River System Research Articles

SNP‐based analysis of European Thymallus spp. (Salmonidae) reveals extensive mito‐nuclear discordance relevant for biogeographic inferences, taxonomy and conservation

AbstractAimPaleohydrological dynamics are well‐documented for European river systems, promoting shifting phases of isolation and connectivity of their aquatic fauna. These conditions coupled with high rates of hybridisation found in freshwater fishes may introduce considerable complexity and potential mito‐nuclear discordance of phylogenetic patterns. We evaluate this hypothesis using the first large‐scale analysis of nuclear SNPs in European species of grayling (Thymallus) compared to mtDNA data with the aim of reassessing the evolutionary history of this group of rheophilic fishes.LocationFreshwater systems in Europe.MethodsBased on mitochondrial (mitogenomes, control region) and nuclear (ddRADseq) data, we applied population‐genetic, phylogenetic, and biogeographic tools to evaluate lineage diversity in the context of paleohydrological alterations.ResultsThe results corroborated previously recognised high levels of lineage diversity, but revealed several cases of mito‐nuclear discordance and signals of both historical (natural) and human‐mediated introgression among major inter‐ and intraspecific lineages of Thymallus in Europe. A time‐calibrated phylogeny and ancestral area estimation, based on nuclear SNP data, supported a late Pliocene diversification of the genus in Europe and suggested an early colonisation of the Black Sea basin with subsequent dispersal into Central and Western Europe.Main ConclusionsThe genetic structure of Thymallus in Europe recovered by nuclear SNPs contrasts considerably with that supported by mtDNA. Several instances of mito‐nuclear discordance underscore frequent contact of allopatric lineages in a dynamic paleohydrological landscape and reveal the weakness of basing both taxonomic and conservation decisions on inferences based on mtDNA alone. The Danube and Rhine drainages were inferred as important zones of contact between divergent phylogeographic lineages. Additionally, our data cast doubt on the genetic integrity of the endangered T. aeliani. Its divergence from T. thymallus, using nuclear SNPs, appears minimal as samples of T. aeliani group within Danubian lineages, despite carrying highly divergent reciprocally monophyletic mtDNA.

The drivers of benthic macroinvertebrates communities along a subtropical river system: Sediments chemistry or water quality?

AbstractImpacts of metal pollution, either on water or in sediments within aquatic systems have been a serious challenge globally. Little is known about the ecological impacts of metal pollution on benthic macroinvertebrates species in sub–tropical river systems. The aim of this study was to examine benthic macroinvertebrates community composition in relation to sediment metal concentrations and other physicochemical variables in the Mutshundudi River system. Benthic macroinvertebrates sampling and community composition analysis, sediment collection, processing, metal analysis and assessment of water variables in the river system were done across two seasons at 12 sampling sites. The river was categorized into three segments: upstream, midstream and downstream. The results from geo‐accumulation (Igeo) values showed that sediments were loaded with Na, Zn, and B in all river segments. In comparison with South African water quality guidelines for aquatic ecosystems, water quality ranged from good at upstream sites because of low anthropogenic activities to very poor in downstream sites because of high anthropogenic activities. Sediments from the Mutshundudi River showed significant differences on high concentrations of metals (i.e., Mg, K, Na, and Cu) and seasonal variations. Both water quality and sediment chemistry were considered the driving factors of benthic macroinvertebrates, since species densities and composition reduced with a decline in water and sediment quality during both cool–dry and hot–wet seasons. Continuous build‐up of the metal contaminants, such as Mg, K, Na, and Cu in river sediments may pose adverse impacts on macroinvertebrate community structure.

Good water governance through cultural evolution along river basins: The role of UNESCO heritage sites and intangible cultural heritage

Highlights Effective water governance is essential for sustainable management of water resources, particularly within river basins where diverse stakeholders intersect. Cultural evolution along these river systems has profoundly influenced water governance practices. UNESCO heritage sites and intangible cultural heritage play a pivotal role in preserving traditional knowledge and practices related to water management. By recognizing and learning from UNESCO sites, we can enhance contemporary water governance strategies. As water experts, we recognize that the preservation of cultural heritage is inseparable from effective water governance. Let us continue to celebrate and protect these invaluable resources.

