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Batang Kuranji is a river located in Kota Padang. The high rainfall and human factors that cause changes in characteristics, especially in the upstream area make the water from the flow of kuranji stems in the rainy season often overflows, and cause flash floods, therefore built Check Dam at the head of the river batang kuranji to prevent the shallowing of the riverbed. Thisresearch aims toreview the structure of the Check Dam 3 building on Batang Kuranji in the city of Padang. This study refers to SNI 2851:2015 with rainfall data for 15 years used from 2005 to 2019, with batu busuk observation station and rice fields obtained from PSDA. Luas DAS is obtained from ArcGIS Applications. Dari hydroligi analysis obtained rainfall plan (R100th) 153,152 m3/dt with Gumbel method, Discharge flood plan for the 100 year anniversary period used Haspers method obtained (Q100th) 165.19 m3/dt. The type of Check Dam that is planned is the type of pelimpah (head work) with a height of Check Dam 8.5 m. Tilt of the body at the upstream 0.6, the distance between the main dam and sub dam 25.2 m, the thickness of the apron floor 1.6 m, with an estimated volume of sediment flow that can be accommodated by 14797.6 m3. The stability of the Check Dam construction was obtained at a value of 3.43 >1.5 and a sliding of 1.53 > 1.5 with a safety coefficient of 1.5, so that the construction of the Check Dam was stable.

In present work Computational fluid dynamics analysis based erosion wear prediction is performed for Francis turbine components, especially the runner. For the geometrical parameters, Francis turbine model with steady state condition and viscous flow turbulence SST model using ANSYS Fluent. The erosion effect on all the three component such as spiral casing, runner & draft tube has been studied for different concentration of sand particles from 1% - 6%. For each of those concentration the effect of variation in size has been studied for different sizes 10 ?m - 80 ?m. Further the effect of total erosion was also analyzed for different particle size. Erosion damage is found close to the upper and lower portions of the leading edge of the stay vane. some erosion spots at guide vane on the blade pressure side where suction side has minimum erosion. Maximum erosion damage observed on runner especially at the middle of the blade. The draft tube situated closer to runner having highest velocity due to high absolute velocity of water coming out from the runner does not produce any serious erosion effect. Results shows that erosion rate is maximum on runner at particle size 80 ?m for all sand concentration 1% to 6% and minimum at 30 ?m. Thus, 30 ?m is the optimum size of sand particles for the erosion.

The hydrological properties of a river basin are extremely affected by the construction of a dam. The discharges and sediment flow distribution, in a modified river basin will not be the same as to a natural catchment. Hydrological models contextually focus on a natural river basin without any modification. Unfortunately, most of the river basins have been under such modification, which is not favorable for a model simulation at a normal condition. This research was done at the Awash River Basin, already modified because of dam construction. A systematic approach was applied to handle the modification in the basin, through an application of the Soil and Water Assessment Tool (SWAT) and Hydrologic Engineering center’s River Analysis System (HEC-RAS) consecutively. SWAT model was implemented to simulate the upstream part of the basin. At the downstream parts of the basin, a simulation process was difficult on a SWAT model, due to the modified hydrologic parameters. Hence, the HEC-RAS model was applied because of its applicability under such circumstances. The model outputs indicate that the SWAT model can simulate the upstream part of the basin, in a good performance range that can be used for practical implementation. The downstream i.e., the modified catchment was simulated relatively better in the HEC-RAS model with good accuracy. Also, this research pointed out that a combined hydrologic and hydraulic model system development can be the best solution for modified catchments.

Accumulation of the sediment in the stream of the diversion channels adversely affects its operational systems. Diversion channels are often constructed perpendicular to the main river. In this study, the water flow and sediment transport in the diversion channel with different angles were investigated in an attempt to maximize water discharge and minimize sediment discharge. A physical model with movable bed was used to simulate water and sediment flow with five diversion angles (θ) between (30°–90°). Moreover, three bed width ratios (Br) (the relation between diversion to main channel bed width) between 30% and 50% and five total discharges between (7.25 L/s to 12.25 L/s) were considered for each case of (θ). The results showed, up to 10%, increasing in proportion discharge ratios for 30 and 45 diversion angles compared with 90° diversion angle. The results also showed that the lowest diversion sediment concentration was provided by the (θ) of 30°. Across all scenarios, the average proportion concentration reduction was 64%, compared with 90° diversion angle. Closer observation of the diversion system mechanism confirmed that decreased (θ) result in decreased sediment concentrations in the diversion channels. In conclusion, the diversion channel water and sediment discharge could be effectively managed by changing the (θ) to 30° or 45° instead of 90°.

