A GIS-based study on the changing course of the River Jiadhal in the Dhemaji district, India

<p>Information on the share of river bank erosion to the total sediment load at catchment scale by using the fingerprinting approach is important to address our knowledge of erosion processes to better target soil erosion control measures. In particular, river bank erosion is affected by many factors such as spatial and temporal variables and is difficult to quantify the relationship of the share of bank erosion to catchment size and upland erosion rate without extensive fieldwork and data analysis. Potential tracers including geochemical, fallout radionuclides, bulk and compound-specific stable isotopes, and magnetic properties have been used, often in combination with sediment source apportionment. In this worldwide review, the global dataset for percent share of river bank and surface erosion using fingerprinting approach was collected to establish the significance of catchment size and other physical controls on river bank erosion. Google Scholar and Web of Science were used to review research articles that included river bank/subsurface as one of the sediment sources in the study areas. This database showed that the UK (n = 84), USA (n = 14) and Brazil (n = 10) had the highest number of catchments, followed by Iran (n = 4), Southern Zambia (n = 1), Australia (n = 1), Spain (n = 1), Mongolia (n = 1) and Burkina Faso (n = 1) ranging in size from 0.31 to 15000 km<sup>2</sup>, predominately agriculture. Based on published studies, there is a clear shift of sediment sources from surface erosion to river bank erosion with increasing catchment size. The results show the wide range of relative contributions of surface and river bank sources to the catchment sediment yield around the globe. There are a number of catchments with river bank contribution exceeding 25% and surface contribution exceeding 90% of total sediment loss. This diversity highlights the many factors that influence river bank erosion. In addition to the wide range, sediment source contribution in the range 1-25% from river bank is generally representative around the World. We recommend that long term monitoring of sediment load and surface and river bank sources at nested sites within a catchment are indispensable. Furthermore, limited information on the share of sources often makes it difficult to target mitigation measures reducing sediment loads at the catchment scale.</p><p><strong>Keywords: </strong>Sediment load, catchment size, fingerprinting approach, river bank share</p>

The processes of lateral and riverbank erosion are among the elements of river morphology dynamic resulting from natural processes and human activities. This process has been studied in detail throughout the research for four months starting from 7 October 2009 to 26 January 2010. In this research, technique of erosion pins were applied at five plots selected along the Chini River in Pahang, Malaysia in order to evaluate the rate of for lateral and river bank erosion. The results in the lateral erosion indicates that, the average highest erosion was recorded at plot 4 (3 cm), followed by plot 3 (2.3 cm), plot 2 (1.42 cm), plot 1 (1.2 cm) and plot 5 recorded the lowest average which is 0.59 cm respectively. Overall, the total average of lateral erosion recorded at all five plots is 8.51 cm. Meanwhile, results obtained from river cross-section variation indicated that plot 1 and 2 show changes from the V shape in early observation to U shape at the end of the observation period. This shows that side-erosion was active in the entire process. Furthermore, plot 3, 4 and 5 remained U shape until the latest observation but it was found that the riverbed was getting shallow. For the regression analysis, two independent variables were selected to relate with rate of river bank erosion namely steep gradient bank height of the bank. These independent variables show a positive relationship with the rate of the side and river bank erosion where the value of r2 is 0.820 and 0.645 for both variable of gradient and height. For the analysis of soil particle distribution, the mean value is a sand and very coarse with phi ø -2.00 to phi ø 0.00. The standard Deviation (D) indicates of worst deposition, between phi ø 1.00 to phi ø 4.00. Skewness (S) shows very small size to oversize which is between phi ø -1.00 to phi ø +1.00 and the value of Kurtosis (K) for this river is dominated by grain size mesokurtic and platikurtic. Therefore, the Slope Stabilization or river bank slope protection of River Chini area is proposed to reduce the river bank erosion and sediment production.