Study on the Geographical Spatial Characteristics of Forest Health Resorts in Fujian Province, China

Forest health tourism is an increasingly popular new form of tourism. Fujian Province, with its abundant forest resources, ranks among the top provinces in China in terms of forest coverage and holds significant development potential. The study focuses on 80 provincial-level forest health resorts in Fujian Province, China. Software such as the ArcGIS geographic information system is used to analyze the resorts’ nearest neighbor index, geographic concentration index, kernel density, etc., thus indicating their spatial distribution characteristics. Overlay analysis, correlation analysis, and fitting analysis are employed to explore the spatial distribution specificity and its influencing factors. The research results indicate that forest health resorts in the area exhibit an aggregated distribution with a higher overall concentration. They are influenced by factors such as the distribution of river systems, the accessibility of transportation, distance to central cities, and socio-economic conditions. The geographic concentration index (G) is 50.28 and the unevenness index (S) is 0.640, both indicating that the forest health resorts in Fujian Province demonstrate a distribution pattern of “overall dispersion with multiple core aggregations”. Based on the research findings, the article puts forward some policy insights. Taking into account the local geographical characteristics, it advocates for the rational development of forest health resort industry models suitable for the region. It suggests incorporating innovative ideas into the forest health resort industry in order to broaden development channels. Additionally, it emphasizes the importance of close collaboration between the government and the market for mutual development.

Environmental DNA-based biodiversity profiling along the Houdong River in north-eastern Taiwan.

This paper describes two datasets: species occurrences, which were determined by environmental DNA (eDNA) metabarcoding and their associated DNA sequences, originating from a research project which was carried out along the Houdong River (), Jiaoxi Township, Yilan, Taiwan. The Houdong River begins at an elevation of 860 m and flows for approximately 9 km before it empties into the Pacific Ocean. Meandering through mountains, hills, plains and alluvial valleys, this short river system is representative of the fluvial systems in Taiwan. The primary objective of this study was to determine eukaryotic species occurrences in the riverine ecosystem through the use of the eDNA analysis. The second goal was, based on the current dataset, to establish a metabarcoding eDNA data template that will be useful and replicable for all users, particularly the Taiwan community. The species occurrence data are accessible at the Global Biodiversity Information Facility (GBIF) portal and its associated DNA sequences have been deposited in the European Nucleotide Archive (ENA) at EMBL-EBI, respectively. A total of 12 water samples from the study yielded an average of 1.5 million reads. The subsequent species identification from the collected samples resulted in the classification of 432 Operational Taxonomic Units (OTUs) out of a total of 2,734. Furthermore, a total of 1,356 occurrences with taxon matches in GBIF were documented (excluding 4,941 incertae sedis, accessed 05-12-2023). These data will be of substantial importance for future species and habitat monitoring within the short river, such as assessment of biodiversity patterns across different elevations, zonations and time periods and its correlation to water quality, land uses and anthropogenic activities. Further, these datasets will be of importance for regional ecological studies, in particular the freshwater ecosystem and its status in the current global change scenarios. The datasets are the first species diversity description of the Houdong River system using either eDNA or traditional monitoring processes.

Threatened fishes of the world: Schizothorax (Racoma) biddulphi (Günther, 1876) (Cyprinidae)

In order to study the individual biology of endemic fish in China, lay a foundation for the conservation of its germplasm resources, and consolidate the basic biological data of endemic fish in the world. According to the ethical code and fishing permit, 21 samples of Schizothorax (Racoma) biddulphi (Günther, 1876) were collected from the Muzati River in Tarim River system from 2021 to 2022, and their morphological characteristics, age identification and anatomical observation were analyzed by classical biological methods. S. biddulphi has a long body, a conical head, a pointed snout and a lower mouth. Requires 2 pairs. The scales are small and neatly arranged; Bare or scaly chest; The lateral line scale is slightly larger. The lateral line is complete. The correlation equation between body length and body weight is: W = 4.148 × 10-5L2.791. There were 5 kinds of age identification materials: 15+ for lapillus and asteriscus, 14+ for vertebra, 11+ for opercular bone, and 9+ for anal scale. The peritoneal wall of S. biddulphi is black; The tooth type is 2·3·5-5·3·2; The gill harrow was 11~13 for laymen and 15~18 for experts. Diphysocyte; Gallbladder oval; The number of vertebrae is 4+42-43+1, and the number of ribs is 23 or 24. S. biddulphi is a special species in the Tarim River system, and its evolutionary adaptation is closely related to the uplift of the Qinghai-Tibet Plateau.