Sediment dynamics play an important role in various aspects of earth system modeling. In this study, we developed a global sediment dynamics model that considers suspended sediment and bedload at short timescales. We validated suspended sediment from four observation stations in the Amazon River basin and over 60 observation stations from around the world based on a variable criteria such as availability of data samples. Our model was able to effectively reproduce seasonality and spatial distribution of suspended sediment flow. However, our global estimate of approximately 4 Bt/a was significantly lower than previous estimates; therefore, we discuss potential causes of this discrepancy, including target time period and discrepancies with previous extrapolated methods. Our newly developed sediment dynamics model could provide a better understanding of global sediment transfer and contributes to various related research fields such as coastal modeling and natural disasters.

Erosion wear of the centrifugal pump impeller are the key issues since its operating in sediment-laden flow. Experiment and numerical method are adopted in this study to investigate the erosion wear of the impeller in a double-suction pump in the Jingtai Yellow River Irrigation Project (JYRIP). Observation during operation combined with morphology study is carried out to verify erosion mechanisms at the different sections of the impeller blade. For numerical study, the Eulerian-Lagrangian approach combined with the Mclaury model is employed to predict the trajectories of the particles under different particle parameters. Also the effects of particle size and concentration on impeller erosion wear is studied. Numerical results are consistent with experimental data. The surface wear of the blade changes obviously from circular shape to strip shape in the direction from the Leading Edge (LE) to the Trailing Edge (TE), and the wear damage area increases correspondingly. Trajectories of larger particles are more uniform and tend to cause more severe erosion wear damage. The wear damage tends to be slow after the particle size increases to a certain extent under the same sediment concentration. Besides, erosion rate increases with an increase in sediment concentration, and the erosion rate of the suction side is greater than the pressure side at the same position of the blade surface. These results can offer a good reference for the design of wear resistance impeller of the double suction pump.

A new sedimentation device, the “lateral sediment flow meter”, was developed and tested for taking samples of substances moving in the water column in lateral directions. The device can be successfully used for solving the sedimentological, biological and environmental problems, and the monitoring of solid pollutant transfers.

This paper aims to argue the extreme fragility of the ecosystem in the Lower Mekong Basin in the process of economic development in the Mekong region. The Lower Mekong Basin has been proud of its richness in nature and high biodiversity. The Basin’s ecosystem has, however, been endangered by the recent development factors such as the dam construction. The dam construction gives negative impacts on the river basin’s fish biodiversity. The dam also traps and curtails almost of all sediment flow to the downstream. The reduced sediment transport would result in the shrinkage of the delta area in Vietnam most seriously, where the channel bet would be eroded and much saltwater would be introduced into the river channel. In a couple of decades later, the modification just for the economic growth may change the river as an artificial unproductive channel.

This work focuses on the study of the relationship between suspended sediment concentration C and liquid flow Q during floods, on one hand, and the quantification of sedimentary flow in the watershed of the Isser wadi, on the other hand. The analysis of 84 floods over a 30-years period (1971/2001) shows a seasonal dynamic of suspended sediment availability, which increases in summer (especially in August) and autumn and decreases in winter and spring when flow is high. An analysis of the events recorded on the Isser wadi is made from the appearance of the graphs representing C as a function of Q which draws four hysteresis models hourly, counterclockwise, linear plus loop and figure in eight. The total flood performance in terms of suspended solid transport is 5.07* 106 tonnes, which corresponds to a specific degradation of 1222 t.km-2.year-1. Suspended solid flux varies considerably from one flood to another depending on many factors such as seasonality and flood duration, and hourly and counterclockwise floods are the most frequent and produce 70% of total sediments. The analysis of seasonal yields has shown that winter contributes a great deal of sediment (49%)., Ce travail s’intéresse à l’étude de la relation entre la concentration de sédiments en suspension C et le débit liquide QL pendant les crues, d’une part, et d’autre part, à la quantification du flux sédimentaire dans le bassin versant de l’oued Isser. L’analyse de 84 crues sur une période de 30 ans (1971/2001) montre une dynamique saisonnière de la disponibilité des sédiments en suspension, qui augmente en été (particulièrement au mois d’aout) et en automne et diminue en hiver et au printemps lorsque le débit est élevé. L’analyse des évènements enregistrés sur l’oued Isser est réalisée à partir de l’allure des graphes représentant C en fonction de QL qui dessinent quatre modèles d’hystérésis horaire, antihoraire, linéaire plus boucle et figure en huit. L’apport moyen annuel des crues en termes de transport solide en suspension est de 5.07 millions de tonnes, ce qui correspond à une dégradation spécifique de 1222 t.km-2.an-1. Le flux solide en suspension varie considérablement d’une crue à l’autre en fonction de nombreux facteurs tels que la saisonnalité et la durée de la crue. Les crues horaire et antihoraire sont les plus fréquentes et produisent 70% des sédiments totaux. L’analyse des rendements saisonniers a montré que l’hiver contribue pour une grande partie des sédiments (49%).

