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Sinuous channels wandering through coastal wetlands have been thought to lack lateral‐migration features like meander cutoffs and oxbows, spurring the broad interpretation that tidal and fluvial meanders differ morphodynamically. Motivated by recent work showing similarities in planform dynamics between tidal and fluvial meandering channels, we analyzed meander neck cutoffs from diverse tidal and fluvial environments worldwide, and show that tidal cutoffs are widespread. Their perceived paucity stems from pronounced channel density and hydrological connectivity in coastal wetlands, comparatively small size of most tidal channels, and typically dense vegetation cover. Although these factors do not efface tidal meander cutoffs, they collectively inhibit oxbow formation and make tidal cutoffs ephemeral features that can escape detection. We argue that similar morphodynamic processes drive cutoff formation in tidal and fluvial landscapes, with differences arising only during post‐cutoff evolution. Such process similarity has important implications for understanding coastal wetland ecomorphodynamics and predicting their long‐term evolution. Plain Language Summary The sinuous channels that wander through tidal coastal wetlands look like meandering rivers. However, features of alluvial floodplains that indicate active river meandering over time, such as oxbow lakes and meander cutoffs, are difficult to find in tidal settings. Their apparent absence has led researchers to infer that tidal and fluvial meanders evolve differently. We re‐examined this inference by identifying, measuring, and compiling examples of meander cutoffs from a variety of tidal coastal wetlands and fluvial floodplains worldwide. Our analysis suggests that the shapes and geometric properties of tidal and fluvial cutoffs are indeed remarkably similar. This indicates that while tidal and fluvial environments differ in many ways, they nevertheless share the same physical mechanism affecting meander morphodynamical evolution. Differences between tidal and fluvial meanders do arise after a meander is cut off. We observe that tidal meanders remain preferentially connected to the parent channel, preventing the formation of crescent‐shaped oxbow lakes and thus making tidal cutoffs more difficult to detect. Our results indicate a close similarity in meandering channel behavior across tidal and fluvial systems, which opens new opportunities for how researchers model tidal wetlands, with important implications for the effective conservation and restoration of these critical ecosystems. Key Points Tidal meander cutoffs are far more common than typically thought and share remarkable morphometric similarities with fluvial counterparts Similar mechanisms trigger cutoffs in both tidal and fluvial landscapes, with differences arising only during post‐cutoff evolution Tidal cutoffs seldom disconnect from parent channels and rarely form oxbows due to the high hydrological connectivity of tidal wetlands

Meandering rivers are diagnostic landforms of hydrologically active planets, and their migration regulates the continental component of biogeochemical cycles that stabilize climate and allow for life on Earth. The rise of river meanders on Earth has been linked to riverbank stabilization driven by the Palaeozoic evolution of plant life about 440 million years ago. Here we provide a fundamental test for this hypothesis using a global analysis of active meander migrations that includes previously ignored unvegetated rivers from the arid interiors of modern continents. When normalized by channel size, unvegetated meanders universally migrate an order of magnitude faster than vegetated ones. While providing irrefutable evidence that vegetation is not required for meander formation, we demonstrate how profoundly vegetation transformed the pace of change for Earth’s landscapes, and we at last offer a mechanistic explanation for the radically distinct stratigraphic records of barren and vegetated rivers. We posit that the migration slowdown driven by the rise of land plants dramatically impacted biogeochemical fluxes and rendered Earth’s landscapes even more hospitable to life. Therefore, the tenfold faster migration of unvegetated rivers may be key to deciphering the environments of barren worlds such as early Earth and Mars.

Distributed hydrological models rely on hydrography data such as flow direction, river length, slope and width. For large-scale applications, many of these models still rely on a few flow direction datasets, which are often manually derived. We propose the Iterative Hydrography Upscaling (IHU) method to upscale high-resolution flow direction data to the typically coarser resolutions of distributed hydrological models. The IHU aims to preserve the upstream–downstream relationship of river structure, including basin boundaries, river meanders and confluences, in the D8 format, which is commonly used to describe river networks in models. Additionally, it derives representative sub-grid river length and slope parameters, which are required for resolution-independent model results. We derived the multi-resolution MERIT Hydro IHU dataset at resolutions of 30 arcsec (∼ 1 km), 5 arcmin (∼ 10 km) and 15 arcmin (∼ 30 km) by applying IHU to the recently published 3 arcsec MERIT Hydro data. Results indicate improved accuracy of IHU at all resolutions studied compared to other often-applied upscaling methods. Furthermore, we show that MERIT Hydro IHU minimizes the errors made in the timing and magnitude of simulated peak discharge throughout the Rhine basin compared to simulations at the native data resolutions. As the method is open source and fully automated, it can be applied to other high-resolution hydrography datasets to increase the accuracy and enhance the uptake of new datasets in distributed hydrological models in the future.