Comparative Analysis of Gut Bacterial Communities in Fish and Shellfish of Great Himalayan River System

Comparative Analysis of Gut Bacterial Communities in Fish and Shellfish of Great Himalayan River System

Hydropeaking mitigation with re‐regulation reservoirs

AbstractThe role of hydropower as a renewable and balancing power source is expected to increase in a Net Zero Emissions by 2050 scenario. As a common phenomenon in hydropower plants, hydropeaking will become more prominent, resulting in additional stresses on the ecological status of rivers. Here we propose a novel approach to design and operate auxiliary reservoirs called re‐regulation reservoirs (RRR) that aim to mitigate the adverse impacts of hydropeaking on rivers. A re‐regulation reservoir aims at smoothing flow fluctuations caused by hydropeaking by diverting and retaining parts of high flows and returning them back to river corridors during low flows. Using actual data from a hydropeaking‐influenced river system, the operation and efficiency of potential reservoirs have been investigated. An open‐access algorithm was developed to analyze the influence of the reservoirs to mitigate hydropeaking, considering peak and minimum flow and up‐ and down‐ramping rates. The findings illustrate that, in most cases, the required reservoir volume increases as the flow thresholds become more stringent. Nonetheless, several exceptions were observed, where larger reservoir volumes were required compared with cases with more stringent thresholds. These findings highlight the importance of understanding the impact of flow adjustments, while carefully considering the river regime, sub‐daily flow patterns, and unique characteristics of the river's ecosystem. Our approach shows theoretical possibilities for regulating hydropeaking and provides a basis for optimizing re‐regulation reservoirs, contributing to practical and adaptable strategies for sustainable hydropower management without increasing the operational cost of power systems.

Applying a Holistic Approach to Environmental Flow Assessment in the Yen River Basin

Environmental flow assessment is an essential tool in water resource management. This study employs a holistic approach to evaluate the environmental flow in the Yen Basin, Thanh Hoa, Vietnam. Based on information gathered from a field survey, the Yen River system is divided into five reaches, and environmental objectives and ecological assets are identified in each reach. Hydrological and hydraulic mathematical models are applied to simulate the flow regime in the river, demonstrating their potential to assess environmental flow, especially in basins with limited data. The detailed results from the mathematical model facilitate selecting environmental flow components to address specific objectives for each river reach. By analyzing and selecting the flow regime, this study aims to ensure environmental protection while also considering basin development requirements, laying the groundwork for defining prescribed flow regimes in basin water management.

A data-driven global flood forecasting system for medium to large rivers.

Losses from catastrophic floods are driving intense efforts to increase preparedness and improve response to disastrous flood events by providing early warnings. Yet accurate flood forecasting remains a challenge due to uncertainty in modeling, calibrating, and validating a useful early warning system. This paper presents the Requisitely Simple (ReqSim) flood forecasting system that includes key variables and processes of basin hydrology and atmospheric forcing in a data-driven modeling framework. The simplicity of the modeling structure and data requirements of the system allows for customization and implementation in any medium to large rain-fed river basin globally, provided there are water level or discharge measurements at the forecast locations. The proposed system's efficacy is demonstrated in this paper through providing useful forecasts for various river basins around the world. This include 3-10-day forecasts for the Ganges and Brahmaputra rivers in South Asia, 2-3-day forecast for the Amur and Yangtze rivers in East Asia, 5-10-day forecasts for the Niger, Congo and Zambezi rivers in West and Central Africa, 6-8-day forecasts for the Danube River in Europe, 2-5-day forecasts for the Parana River in South America, and 2-7-day forecasts for the Mississippi, Missouri, Ohio, and Arkansas rivers in the USA. The study also quantifies the effect of basin size, topography, hydrometeorology, and river flow controls on forecast accuracy and lead times. Results indicate that ReqSim's forecasts perform better in river systems with moderate slopes, high flow persistence, and less flow controls. The simple structure, minimal data requirements, ease of operation, and useful operational accuracy make ReqSim an attractive option for effective real-time flood forecasting in medium and large river basins worldwide.

