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Abstract Brahmaputra is a large, tropical, trans-boundary river with high sediment load and has the unique distinction of possessing both largest and smallest inhabited river islands. Majuli is the largest inhabited river island situated in the Indian state of Assam and bounded by Brahmaputra on the south, Subansiri River on the northwest, and the Kherkatia River (anabranch of Brahmaputra) on the northeast. The island was formed during a flooding event in 1750 with a sudden change in the course of the Brahmaputra from a low energy meandering to a high energy braided river and subsequent capture of one of its tributaries. The island is a part of the Brahmaputra alluvium squeezed between active Himalayan and Indo-Burmese orogenic belts in an intricate tectonic regime. The dominant flow path of Brahmaputra is controlled by the crustal scale reorganization in this part of the world. The tectonic factors that controlled the anabranching process and created the island, is at present acting as the destroyer of the same by the means of unabated erosion. The erosion pattern of the two rivers viz. Brahmaputra and Subansiri were studied and areas with marked selective erosion have been found. From a combined study of satellite imaging, bathymetric survey and mapping, it is found that the lobate shaped erosions in the study areas are restricted to traces of the tectonic elements related to the Himalayan thrust system through which the rivers are trying to anabranch.

Water level adjustment downstream of dams significantly impacts river regimes and flood control. However, due to constant strong scouring, our quantitative understanding of the characteristics of water level variations and their causes in the Chenglingji–Jiujiang Reach of the Yangtze River remains limited. Here, we analyzed the water level change trend via the Mann–Kendall method and analyzed geomorphic change and river resistance using 406 cross-sectional profiles as well as data on discharge and water levels from 1991 to 2022. Results showed that the critical conversion discharges (CCD) in the Chenglingji-Hankou Reach and the Hankou-Jiujiang Reach were approximately 35,000 and 30,000 m3/s, respectively, after the operation of the Three Gorges Dam. The water level exhibited an overall decline mainly due to river erosion when the discharge was lower than the CCD. The water level exhibited a nonsignificant upward trend mainly due to increased river resistance (7–20%) when the discharge was higher than the CCD. The obvious increase in the floodwater level in individual years was caused by the effect of downstream water level increase. Our findings further the understanding of downstream geomorphic response to dam operation and their impacts on water levels and have important implications for flood management in such rivers worldwide. HIGHLIGHTS The critical conversion discharges of the water level changes in the Chenglingji-Hankou Reach and Hankou-Jiujiang Reach are approximately 35,000 and 30,000 m3/s, respectively.; The dominant cause of the water level decrease below or increase above the critical conversion discharge is river erosion or greater increase in resistance.; The obvious increase in the floodwater level in individual years was due to the more obvious increase of downstream water level.;

Granitic forms resulting from turbulent flow, with hydraulic vortices, characterize the rocky bed of the lower course of the Carnaúba River, in a geosite of the Seridó Geopark, in the Seridó Oriental microregion, Northeast Brazil. These forms constitute a variety of types of potholes that individually represent various stages of evolution, in addition to reflecting the variation in the erosive potential of river flow throughout the Quaternary. From a bibliographical review, fieldwork (quantification and measurements of the potholes), high-resolution photogrammetry and morphostructural analysis of the generated cartographic products, it was possible to establish a correlation between the preferential orientation of the potholes and the direction of the planes of weakness, as well as the classification of potholes by morphometric parameters. In this work it was demonstrated that the efficiency of hydraulic vortices is associated with discontinuity structures and the mineralogical composition of granite facies, with abrasive erosion being responsible for sculpting potholes, with different dimensions and geometries. In the rocky bed of the Carnaúba River, the small potholes deepen and their diameter evolves into cylindrical shapes as the turbulent vertical flow increases, eventually becoming sigmoidal. The lateral potholes, located on the walls of the river channel, are deeper than they are wide, and represent a destructive phase of evolution.

Glaciers continue to erode and transport material, forming an accumulation area at the front of the glacier. The trunk glacier, which has many tributary glaciers upstream and converges on the main channel, deposits vast amounts of material in the main channel. It blocks the main channel, forming barrier lakes, and eventually turns into mountain disasters, such as debris flows or outburst floods. Therefore, the accumulation rate of the material is a major parameter in such disasters and can determine the frequency of disasters. The material usually comes from bedrock erosion by glaciers, weathering of bedrock walls, and upstream landslides, and the material loss depends on river erosion. Based on this, we set up a method to calculate the material accumulation rate in the glacier front based on satellite images. Then, the Peilong catchment was taken as an example to validate the proposed method. The results indicate that climatic fluctuations may increase landslides, resulting in more actual accumulation than the calculated value according to the average rate of bedrock retreat. The material provided by the retreat of bedrock accounts for 92% of the total volume. Our method provides a practical reference for the mid- and long-term prediction of glacial catastrophic mass movement, as global warming seriously threatens glacier instability and downstream communities. [ABSTRACT FROM AUTHOR]