The majority of tidal channels display marked meandering features. Despite their importance in oil-reservoir formation and tidal landscape morphology, questions remain on whether tidal-meander dynamics could be understood in terms of fluvial processes and theory. Key differences suggest otherwise, like the periodic reversal of landscape-forming tidal flows and the widely accepted empirical notion that tidal meanders are stable landscape features, in stark contrast with their migrating fluvial counterparts. On the contrary, here we show that, once properly normalized, observed migration rates of tidal and fluvial meanders are remarkably similar. Key to normalization is the role of tidal channel width that responds to the strong spatial gradients of landscape-forming flow rates and tidal prisms. We find that migration dynamics of tidal meanders agree with nonlinear theories for river meander evolution. Our results challenge the conventional view of tidal channels as stable landscape features and suggest that meandering tidal channels recapitulate many fluvial counterparts owing to large gradients of tidal prisms across meander wavelengths.

Abandoned meanders and former river channels represent important depositional units of fluvial river systems, making them suitable sedimentary archives for assessing pollution trends. The objective of this study is to provide insight into temporal trends and spatial variability in pollution levels in the selected fluvial elements (an abandoned meander, a former river channel, and a semi-open meander) within the Rezavka Nature Reserve (part of the Poodří protected landscape area) along the Odra River and Mlýnka stream, located in the heavily polluted Ostrava urban agglomeration (Czech Republic). Initial stages of the abandoned meander evolution were characterised by high sediment accumulation rates and decelerated over time, while more regular sediment supply continued in sites close to the semi-open meander of the Mlýnka stream. Pollutants were effectively captured by abandoned meanders with fine-grained infill, while the coarser-grained infill of the former channel was less effective pollutant scavenger. A time frame for deposition was assigned using vertical trends in 137 Cs mass activity and selected organic pollutants. The sedimentary record, covering the last ~ 70 years, reveals a distinct vertical pollution trend that reflects industrial development. Pollution levels have increased since the 1950s and will remain high at the end of the 20th century. The depth pattern of heavy metals, as well as their enrichment factors, shows an upward increase. Levels of persistent organic pollutants are typically low or under the limit of detection in the deepest strata, gradually or sharply rising upward.

River meandering dynamics are here explored in light of unsteady water flows. While mathematical models have usually focused on constant discharges—a reasonable and widely adopted approach for long‐term considerations—we show that varying flows strongly affect the short‐term planimetric evolution of meanders, before the cutoff occurrence. In particular, flow variability slows down the meanders' dynamics while does not significantly influence the wavelength selection. We support our arguments with numerical simulations and theoretical (linear and nonlinear) analyses, showing that an interplay between out‐of‐phase river geometry and flow is responsible for the meander‐dynamics slowdown. Our results suggest that accounting for flow variability is critical in assessing yearly to decadal meander dynamics with important implications for river engineering and management strategies. Plain Language Summary Meandering rivers are natural sinuous channels shaping the Earth's surface with their lateral migration motion. Beyond theoretical interest, the investigation of such dynamics is fundamental for river management and restoration. A common way to study river meander dynamics is through numerical simulations that simulate the planform evolution of the river geometry in space and time. A classic assumption in these simulations is a constant water flow. In this study, we show that considering more realistic temporally varying flow discharges slows down the meander growth compared to the case with a constant flow discharge. Key Points Numerical simulations and linear and nonlinear theoretical analyses feature how the river planimetry evolves under variable flows Unsteady water flows slow down the planimetric evolution of river meanders compared to constant discharges Flow variability is crucial for meander dynamics on yearly to decadal timescales, with implications for river engineering and restoration