Bank failure and erosion on the Ohio river

The Brahmaputra River has been the lifeline of north- eastern India since ages. This mighty trans-Himalayan trans-boundary river runs for 2880 kms through China, India and Bangladesh. The gradient of the Brahmaputra River varies from very steep near the source at the Tibetan plateau (1:385) to very flat in the lower part of Bangladesh (from 1:11,340 to 1:37,700). Geomorphologically, the Brahmaputra basin is very unstable as it is located in a high seismic zone. The Brahmaputra is a large alluvial river with highly variable channel morphology and a high degree of braidedness. The dominant flow is multichannel flow acknowledged to be very complex for mathematical modelling. The problems of flood, erosion and drainage congestion in the Brahmaputra basin are gigantic. The river bank failures are responsible for large scale bank erosion, aggradations and widening of the river channel. This in turn is responsible for lateral channel changes of the Brahmaputra River in many reaches leading to a considerable loss of good fertile land each year. Bank dynamics is also causing shifting of outfalls of its tributaries bringing newer areas under waters. Frequent changes of channel courses and bank erosion with high rate of siltation have also been identified as major threats to the riverine biota. This in turn has a negative impact on the sustainability of the wetlands. Degradation and destruction of the wetlands have considerable impact on the deteriorating flood hazard scenario in the state. This paper outlines the types of river bank failure mechanism and erosion process in the Brahmaputra River. The paper also presents information on the river reaches of Brahmaputra suffering from high bank erosion rates and the impacts of bank erosion on the Brahmaputra basin and people of the region.

Assessment of river bank erosion in Southern Minnesota rivers post European settlement

The impacts of floods on river bank erosion are generally significant in the alluvial river reaches. This paper presents the prediction of the river bank erosion along the right bank in the reach of Chenab River (starting from downstream of Marala Barrage) where excessive erosion had been reported. The bank erosion is predicted due to flow/flood events of 2010 by coupling the output from the two-dimensional numerical model to the excess shear stress approach. The predicted bank erosion was compared with the one estimated from Landsat images. The Landsat ETM+ images were processed in the ArcGIS software to assess the external bank erosion. The results show that the excess shear stress approach underpredicts the bank erosion. Therefore, the erodibility coefficient was modified by forcing the best agreement between predicted and estimated (i.e., from Landsat images) bank erosion which was used for further analysis. The results reveal that coupling the output from the numerical model to the excess shear stress approach (by modifying the erodibility coefficient) predicts the river bank erosion with a reasonable level of accuracy, thus helpful to identify the locations for the protection works. The predicted river bank erosion presents good coefficient of determination (R2) of 0.82 when compared with the estimated bank erosion from Landsat images. The findings of the present study will help to implement the river protection works at the identified locations in the selected reach of River Chenab and will also act as a guideline for similar river reaches.

Braided reaches of large rivers in alluvial plains show major morphological changes, particularly the external bank erosion, due to the flood events. This paper highlights the bank erosion and channel evolution induced by eleven different flood events in a 7-km long reach of the River Chenab, Pakistan. The impact of floods on river bank erosion and channel evolution is analyzed under low and high flow conditions. Flood-induced changes, for river’s external banks and channel evolution, were assessed by processing Landsat ETM+ images in ArcGIS tool, and their inter-relationship is evaluated through regression analysis. The results revealed that the major morphological changes were triggered by the flood events occurred during the high flow or Monsoon season (July–September), whereas the flood events of similar magnitude occurring during low flow season (October–March) did not induce such changes. Mostly, the erosion remained limited to the middle part of the reach, where the branch channel flows along the bank. The average annual bank erosion rates are much higher as compared with a global scale. Data analysis showed a strong correlation between the mean high flows and total bank erosion indicating that Monsoon seasonal flows and floods are responsible for bank erosion. The present study further identifies the river bank locations highly susceptible to erosion by developing the correlation between bank erosion and branch channel progression. Strong correlation for bank erosion could be established with the shift of branch channels position flowing along the banks in braided reaches of sand bed rivers. However, the presence of sand bars along the river banks resulted in reduced erosion that weakens this relationship. The findings of the present study can help develop better understanding about the bank erosion process and constitute a key element to inform and improve river bank management.

We evaluate links between climate and simulated river bank erosion for one of the world's largest rivers, the Mekong. We employ a process-based model to reconstruct multidecadal time series of bank erosion at study sites within the Mekong's two main hydrological response zones, defining a new parameter, accumulated excess runoff (AER), pertinent to bank erosion. We employ a hydrological model to isolate how snowmelt, tropical storms and monsoon precipitation each contribute to AER and thus modeled bank erosion. Our results show that melt (23.9% at the upstream study site, declining to 11.1% downstream) and tropical cyclones (17.5% and 26.4% at the upstream and downstream sites, respectively) both force significant fractions of bank erosion on the Mekong. We also show (i) small, but significant, declines in AER and hence assumed bank erosion during the 20th century, and; (ii) that significant correlations exist between AER and the Indian Ocean Dipole (IOD) and El Niño Southern Oscillation (ENSO). Of these modes of climate variability, we find that IOD events exert a greater control on simulated bank erosion than ENSO events; but the influences of both ENSO and IOD when averaged over several decades are found to be relatively weak. However, importantly, relationships between ENSO, IOD, and AER and hence inferred river bank erosion are not time invariant. Specifically, we show that there is an intense and prolonged epoch of strong coherence between ENSO and AER from the early 1980s to present, such that in recent decades derived Mekong River bank erosion has been more strongly affected by ENSO.

