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The Tongtian River is the source of the Yangtze River and is a national key ecological reserve in China. Monitoring and predicting the changes and mechanisms of the Tongtian River channel morphology are beneficial to protecting the “Asian Water Tower”. This study aims to quantitatively monitor and predict the accretion and erosion area of the Tongtian River channel morphology during the past 30 years (1990–2020). Firstly, the water bodies of the Tongtian River were extracted and the accretion and erosion areas were quantified using 1108 Landsat images based on the combined method of three water-body indices and a threshold, and the surface-water dataset provided by the European Commission Joint Research Centre. Secondly, an intelligent lightweight neural-network model was constructed to predict and analyze the accretion and erosion area of the Tongtian River. Results indicate that the Tongtian River experienced apparent accretion and erosion with a total area of 98.3 and 94.9 km2, respectively, during 1990–2020. The braided (meandering) reaches at the upper (lower) Tongtian River exhibit an overall trend of accretion (erosion). The Tongtian River channel morphology was determined by the synergistic effect of sediment-transport velocity and streamflow. The lightweight neural network well-reproduced the complex nonlinear processes in the river-channel morphology with a final prediction error of 0.0048 km2 for the training session and 4.6 km2 for the test session. Results in this study provide more effective, reasonable, and scientific decision-making aids for monitoring, protecting, understanding, and mining the evolution characteristics of rivers, especially the complex change processes of braided river channels in alpine regions and developing countries.

Channel response to dam removal is still poorly understood, as there is a lack of monitoring data. A small dam in the gravel bed Krzczonówka Stream was lowered in 2014 as the first in the Polish Carpathians. The paper describes the direction and magnitude of channel changes after the check dam lowering against the backdrop of slow changes in the riverbed occurring over a period of several decades. Geomorphologic mapping and geodetic measurements started in 2013 and were repeated in 2014. Archived cartographic sources were used to identify channel morphology in the past. After the studied check dam had been partially lowered, a flood occurred and caused movement of sediment from the reservoir into the channel downstream. Debris filled pools and artificial riffles were created in 2013—the largest deposition occurred just below the dam. The channel width also increased in this area. The channel reach upstream from the dam was incised. Additional gravel supply is limited because of a sequence of drop structures just upstream of the studied reach. Long-term channel evolution after dam lowering depends on flood events and the availability of material for fluvial transport.

The anthropogenic activities affect the river channel as well as the whole system in different magnitudes and dimensions. Barakar River, the main tributary to the Damodar River in eastern India, is modified by several engineering structures. Hydrological parameters, such as monthly discharge, peak flow discharge and geomorphological factors, such as gradient, width–depth ratio, grain size, braid–channel ratio, sinuosity ratio, riffle-pool sequence, and stream power are taken into consideration to highlight the significant alterations of the river due to dam and bridge construction. The alterations are assessed with the help of hydrological data, satellite images, and digital elevation data along with field survey. The downstream section of the dams, the river is characterised by high braiding, sinuous, total and unit stream power along with the presence of a box-shaped bedrock channel, high gradient, bed coarsening and armouring due to the release of high-velocity sediment-free ‘hungry water’. In the upstream reach, the grain size decreases towards the dam, and it increases suddenly with poor sorting at the immediate downstream regime of the dam. The effects of bridges on the Barakar river morphology include an increase of gradient, width and depth of the river channel at the downstream of the bridges. The construction of bridges influences riffle-pool sequences. Thereby, the pool depth spacing is greater than the riffle crest spacing. However, the integration of natural as well as human-induced factors can be the best approach to understand the anthropogenic alteration of the river. Moreover, construction of some check dams at the upper section of the tributaries of the Barakar River can be very effective for morphological stability.

Flooding remains one of the major natural disasters that threatens human lives and property. Flood management has taken a new look, whereby flood risk in rivers is now viewed as driven by not just climate change but also by river channel morphological adjustment which have been overlooked in the past. This study aimed at evaluating the contributions of channel morphological adjustment to flood risk in rivers using river Elbe in Germany as a case study. To achieve this, an inundation model for the June 2013 flood event was developed using the LISFLOOD-FP model. A total of thirteen additional flood inundation models were ran at varying scenarios of river width, bed elevation and channel friction coefficient under a fixed discharge series. The results of these simulations revealed that, variability in river channel morphology constitutes an integral part of flood risk in rivers, hence a complementary driving factor to flood risk in addition to climate change. Thus, the assumption of a constant river channel morphology during flood modelling should consequently be open to question for flood hazard management. Flood frequency analysis for the Elbe basin was also presented. Discharge data spanning an interrupted period of 61 years (1958–2018) from 10 gauges along river Elbe were analysed for various return periods. It was concluded that any discharge rate having a return period of 5 years (2544 m 3 /s) and more would likely exceed the water carrying capacity of the Elbe river. The study proposes potential measures for effective flood modelling in rivers and can also serve as important tool for informing and supporting environment related decision making in flood risk management, land use regulation and floodplain management in the study area.