The Heihe Water Diversion Project in Zhouzhi County, Shaanxi Province is a "lifeline" engineering project that supplies water as well as electric power to Xi'an City, China. This canyon-type reservoir is located at the mouth of the Heihe River on the northern flank of the Qinling Mountain. Slope stability of the reservoir bank is one of the critical geological engineering problems, among which the toppling rock slope of Shuimengou is a major threat to the dam and downstream residents. The toppling rock mass was formed by downcutting of the river, and the hard thin-layer metamorphic schist gradually bent under the action of gravity. Monitoring data in recent decade showed that the process of toppling continued slowly. Under the erosion of the reservoir water the stability of the toppling slope may deteriorate in the coming time. Hence, it is essential to predict the stability of the slope and to give a proposal for mitigation. For this purpose, this paper simulates and analyzes the deforming process of the toppling slope in geological history using the discontinuous deformation analysis (DDA) method. Furthermore, in consideration of the reservoir erosion at the foot of the slope the future deformation-failure of the slope is also simulated. Based on the result, a reasonable counter measure is proposed for stabilizing the slope. [ABSTRACT FROM AUTHOR]

The rate of deformation of the longitudinal profile for a period of half a century in the sediment flow and riverbed morphology has been assessed by comparison of the leveling survey data on the longitudinal profile of a number of lowland rivers in Russia. This problem remains relevant in both the theoretical and practical aspects, especially for rivers in which a range of in-stream mines occupies kilometers and tens of kilometers and they have operated for decades. The removal of a large amount of alluvial material from the sediment transport and changes in the riverbed morphometric characteristics have given impetus to the leveling process of the sediment transport capacity along the river due to scouring. The result is lowering of the bottom and water surface. The scouring reaches 3–8 cm in rate and spreads 400–700 m/yr along the river. Retrogressive erosion (headcutting) is well-defined, whereas progressive erosion is less pronounced, because it is partially replaced by the mechanical removal of alluvial material. Under these deformations, the longitudinal profile has changed from convex or straight to concave, and there are no signs of recovery over the past decades, despite the fact that the mining has been relatively moderate for the past 30 years or has been completed in the rivers under consideration. [ABSTRACT FROM AUTHOR]

Frequent floods and river erosions, exacerbated by global climate change, are causing miseries to millions of people worldwide. Thousands of citizens in Bangladesh become homeless every year due to recurrent floods and river erosions. This study reveals an unusual fact that the inhabitants of the Jamuna river floodplain are choosing immobility over migration to safe locations in such situations. The victims of forced migration usually stay within the same zone of calamity. To understand the dynamics, this study focused on determining the factors influencing immobility of the victims in Dewanganj sub-district of Jamalpur district in north-central Bangladesh. Primary data were collected from three distinct locations through oral histories, Focus Group Discussions, Key Informant Interviews, and household questionnaire surveys. Migration has a negative correlation (− 0.29) with flood experiences and a positive correlation (0.63) with erosion experiences of the victims. Thus, the flood-victims tend to be immobile more than the erosion-victims. The tipping-depth for flood is the highest among women in the island char, and the tipping-distance for erosion is the lowest in the attached char. The low living cost, working opportunities for women, and non-government/ government supports are the most important facilitators of immobility, and poverty and uncertainty in adapting to a new place are the major obstructive indicators of mobility. Suggestions are provided as to how immobility can be encouraged in hazard-prone vulnerable settings. [ABSTRACT FROM AUTHOR]

This study was carried out to evaluate the recent morphological changes of Padma River with consequent socioeconomic impacts on the downstream riverbank area. Morphological changes of the river reach were analyzed using remote sensing (RS) data (from 2010 to 2019) and GIS technique. Social survey was performed in Zajira and Naria upazilas of Shariatpur district among 150 respondents to determine the social and economic losses. The GIS analysis showed that the average rate of erosion of major channel was 42 m/yr and the average accretion rate was 38 m/yr at the secondary channel. The northeastern channel was abandoned and shifted toward south at the rate of 262 m/yr. Shariatpur site was affected by noticeable erosion at the rate of 52 m/yr. The changing pattern of chars showed that sedimentation rate was higher at the northern side comparing the south. Statistically significant differences were found from independent sample T test for the mean shifting in main channel (t (3) = − 3.87, p <.03), secondary channel (t (6) = 3.32, p <.02), and char area (t (8) = 4.32, p <.005) before and after 2014. Welch's ANOVA showed significant differences in the mean river width shifting among the reference lines for both main and secondary channels. The data from social survey showed that 95% people living along riverbank had lost most of their lands in between 2014 and 2019. Majority of the respondents (67%) noticed the anthropogenic influences around the bridge site to be one of the contributors to accelerate the recent erosion. In addition to settlement, structural, and economic loss, both physical and mental health of the riverbank people is affected due to frequent migration. Immediate necessary steps through effective river management policy guidelines and implementation to adopt a permanent solution are required. [ABSTRACT FROM AUTHOR]

