enhance our understanding of present-day landscapes and, more importantly, the role that past human actions have played in shaping them. [ABSTRACT FROM AUTHOR]

Arsenic (As) contamination in groundwater represents a major global health threat, potentially impacting billions of individuals. Elevated As concentrations are found in river floodplains across south and southeast Asia, as well as in the inland basins of China, despite varying sedimentological and hydrogeochemical conditions. The specific mechanisms responsible for these high As levels remain poorly understood, complicating efforts to predict and manage the contamination. Applying hydro-chemical, geological, and soil parameters as explanatory variables, this study employs multiple linear regression (MLIR) and random forest regression (RFR) models to estimate groundwater As concentrations in these regions. Additionally, random forest classification (RFC) and multivariate logistic regression (MLOR) models are applied to predict the probability of As levels exceeding 10 μg/L in the Hetao Basin (China) and Bangladesh. Model validation reveals that RFR explains 80% and 70% of spatial variability of As concentration in the Hetao Basin and Bangladesh, respectively, outperforming MLIR, which accounts for only 35% and 32%. Similarly, RFC outperforms MLOR in predicting high As probability, achieving correct classification rates of 98.70% (Hetao Basin) and 98.25% (Bangladesh) on training datasets, and 82.76% (Hetao Basin) and 91.20% (Bangladesh) on validation datasets. The performance of the MLOR model on the validation set yields accuracy rates of 81.60% and 72.18%, respectively. In the Hetao Basin, Ca2+, redox potential (Eh), Fe, pH, SO42−, and Cl− are key predictors of As contamination, while in Bangladesh, soil organic carbon (SOC), pH, and SO42− are significant predictors. This study underscores the potential of random forest (RF) models as robust tools for predicting groundwater As contamination. [ABSTRACT FROM AUTHOR]

Vertical heterogeneity in lakes and estuaries can present cold‐adapted fishes with a temperature–oxygen squeeze, such that the epilimnion is stressfully warm and the cooler hypolimnion is hypoxic, thereby restricting fishes to the metalimnion. In temperate floodplain rivers, patches of lentic habitat (e.g., alcoves) have the potential to provide thermal refuge for cold‐water fishes during summer, but little is known about whether these smaller habitat features present fish with temperature–oxygen constraints. In this study, we measured temperature and oxygen profiles in six cold‐water alcoves on the Willamette River floodplain (Oregon, U.S.A.) to characterise potential trade‐offs in temperature and oxygen for a cold‐water fish, coastal cutthroat trout (Oncorhynchus clarkii clarkii).To evaluate how fish responded to trade‐offs, we used synergistic methods (needle probe thermocouple, surgically implanted iButtons, and external temperature transmitting radio tags) to monitor fish body temperatures at different temporal scales and compare them to temperature–depth profiles.The cold‐water alcoves displayed a linear relationship between dissolved oxygen and temperature, where cooler temperatures came at the expense of reduced oxygen. Fish body temperatures were intermediate to temperatures recorded at the surface and bottom of the alcove. The span of depths selected by these fish represents less than 20% of the available vertical habitat in these alcoves.These results demonstrate that refuges formed by cool hyporheic upwelling can generate a temperature–oxygen squeeze where fish use only a subset of the refuge habitat feature. Oxygen constraints on thermal refuge use may be a blind spot for climate adaptation planning for cold‐water fishes, because dissolved oxygen data are limited compared to water temperature data, and many cool refuges are fed by subsurface flows which are potentially hypoxic. [ABSTRACT FROM AUTHOR]

Hemeroby and naturalness are indicators of ecosystem health and can be used to assess the state of aquatic macrophyte communities in floodplain landscapes under anthropogenic pressure. This article verifies the hypothesis that hemeroby and naturalness are distinguished by specific spatial patterns. Hemeroby is sensitive to changes in the level of anthropogenic pressure under conditions of a high level of ecosystem transformation. Naturalness is capable of responding to environmental disturbances of both natural and anthropogenic origin and is sensitive to changes in the state of ecosystems as they approach natural conditions. The variability of the naturalness of aquatic macrophyte communities does not depend on the direction of spatial patterns. Accounting for the directionality of spatial patterns provides a better explanation for the small-scale component of community hemeroby variability. [ABSTRACT FROM AUTHOR]