Assessment of Movement and Dam Passage of Paddlefish in the Ohio River, West Virginia.

Paddlefish (Polydon spathula), a large-bodied and highly migratory species of large river systems, has experienced population declines or extirpation in parts of its range. As an effort to reestablish Paddlefish populations in the Ohio River of West Virginia, the West Virginia Division of Natural Resources has periodically stocked Paddlefish, but post-stocking studies are needed to assess the status of the reintroduced population, including information on movements of Paddlefish or on their passage through navigation dams of the Ohio River. Using telemetry techniques, we monitored seasonal movements and assessed dam passage of five Paddlefish in the Robert C. Byrd pool of the Ohio and Kanawha rivers. Paddlefish were highly mobile with two individuals using the entire R.C. Byrd pool during the 11-month study period. The highest movement rates occurring during the expected spawning period of April and May, where all individuals frequented the upper section of the pool in Kanawha River. Downstream passage was documented for one individual at the R.C. Byrd lock during July 2023, but no evidence of passage was documented for the locks at Racine or Winfield. Tagging of additional Paddlefish is planned, which will increase sample size for future assessments and continue efforts toward the long-term conservation and management of Ohio River Paddlefish.

Use of the HEC RAS model for the analysis of exceptional floods in the Ouémé basin

Abstract. The Ouémé River basin extends over almost half of Benin's territory, entirely located in a humid tropical climate. This river system includes a deltaic zone (delta of the Ouémé) known for its high agricultural potential and thus subject to a socio-economic development agenda. The Ouémé delta is facing recurrent floods that maintain rural agricultural population into a retrograding crisis with significant damages such as losses of properties. The objective of this study is to improve decision-making in the Ouémé basin through the simulation of exceptional floods using the HEC-RAS model. The HEC RAS model is a conceptual model, which works through mathematical and physical formulas to implement environmental phenomena for forecasting, understanding and analysis purposes. The model inputs used are basin GIS data, hydro-meteorological data, characteristics of existing hydraulic structures, etc. The targeted outputs include 1D/2D/3D view plans with support of satellite images, tables, graphs and curves. It is worth mentioning that the model provides outputs compatible with other tools, such as civil engineering (Civil 3D, Revit, Infraworks, etc.) and GIS, that help to expand the valorization fields. The implementation of the model in the Ouémé basin has made it possible to note: (i) that the recurring effect of losses and damages is justified by the settlement of the population on the river banks; (ii) that there is an important agricultural production in areas of high flood risk; (iii) that depending on the occurrence of the phenomenon, the flooded extent and the height of submersion remains variable, and more important for extreme flooding; (iv) about 12.07 % occurrence of river flood against 13.24 % for flash flood at a return period of 30 years. Moreover, it is very relevant to note that most of flood waters converge to the western part of the basin (an area with a low risk of flooding, stretched over 63.68 km2) and to the eastern part around the Damè-Wogon depression (an area at high risk of flooding, stretched over 10.49 km2).

Coupling model predictive control and rules-based control for real-time control of urban river systems

Model Predictive Control (MPC) has the potential to enhance flood control in urban river systems. However, the computational burden of online optimization hinders the application of MPC to large-scale areas. To address this, we propose a method incorporating both Rules-Based Control (RBC) and MPC based on surrogate models. MPC optimizes the operation of gates and pumping stations in the area of interest, while RBC is implemented in a specific region that does not participate in online optimization, thereby reducing calculation time. We have successfully validated this approach in coastal urban river systems in China, reducing the decision variables from 109 to 24 and narrowing the simulation area from 165 km2 to 15 km2. During the Typhoon Lupit rainfall test, the total computation time and the highest online optimization time were only 33.9 % and 38.1 % of the full MPC system, respectively. Additionally, the method demonstrated impressive results, including a significant 94.62 % reduction in flood volume and a remarkable 96.5 % decrease in flood duration. These findings demonstrate that our method effectively addresses the challenge of long computation times for online optimization in urban river systems and presents a novel approach for implementing urban flood mitigation strategies.