Monitoring river morphology & bank erosion using UAV imagery – A case study of the river Buëch, Hautes-Alpes, France

Sediment yield is a key factor in river basins management due to the various and adverse consequences that erosion and sediment transport in rivers may have on the environment. Although various contributions can be found in the literature about sediment yield modeling and bank erosion monitoring, the link between weather conditions, river flow rate and bank erosion remains scarcely known. Thus, a basin scale assessment of sediment yield due to riverbank erosion is an objective hard to be reached. In order to enhance the current knowledge in this field, a monitoring method based on high resolution 3D model reconstruction of riverbanks, surveyed by multi-temporal terrestrial laser scanning, was applied to four banks in Val Tartano, Northern Italy. Six data acquisitions over one year were taken, with the aim to better understand the erosion processes and their triggering factors by means of more frequent observations compared to usual annual campaigns. The objective of the research is to address three key questions concerning bank erosion: “how” erosion happens, “when” during the year and “how much” sediment is eroded. The method proved to be effective and able to measure both eroded and deposited volume in the surveyed area. Finally an attempt to extrapolate basin scale volume for bank erosion is presented.

River bank erosion is a hazardous and common phenomenon in diara region near Malda district of North East India during monsoon and post monsoon periods of every year. The left bank of Ganga river is texturally very weak along diara region of Malda district. The present work explores relations between stream power, braiding intensities and bank erosion in certain stretches of upstream of the Ganga river near Malda district of West Bengal in India. In the present study, we have tried to do a quantitative assessment of channel braiding process of the Ganga river by applying the Plan Form approach and equivalent measurement of stream power. A comparative study of discrete years has been done through braiding index to understand morphological behaviour of the channel. Beside its stream power of the selected stretches of the study area is estimated and compared with braiding intensity and bank erosion. This paper presents the dynamic behaviour of the channel pattern of the Ganga river system in Malda district over a time span of 40 years. This procedure addresses the selection of input parameters from digital satellite images comprising scenes for the years 1975, 1995 and 2015 with specific dates, from Rajmahal in Jharkhand district to Farakka barrage in Malda district. To obtain Plan Form Indices for the entire study area, required parameters were extracting through using GIS techniques. Stream power is measured through analyzing latest flood records and satellite images. The present study concluded that a wide spread and continuous braiding process has occurred in the study area due to aggradations of riverbed and temporal declination of stream power.

River bank erosion is a fluvio-hydrological hazard, and sometimes, it turns into disaster in the human-encroached river bank and flood plain. The principal objective of this study is to detect the river bank erosion potential zone using new Bank Erosion Susceptibility Index (BESI) model and spatiotemporal shifting of river Raidak-II (1980–2020). Sedimentary bank facies (SBF) analysis was conducted to identify the nature of cohesiveness of bank materials. The result showed that the maximum average lateral shifting (213.20 m) was recorded in the year 1990 (right bank), whereas the minimum average shifting (77.32 m) was measured in the year 2020 (right bank). The result also showed that the right bank of Raidak-II was mostly oscillated due to poorly sorted quaternary non-cohesive bank materials. The Bank Erosion Hazard Index (BEHI) model showed that 46.15% and 50% bank erosion sites are fallen in high-to-extreme bank erosion susceptibility zones in the years 2020 and 2022. In the case of BESI model, 69.23% and77.77% bank erosion sites are confined in high-to-extreme bank erosion susceptibility zones in the years 2020 and 2022. Therefore, BSEI model gives more precise results compared with BEHI due to three additional factors. The poorly sorted non-cohesive quaternary sediments stimulate high rate of bank erosion within Himalayan foreland basin.