We investigate whether geomorphic signatures of permafrost are embedded in planforms of river meanders, and we inquire as to how physical factors unique to permafrost environments are able to affect their dynamics. By exploiting satellite imagery, a data set of 19 freely‐meandering Arctic rivers is compared against an independent data set of 23 freely‐meandering streams flowing through temperate and tropical regions. Suitable dimensionless metrics are defined to characterize morphometric properties of meanders in terms of the spatio‐temporal distribution of curvature and channel width. Results show the absence of marked contrasts in the amplitude of bend‐curvature between the two data set. Differently, we find a permafrost signature in the channel width response, which manifests itself through larger values of the average bend‐width and by peaks of width fluctuations. Field data suggest that permafrost meanders tend to widen for increasing bend sinuosity, likely promoting a shift of their morphodynamic regime as final cutoff is approached. Plain Language Summary One of the most striking impacts of climate warming in the Arctic region is permafrost thaw. Arctic rivers typically flow through perennially‐frozen floodplains, thus they are particularly susceptible to ground thawing. In order to understand the response of Arctic rivers to climate variability, basic knowledge about key differences with respect to non‐permafrost streams is needed. Despite recent studies which have emphasized the slower yearly movement rates distinguishing Arctic streams, we still do not understand whether permafrost‐affected rivers show distinctive features in their morphology due to specific physical mechanisms. By exploiting satellite imagery, we show that permafrost leaves a signature in the shape of meandering Arctic rivers. Specifically, their average bend‐width increases as sinuosity develops, while the amplitude of width oscillations is larger than that displayed by their non‐permafrost kin. Key Points Permafrost is found to leave a morphological signature in the spatio‐temporal signal of channel width at the bend scale Permafrost meander bends show larger amplitude of width oscillations and widen as sinuosity increases Bend curvature as a standalone indicator does not provide evidence of any significant permafrost‐fingerprint

Soft machines are a promising design paradigm for human-centric devices 1 , 2 and systems required to interact gently with their environment 3 , 4 . To enable soft machines to respond intelligently to their surroundings, compliant sensory feedback mechanisms are needed. Specifically, soft alternatives to strain gauges—with high resolution at low strain (less than 5 per cent)—could unlock promising new capabilities in soft systems. However, currently available sensing mechanisms typically possess either high strain sensitivity or high mechanical resilience, but not both. The scarcity of resilient and compliant ultra-sensitive sensing mechanisms has confined their operation to laboratory settings, inhibiting their widespread deployment. Here we present a versatile and compliant transduction mechanism for high-sensitivity strain detection with high mechanical resilience, based on strain-mediated contact in anisotropically resistive structures (SCARS). The mechanism relies upon changes in Ohmic contact between stiff, micro-structured, anisotropically conductive meanders encapsulated by stretchable films. The mechanism achieves high sensitivity, with gauge factors greater than 85,000, while being adaptable for use with high-strength conductors, thus producing sensors resilient to adverse loading conditions. The sensing mechanism also exhibits high linearity, as well as insensitivity to bending and twisting deformations—features that are important for soft device applications. To demonstrate the potential impact of our technology, we construct a sensor-integrated, lightweight, textile-based arm sleeve that can recognize gestures without encumbering the hand. We demonstrate predictive tracking and classification of discrete gestures and continuous hand motions via detection of small muscle movements in the arm. The sleeve demonstration shows the potential of the SCARS technology for the development of unobtrusive, wearable biomechanical feedback systems and human–computer interfaces. Strain gauges with both high sensitivity and high mechanical resilience, based on strain-mediated contact in anisotropically resistive structures, are demonstrated within a sensor-integrated, textile-based sleeve that can recognize human hand motions via muscle deformations.