The failure patterns and retrogression distances in sensitive clays induced by river erosion are two significant factors of concern in landslide risk assessment. For the former, empirical criteria, based on past events and numerical results, can hardly produce a unified guideline and explain their complex mechanism. For the latter, the capacity of the river cross section is rarely considered in existing studies, even though the failed soil would deposit on the riverbed and further affect upslope failure extension. The present study proposes an analytical method to quantitatively assess the failure patterns and retrogression distance by combining the shear band propagation method (SBP) with limit analysis on active block failure. A closed‐form active earth pressure (CAEP) and the shape function of the failure surface are proposed with the variational calculus method (VCM), providing a tool to understand the transformation mechanism of the failure patterns. The criteria for initiation failure positions and stages are formulated following the competition results between the induced minimum slope‐parallel force by foot unloading and the proposed CAEP. Further, the terminal retrogression distance is given considering two possible river cross sections. The proposed CAEP solution is validated against Buss's solution and further applied to a parametric study on the failure patterns. Finally, three practical cases are analyzed with the proposed method, and the predictions are shown to agree well with the field observations. [ABSTRACT FROM AUTHOR]

Intensive human activities in river basins have substantial effects on fluvial hydrological and morphological processes and developmental trends. In this study, we assessed the evolutionary characteristics and developmental trends of the fluvial morphological system of the Three Gorges Dam (TGD) downstream to understand the impacts of human activities on the fluvial hydrological–morphological system of the region. The results indicated that the Three Gorges Project (TGP) and other upstream cascade reservoirs promoted sediment retention, which in turn aggravated the trend of declining sediment load and cumulative scouring over a long distance in the channels downstream of the TGD. Approximately 84% of scouring occurred in the low‐water channels, along with thalweg scouring and riverbank collapse. Notably, extended operation of the TGP and other upstream cascade reservoirs has resulted in gradual changes in the downstream riverbeds. Specifically, we found that the most intensive scouring zone shifted downstream from the near‐dam Yichang–Chenglingji reach (0–408 km) to the Chenglingji–Hankou reach. The scouring–silting distribution in swales has also changed: the scouring of deep swales and silting on floodplains prior to the TGP have been replaced by the scouring of both deep swales and floodplains. The scouring intensity of riverbeds in the Yichang–Hukou reach (954 km) was slightly higher than that forecasted prior to the TGP; the scouring intensities increased significantly during 2013–2021, which could be attributed to the TGP and other upstream cascade reservoirs; river sand mining and waterway dredging are secondary factors. We conclude that, owing to the effects of sediment retention by cascade reservoirs in the upper reaches of the Yangtze River (or Changjiang River), the cumulative scouring intensities of riverbeds in the middle and lower reaches of the Yangtze River will continue to increase in future decades. [ABSTRACT FROM AUTHOR]

Irrigation water for agriculture in Ningxia during the summer is primarily sourced from the Yellow River self-flow irrigation region. However, the water conveyance system in this region is significantly influenced by hydrodynamic factors, morphological factors, human factors, and the infrastructure used for social purposes, all of which directly impact the irrigation water utilization coefficient. In order to improve the irrigation water utilization coefficient, reduce suspended sediment deposition in the water conveyance channels, and mitigate negative effects on the water supply system, this study implemented a sediment diversion system at the channel head. This is expected to increase water usage efficiency to a certain degree. Using actual data on hydrodynamic factors from the Shizuishan section of the Yellow River in Ningxia, a two-dimensional numerical simulation was performed, and a two-dimensional hydrodynamic model and sediment model of the Shizuishan section of the Yellow River in Ningxia were developed using MIKE 21. The water conveyance method at the channel head was simulated under two different operating conditions. Results indicated that compared to operating condition 1, operating condition 2 had a beneficial effect on diverting and reducing sediment at the fish mouth of the channel head: the sediment accumulation thickness of one day in operating condition 1 was 0.16 m, 0.003 m, 0.15 m, and 0.21 m under actual flow, scenario 1, scenario 2, and scenario 3, respectively; whereas in operating condition 2, the sediment accumulation thickness of one day was 0.11 m, 0.001 m, 0.09 m, and 0.12 m under the same conditions, respectively. Additionally, as the computation period lengthened, the sediment accumulation thickness of operating condition 2 was significantly smaller than that of operating condition 1. In conclusion, operating condition 2 is superior for the design of the channel head in the Yellow River self-flow irrigation region. [ABSTRACT FROM AUTHOR]