Contextualization: The aquatic-terrestrial transition zone (ZTAT) in the floodplain (alluvial plain) Ramsar Ayapel (Colombia) remains flooded for more than half of the year, and its coastal strip generates a strong influence on the ecosystem. An approach to the spatial and temporal characterization of this zone is crucial for further functional analysis, especially when tropical floodplains are little explored except for some Amazonian ecosystems. Knowledge gap: Floodplain dynamics are mainly regulated by flood pulses, directly influencing he physical and chemical conditions of water and sediment. Therefore, the biota is adapted to the flooding and waterlogging conditions of the ecosystem. However, research has addressed the terrestrial and aquatic phases as separate systems, making it necessary to resort to methodologies that demonstrate connectivity in the system and facilitate the interpretation of key factors in the ecological functioning of tropical wetlands. Purpose: The research analyzed the structure and functioning of the ZTAT through physical and chemical variables at different times of the flood pulse. Methodology: In two wetlands of the muddy complex, sensitive to the flood pulse, three samplings were carried out: rising water (July 2021), high water (September/2021), and declining water (March/2022). The ZTAT was monitored by delimiting it into four subzones: water, sediments, floodable soil, and soil. Results and conclusions: Significant changes in time associated with water level and nitrogen concentrations were revealed; while in space, assisted by the contrast of the ZTAT at the two sites, differences were reflected through in situ variables and soil characteristics. It was detected that depth, transparency, and a higher concentration of nitrogen forms, and some ions such as aluminum and magnesium generated differences on a time level. On the contrary, conductivity, calcium concentration, and variables associated with soil characteristics expressed it at the spatial level due to exploring the ZTAT. Therefore, the physicochemical dynamics of moments and sites in a wetland require a sampling design that, using the ZTAT, facilitates the scale of physicochemical analysis. [ABSTRACT FROM AUTHOR]

The floodplain lakes of the Amazon constitute one of the most important aquatic systems in terms of fish biodiversity. These ecosystems are influenced by the flood pulse, which in turn, affects the behaviour of fish communities within this lake ecosystem. In this study, we tested the hypothesis that the facets of taxonomic and functional diversity may be influenced by the conditions of 'patches' of internal habitats, considering the margins and central environments of a floodplain lake in the Amazon. Lake Cujubim, located on the right bank of the Madeira River, was evaluated via fisheries carried out in the high‐water and low‐water phases, during the day and night, and considering two location strata. The results suggest that the absence of significant differences in alpha taxonomic diversity between the two phases may be a possible seasonal mischaracterisation in Lake Cujubim attributed mainly to dam constructions along the Madeira River. Apparently, no major differences occur in the assembly of fish in terms of their taxonomic and functional characteristics, regardless of luminosity. In the strata of the locations, demonstrates noticeable habitat patches, with the margins being bioregions with high incidences of individuals of the Engraulidae family, confirmed by both taxonomic and functional diversity (alpha and beta). It can be seen that, even in connected lakes, there are differentiated metacommunities between the bioregions, thus forming patches of habitat, and that the shores of the lake, especially those located in proximity or distant from the river, are more suitable areas for food and refuge. [ABSTRACT FROM AUTHOR]

Floodplains are regularly inundated areas of land that provide ecosystem benefits for the entire catchment area, along with numerous benefits for communities making them ideal for human settlement. The management of floodplains involves an ongoing dilemma; how best to balance the need to protect urban settlements from significant flood events with the benefits that inundation brings to the environmental and cultural values of the floodplain. These flood events have been traditionally addressed using technical flood protection measures. However, nature‐based solutions (NbS), provide a potential alternative approach. In this research, we analyze 29 global case studies centered on river floodplain management to investigate the barriers and enablers that affect the implementation of NbS, including floodplain restoration, mangroves, riparian forest restoration, wetland green infrastructure, among other strategies. The aim of this paper is to gain insights into improving floodplain management through the assessment of barriers and enablers evident in these case studies. The barriers and enablers were divided into six categories: social, technical, financial, political, institutional and economic and further into several sub‐divided categories. Social and technical categories were the most commonly described barriers and enablers closely followed by the institutional category. The discussion is centered around four topics: understanding community and decision‐maker risk perceptions, increased focus on stakeholders, managing multiple conflicting objectives, and consideration of multiple spatial scales. Further research on the uptake of NbS needs to focus on addressing risk communication and modeling, managing trade‐offs, and demonstration of delayed benefits. This article is categorized under:Water and Life > Conservation, Management, and AwarenessScience of Water > Water and Environmental Change [ABSTRACT FROM AUTHOR]

