River Bed Slope Research Articles

Quantifying Predictive Uncertainty and Feature Selection in River Bed Load Estimation: A Multi-Model Machine Learning Approach with Particle Swarm Optimization

This study presents a comprehensive multi-model machine learning (ML) approach to predict river bed load, addressing the challenge of quantifying predictive uncertainty in fluvial geomorphology. Six ML models—random forest (RF), categorical boosting (CAT), extra tree regression (ETR), gradient boosting machine (GBM), Bayesian regression model (BRM), and K-nearest neighbors (KNNs)—were thoroughly evaluated across several performance metrics like root mean square error (RMSE), and correlation coefficient (R). To enhance model training and optimize performance, particle swarm optimization (PSO) was employed for hyperparameter tuning across all the models, leveraging its capability to efficiently explore complex hyperparameter spaces. Our findings indicated that RF, GBM, CAT, and ETR demonstrate superior predictive performance (R score > 0.936), benefiting significantly from PSO. In contrast, BRM displayed lower performance (0.838), indicating challenges with Bayesian approaches. The feature importance analysis, including permutation feature and SHAP values, highlighted the non-linear interdependencies between the variables, with river discharge (Q), bed slope (S), and flow width (W) being the most influential. This study also examined the specific impact of individual variables on model performance by adding and excluding individual variables, which is particularly meaningful when choosing input variables for the model, especially in limited data conditions. Uncertainty quantification through Monte Carlo simulations highlighted the enhanced predictability and reliability of models with larger datasets. The correlation between increased training data and improved model precision was evident in the consistent rise in mean R scores and reduction in standard deviations as the sample size increased. This research underscored the potential of advanced ensemble methods and PSO to mitigate the limitations of single-predictor models and exploit collective model strengths, thereby improving the reliability of predictions in river bed load estimation. The insights from this study provide a valuable framework for future research directions focused on optimizing ensemble configurations for hydro-dynamic modeling.

Scour-depth variability controls channel-scale stratigraphy in experimental braided rivers

ABSTRACT Braided rivers distribute sediment across landscapes, often forming wide channel belts that are preserved in stratigraphy as coarse-grained deposits. Theoretical work has established quantitative links between the depth distribution of formative channels in a braided river and the geometry of their preserved strata. However, testing these predictive relationships between geomorphic process and stratigraphic product requires examining how braided rivers and their deposits coevolve, with high resolution in both space and time. Here, using a series of four runs of a physical experiment, we examine the controls of water discharge and slope on the resulting geometry of preserved deposits. Specifically, we focus on how a twofold variation in water discharge and initial riverbed slope affects the spatiotemporal distribution of channel depths and the geometry of preserved deposits of a braided river. We find that the channel depths in the laboratory experiment are described by a two-parameter gamma distribution and the deepest scours correspond to zones of erosion at channel-belt margins and channel-thread confluences in the channel belt. We use a reduced-complexity flow model to reconstruct flow depths, which were shallower compared to channel thalweg depths. Synthetic stratigraphy built from timeseries of topographic surfaces shows that the distribution of cut-and-fill-unit thickness is invariant across the experiments and is determined by the variability in scour depths. We show that the distribution of cut-and-fill-unit thickness can be used to reconstruct formative-channel-depth distributions and that the mean thickness of these units is 0.31 to 0.62 times the mean formative flow depth across all experiments. Our results suggest that variations in discharge and slope do not translate to measurable differences in preserved cut-and-fill-unit thickness, suggesting that changes in external forcings are likely to be preserved in braided river deposits only when they exceed a certain threshold of change.

The Effect of Sabo Works Design and River Improvement on the Magila River with Consideration on Morphological Changes Influenced by Debris Flow Events

The morphological changes of a river due to debris flow are essential considerations in understanding the dynamics of a river. The Magila River, located in the Sigi Regency, Central Sulawesi Province, is a small river with an area of approximately 125 hectares, but the average riverbed slope exceeds 10%. This river faced water damage issues, such as debris floods on December 12, 2019, and overflowing floods on October 11, 2022. Based on the ongoing mitigation (Sabo Works and River Improvement), an analysis of flow modeling through HEC-RAS software with non-Newtonian parameters is also being conducted. Simulations are performed on both the existing river scenario and the design river scenario. The flood and sediment transport simulations indicate that the capacity of the existing river is insufficient to accommodate the planned 100-year return period flood discharge, leading to overflow in several river sections with a maximum inundation height of 42.80 centimeters. The river also tends to experience riverbed degradation, triggering landslide events. In contrast, in the design river, overflow in river sections is reduced, although some areas still experience inundation with a maximum height of 18 centimeters. The river morphology in this scenario is more stable, with a balanced level of degradation and aggradation. The conclusion of this research indicates that a series of ongoing mitigation efforts needs to be expanded to minimize the risk of floods but is already optimal in maintaining river morphology stability. The research findings are expected to be beneficial in maximizing the management of the Magila River.