Network connectivity contributes to native small‐bodied fish assemblages in the upper Mississippi River system

Abstract Effective management and conservation of fishes requires understanding habitat use across multiple life stages while ensuring necessary habitats are both available and accessible. Tributary habitats may play an important role in recruitment and dispersal of fishes in anthropogenically modified rivers such as the Mississippi and Illinois Rivers of the Midwest U.S.A. Identifying source locations that contribute to recruitment of fish populations can determine the importance of connectivity within river networks and pinpoint critical habitats that sustain fish populations. In the Upper Mississippi River System (UMRS), the environments that fish use in early life stages (i.e., natal origin) can be identified using otolith trace element analysis due to stability and distinctness in water chemistry (strontium: calcium [Sr:Ca]) among water bodies that is reflected in otoliths. Here, we used trace element analysis to determine natal origin of six small‐bodied fishes including bullhead minnow (Pimephales vigilax), emerald shiner (Notropis atherinoides), gizzard shad (Dorosoma cepedianum), bluegill (Lepomis macrochirus), orangespotted sunfish (Lepomis humilis), and yellow perch (Perca flavescens) across six reaches of the UMRS (Pools 4, 8, 13, 26, the Open River of the Middle Mississippi River, and the La Grange Pool of the Illinois River). Otolith core Sr:Ca for fishes was quantified using laser ablation inductively coupled plasma mass spectrometry. Using the resulting Sr:Ca chemical signatures of otolith cores, natal origin (tributary, immigrant, or potential resident) was determined for individual fish based on family‐specific relationships between otolith and water chemistries. We found that all species originated from tributaries and other reaches (i.e., were immigrants) to varying extents, which acted as evidence for network connectivity. Specifically, tributaries contributed up to 48% of individuals at a given reach. In certain reaches, Pool 26 and the Open River reach, up to 80% of individuals in a species immigrated from another mainstem river reach. Network connectivity was also important in both upstream and downstream directions. Contributions from network connectivity varied among species: bullhead minnow used less whereas orangespotted sunfish used more network connectivity than when all species were combined. Further, the use of network connectivity varied spatially where individuals captured in Pool 8 and the La Grange Pool less often and those from Pool 26 and the Open River more often originated from network connectivity compared to the whole assemblage across reaches. These results indicate that species' life history traits probably interacted with the physical environment, which differs spatially, to yield observed recruitment source patterns. Our results show that network connectivity contributes to established assemblages of native small‐bodied fishes throughout the UMRS and underscore the role of interjurisdictional management in maintaining network connectivity to sustain fish populations.

Evidence of deviations between experimental and empirical mixing lengths: Multi-discharge field tests in an arid river system

Despite advances in wastewater treatment plant (WWTP) efficiencies, multiple contaminants of concern, such as microplastics, pharmaceuticals, and per- and poly-fluoroalkyl substances (PFAS) remain largely untreated near discharge points and can be highly concentrated before they are fully mixed within the receiving river. Environmental agencies enforce mixing zone permits for the temporary exceedance of water quality parameters beyond targeted control levels under the assumption that contaminants are well-mixed and diluted downstream of mixing lengths, which are typically quantified using empirical equations derived from one-dimensional transport models. Most of these equations were developed in the 1970s and have been assumed to be standard practice since then. However, their development and validation lacked the technological advances required to test them in the field and under changing flow conditions. While new monitoring techniques such as remote sensing and infrared imaging have been employed to visualize mixing lengths and test the validity of empirical equations, those methods cannot be easily repeated due to high costs or flight restrictions. We investigated the application of Lagrangian and Eulerian monitoring approaches to experimentally quantify mixing lengths downstream of a WWTP discharging into the Rio Grande near Albuquerque, New Mexico (USA). Our data spans river to WWTP discharges ranging between 2-22x, thus providing a unique dataset to test long-standing empirical equations in the field. Our results consistently show empirical equations could not describe our experimental mixing lengths. Specifically, while our experimental data revealed “bell-shaped” mixing lengths as a function of increasing river discharges, all empirical equations predicted monotonically increasing mixing lengths. Those mismatches between experimental and empirical mixing lengths are likely due to the existence of threshold processes defining mixing at different flow regimes, i.e., jet diffusion at low flows, the Coanda effect at intermediate flows, and turbulent mixing at higher flows, which are unaccounted for by the one-dimensional empirical formulas. Our results call for a review of the use of empirical mixing lengths in streams and rivers to avoid widespread exposures to emerging contaminants.