Human activities have greatly reduced the sediment load in the Yangtze River Basin and have changed the channel connectivity of the Jingjiang River. In this paper, the analytic hierarchy process (AHP) is used to establish the assessment model of channel connectivity based on the river function. Then, combined with the flow, sediment and boundary data of the main hydrological stations, we analyze the variation in processes of the channel connectivity of the Jingjiang River from 1955 to 2015. The results show that the change in process of channel connectivity of the Jingjiang River is basically the same in different reaches. The value of the comprehensive function of connectivity increases gradually with time and is greater than 1.0 after 1990, indicating that the channel connectivity has improved. Spatially, the Shashi-Jianli reach has the best connectivity, while the Zhicheng-Shashi reach has the worst connectivity. In addition, reservoir construction and river straightening are the main factors affecting the channel connectivity of the Jingjiang River. The influence of water and soil conservation on channel connectivity is mainly realized by basin erosion, which is the secondary factor. Some research methods and results can be used as reference for studying channel connectivity in other basins. [ABSTRACT FROM AUTHOR]

This study is aimed at developing a remote sensing technique for assessing the probability of an impact on linear engineering structures by the example of lateral river erosion. The suggested approach for assessing the probability of an impact on linear engineering structures takes into account the process of lateral erosion, while bending and straightening of bends is at the same time the main formatting factor for the landscape morphological pattern of alluvial plains. The basis of the technique is a mathematical model of the landscape morphological pattern for alluvial plains. It was essentially tested at key sites within river valleys in different nature environments. The exponential distribution of arrows of the packages and the time of bend development is a general law of the landscape morphological pattern of alluvial plains in different nature environments; numerous testing results confirm it. The model of the morphological pattern of the alluvial plain gives a solution of the quantitative assessment of the impact probability to a linear structure by river erosion under limited conditions; the necessary parameters can be estimated from the remote sensing data. [ABSTRACT FROM AUTHOR]

This paper focuses on the back analysis of an ancient, catastrophic rock avalanche located in the small city of Lettopalena (Chieti, Italy). The integrated use of various investigation methods was employed for landslide analysis, including the use of traditional manual surveys and remote sensing (RS) mapping for the identification of geological structures. The outputs of the manual and RS surveys were then utilised to numerically model the landslide using a 2D distinct element method. A series of numerical simulations were undertaken to perform a sensitivity analysis to investigate the uncertainty of discontinuity properties on the slope stability analysis and provide further insight into the landslide failure mechanism. Both numerical modelling and field investigations indicate that the landslide was controlled by translational sliding along a folded bedding plane, with toe removal because of river erosion. This generated daylighting of the bedding plane, creating kinematic freedom for the landslide. The formation of lateral and rear release surfaces was influenced by the orientation of the discrete fracture network. Due to the presence of an anticline, the landslide region was constrained in the middle-lower section of the slope, where the higher inclination of the bedding plane was detected. The landslide is characterized by a step-path slip surface at the toe of the slope, which was observed both in the modelling and the field. This paper highlights the combined use of a geological model and numerical modelling to provide an improved understanding of the origin and development of rock avalanches under the influence of river erosion, anticline structures, and related faults and fractures. [ABSTRACT FROM AUTHOR]

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Delivery of large volumes of sediment by debris flows in a short time into rivers often initiates a hazardous chain reaction in alpine valleys. Predicting the multi-hazard chain’s evolution and intervening in its cascading effects by artificial countermeasures face major challenges due to the spatial and temporal variability of controlling factors. On June 17, 2020, a rainstorm-induced debris flow event with a volume of 2.4 × 105 m3 occurred in the Meilong catchment, Danba County, Sichuan Province, Southwest China, which triggered a debris flow–outburst flood–landslide hazard chain. Large amounts of sediment entered the Xiaojinchuan River and formed a barrier lake. The outburst flood and narrowed river flow eroded 2.76 × 106 m3 of deposits and reactivated the Aniangzhai landslide. Engineering measures were implemented to prevent the hazard, including dredging, rechanneling, and embankment construction. The deformation rate and acceleration of the landslide decreased from a peak of 75 mm/h to 8.74 mm/h and a peak of 16.46 mm/h2 to 0.13 mm/h2 before and after the engineering, respectively, according to measurements of a ground-based monitoring radar. Without the engineering measures, the factor of safety of the landslide would be reduced to 0.93, and a larger landslide dam hazard would occur if the foot were eroded by more than 17 m. The case and its successful engineering demonstrate that artificial intervention measures are effective in halting the cascading process of natural hazards.