Between 2013 and 2017, we carried out nine field missions in the Lago Grande de Curuai floodplain, located in Pará state – North of Brazil – to collect samples for monitoring surface water quality. This site separated from the river by a narrow bank is composed of a network of channels and shallow lakes, a morphology shared by the floodplains of the lower Amazon. A multiparameter probe was used in situ to measure electrical conductivity, temperature, pH, dissolved oxygen, chlorophyll, turbidity, depth and a Secchi disk to estimate transparency. Water grab samples were analysed for suspended material, alkalinity, humic acid, phosphorus, nitrogen, carbon and chlorophyll. Sampling stations were distributed over the seven larger lakes in the floodplain and sampled at different periods of the hydrological cycle. The number of samples varied with the floodplain water level, with a minimum of 25 samples for each field visit. This data set is a collection of water quality data to assist in the limnological or biogeochemical studies of surface waters in Amazonian floodplain lakes, and the product of successive French‐Brazilian projects: (1) the Clim‐FABIAM 'Climate changes and Floodplain lake biodiversity in the Amazon Basin: how to cope and help the ecological and economic sustainability' funded by the French Foundation for biodiversity research (FRB), (2) the project Bloom‐ALERT –'Environmental sensitivity and population health vulnerability to cyanobacteria in the Amazon: towards shared indicators' funded by the French‐Brazilian research program GUYAMAZON 2014, and the project (3) 'Ecossistemas das várzeas e biodiversidade: Impactos das mudanças ambientais e climáticas considerando cenários de desenvolvimento sustentáveis' (Project number 490634/2013‐3) funded by the Brazilian National scientific Research Council CNPq. [ABSTRACT FROM AUTHOR]

Most cyprinid fish breed from spring to summer. On the other hand, the timing of initiation and duration of gametogenesis in preparation for reproduction vary widely depending on the species. It is unclear what factors determine the types of timing and duration of gametogenesis. In order to infer the factors, it is necessary to clarify the gametogenesis process of as many species as possible, categorize them, and explore commonalities and differences between species belonging to different types of gametogenesis. In the present study, we determined the maturity of Hemigrammocypris neglecta, a temporary water-spawning fish of the subfamily Oxygastrinae, based on histological observations of the gonads. Female vitellogenesis began in May and continued during the breeding season from May to August. This species was a multiple-spawner that repeatedly ovulates and spawns multiple times during the breeding season. Male spermatogenesis (meiosis) began in April, and a large number of spermatozoa were observed in the testes and sperm duct from May to August, indicating that reproduction is possible during this period. The timing of the initiation of gametogenesis in spring/summer-spawning cyprinid fishes has been roughly divided into three types: autumn type, winter/spring type, and breeding season type. The female H. neglecta was the breeding season type. There are few species that belong to this type, suggesting that the type may have evolved independently with reflect the reproductive ecology of each species. The male is the winter/spring type, a characteristic common to the subfamily Oxygastrinae. [ABSTRACT FROM AUTHOR]

Topography and the computational mesh grid are fundamental inputs to all two‐dimensional (2D) hydrodynamic models, however their resolutions are often arbitrarily selected based on data availability. With the increasing use of drone technology, the end user can collect topographic data down to centimeter‐scale resolution. With this advancement comes the responsibility of choosing a resolution. In this study, we investigated how the choice of mesh grid and digital elevation model (DEM) resolutions affect 2D hydrodynamic modeling results, specifically water depths, velocities, and inundation extent. We made pairwise comparisons between simulations from a 2D HEC‐RAS model with varying mesh grid resolutions (1 and 2 m) and drone‐based lidar DEM resolutions (0.1, 0.25, 0.5, 1, and 2 m) over a 1.5 km reach of Stroubles Creek in Blacksburg, Virginia. The model was rerun for up to ±4% change in floodplain roughness to determine how the DEM and mesh grid changes relate to an equivalent change in roughness. We found that the modeled differences from resolution change were equivalent to altering floodplain roughness by up to 12% for depths and 44% for velocities. The largest differences in velocity were concentrated at the channel‐floodplain interface, whereas differences in depth occurred laterally throughout the floodplain and were not correlated with lidar ground point density. We also found that the inundation boundary is dependent on the DEM resolution. Our results suggest that modelers should carefully consider what resolution best represents the terrain while also resolving important riparian topographic features. Key Points: Two‐dimensional hydrodynamic model results are affected by digital elevation model and computational mesh grid resolutionsResolution changes are equivalent to altering floodplain roughness by up to 12 percent for depths and 44 percent for velocitiesModeled inundation boundary is dependent on digital elevation model resolution [ABSTRACT FROM AUTHOR]