HydroFATE (v1): a high-resolution contaminant fate model for the global river system

Abstract. Pharmaceuticals and household chemicals are neither fully consumed nor fully metabolized when routinely used by humans, thereby resulting in the emission of residues down household drains and into wastewater collection systems. Since treatment systems cannot entirely remove these substances from wastewaters, the contaminants from many households connected to sewer systems are continually released into surface waters. Furthermore, diffuse contributions of wastewaters from populations that are not connected to treatment systems can directly (i.e., through surface runoff) or indirectly (i.e., through soils and groundwater) contribute to contaminant concentrations in rivers and lakes. The unplanned and unmonitored release of such contaminants can pose important risks to aquatic ecosystems and ultimately human health. In this work, the contaminant fate model HydroFATE is presented, which is designed to estimate the surface-water concentrations of domestically used substances for virtually any river in the world. The emission of compounds is calculated based on per capita consumption rates and population density. A global database of wastewater treatment plants is used to separate the effluent pathways from populations into treated and untreated and to incorporate the contaminant pathways into the river network. The transport in the river system is simulated while accounting for processes of environmental decay in streams and in lakes. To serve as a preliminary performance evaluation and proof of concept of the model, the antibiotic sulfamethoxazole (SMX) was chosen, due to its widespread use and the availability of input and validation data. The comparison of modelled concentrations against a compilation of reported SMX measurements in surface waters revealed reasonable results despite inherent model uncertainties. A total of 409 000 km of rivers were predicted to have SMX concentrations that exceed environmental risk thresholds. Given the high spatial resolution of predictions, HydroFATE is particularly useful as a screening tool to identify areas of potentially elevated contaminant exposure and to guide where local monitoring and mitigation strategies should be prioritized.

Influence of river structure and hydrodynamics on water quality in the upper Taihu Basin, China

The Taihu Basin constitutes a complex river network and variable hydrodynamic forces, which contributing to alterations in regional water quality within the Yangtze River Delta. In this study, to explore the underlying mechanism of these dual factors on water quality in the upper Taihu Basin, a combination of graphical analysis, the water quality index (WQI) method, and the partial least square-structural equation model (PLS-SEM) were employed to quantitatively investigate the river structure indices (water surface ratio, WP; river system fractal, Δα; river network connectivity, γ) and hydrodynamic force indices (the flow index, FI), and their influence on water quality. Negative correlations were found between both WP and Δα with FI and a positive correlation between γ and FI. The southern water network had a higher water body area and greater difference in river network density, while the northern river network had enhanced connectivity and stronger water flow, thus exhibiting superior water quality. Regarding the influence of these factors on water quality, the impact of river structure on WQI was statistically insignificant (P > 0.05), while hydrodynamic force was significantly positively correlated with the WQI (P < 0.05). Moreover, in comparison to the path coefficient of 0.657 for the river structure's influence on the WQI, the hydrodynamic force exerted an even more significant impact on water quality with a path coefficient of 0.715. This study suggested that water quality improvements depend on optimizing the structural integrity of river systems and promoting favorable hydrodynamic conditions, with the latter having greater influence. This research provided theoretical underpinning for optimizing river structure and advancing river and lake water environments within the Taihu Basin.

Distribution patterns and controlling factors of beach bars in Qinghai Lake, NW China

The significance of beach-bar reservoirs, which are intricately linked to unconventional hydrocarbon reservoirs, has gained increased attention. This study elucidates the complex mechanisms governing the formation, spatial distribution, and morphological characteristics of beach bars in Qinghai Lake, NW China, highlighting the interplay of lake-level fluctuations, wind wave dynamics, sediment provenance, and terrain gradient. Our findings reveal that large-scale lake-level fluctuations primarily dictate the initial formation settings of beach bars, while small-scale fluctuations refine their internal stratification and sedimentary features. Wind wave dynamics play a critical role in defining suitable depth zones for beach bar development, influencing their morphology and resulting in distinct sedimentary characteristics across different lake zones. Furthermore, the study categorizes beach bars into three main systems based on sediment provenance—bedrock, alluvial fan (fan delta), and braided river systems—each exhibiting unique compositional and structural attributes. Terrain gradient around the lake significantly affects beach bar formation, with areas having a gradient less than 0.7° being particularly favorable. This research advances our understanding of lacustrine beach bar dynamics, offering insights into their potential as indicators of past environmental conditions and their implications for hydrocarbon exploration. The comprehensive analysis of controlling factors provides a foundation for predicting beach bar distribution and contributes to the broader field of sedimentary geology by integrating multi-disciplinary approaches to study lacustrine sedimentary processes.