The Effectiveness of Ground Sill Structure in Reducing Local Scouring at Cipamingkis River

Cipamingkis River is a subriver of Cibeet river located in Jonggol District, Bogor Regency, West Java Province. On the Cipamingkis river, there is a vital irrigation infrastructure known as the Cipamingkis Dam, which can irrigate approximately 4,591 hectares of rice fields in Bogor Regency and Bekasi Regency. Cipamingkis dam located in Jatinunggal Village, is on the northern slope of the West Java hills which has a relatively steep riverbed slope so that the possibility of degradation of the riverbed is relatively high. slope of the riverbed is relatively steep so that the possibility of riverbed degradation is quite high. riverbed degradation is quite high. In 2020 there were two Ground Sills that had been built upstream of the Cipamingkis weir. The Ground Sill built across the river aims to reduce the current velocity and increase the sediment deposition rate upstream of the Ground Sill so that the slope of the riverbed is relatively gentle and the Cipamingkis Dam does not experience structural failure as has happened before. The effectiveness is determined by comparing the riverbed elevation around the dam structure, before and after years construction of the Ground Sill structure.

Groundwater-surface water exchange affects nitrogen and phosphorus exports from tideless rivers to a ria coast in the sea of Japan

• Groundwater discharge in the downstream area of six tideless rivers was quantified. • Riverbed slope affected the relative contribution of groundwater to surface water. • Groundwater-derived nitrogen and phosphorus were critical for the coastal ecosystem. Groundwater discharge in downstream regions along the river continuum is considered a significant source of water and nutrients. However, the influence of groundwater discharge on the net export flux of surface water and nutrients from tideless rivers to coastal seas has not been thoroughly assessed. We conducted field surveys in the downstream region of six tideless rivers with different watershed properties along the ria coast of Wakasa Bay in the Sea of Japan during the summer. Mass balance models of water, salt, and 222 Rn were constructed to determine groundwater fluxes and associated fluxes of nitrogen and phosphorus. The model revealed that groundwater discharge ranged from 0.08 to 3.89 m d −1 , accounting for 1.3–14.8% of the export flux. This variability among the rivers correlated with the riverbed slope in each river, indicating that the local topographic gradient was a significant factor controlling groundwater-surface water exchange in tideless rivers. Groundwater discharge accounted for 0.8–16.7% of the nitrogen export and 0.9–27.4% of the phosphorus export to coastal seas. We concluded that the groundwater inflow driven by the hydrological and geographic properties of the watershed in the downstream region of tideless rivers was nonnegligible for nutrient dynamics and biological production in the coastal seas.

Shoreline change and coastal erosion: The role of check dams. First indications from a case study in Calabria, southern Italy

Currently, most of the world’s coastal territories are subject to erosive processes, often caused by an alteration of sediment balance due to both natural and anthropogenic factors. This issue is relevant in many Mediterranean territories such as Calabria region, in southern Italy. Here, considerable anthropogenic pressures affect about 750 km of coast on which debouch short torrential rivers locally termed ‘fiumare’. The regional climate, hydrology and geomorphology leads to intensive fiumare catchment erosion and high fluvial solid loads.The work focuses on the Gallico fiumara, chosen as case study affected by an intense hydraulic regulation programme in order to investigate the poorly studied effects of engineering control works on shoreline changes.The paper has considered the effects of the 264 check dams (completely filled a few years after their realization) only investigating the relationships between the volume retained by the structures and shoreline change during the several arrangement campaigns. Although the work does not consider the other processes that explain the complexity of the watershed-coast sediment balance, it has been clearly demonstrated an influence of check dam system on the evolution of the shoreline, especially due to the hydraulic works installed in the lower part of the watershed. In the light of the results obtained, it would be desirable to promote a debate on the opportunity to convert or demolish the check dams in the torrent reaches closest to the coast, where, moreover, the engineering control most reduced the already limited natural riverbed slope.