In mountainous watersheds, floodplain sediments are typically characterized by gravel bed layers capped by an overlying soil unit that serves as a hotspot for biogeochemical reactivity. However, the influence of soil biogeochemistry on gravel bed underflow composition remains unclear, especially during hydrological transitions that alter the vertical connectivity between overlaying soils and the underlying gravel bed. This study investigates these dynamics by measuring hydraulic gradients and water compositions over three hydrological years in a typical mountainous, low‐order stream floodplain in the Upper Colorado River Basin. Results indicate that the timing of hydrological conditions strongly influences the vertical exchanges that control water quality. Specifically, during flooding events such as beaver ponding, that induce downward flushing of the soil, anoxic conditions prevalent in the biogeochemically active soil are transferred downstream via gravel bed underflow. Conversely, snowmelt and drought conditions increase oxic conditions in the gravel bed due to diminished hydrological connectivity with the overlying soil. To compare water quality response to hydrological transitions across similar floodplain environments, we propose a conceptual model that quantifies the inundation‐induced flushing of soil porewater to measure solute exchange efficiency with the gravel bed solute convergence efficiency (SCE). This model provides a framework for quantifying biogeochemical processes in hydrological underflow systems, which is critical for water and elemental budgets in these globally important mountainous ecosystems. Plain Language Summary: Mountains are important sources of freshwater for humans and ecosystems. They are however increasingly impacted by climate change. In this paper, we investigate how changes in water availability (droughts, snowmelt, inundations) can cascade into changes in water quality (concentrations of dissolved chemical elements). We show that in mountain valleys, the zone of contact between the soil and the underlying gravel bed aquifer is important for water quality. Chemical elements from the soil can be flushed down into the gravel bed aquifer, then transported by groundwater to the stream. Chemical elements from the soil can also react with chemical elements present in the aquifer. Our research can be used to better predict the water and elemental budgets in these important mountainous systems. Key Points: Soil / gravel bed connectivity in floodplains is important for water qualitySnowmelt and drought both reduce soil / gravel bed connectivityBeaver ponding increases downward flushing to gravel bed unit [ABSTRACT FROM AUTHOR]

Floodplain area of the Lower Yellow River is not only a place for flood detention and sediment settling, but also the homeland for people living there. The contradiction between flood control and economic development in the flood plain has existed for a long time, which is a key point and great challenge of the Yellow River management and protection. Applying people-centered development philosophy and pursuing people's all-round development, an overall strategy was proposed to optimize and adjust the safety construction of floodplain, which could firmly guarantee the function of flood detention and sediment settling as well as effectively safeguard the people's interests in floodplain. In the overall strategy, the relocation of majority residents outside floodplain was adopted as the strategic direction, and the work focus was shifted from "housing" and "land" to "people". Based on the strategic direction and work focus, it was proposed to build a "2+N+X" planning and policy framework system, comprehensively promoted "comfortable living" and "booming industry", and payed more attention to the guiding role of education and employment, so as to make solid progress in the safety construction of floodplain. [ABSTRACT FROM AUTHOR]

When species are introduced to a new environment, they can quickly adapt to the environment and may differ from the indigenous species. The indigenous population of Protosalanx chinensis has a high level of genetic diversity, but it is unclear on the genetic diversity of the introduced populations in northeast China, which supports the major production of P. chinensis in the world. A total of 556 individuals of P. chinensis were collected during 2016–2021, from Lianhuan Lake (LHL), Xingkai Lake (XK), and Shuifeng Reservoir (SF), and one population was collected from the indigenous Taihu Lake (TH). Overall, 36 haplotypes were detected, and the genetic differences in P. chinensis populations within and between river basins were investigated. The nucleotide diversity (π) of the populations ranged from 0.0005 to 0.0032, and the haplotype diversity (Hd) ranged from 0.455 to 0.890, with the highest genetic diversity in the TH population, followed by the SF population, and lower genetic diversity in the XK and LHL populations. The analysis of the genetic differentiation index (Fst) and the genetic distance between populations showed that there was significant genetic differentiation between the TH population and the other populations. More sampling points have been set up in LHL for further analysis; the Dalong Lake (DL) and the Xiaolong Lake (XL) populations were far from the other populations within the LHL population. In this study, we didn't find a correlation between population size, stability, and genetic diversity, and the ecological measures of management should be decisive to the population dynamics. These results provide a basis for the rational utilization and effective management of P. chinensis. [ABSTRACT FROM AUTHOR]