The variation in the structural characteristics (cooling joints and tectonic fractures) of basaltic flows implies potential variability in the intensity of erosion by plucking. The erosive behavior of the rivers that sculpt these areas depends on their interaction with the diverse fracture systems. In view of this, we analyzed the effect of fracture variability (tipology, density and direction) in basalts on erosion in a bedrock river reach located in the Continental Volcanic Province of the Paraná Basin, southern Brazil. The fracture density and fracture direction were evaluated through field photogrammetry in seven sample areas distributed along a reach of 120 m. The fracture direction and main erosion axes were also surveyed by remote piloted aircraft (RPA) aerial imaging. The main erosion axes coincide with the principal fracture directions (tectonic fractures), which are disposed obliquely to the channel flow direction, making an average angle of 50°. The small, more abundant, and multidirectional cooling joints control the plucking process, but do not determine the erosion direction. The fracture density systematically decreases upstream from 9.62 to 3.73 m/m², probably related to distance from a structural lineament which river crosses downstream. The higher fracture density favors more intense plucking due to decrease in the size of the rock blocks. The lower fracture density limits the plucking and favors the macroabrasion, mainly if associated with vesicular-amygdaloidal basalt. [ABSTRACT FROM AUTHOR]

1 Study Region: The unconfined Wairau Aquifer in the Marlborough District of New Zealand is almost exclusively recharged by the Wairau River and serves as the major resource for drinking water and irrigation in the region. A declining trend in aquifer levels and low-land spring flows has been observed for the past decades. 2 Study Focus: The aim of this study is to identify and analyse natural and anthropogenic factors controlling the hydrological regime of the Wairau Aquifer. Concurrent trends in the long-term water balance components for the Wairau catchment and in low-flow statistics as well as the correlation between hydro-meteorological drivers and the Interdecadal Pacific Oscillation (IPO) index were investigated. The impact of river morphology changes on river recharge rates was studied using a previously developed groundwater flow model. 3 New Hydrological Insights for the Region: Our study found that long-term trends in declining catchment-scale precipitation are superimposed on climate oscillation and a strong annual variability. Jointly, these processes have resulted in lower than average river flows, increased low-flow periods, and consequently in lower rates of aquifer recharge. River engineering caused erosion of the braided river morphology, leading to a possibly permanent loss of aquifer storage. Groundwater abstraction is not accurately known which is a limitation of this study. This additional information and adaptation strategies are required for sustainable management of the groundwater resources.

The winding Dasha River section of the Central Cross Island Highway in Taiwan is 9.44 km long. More than 20% of its length has been rerouted in the past six decades due to landslide-induced maintenance problems. To investigate the influence of geological conditions on the maintenance of this mountainous road section, this study establishes inventories of highway alignments and nearby landslides based on interpretations of multi-temporal aerial photos and highway maintenance records. Types of landslide and topographic features are verified through field investigation, and the engineering characteristics of rock masses are evaluated using the Q-method semi-quantitatively. The results reveal that three sections with rerouting of road or structural modification are located near the undercut slopes of the Dasha River and the boundaries of strata where water erosion and scouring are active and considerable gullies develop. Various metamorphic strata with intricate folds are formed by orogenic deformation and metamorphism under the influence of weathering, such as water erosion and scouring; these evolve into meanders and steep slopes. Gullies develop along the boundaries of strata with distinct lithology, where the engineering characteristics of rock masses vary markedly, disturbing the stability of nearby slopes and hindering the maintenance of the mountain road for long periods. Rerouting the highway and the use of a tunnel instead of the slope-cut-in halfway road effectively mitigate the influence of landslides near meanders where water erosion and scouring are significant. A gallery tunnel effectively mitigates rock fall. However, a gallery tunnel must be constructed without causing overcut-induced slope instability. [ABSTRACT FROM AUTHOR]

The repeated cut-and-fill process induced by the late Quaternary glacial damming and catastrophic outburst events in the Yarlung Tsangpo Gorge (YTG) in the eastern Himalaya may reflect the interaction between rock uplift, climate change and river incision in the southeastern Tibetan Plateau. Here we provide the detailed reconstruction of the cut-and-fill history recorded at the entrance of the YTG, based on geomorphological, sedimentological and chronological analyses. The results reveal a catastrophic glacial-dam breach during the last deglaciation (∼18 ka), and the outburst flood eroded a ∼30–45 km long valley floor filled with glacial diamicton and glaciofluvial deposits, which was later further incised to form terrace T 2 with a height of ∼350 m. The second dam failure occurred at ∼5 ka, producing a spillway, forming terrace T 1 with a height of ∼100 m. The vertical incision and horizontal migration rate of the knickpoint at the glacier dams were estimated as 0.02 m/yr, and 2.5 m/yr since the last deglaciation, based on the age of the terraces and distance of the knickpoints. We consider the glacial dams to be effective in impeding headward river erosion during glacial periods. This, along with rapid river headward erosion during the last interglacial period, results in two knickpoints on the longitudinal profile due to the differences in erosion resistance. The fluvial reaches corresponding to the repeated cut-and-fill processes are confined to the center of the Namche Barwa massif, suggesting that rapid rock uplift counteracted fluvial headward erosion and maintained the stability of the bedrock knickpoint. Therefore, in comparison to glacial dams, tectonic uplift is the most important component in plateau margin stabilization. • Two primary terraces have developed in the Yarlung Tsangpo Gorge since the last glacial period. • Vertical and horizontal migration rate of the knickpoint were estimated as 0.02 m/yr, and 2.5 m/yr. • Glacial dams have impeded erosion of bedrock channels, resulting in two knickpoints on the profile. • Maintaining stability of knickpoints over millions of years requires long-term continuing rock uplift. [ABSTRACT FROM AUTHOR]