To investigate the root and canal morphology of permanent mandibular anterior teeth in a Chongqing population using cone-beam computed tomography (CBCT). CBCT images of 1,725 patients in a Chongqing population were selected, and a total of 9,646 mandibular anterior teeth were analyzed. The number of root canals and the canal configurations were investigated. In total, 0.3% (11/3,257) of lateral incisors and 0.8% (26/3,014) of canines had double roots, and 3.8% (127/3,375) of central incisors, 10.6% (345/3,257) of lateral incisors, and 4.2% (127/3,014) of canines had multi-root canals. The difference in the incidence of multi-canals in lateral incisors between female and male was statistically significant. The frequency of multi-canals in the different age groups was 5.0% for central incisors for ages 21-30 years, 14.7% for lateral incisors for ages 41-50 years, and 8.1% for canines for ages 41-50 years. With the limitations of the current study, we found that a high percentage of mandibular anterior teeth had multiple canals in the studied Chinese Chongqing population. The current data may provide clinicians practicing in Chongqing with a more thorough understanding of root canal morphology.

One of the most dramatic events in river environments is the natural diversion, or avulsion, of a channel across its floodplain. Though rarely witnessed, avulsions can cause massive floods, and over geologic time they create most of the fluvial stratigraphic record. Avulsions exhibit behavior ranging from reoccupying abandoned channels to constructing new channels and splay complexes. To quantify avulsion behavior, or style, we measure avulsion-related floodplain disturbance in modern environments. We show that for 63 avulsions from Andean, Himalayan, and New Guinean basins, avulsion style correlates with channel morphology and changes systematically downstream. Avulsions in braided rivers reoccupy abandoned channels, whereas avulsions in meandering rivers often produce flooding and sediment deposition during channel construction. These downstream changes in avulsion style can explain the abrupt transition from channel-dominated to floodplain-dominated facies commonly observed in foreland basin stratigraphy. These dynamics also explain why some avulsions are more hazardous than others. River avulsions are dramatic events that can cause the loss of many human lives. The authors here investigate how river avulsion style changes with river morphology, and how these changes impact flooding and stratigraphy.

Nature has protein channels (e.g., aquaporins) that preferentially transport water molecules while rejecting even the smallest hydrated ions. Aspirations to create robust synthetic counterparts have led to the development of a few one-dimensional channels. However, replicating the performance of the protein channels in these synthetic water channels remains a challenge. In addition, the dimensionality of the synthetic water channels also imposes engineering difficulties to align them in membranes. Here we show that zero-dimensional porous organic cages (POCs) with nanoscale pores can effectively reject small cations and anions while allowing fast water permeation (ca. 10 9 water molecules per second) on the same magnitude as that of aquaporins. Water molecules are found to preferentially flow in single-file, branched chains within the POCs. This work widens the choice of water channel morphologies for water desalination applications. Replicating the performance of protein water channels (aquaporins) in artificial one-dimensional channels are often synthetically challenging. Here, the authors show that porous organic cages allow water permeation on the same magnitude as that of aquaporins while effectively rejecting small ions.

Ecological restoration has grown rapidly and now encompasses not only classic ecological theory but also utilitarian concerns, such as preparedness for climate change and provisioning of ecosystem services. Three dominant perspectives compete to influence the science and practice of river restoration. A strong focus on channel morphology has led to approaches that involve major Earth-moving activities, such as channel reconfiguration with the unmet assumption that ecological recovery will follow. Functional perspectives of river restoration aim to regain the full suite of biogeochemical, ecological, and hydrogeomorphic processes that make up a healthy river, and though there is well-accepted theory to support this, research on methods to implement and assess functional restoration projects is in its infancy. A plethora of new studies worldwide provide data on why and how rivers are being restored as well as the project outcomes. Measurable improvements postrestoration vary by restoration method and measure of outcome.

Many fluvial systems have undergone significant changes in their morphology due to base level fall since the last glaciation. Channels in such transient fluvial systems continuously adjust their morphology and may still be incising until reaching a new equilibrium condition. This study examines morphometric change detection indices and techniques to quantify and analyze the recent variations in the channel properties of the lower portions of the Le Sueur and Maple Rivers, in response to upstream knickpoint migration. The results reveal that channel reaches upstream of the knickzones remain relatively stable, exhibiting low channel bed gradients and minimal morphological change. In contrast, the local channel gradient increases about ∼3 fold near the knickpoints and continues with predominantly high rates into the downstream direction. Together, the morphometric indices indicate that the channel geometry of the Maple and Le Sueur Rivers downstream of the knickpoints is actively adjusting to accommodate the rapid base level drop. Because of incomplete adjustment processes, both rivers experienced remarkable change in channel geometry between 2008 and 2015, albeit with differing adjustment patterns. In particular, the percentage change in channel properties along the knickzone reaches up to 120% for the channel cross-sectional area, 60% for the channel width, and 75% for the mean hydraulic depth. These changes are accompanied by a sharp increase in cross-sectional stream power and impose boundary shear stress along the knickzones which amplify sediment transport capacity and drive further modifications to channel size and shape. This study provides a quantitative framework for assessing geomorphic responses to base level drop and provides insights into the feedback mechanisms between hydraulic forces and channel morphology. The findings have broader implications for understanding channel evolution under non-equilibrium conditions and for guiding river management in similar fluvial systems.

Reportedly,maxillary premolars are the most complex teeth for performing endodontic treatment,[1] with root canals varying based on race,genetic predisposition,diet,region,gender,[2] and perhaps age.To date,few detailed studies have been conducted to assess number of roots and root canal morphology of maxillary premolars in the elderly.The present study analyzed root canal morphology of maxillary premolars in elderly individuals using cone-beam computed tomography （CBCT）,which has substantial clinical value in guiding endodontic treatment.[3]