Accurate flood susceptibility mapping (FSM) is critical for mitigating the environmental, social and economic consequences of floods. The influence of model generalizability onto new watersheds, and the impact of arbitrarily selecting a small subset of flooded and nonflooded locations are current major knowledge gaps in FSM research impacting predictive accuracy. As such, this study conducts an assessment of machine learning models - (i) an Artificial Neural Network - Synthetic Minority Oversampling Technique (ANN-SMOTE) hybrid ensemble with (ii) knowledgebased Analytical Hierarchy Process (AHP) and (iii) diversity-based Shannon Entropy approaches. The ANN-SMOTE, AHP and Entropy models were trained and tested on the Don River watershed in Ontario, Canada, with Overall Accuracy (OA) results of 0.549, 0.404 and 0.452, respectively. ANN-SMOTE's predictive accuracy remained high when it was tested on four independent watersheds from southern Ontario, indicating strong generalization ability. To simulate the commonly used flood point inventory approach, the number of training samples was reduced by a factor of a 1000, which resulted in a 28% decrease in accuracy. The high performance and generalization potential of the ANN-SMOTE model demonstrate its utility and versatility for future FSM studies, and as a support tool in flood risk management decision making. [ABSTRACT FROM AUTHOR]

Wetland reclamation was an intrinsic part of nineteenth-century global agricultural transformations. In Swedish research, reclamation has mainly been situated in larger general processes of population rise, commercialization and societal/technological development. The intersection of reclamation, physical environments and local economies has seldom been studied in detail. This paper conducts a local analysis of nineteenth-century wetland reclamation in two parishes in Sweden, Knätte and Mörlunda, through combining a study of specific reclamation processes with an analysis of local agrarian-economic development. The results show that these processes varied depending on specific historical-geographical circumstances. In Knätte, reclamation was not primarily related to population rise, but to increasing commercialization during the period. The case in Mörlunda instead shows how reclamation was first a response to increasing population but later developed into a project of agricultural market adaptation. In both cases, the physical environment led to varying degrees of geographic constraint in the process. In combination, these results point to the importance of detailed case studies in nuancing our understanding of nineteenth-century wetland reclamation both in Sweden and internationally. • Local factors are important for nuancing general trends in wetland reclamation. • In Sweden, population rise and commercialization are considered primary drivers. • The active drivers vary between the compared cases, depending on context. • Reclamation was primarily a part of local agrarian developments. • Wider relations of the local economy, for example through trade, also impacted. [ABSTRACT FROM AUTHOR]

Floodplains are one of the most threatened ecosystems. Even though the vegetation composition in floodplain forests is expected to reflect the variation in groundwater levels and flood duration and frequency, there is little field data on the inundation dynamics (e.g., the variability in flood duration and flood frequency), especially for the understudied seasonally dry tropics. This limits our understanding of these ecosystems and the mechanisms that cause the flooding. We, therefore, investigated six floodplain forests in the state of Minas Gerais in Brazil for 1.5 years (two wet seasons): Capivari, Jacaré, and Aiuruoca in the Rio Grande basin, and Jequitaí, Verde Grande, and Carinhanha in the São Francisco basin. These locations span a range of climates (humid subtropical to seasonal tropical) and biomes (Atlantic forest to Caatinga). At each location, we continuously measured water levels in five geomorphologically distinct eco‐units: marginal levee, lower terrace, higher terrace, lower plain, and higher plain, providing a unique hydrological dataset for these understudied regions. The levees and terraces were flooded for longer periods than the plains. Inundation of the terraces lasted around 40 days per year. The levees in the Rio Grande basin were flooded for shorter durations. In the São Francisco basin, the flooding of the levees lasted longer and the water level regime of the levees was more similar to that of the terraces. In the Rio Grande basin, flooding was most likely caused by rising groundwater levels (i.e., "flow pulse") and flood pulses that caused overbank flooding. In the São Francisco basin, inundation was most likely caused by overbank flooding (i.e., "flood pulse"). These findings highlight the large variation in inundation dynamics across floodplain forests and are relevant to predict the impacts of changes in the flood regime due to climate change and other anthropogenic changes on floodplain forest functioning. [ABSTRACT FROM AUTHOR]