Alpha Parameter Modeling of Nakayasu Synthetic Unit Hydrograph Based on the Watershed Shape Factor

The limitation of hydrograph data availability becomes an obstacle for the design of water resources. The obstacle makes the Synthetic Unit Hydrograph give the big enough benefit for the design of water resources. Ideally, every watershed has its unit hydrograph. The Nakayasu Synthetic Unit Hydrograph is one of the synthetic unit hydrographs frequently used in the analysis of design flood discharge in Indonesia. However, the Nakayasu Synthetic Unit Hydrograph concept has been widely used and evaluated in some areas in Indonesia, and there is bias in determining the watershed characteristic coefficient. This research intends to investigate the characteristic of the observed hydrograph in every watershed and the whole watershed in the South Sulawesi Province-Indonesia. The research aims to build the alpha formula using alpha modeling with the affected parameters of watershed area, river length, river bed slope, shape factor, and the time concentration. Based on the ArcGIS version 10.7, most of the watershed’s shapes are elongated. The methodology consists of analyzing observed unit hydrograph by using the Collins method and Nakayasu Synthetic Unit Hydrograph. Then the model is built by using the statistical analysis of SPSS version 23 software for obtaining the affected level of each parameter that is determined. However, the modeling analysis uses the non-linear regression after there is carried out the descriptive test. The alpha formula for the elongate watershed in the Jeneberang River is proposed.

The Influence of Tides on Coastal Plain Channel Geomorphology: Altamaha River, Georgia, USA

AbstractRivers that traverse the terrestrial‐marine interface may have lower reaches that are influenced by both terrestrial and marine processes. However, only a handful of studies have focused on how the interactions of fluvial and tidal processes translate to channel geomorphology, and those are largely from delta/distributary systems. Here we quantify channel properties along the fluvial‐tidal transition reach of a coastal plain river and provide insight into their origins. The study site is a 47 km long tidal, single‐thread freshwater section of a river at 29 to 76 river kilometers inland of the estuary mouth, upstream of the delta/distributary system, and with average riverbed slope of 10−4. Results show that a tidal wave approaching the study reach loses 15%–17% of its incident energy (per horizontal area) per kilometer of channel, and at 51 km upstream of the mouth the incident energy is reduced to <1%. Also, at or near 51 km we observed breaks in along‐channel trends of channel cross‐section geometry, bed grain size, sinuosity, channel bed and water surface slopes. We propose that fluvial‐tidal flow processes and corresponding geomorphic feedbacks are apparent as abrupt changes in channel properties that highlight the influence of tides, and these discontinuities may be endemic to fluvial‐tidal transition zones in general. How these transition reaches self‐adjust in response to climate change remains largely unexplored but these reaches are likely to become important geomorphic hotspots.

Hydrological analysis of the September 2014 torrential floods of the Danube tributaries in the Eastern Serbia

Torrential flood as a rainfall precipitation driven natural hazard occurs in the watershed that responds within several hours due to a rugged topography. The extraordinary torrential flood event from September 15 2014 in the Eastern Serbia with its severe consequences, widespread material damages and casualties, draw an attention of the Serbian public and is a topic of this work. The combined method of Soil Conservation Service and synthetic unit triangular hydrograph is used to calculate the effective rainfall and peak discharges in five affected watersheds (Podvrska, Velika Kamenica, Slatinska, Zamna, and Mala Kamenica) in order to define the extremeness of this event. Special attention is given to the determination of the lag time defining the unit hydrograph and the curve numbers of the studied watersheds on the base of land use and hydrological class of soils with regard to geology, considering antecedent soil moisture conditions. Taking into account the high curve number (due to the high share of soils with an unfavorable hydrological conditions and high share of agriculture areas in land use), the shortest time to peak (due to the highest mean slope of river bed), the highest specific maximal discharge on subject date (4.58 m3s−1 km−2) as well as sediment transport data, the highest priority for erosion and torrential flood control works is attributed to the Mala Kamenica watershed. The results of this work may be a significant contribution to the flood risk assessment on a watershed level in this part of Eastern Serbia that should always start with reviewing and analyzing the historical torrential flood events.