Floodplain encroachment by embankments heightens flood risk. This is exacerbated by climate change and land‐use modifications. This paper assesses the impact of embankments on sediment transport, channel geometry, conveyance capacity, and flood inundation of a reach of the Nakkhu River, Nepal. Using the CAESAR‐Lisflood landscape evolution model based on a 2‐m digital elevation model, we simulate four flood scenarios with and without embankments and sediment transport: a historical 25‐year return period flood event used to design the embankments, 50‐year, 100‐year, and 1000‐year return period flood events forecast using the Generalized Logistic Model (using data from 1992 to 2017). Our results indicate that flow confinement by embankments reduces inundation by 99% (from 22.5 to 0.3 ha) for the historical 25‐year flood discharge of 42.23 m3/s${\\mathrm{m}}^{3}/\\mathrm{s}$and by 15% (from 28.8 to 24.4 ha) for the 1000‐year return period flood discharge of 95 m3/s${\\mathrm{m}}^{3}\\mathrm{/}\\mathrm{s}$(similar to a 25‐year maximum mid‐future). The presence of embankments increases downstream sediment transport by more than 32% for all flood scenarios considered. Inclusion of sediment transport leads to a fivefold increase in predicted inundation area for a 25‐year maximum mid‐future flood compared to the no‐sediment case in the embanked channel. Changes in channel geometry due to sedimentation significantly reduce conveyance capacity increasing overtopping flood risk, particularly where the channel is sinuous or located on flat terrain. Our results indicate that sediment erosion in outer meanders may threaten embankment stability by promoting undercuts. It is recommended that sediment transport effects be factored into embankment design and floodplain planning. Plain Language Summary Our research explores the impact of flood protection embankments being constructed along the Nakkhu River in the Kathmandu Valley, Nepal, in a region that is experiencing rapid urban growth. Using advanced computer simulations, we study how these embankments influence the erosion and deposition of sediment in the river, and hence impact flood risk. Our findings indicate that the construction of embankments increases sediment transport, and alters the geometry of the river increasing downstream flood risk during extreme flood events. This is particularly the case for embankments designed to follow natural, meandering river courses. We recommend incorporating sediment transport analysis into the planning and design of embankments and developments in floodplain areas to reduce the risk of flooding. Our study indicates that embankment construction by itself may not always be a sustainable long‐term flood‐protection measure for rivers carrying high sediment loads. Key Points Inclusion of sediment processes is very important in predicting the effect of embankments on river flood risk For the embanked Nakkhu, predicted inundation is fivefold larger for 25‐year maximum mid‐future event when sediment transport is included Sedimentation reduces channel capacity for flat terrain and large meanders; erosion at outer meanders threatens Nakkhu embankment stability

River meanders are one of the most recurrent and varied patterns in fluvial systems. Multiple attempts have been made to detect and categorize patterns in meandering rivers to understand their shape and evolution. A novel data‐driven approach was used to classify single‐bend meanders. A data set containing approximately 10 million single‐lobe meander bends was generated using the Kinoshita curve. A neural network autoencoder was trained over the curvature energy spectra of Kinoshita‐generated meanders. Then, the trained network was tested on 7521 real meander bends extracted from satellite images, and the energy spectrum in the meander curvature was reconstructed accurately thanks to the autoencoder architecture. The meander spectrum reconstruction was clustered, and three main bend shapes were found associated with the meander data sets, namely symmetric, upstream‐skewed, and downstream‐skewed. The autoencoder‐based classification framework allowed bend shape detection along rivers, finding the dominant pattern with implications on migration trends. The classification framework proposed in this study was used to analyze the morphological evolution of the Ucayali river over 32 years. The shift from prevalent downstream‐skewed to prevalent upstream‐skewed bends (or vice versa) after big cutoffs suggests a plausible transition from super‐resonant dominated to sub‐resonant dominated behavior (or the reverse). Overall, the method proposed opens the venue to data‐driven classifications to understand and manage meandering rivers. Bend shape classification can thus inform restoration and flood control practices and contribute to predicting meander evolution from satellite images or sedimentary records. Plain Language Summary Single‐thread rivers commonly cut through alluvial floodplains with continuous sinuous curves. Classifying meanders provides a key to understanding their shape and, thus, learning how they have changed over time. A novel classification framework was proposed using a machine‐learning model for pattern recognition in images. This model was trained over the energy of curvature distribution within meander bends generated from analytical relations. The classification framework was then tested over a set of real meander bends extracted from satellite images. The trained model grasped the most important features contained in curvature energy distribution, grouping the meander data set into three bend‐shaped clusters, namely symmetric, upstream‐skewed, and downstream‐skewed. The proposed framework was eventually used to find the predominant bend class and its shifts during migration of the Ucayali river, offering a different perspective on meander evolution. Bend shape classification can be used to guide restoration and flood control plans and predict meandering trends from satellite images or sedimentary records. Key Points A curvature‐based classification framework of meander bends was successfully trained over Kinoshita‐generated meanders By testing the trained framework over real meander bends, 3 classes were found, namely symmetrical, downstream‐skewed, and upstream‐skewed The proposed framework detects the dominant shape class in river reaches and how this changes over time when cutoff events occur