In order to understand the effect of creep on the deformation and failure of loess slope, and to provide technical reference for the treatment of loess landslide caused by river erosion, the creep test of loess in the loess plateau area of the downstream region of Jinghe River was carried out. A self-defined creep model suitable for the loess in this area was established and simulated with numerical method in this paper. It is concluded that the creep effect on the deformation and failure process of loess landslides is obvious, which accelerates the development and penetration of the plastic zone, and intensifies the enlargement and concentration of the shear strain increment in the soil, and the horizontal displacement of landslide is obviously increased. [ABSTRACT FROM AUTHOR]

The stream power law model has been widely used to represent erosion by rivers but does not take into account the role played by sediment in modulating erosion and deposition rates. Davy and Lague (2009, https://doi.org/10.1029/2008JF001146) provide an approach to address this issue, but it is computationally demanding because the local balance between erosion and deposition depends on sediment flux resulting from net upstream erosion. Here, we propose an efficient (i.e., O(N) and implicit) method to solve their equation. This means that, unlike other methods used to study the complete dynamics of fluvial systems (e.g., including the transition from detachment‐limited to transport‐limited behavior), our method is unconditionally stable even when large time steps are used. We demonstrate its applicability by performing a range of simulations based on a simple setup composed of an uplifting region adjacent to a stable foreland basin. As uplift and erosion progress, the mean elevations of the uplifting relief and the foreland increase, together with the average slope in the foreland. Sediments aggrade in the foreland and prograde to reach the base level where sediments are allowed to leave the system. We show how the topography of the uplifting relief and the stratigraphy of the foreland basin are controlled by the efficiency of river erosion and the efficiency of sediment transport by rivers. We observe the formation of a steady‐state geometry in the uplifting region, and a dynamic steady state (i.e., autocyclic aggradation and incision) in the foreland, with aggradation and incision thicknesses up to tens of meters. Key Points: We present an efficient (O(N) and implicit) method to solve a river erosion model taking into account sediment depositionWe show how the foreland stratigraphy is controlled by the efficiency of river erosion and the efficiency of sediment transport by riversWe observe autogenic aggradation and incision cycles in the foreland once the system reaches a dynamic steady state [ABSTRACT FROM AUTHOR]

Phitsanulok province is located in the northern region of Thailand, approximately 400 km away from Bangkok. One of its major river is Nan river, which runs thru the business district of Phitsanulok. Every year, Nan river severely erodes the riverbanks and damages the infrastructures located along the riversides. The river erosion also intimidates the inhabitants who live nearby the river. In the studied area, the ancient city walls have been discovered. These ancient city walls have continually been destroyed by the river erosions every year. Moreover, the area has been reported flooding every five to ten years. Accordingly, the mitigation system is required in the area to serve two main purposes. The first purpose is protecting the nearby communities from severe flooding and river erosions. Secondly, the mitigation system should provide comforts to the communities. The public hearing event was organized to gather the needs from the communities. As a result, the flexible sheet-pile wall was chosen as the flood protection and river erosion mitigation system in the area. The mitigation system was designed to harmonize with the ancient city walls and served as the recreation area for the communities. [ABSTRACT FROM AUTHOR]

In the second half of the twentieth century, the Volga and the Danube were regulated. As a result, channel processes and the processes of alluvium deposition and humus accumulation in soils, surface and underground waters were changed. The comparative analysis of Volga-Akhtuba and Lower Dunabe floodplains is carried out in the article. It was found that due to the regulated flow, hydraulic engineering and land reclamation construction had provoked direct (immediate) changes in natural systems, as well as indirect (mediated) changes in the landscapes. The Volga-Akhtuba floodplain is characterized by the dominance of indirect effects resulting from changes in the hydrological regime of the Volga to produce cheap electricity and irrigation of vegetable plantations. Therefore, the landscape can be attributed to the natural type. The Lower Danube is characterized by immediate impact, namely, leveling the surface and creating a drainage system, the purpose of which was to increase the area of agricultural land within the floodplain and to decrease the number of catastrophic floods. This led to the formation of technogenically anthropogenic landscape within the floodplain. The components and relationships in the downstream of the Volga hydroelectric are degraded, but not destroyed in comparison with the Great Balta Braila, so the natural complexes of the Volga-Akhtuba floodplain and associated natural processes can be restored by means of environmental management. Abnormalities in the flow regulation of the Volga and the Danube led to the destruction of hydraulic connection between the two bodies of water floodplains, alluvial processes slow down and change in the level of groundwater. Within the floodplain the erosion and accumulation also lowered their rates. The river channels, on the contrary, increased erosion and accumulation, causing the decrease of rivers level, and there is an active formation of braid, shoals and islands.