Riverbed dune morphology of the Lowermost Mississippi River – Implications of leeside slope, flow resistance and bedload transport in a large alluvial river

Dunes are critical for understanding riverine sediment transport, deposition, flow resistance and channel flow processes. Although previous studies have examined the riverbed micromorphology of the Lower Mississippi River in the USA, our knowledge of detailed quantification of dune morphology in this and other large alluvial rivers is still limited. It is also not well understood how dunes in a straight channel reach and a meander bend differ in their characteristics, as well as how dune morphology may have been affected by human activities (i.e., river engineering). In this study, we utilized multi-beam bathymetric measurements over four 1.6–8.0 km long reaches in the Lowermost Mississippi River (LmMR) to analyze riverbed micromorphologic features. Three of the four reaches were located in the upper part of the LmMR between river kilometers (RK) 474–477, 483.6–485.2 and 491.7–493.3, and the other reach was located in the lower part, between RK 120 and RK 128. We analyzed a total of 3258 dunes in these river reaches and found that large dunes were dominant in the LmMR. These dunes were characterized by low mean leeside slope angle (10.8°), indicating that flow resistance caused by dunes should be relatively small. When compared with dunes in the straight reaches, dunes in the meander bends were much larger (1.06 m vs. 0.81 m) and had a higher bed roughness (0.91 vs. 0.68), which may be related to the varied flow velocity. Dune size increased with increasing water depth across the river channel of a straight reach, while it decreased with increasing water depth across the river channel of a meander bend. When compared with the dunes in the lower-river reach, the dunes in the upper-river reach were significantly higher in height and shorter in wavelength, and showed much higher bed roughness (1 vs. 0.68), which may be closely related to the greater riverbed slope and grain size of bed sediment occurred in the upper-river reach, as well as a combined effect of the Old River Control Structure (RK 500) and backwater. These findings indicate the strong impact of turbulent flow, slope and sand source on dune formation and riverbed deposition.

Deriving water level and discharge estimation using satellite altimetry for Krishna River, Karnataka

Radar altimetry is the most commonly used approach for monitoring ocean's water level or inland water bodies over ungauged or poorly gauged regions. In this study, a network of three altimetry missions (i.e., Jason 3, Sentinel 3A, and Sentinel 3B) was traced in the Krishna river, Karnataka, India, for 2018 and 2019. The network consists of 13 virtual stations, of which two are of Jason 3, five are of Sentinel 3A, and six are of Sentinel 3B. This paper proposes a method to find river discharge solely using remote sensing derived data. The river depth is calculated using satellite altimetry, and other hydraulic parameters (river width and river bed slope) are used in modified Manning's equation for calculation of discharge. To estimate river width, Google Earth Engine is used to process Sentinel 1 and Sentinel 2 images. All three missions showed excellent results with an average RMSE of 1.43 m, and the best correlation is showed by Sentinel 3B (>0.97). The discharge calculated using this method also provides adequate results, with NS value for station 1 is 0.53, and for station 2 is 0.63. These results show the potential of the proposed approach for monitoring water level and estimation of discharge solely using satellite-derived products.

Intrusion Distance and Flow Discharge in Rivers during the 2011 Tohoku Tsunami

On 11 March 2011, the Great East Japan Earthquake generated huge tsunami waves. Then, tsunami propagation occurred in rivers, resulting in further expansion of the flooded area. Full data sets of tsunami characteristics such as tsunami inland and river propagation distances as well as the river geometries from all rivers within the Tohoku District were compiled and analyzed. It was found that tsunami propagation distance in rivers was about 1.2 to 4.5 times that of the inland area. There was a good correlation between propagation distance in rivers and the river bed slope. Furthermore, new empirical formulae for calculating the damping coefficient of tsunami wave height and tsunami intrusion length were successfully derived based on the current comprehensive data sets covering a wide range of river geometry and bottom slope. Moreover, tsunami-induced flow discharge was evaluated by using measured water level variation.

The structure of the Karay river basin by the longitudinal slopes of the river beds and the average gradients of water catchments slopes

The problems of water lag time during flood forecasting, the rate of pollution spreading over the basin area in the event of industrial accidents, the transport of suspended and dissolved substances by rivers, and planning of erosion control measures are very relevant today. Within the framework of the basin approach, an elementary water catchment can be adopted as an elementary unit for the analysis of a particular territory. At the same time, river bed slopes determine the power of the water flow, and the average slopes of water catchments significantly affect the formation of river flow, the nature of the hydrological regime and determine the erosion potential of the territory. The object of the study is the basin of the Karay river, located in the southeastern part of the OkaDon plain. The Karay river is a right tributary of the Khoper river (the Don river basin). For the Karay river basin the river bed slopes and average gradients of catchment slopes are calculated and analyzed. The calculations were based on the digital elevation model created in GIS MapInfo. It is shown that the average slopes of the territories within the Karay river basin range from 0.4° to 1.4°.