Monodominant woody species are frequent in the Pantanal. Monodominant forests of Erythrina fusca (Fabaceae) occur in Northern Pantanal, but little is known about the environmental factors that influence this dominance. This work investigated the relationship between flooding and soil characteristics and the E. fusca monodominance. We hypothesized that the dominance of E. fusca is mainly associated with extended flooding periods and lower soil fertility, factors frequently related to monodominance. We sampled 16 sites within the study area of 115 km2. We sampled three 50 × 5 m vegetation plots in each site, for species composition and abundance in multispecies forests and E. fusca monodominant forests. Soil samples were taken in each plot, and the duration of flooding was determined. We performed Canonical Correspondence Analysis and Regression Trees to verify the variation of species composition along environmental gradients and to identify which environmental factors influence this monodominance. We observed that flooding is the main factor driving E. fusca dominance, where higher flooding duration led to higher dominance. Further, the dominance of E. fusca is related to low soil fertility and higher concentration of sulfur and organic matter, than multispecies forests. Our findings confirm the hypothesis that dominance of E. fusca is associated with high flooding regimes with low soil fertility, which together act as a strong filter for other riparian forest species, thus favoring the dominance of E. fusca. [ABSTRACT FROM AUTHOR]

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Rice serves as a crucial staple food crop for half of the world's population. In the Vietnamese Mekong Delta (VMD), rice production plays a vital role in national food security. However, the majority of the existing intensified rice cultivation schemes in the VMD, which are typically traditional, have rendered many farmers' livelihoods unsustainable due to issues such as land degradation, water pollution, health risks, and low profitability. Therefore, it is imperative to explore alternative sustainable farming systems. This study investigates the benefits of two ecological farming systems, specifically organic rice and rice mixed with lotus, as alternatives to conventional rice farming in the upper VMD floodplain province of An Giang. These two farming systems have demonstrated long-term socioecological and economic advantages. On the one hand, they allow the introduction of rice products to the market at more affordable prices. Additionally, they contribute to improved water quality, improved soil fertility, and increased biodiversity such as bird, fish, and plant species compared to traditional rice farming systems. Although we acknowledge that the availability of floodwater poses a significant constraint for alternative farming systems, the business opportunities and socioecological benefits associated with these systems outweigh the limitations. Our findings provide evidence that ecological farming practices that support rice cultivation represent promising alternatives to sustainable rice production, which can help mitigate vulnerabilities in intensified rice farming systems and can be scaled up for other floodplain provinces in the VMD and beyond.

River restoration programmes with the goal of conserving and rehabilitating inland fishes have a multi‐decadal history, but evaluation and synthesis of past restoration actions have been limited by a lack of monitoring and reporting. Given that calls for both monitoring and systematic reviews of restoration have increased, we were interested in the influence that restoration has had on improving conditions for riverine fishes resulting from long‐standing and increasingly prominent stressors. Our objectives were to (1) identify which stressors were targeted in river restoration efforts, (2) determine the proportion of published studies that articulate restoration goals and develop comparative monitoring designs for assessing the effects of restoration on fishes, and (3) conduct a meta‐analysis to synthesise fish responses to restoration projects.We assessed restoration effectiveness for increasing fish density and richness from peer‐reviewed papers published over the past decade using a global systematic review and meta‐analysis.We found that restoration actions addressed major stressors primarily by improving in‐stream habitat (37%), increasing in‐stream longitudinal connectivity (26%) and increasing lateral floodplain connections (9%). Although 81% of studies had comparative monitoring designs (i.e., before/after and control/impact) and stated restoration goals, only 40% of those studies reported sufficient data to be included in the meta‐analysis. Projects which increased in‐stream connectivity had the largest positive effect size on fish density and richness compared to in‐stream habitat improvements and increasing floodplain connections. Time since restoration and restoration size (i.e., geographical footprint) were not strong predictors of fish response effect sizes.Restoration effectiveness was highly variable among project types. Authors of studies included in the meta‐analysis often identified spatial or temporal scale of monitoring, overriding catchment conditions, and recolonisation potential as sources of variability and effectiveness in restoration outcomes. Systematic reporting of these and other covariates may help guide processes in restoration evaluation and provide valuable research insights. Despite increased emphasis on monitoring, incomplete data reporting limited the number of studies that could be included for quantitative meta‐analysis. Persistent emphasis on setting specific criteria (e.g., measurable outcomes of fish response) for restoration goals, project monitoring, data reporting, information sharing and collaborative projects is likely to continue to improve understanding of restoration effectiveness transferable to future endeavours.Our results can be used to support river restoration practitioners with evidence‐based information to evaluate the cost–benefit ratio of competing restoration priorities, and inform restoration planning and implementation for riverine fish. [ABSTRACT FROM AUTHOR]