Inferring channel incision in gravel‐bed rivers: Integrating LiDAR data, historical aerial photographs and drone‐based SfM topo‐bathymetry

AbstractChannel incision is an evident trend for river evolution in many European rivers and notably the Western Carpathians, whose former braided and multichannel wandering river system is transforming into a single‐thread channel, but it is often difficult to separate drivers and determine if incision is finished or is still ongoing. To overpass these research gaps, this paper presents an innovative approach to assess the multidecadal incision of the Belá River in the Western Carpathians since 1949 by LiDAR‐based analyses of floodplain surfaces above the river channel dated from historical aerial images. Detailed analyses of ongoing incision were also calculated based on DEM of differences (DoD) using Structure‐from‐Motion (SfM) photogrammetry‐derived topo‐bathymetric models. The study applied the BACI (Before‐After‐Control‐Impact) approach that compared pre‐state (Before), post‐state (After) and reach (Control) that is not affected by potential external effects with degraded (impacted) reach to be able to distinguish the driver effects. Floodplain channel surface analyses indicate the maximum incision up to 4 m and incision rate of 5.7 cm/year that occurred in the most degraded reach. Moreover, cross‐section profiles point to accelerated incision of 24.5 cm/year in the last 10 years (2011–2021) by the propagation of incision upstream. Overall, the net changes from the UAV survey pointed to 22 759 m3 of gravel sediments, constituting outwash from the 1.6 km long channel system (2015–2022) by incision, whereas analyses of historical channel surfaces estimated erosion of 573 303 m3 from impacted reaches between 1949 and 2020. Incision evidence is only observed in the downstream part below the control section due to local drivers (channel regulation, comprising embankment and gravel mining that activated a backward erosion of the system with knickpoint migration upstream). This analysis shows the benefits of combining different sources of data to separate long‐term and ongoing channel responses and the BACI‐approach to better target cause–effect relationships in space and time.

Late Triassic paleogeography of southern Laurentia and its fringing arcs: Insights from detrital zircon U-Pb geochronology and Hf isotope geochemistry, Auld Lang Syne basin (Nevada, USA)

Fluvial strata of the Upper Triassic Chinle Formation and Dockum Group, exposed across the Western Interior of North America, have long been interpreted to record a transcontinental river system that connected the ancestral Ouachita orogen of Texas and Oklahoma, USA, to the Auld Lang Syne basin of northwestern Nevada, USA, its inferred marine terminus. Fluvial strata are well-characterized by existing detrital zircon data, but the provenance of the Auld Lang Syne basin is poorly constrained. We present new detrital zircon U-Pb and Hf isotopic data that characterize the provenance of Norian siliciclastic strata that dominate the Auld Lang Syne basin. Mixture modeling of Auld Lang Syne basin data identifies the Alleghany−Ouachita−Marathon belt of eastern Laurentia as a dominant source of sediment, but the presence of Triassic detrital zircon grains in Auld Lang Syne basin strata indicates that at least one peri-Laurentian arc segment had to have also contributed sediment. A comparison of new Hf isotopic data with those characterizing various peri-Laurentian volcanic arcs demonstrates that although multiple arc segments may have simultaneously contributed zircons to the Auld Lang Syne basin, the west Pangean arc of northern Mexico stands out as a unique source of highly evolved Permian to Triassic detrital zircon grains in samples from the Auld Lang Syne basin. Altogether, our data and analyses demonstrate source-to-sink connectivity between the Late Triassic (Norian) Cordilleran margin and remnant late Paleozoic highlands of southern to eastern Laurentia, which ultimately framed a Mississippi River−scale, transcontinental watershed that traversed the topographically subdued Laurentian continental interior.