Riverbank erosion is a significant contributor to sediment transport in rivers and a key factor shaping river ecosystems, which are affected by natural and human activities. Its dynamics depend on a variety of factors, including river flow, water levels, soil properties and composition, groundwater flow, topography, climate, soil moisture, temperature, and vegetation. The main drivers of riverbank erosion are particle detachment by water flow, gravity-induced mass failure, and seepage erosion. While these processes shape river channels and floodplain morphology and support ecological functions like habitat creation, they also pose risks such as land degradation and infrastructure damage.  In seasonally frozen rivers, bank erosion dynamics are further complicated by unique climatic and hydrogeomorphic conditions, including temperature fluctuations and variations in groundwater flow. These additional processes can cause erosion by themselves and can interact with the other processes. Especially, the interactions between these factors remain poorly understood, hindering accurate predictions of bank erosion events. This study examines how topography, river stage changes, groundwater flow, soil moisture, and temperature variations affect riverbank erosion in seasonally frozen rivers. The research focuses on three objectives: (i) assessing how topography influences riverbank erosion, (ii) examining the role of river stage fluctuations and soil types in erosion processes, and (iii) analyzing the impact of freeze-thaw cycles on groundwater movement and soil stability, bank erosion. A two dimensional (2D) vertical bank erosion model was developed that integrates temperature dynamics with groundwater flow, allowing realistic simulations of temperature-induced changes in soil permeability and groundwater behavior. The framework applied with dynamic boundary conditions, offering novel insights into riverbank erosion mechanisms. The simulations were at this first stage performed by using a hypothetical riverbank geometry. First findings show that the interactions of processes can lead to temporally varying rates of erosion which cannot be understood in isolation. Bank geometry is expected to play a significant role, with some profiles more prone to collapse than others. Additionally, river stage fluctuations and dynamic soil conditions are likely to exacerbate erosion risks. These insights will support the development of predictive tools for sediment management, climate-resilient riverbank protection, and sustainable ecosystem management in cold-region rivers.Keywords: Riverbank erosion, groundwater modeling, temperature, seasonally frozen rivers, numerical modeling, freeze-thaw cycles.

The Haw River, a high order river in the southeastern United States, is characterized by severe bank erosion and geomorphic change from historical conditions of clear waters and connected floodplains. In 2014 it was named one of the 10 most threatened rivers in the United States by American Rivers. Like many developed areas, the region has a history of disturbance including extensive upland soil loss from agriculture, dams, and upstream urbanization. The primary objective of this study was to identify the mechanisms controlling channel form and erosion of the Haw River. Field measurements including bank height, bankfull height, bank angle, root depth and density, riparian land cover and slope, surface protection, river width, and bank retreat were collected at 87 sites along 43.5 km of river. A Bank Erosion Hazard Index (BEHI) was calculated for each study site. Mean bank height was 11.8 m, mean width was 84.3 m, and bank retreat for 2005/2007-2011/2013 was 2.3 m. The greatest bank heights, BEHI values, and bank retreat were adjacent to riparian areas with low slope (<2). This is in contrast to previous studies which identify high slope as a risk factor for erosion. Most of the soils in low slope riparian areas were alluvial, suggesting sediment deposition from upland row crop agriculture and/or flooding. Bank retreat was not correlated to bank heights or BEHI values. Historical dams (1.2–3 m height) were not a significant factor. Erosion of the Haw River in the study section of the river (25% of the river length) contributed 205,320 m3 of sediment and 3759 kg of P annually. Concentration of suspended solids in the river increased with discharge. In conclusion, the Haw River is an unstable system, with river bank erosion and geomodification potential influenced by riparian slope and varied flows.

The spine of Assam’s agro-valley is the Brahmaputra River, one of the world’s greatest rivers. However, the stability of the riverbank is negatively impacted by the river’s temporal shifting, frequent floods, and severe erosion. One of the main natural risks in Laharighat, Morigaon district, is river bank erosion. In the northern area of the Morigaon District, several villages disintegrate completely or partially each year. In many areas of Assam, especially the Morigaon district, bank erosion of the Brahmaputra River has reached worrisome proportions. The study’s goals are to assess the Brahmaputra River’s bank erosion situation in the Morigaon District of the Laharighat Circle (1986– 2021). Consequently, a study on river bank erosion is conducted in the Morigaon area under the Laharighat circle of the Brahmaputra River (1986-2021). The people of the Northern Side experienced numerous issues annually as a result of bank erosion. There is a serious social and economic crisis in the impacted area as a result of the affected people leaving their home country to migrate elsewhere and the river bank’s width growing at a rate of 79.6 meters per year.