Many alluvial rivers worldwide are plagued with significant geomorphology changes due to severe riverbank collapse. This study developed an approach for quantifying riverbank erosion and outlined a structure for riverbank preservation based on insights gained from field investigations conducted in the lower Yellow River. Using the erosional forces, the newly introduced assessment method enables convenient measurement of riverbank erosion at various locations, even without cross-sectional profiles or channel-specific data. Abundant evidence highlights the severe riverbank collapses in the lower Yellow River, exemplified in the Jiyang Reach, where the left riverbank retreated at 26.0 m/yr from March 31, 2016 to May 10, 2018. The presence of weak soil erosion resistance is an inherent cause of riverbank collapse, with the critical shear stress of the soil being only 0.1 N/m2, significantly lower than that of the flow of 3.1 N/m2. Climate change and human activities, such as increased heavy rainfall frequency, reduced incoming water-sediment conditions and changes in riverbank boundary conditions, have triggered riverbank collapse. To prevent the occurrence of riverbank collapse, this study proposes a theoretical framework for a riverbank protection structure that simultaneously addresses the need for flood control and ecological conservation. [ABSTRACT FROM AUTHOR]

Aiming to understand the responses of soil seed bank to different water levels, we investigated vegetation and soil seed bank along a water level gradient (frequently flooded area, unflooded area) on the floodplain wetland of Juzhang River. We used the structural equation model to explore the direct and indirect effects of water level on soil seed bank, and used non-metric multidimensional scaling (NMDS) to assess the role of soil seed bank for vegetation regeneration. The results showed that the density of transient and persistent seed banks at unflooded area was 36.9% and 7.8% higher than that of frequently flooded area, respectively. Shannon index and Pielou index of seed bank and vegetation were significantly affected by water level and sampling location. Water level significantly affected the similarity between seed bank and aboveground vegetation, and the similarity of persistent seed bank with aboveground vegetation was significantly higher than that with transient seed bank. Structural equation model showed that water level had a direct effect on seed bank density, and indirect effects on density and richness of seed bank via affecting soil pH and NH4+-N content. NMDS results showed that there was no significant difference in the composition of the persistent seed bank and vegetation community in autumn under different water levels, but water level significantly changed the community composition of transient seed bank. Transient seed bank was affected by the vegetation and soil property, while persistent seed bank was determined by aboveground vegetation and water level. Although soil seed bank had low regeneration potential for the vegetation communities in floodplain wetlands, soil seed bank could not be neglected during the restoration of propagule diversity after disturbance in wetlands. Persistent seed bank would be an importance source of diversity of propagules for floodplain wetlands restoration following disturbance. [ABSTRACT FROM AUTHOR]

We used imagery from remote sensing (FORCE Time Series Analysis submodule (combining Landsat and Sentinel-2 imagery) to derive spatially distributed times series (8 years) of NDWI data to infer patterns of floodplain inundation and riverfloodplain connectivity in two contrasting polders in the Lower Oder Valley National Park. The upstream Polder A (14.4 km2) was extensively flooded for prolonged periods most winters. Wavelet analysis showed that this strong seasonality was primarily driven by winter water levels in the river Oder that could enter and leave the polder through two opened floodgates. Subsequent drainage was slow and aided by a pumping station. Inundation of the downstream Polder 10 (17.7km2) was lower and had less marked seasonality. This reflected the impact of flood attenuation by storage in Polder A upstream, but also the greater connectivity (via 10 floodgates) to the Oder and a functional network of channels, which facilitated rapid drainage after flood peaks. In Polder A, secondary periods of transient inundation could also occur in response to local intense summer rainfall. Wavelet analysis also showed that groundwater recharge in and around Polder A is primarily induced by floodwater, whilst Polder 10 also reflects the influence of local rainfall-driven recharge. The flood regimes of the two polders showed marked inter-annual variation, largely dependent on flows from the upper Oder catchment. Understanding these patterns and processes of inundation is important for both managing flows and sustaining valuable wetland habitats within the National Park. Given projected climate change in eastern Europe and possible management alterations to the flow regime of the Oder, the potential implications for these habitats needs urgent attention. [ABSTRACT FROM AUTHOR]