Efektivitas Dan Kelengkapan Bangunan Sabo Di Sungai Togurara Daerah Gunungapi Gamalama

The lahar flow that occurred after the 2012 Gamalama Volcano eruption, leading to the eastern valley flowing downstream through the Togurara River to the center of Ternate City and Sultan Babullah Airport. To overcome the potential of lahar flow in the river since 2013 - 2016, several sabo dams and building facilities have been built. Based on the results of the calculation of deposits that potentially become lahar flows in 2016, the built-in capacity of the Sabodam has not been able to control the volume of sediment in the upstream of the river, then in the year 2017, 2018 constructed several additional Sabodam. In order to determine the effectiveness, feasibility and conditions of the completeness of Sabodam, is done field assessment on 25 ~ 27 September 2018, the method used was a mathematical approach based on sabo technology. The assessment was in the form of a field survey, simple measurements, interviews with the Sabodam management agency and local residents related to the lahar flow that had occurred. With the capacity of several additional Sabodams built in series, the average river bed slope was originally 9.09% to 6.83%. After the construction of Sabodam, the maximum lahar flow was once as high as 7 m, but now it decreases do 4.2 m. As the slope of the Togurara River slopes progressively, the lahar flow rate and its destructive power are reduced, so that Ternate City and Sultan Babullah Airport are spared from lahar disaster.Keywords: Lahar flow, sabodam, sabo technology, slope of riverbed, Togurara River.

Evolution Pattern of Tailings Flow from Dam Failure and the Buffering Effect of Debris Blocking Dams

Tailings ponds are the indispensable facilities in the mine production and operation. Once the dam is destabilized and damaged, it will pose a serious threat on the life and property of the downstream population and could also potentially cause an environmental disaster. With an engineering background, this paper dynamically and numerically simulates the evolution process of tailings flow from dam failure and the influence scope of any resulting disaster in context. The evolution characteristics of leaked tailings flow are analyzed at various downstream riverbed slopes and debris blocking dam settings. In addition, parameters such as flow rate, impact force and deposition range of leaked tailings flow at downstream arrival are studied, as well as their correlations. The results indicate that the flat terrains upstream and downstream of passage zone show a relatively larger area of inundation by tailings flow. Both the maximum and final downstream inundated ranges increase with the elevating slope of downstream riverbed, and the leaked tailings are deposited mainly in the nearby villages in front of the dam and the flat terrains of the downstream passage zone. Additionally, rational establishment of debris blocking dams on the downstream side is effective in diminishing the damage of tailings flow to the downstream section. This study can also provide an important basis for the quantitative evaluation of post-disaster influence scope for tailings pond as well as for the design of dam body.

Sediment removal from run-of-the-river hydropower reservoirs by hydraulic flushing

ABSTRACTThe concept of sustainable development is gaining popularity and hydroelectric projects designed and operated on this concept require sediment management as prime design criteria. Drawdown flushing is being practised in such projects for sediment management. Investigations using hydraulic models are required for the projects to address the site-specific design concerns. In the present study, simulations conducted using hydraulic model for sediment removal by drawdown flushing of the reservoir of Punatsangchhu hydroelectric project, Bhutan, is presented. The experiments on 1:100 geometrically similar scale model indicated that flushing is effective in maintaining the power intake area clear of sediment deposition. Deposition from the upstream reaches could not be flushed hydraulically. Furthermore, based on wide range of experimental data from hydraulic model studies, empirical equations have been developed for predicting the quantity of sediment that can be flushed from the reservoirs. The present equations have been developed including more parameters than those used in equations already available in literature. Two equations have been developed for different riverbed slope ranges with steep slope (0.005–0.04) and moderate slope (0.001–0.005). The equations developed were validated against different sets of data and it indicated that the predictions could be made within reasonable accuracy. These equations can be effectively used for hydraulic design of sediment removal from run-of-the-river hydropower reservoirs.