The main objective of this study is to investigate and monitor the landuse and morphological changes in the floodplain part of the Talar River, northern parts of Iran. In the present study, the aerial photographs have been used to produce landuse maps of the floodplain for three periods including 1968, 1994, and 2013. The quantitative analysis of the produced landuse maps showed that the floodplain has undergone substantial landuse changes. Moreover, the sediment bar and the beach area have been decreased about 97 and 90%, respectively, during the 45-year period. Substantial increases of 192 and 622% have been observed for orchards and residential areas, respectively. On the other hand, not only the forest and riparian vegetation were decreased but also the average width of river was decreased about 25.5 m. In addition, flow length of the study reach increased about 8 m. The RNCI was about −0.7 m per year indicating sedimentation process. During the period of 1968-2013, Caspian Sea has retreated about 150 m and the delta of Talar River was changed. This study showed that morphological actions during first 26 years (1968-1994) were the stable and last 19 years had the change period, especially sedimentation (bar). [ABSTRACT FROM AUTHOR]

The potential catastrophic event of a landslide bringing contaminants to surface waters has been highlighted in public media, but there are still few scientific studies analyzing the risk of landslides with contaminated soil. The aim of this study is to present a method to estimate the risk of potential long-term ecological effects on water bodies due to contaminated soil released into a river through a landslide. The study constitutes further development of previous work focusing on the instantaneous (short-term) release of contaminants and associated effects. Risk is here defined as the probability of surface water failing to comply with environmental quality standards (EQS). The transport model formulation is kept simple enough to allow for a probabilistic analysis as a first assessment of the impact on the river water quality from a landslide runout deposit containing contaminated soil. The model is applied at a contaminated site located adjacent to the Göta Älv River that discharges into the Gothenburg estuary, in southwest Sweden. The results from the case study show that a contaminated runout deposit will likely cause contamination levels above EQSs in the near area for a long time and that it will take several years for the deposit to erode, with the greatest erosion at the beginning when water velocities are their highest above the deposit. A contaminated landslide runout deposit will thus act as a source of contamination to the downstream water system until all the contaminated deposit has been eroded away and the contaminants have been transported from the deposit to the river, and further to the river mouth – diluted but not necessarily negligible. Therefore, it is important to prevent landslides of contaminated soil or waste, and if such events were to occur, to remove the contaminated runout deposit as soon as possible. [ABSTRACT FROM AUTHOR]

Geomorphologists often rely on simple models of river channel incision for predicting rates of landscape evolution and channel response to perturbations, as well as extracting climatic and tectonic signals from river longitudinal profiles. Recent work has shown that large, hillslope‐derived blocks delivered to rivers may noticeably alter the form and evolution of river profiles from the behavior predicted by the most common models. Here we use a 1‐D model of river reach erosion and hillslope block delivery to explore the conditions under which block delivery strongly influences channel evolution. We use global sensitivity analysis to understand which model parameters most strongly affect the channel longitudinal profile. We explore the effects of blocks on the relationship between erosion rate and channel gradient, and on the erosion rate‐channel steepness exponent ϕ, and find that block effects result in highly variable slope and ϕ over the range of erosion rates and climatic conditions (discharge mean and variability) tested. The influence of blocks on erosion rate‐slope scaling may be approximated by a piecewise model: The erosion threshold imposed by blocks scales linearly with erosion rate when blocks are infrequently mobile and remains constant when blocks are frequently mobile. We explore the implications of this variable‐threshold model for the erosion rate‐channel steepness relationship and find that erosion rate‐dependent thresholds imposed by hillslope‐derived blocks cause significant departures from previous models but may be consistent with existing field data sets. Our work has implications for landscape evolution modeling and the inversion of channel profiles for forcing information. [ABSTRACT FROM AUTHOR]

The article describes anthropogenic transformations of relief features associated with former economic use of rivers and the changes that occurred in individual sections of artificial canals as a result of their naturalisation. The study was carried out in two river valleys - of the Sumina and Wierzbnik Rivers, which are located in the Ruda River catchment (within the Odra River drainage basin), on the boundary of the Rybnik Plateau and the Racibórz Basin. The use of water in these rivers for the purposes of former grain mills, sawmills and other industrial facilities as well as fish ponds involved the construction of bypasses. The deep erosion gullies recorded in the relief of the Sumina and Wierzbnik River valleys are in fact transformed anthropogenic forms: artificial river channels and old bypasses. In the Wierzbnik River valley, these canals - today dead, but still visible in relief, reflect the technical solutions which were once used to protect ponds from damage during floods. The sections of old artificial canals such as the man-made channel of the Sumina River, are still subject to naturalisation processes, being were later transformed by natural fluvial processes. This is reflected in an increase in channel sinuosity and the development of meanders. It is proposed that the erosive forms described in the article be referred to as anthropogenically determined river gorges. [ABSTRACT FROM AUTHOR]