Phenotypic diversity and abundance drive salmon resilience in the face of increasing environmental variability. But what happens when human activities fundamentally alter the habitat complexity that drives this diversity? And how can we restore habitats to recover both diversity and abundance to support salmon persistence in a warming climate? Here, we looked at the impact of a large watershed restoration effort on the abundance and climate resilience of the three remaining core natural spring‐run Chinook Salmon populations in the California Central Valley (Butte, Mill, and Deer Creek). Butte Creek fish, which have floodplain access, had higher overall productivity and faster juvenile growth compared with Mill and Deer Creek populations, and the proportion of floodplain inundation was positively correlated with Butte Creek adult abundance two years later. While Butte Creek exhibited significant increases in abundance post‐restoration (~2000%), it generally exhibited lower phenotypic diversity and only a marginal increase in population stability after restoration based on the coefficient of variation (CV). In particular, Butte Creek salmon tended to exhibit larger drops in escapement following dry years (e.g., return years 2010, 2017) compared with Mill and Deer Creek populations, presumably due to limited inundation of its downstream floodplain. The late‐migrating juvenile strategy (i.e., yearling), which disproportionately supported Mill and Deer Creek populations during droughts, was uncommon among Butte Creek adults (averaging 60% of returns for Mill and Deer Creek vs. 0.3% for Butte Creek). Increased spring‐run stock complex stability was found, post‐restoration, when combining the three spring‐run populations (i.e., lower aggregate CV). However, among‐river pairwise correlations also suggested increased synchronization in population abundances post‐restoration, potentially due to increasing frequency and severity of extreme climatic events (e.g., droughts and ocean warming). This study underscores the importance of restoring a connected mosaic of aquatic habitats across modified landscapes, such as cold water refugia and floodplains, to preserve multiple (across‐population) life history pathways for increasing salmon stock complex stability and abundance. These landscape‐scale process‐based habitat restoration efforts are likely to be crucial for the successful long‐term recovery of vulnerable species in a rapidly changing climate. [ABSTRACT FROM AUTHOR]

Abstract Tropical wetlands account for ∼20% of the global total methane (CH4) emissions, but uncertainties remain in emission estimation due to the inaccurate representation of wetland spatiotemporal variations. Based on the latest satellite observational inundation data, we constructed a model to map the long‐term time series of wetland extents over the Sudd floodplain, which has recently been identified as an important source of wetland CH4 emissions. Our analysis reveals an annual, total wetland extent of 5.73 ± 2.05 × 104 km2 for 2003–2022, with a notable accelerated expansion rate of 1.19 × 104 km2 yr−1 during 2019–2022 driven by anomalous upstream precipitation patterns. We found that current wetland products generally report smaller wetland areas, resulting in a systematic underestimation of wetland CH4 emissions from the Sudd wetland. Our study highlights the pivotal role of comprehensively characterizing the seasonal and interannual dynamics of wetland extent to accurately estimate CH4 emissions from tropical floodplains.

ABSTRACT We use metagenome-assembled genomes (MAGs) to understand single-carbon (C1) compound-cycling—particularly methane-cycling—microorganisms in montane riparian floodplain sediments. We generated 1,233 MAGs (>50% completeness and 50% abundance in the MAG library) in one sample that also contained aceticlastic methanogens, indicating a potential C1/methane-cycling hotspot. Ca. Methylomirabilis MAGs from SR encode pathways for methylotrophy but do not harbor methane monooxygenase or nitrogen reduction genes. Comparative genomic analysis supports that one clade within the Ca. Methylomirabilis genus is not methanotrophic. The genetic potential for methylotrophy was widespread, with over 10% and 19% of SR MAGs encoding a methanol dehydrogenase or substrate-specific methyltransferase, respectively. MAGs from uncultured Thermoplasmata archaea in the Ca. Gimiplasmatales (UBA10834) contain pathways that may allow for anaerobic methylotrophic acetogenesis. Overall, MAGs from SR floodplain sediments reveal a potential for methane production and consumption in the system and a robust potential for methylotrophy.IMPORTANCEThe cycling of carbon by microorganisms in subsurface environments is of particular relevance in the face of global climate change. Riparian floodplain sediments contain high organic carbon that can be degraded into C1 compounds such as methane, methanol, and methylamines, the fate of which depends on the microbial metabolisms present as well as the hydrological conditions and availability of oxygen. In the present study, we generated over 1,000 MAGs from subsurface sediments from a montane river floodplain and recovered genomes for microorganisms that are capable of producing and consuming methane and other C1 compounds, highlighting a robust potential for C1 cycling in subsurface sediments both with and without oxygen. Archaea from the Ca. Methanoperedens genus were exceptionally abundant in one sample, indicating a potential C1/methane-cycling hotspot in the Slate River floodplain system.