Dynamic evolution of riverbed potholes in the granitic bedrock of Chota Nagpur Plateau, middle part of Subarnarekha River basin, India

Potholes are an extraordinary abiotic micro geomorphic feature on the granite and quartzite topography of the Subarnarekha River basin. These erosional features are carved by the running water actions of River Subarnarekha and its tributaries. The study has been conducted on 17 sites (n = 1707) which are exemplary for the development of this micro fluvial feature located on the rejuvenated middle part of Subarnarekha River basin. Hydrological and geological factors are imperative for their formation. Joint length, joint density, joint orientation, rock hardness, variations of fluvial hydraulic, bed roughness, river bed slope and hydraulic gradient are conducive factors for the development of this geomorphic feature. Monsoon is the ideal season for carving these features by river turbulence, when abrasive work of river is predominant on the river bed (monsoon = 3000–6500kg.m2s-3, non-monsoon = 0.50–3.0kg.m2s-3). The evolutionary sequence of potholes is from round to oval and then elongated with vertical scouring. The relation between pothole radius and depth has been established to explain the process of its expansion. Joint length shows positive relation (R2 = 0.71) with pothole area while joint density has a negative relation (R2 = 0.29) as these are structurally weaker zones, characterised by destruction of these features. Suspended load is also a hindrance in their formation. Sites with high suspended load are delineated as pothole destructive zones. The mean dynamic evolution of circular, oval and elongated shaped potholes occurs at spatio-temporal level (Δoe=0.005-0.60m3,Δce=0.01-0.25m3,Δee = 0.005–0.30m3) and the initiation of this development depends on inner depth and radius of individual pothole.

Unidimensional, non-stationary modeling of a high mountain river in southern Ecuador

Floods represent a severe cause of deaths and economic loss. In order to prevent, mitigate, and reduce flood risks and their consequences, hydraulic models allow analysing and mapping floods. The results of an appropriate model that works under local conditions are a valuable tool for local governments leading to sustainable management of floodplains. Around the world, high-mountain rivers have been poorly modelled; their orography and data scarcity present an extra research difficulty. Considering that all one-dimensional models assume that the river bed slope is small, this study evaluated two widely applied one-dimensional models: Mike11 and HEC-RAS, for modelling a high mountain river. Their best configuration under complex topographical conditions and their potential use was assessed by calibration and validation of the models. We found that the HEC-RAS model was not able to define a stable solution of the hydrodynamic modelling of the river, while Mike11 yielded stable results. Furthermore, the validation of the Mike11 model showed good performance. This study sets a precedent in the 1D modelling of high-mountain rivers with data scarcity.

Analysis on Scour Characteristics under River Bed Variation in Weir Downstream

Various river projects are underway in small rivers in Korea that typically have natural flows. However, recent findings have shown that damages could be aggravated by structures such as weirs and drop structures during flood incidents. Experimental studies for securing the stability of flood control for these artificial structures have been insufficient, and designs applying the existing domestic design standards would not be suitable for the steep flow sections such as the actual small rivers, possibly aggravating the damages. The present study involved hydraulic model experiments conducted in a laboratory to investigate the surrounding flow patterns according to the river bed slope at the downstream part of the weir model. Further, the scour characteristics in the apron section during the overflow of the structure were analyzed to determine the appropriateness of the apron length. Thus, as the upstream river bed slope gradually increased, the experimental scour length deviated more from the design criteria formula. The results suggest that both the formula suggested by the National Construction Research Institute and Bligh’s formula presented in the River Design Criteria are not suitable for steep-slope rivers, such as small rivers in Korea, because both formulas were proposed based on the seepage line distance and river bed materials without considering the slope of the river bed. Thus, in designing the apron and bed pitching of weirs and drop structures, the river bed slope, scour characteristics of weir overflow, and existing design factors should be comprehensively considered to devise a design formula appropriate for environment of the small rivers in Korea.

Effects of Influential Parameters on Long-Term Channel Evolution Following Low-Head Dam Construction and Removal

The long-term existence of dam structures significantly modified the river channel. In accordance with a drastic increase of low-head dams under consideration for removal in recent years, it is important to predict the effects of low-head dam removal from the modified river channel by the low-head dam construction. This study intends to investigate the long-term channel evolution process following low-head construction and removal and to find out the influential parameters (sediment diameter, river bed slope, dam height) for those channel evolution by two-dimensional numerical simulation model. Following the low-head dam construction, sediment deposition rates in upstream of the low-head dam are varied with the influential parameters. The sediment deposition rates and sandbar formation with riparian vegetation settlement on sandbars have significantly affected for channel evolution following low-head dam removal. Especially the knickpoint formation and the types of vegetation (grass type and tree type) on the sandbars are critical factors for channel evolution following low-head dam removal. Through the numerical simulation results of low-head dam construction (50 years) and low-head dam removal (50 years), it is identified that the modified river channel by low-head dam may not be easily restored to pre-dam conditions following its removal especially in river geomorphology and riparian vegetation. Consequently, this study found that the reversibility following low-head dam construction and removal depends on the sediment deposition rates in upstream of the low-head dam.