The Amur flood in 2013 have caused catastrophic damage in the coastal area of Khabarovsk. Prolonged flooding caused the destruction of buildings, roads, pollution of the urban environment. The purpose of the study is to monitor the negative effects of flooding in the affected areas of the city. In the article the analysis of the urban environment and a description of the effects of flooding.

With the need to conserve and improve the environment, it is recommended to employ plant materials in the erosion control of torrents and slopes alongside roads. Considering the well-known properties of some willow species regarding their power of vegetative reproduction, survival in poor soils and often flooded alluvium, we researched into the potentials of the following species: Salix triandra L., Salix purpurea L. and Salix incana Schrk. in the catchment of the warehouse 'Gvozdac', Experimental Estate Goč, Serbia. The research started in 2004 and has continued till the present day. The above-mentioned willow species showed significant efficiency in the bank protection of torrential watercourses and on the moist slopes of embankments and cuts of roads. Some of them can even stand a certain degree of aridity, while other species, on poor, eroded soil exposed to long and extreme drought, could not survive and did not show the expected effect, which is also the consequence of the absence of maintenance and adequate attention to such erosion-control works. In spite of the above, one of the willow species survived even in the most severe conditions, checking the erosion of the road cut slope and the road construction itself, and prevented the impacts of aggressive atmospheric waters, thus halting the erosion ridges and the removal of the asphalt road surface. The above facts prove that, with adequate measures of maintenance, plant materials can be very successfully applied for both longitudinal structures and to check dams in torrent control, as well as in erosion control on the slopes in catchments, both in civil engineering works and in forest exploitation. The research requires closer attention, extending the interests to some grass and shrub species, with the aim of ecological erosion control and reclamation of endangered watercourses, slopes and, in general, environmental protection and nature conservation. .

The Siwanli landslide is located in the middle section of the Dadu River in the eastern part of the Qinghai-Tibet Plateau in a complex regional geological environment. Strong erosion of the river valley has caused numerous rockfalls and slides on both sides of the valley since the Late Pleistocene. A large number of landslide deposits provide the opportunity for examination of the sedimentary and erosional environment along the Dadu River. Identifying the spatial and temporal characteristics of the large, ancient landslides in the Dadu River valley can help improve understanding of the formation mechanism and evolutionary process of ancient and recurrent landslides. In this paper, the formation mechanism of the ancient, complex, and multistage Siwanli landslide is discussed, as well as an important link between river erosion and the formation and evolution of the landslide. In the first stage, the initial landslide blocked the Dadu River, forming a barrier lake, and multistage landslide dam breaches occurred. The entire landslide dam experienced creep deformation, and local minor multistage sliding occurred at the front and middle parts of the initial landslide. Subsequently, a large landslide formed at the scarp of the initial landslide. [ABSTRACT FROM AUTHOR]

Two river crossing cases are considered in which a pipe is installed beneath the Yangtze River using horizontal directional drilling (HDD). In both cases, a length of pipeline located on the rock strata near the north bank, including a local protrusion, is disrupted by river erosion. A three-dimensional (3D) model is developed to simulate the river erosion based on the finite-element software ABAQUS, which is capable of modeling the properties of the soil and pipelines, as well as their interaction. Results are presented based on an analysis of the stress concentration points at the ends of the rock protrusion, in the vicinity of the erosion. The effect on the pipelines is investigated as a function of the depth, extent, and location of the erosion. The resulting stress and displacement along the crown, spring, and invert lines of the pipelines are shown and compared to the function of the depth, extent, and location. And the stress concentration points occur at the location of rock protrusion and in the vicinity of the eroded soil. [ABSTRACT FROM AUTHOR]

This paper focuses on the relationship between climate change and migration in Bangladesh. The country is expecting 49 million, 63 million, and 78 million displaced people in 2010, 2015, and 2020 respectively due to climate change. Bangladesh is the most vulnerable country in the world because of frequent floods. The country becomes the third and the sixth most vulnerable country in terms of tsunami and cyclones. Drought will affect eight million people by 2050. In future, the combined effect of high population growth and displaced population will make the country more vulnerable to social and economic underdevelopment. With increasing climate change vulnerabilities, people will consider taking an advantage of international migration if resources became exhausted. For resolving the problems of many more environmental migrants in upcoming years, this is high time to think about future floods of environmental migrants and the adaptation measure necessary for the survival of many. [ABSTRACT FROM AUTHOR]