In view of the weak research on the rheological characteristics involved in the variation of the fluid movement caused by the storm runoff carrying a large amount of pollutants and sediments, this study uses the NDJ-5S rotary viscometer and the self-made slim tube viscometer of Northwest Agriculture and Forestry University. On the basis of the research, the influence of pollutants on the rheological characteristics of high-concentration sandy water flow is studied. The results show that the NDJ-5S rotary viscometer can be used well under the sand content of less than 300kg/m3. The double vertical tube slim tube viscometer made by Northwest A&F University can better simulate the sand content of 0～800kg/m3; The structure of flocculation between particles in sandy water flow will affect the viscosity of muddy water, and the concentration of sediment and other pollutants will have a certain impact on flocculation. Under the same conditions, the concentration of pollutants increases (0～440kg/m3), the viscosity coefficient of fluid increases (90%～114%), and the variation of sand content from Newtonian body to Bingham body is about 300～400kg/m3, The influence of pollutants on the variation points of rheological properties is not significant.Keywords: pollutants; sediment; variation; viscometer; Newtonian fluid; Bingham fluidFunding: This study was funded by the National Natural Science Foundation of China (No. 41877078, 41371276), Key research and development project of Shaanxi Province (2020ZDLSF06-03-01), National Key Research and Development Program of China (No. 2017YFC0504703) and Knowledge Innovation Program of the Chinese Academy of Sciences (No. A315021615).

Lake Chūzenji in Tochigi Prefecture, Japan, was contaminated by radiocesium released during the Fukushima Dai-ichi Nuclear Power Plant accident on March 11, 2011. 137Cs activity in sediment from the center of the lake was 15,100 Bq/m2 after the accident. The sum of dissolved 137Cs in a layer of lake water at about 20 m depth and at the bottom water layer was high, accounting for about half of total dissolved 137Cs in the lake. The fluxes of 137Cs activity associated with sediment flow in and out of Lake Chūzenji from 2014 to 2016 were 161.8, 223.7, and 65.0 Bq/m2/year, respectively. In 2014, the total annual inflow and outflow of 137Cs activity in Lake Chūzenji were 1.34 and 2.0 GBq, resulting in a net outflow of 0.66 Bq which accounted for about 1% of the cumulative dose in the lake since the 2011 nuclear accident. The total 137Cs activity of suspended and dissolved matter in Lake Chūzenji in July 2015 were 28 and 36.2 GBq, respectively. About 40% of the 137Cs activity from the 2011 nuclear accident was still in lake water in 2014. 137Cs activity of sedimentation flux of Lake Chūzenji was 1.1%/year.

This article aims to advance in the knowledge of the relationships between the sand cycle and the behaviour of small river mouths (outlets) flowing into sandy beaches in the Río de la Plata estuary, Uruguay. The bars of these watercourses respond quickly with processes of erosion and/or migration of the channel when the "sand cycle" (coastal sedimentary balance) undergoes modifications, due to i) the effect of the fixation of dunes (sediments) by afforestation with exotic species and ii) the construction of infrastructure. Two watercourses were analysed: the Pando River and the Carrasco Creek that both have received different impacts and suffered modifications, not only in the sediment flow but also in their hydrological regime. A multitemporal analysis was based on a series of aerial photos and cartography since 1928, a background review, and the support of documents and chronicles. The data obtained were analysed statistically. Results evidence a significant loss of beach surface at the Pando River mouth, and an increase at the Carrasco Creek mouth, since the channelling of a wetland located upstream, allowing the entrance of sediments from the basin upstream of the wetland. Relevant outcomes are: i) the description and analysis of the relationships established between dune systems and the outlets of the watercourses, an aspect that has not received due attention in the scientific literature, in which the dissociation between the analysis of wind and fluvial dynamics is usual, and ii) the sedimentary balance was of both systems: erosion and accretion at the Pando and the Carrasco outlets respectively. The reconstruction of the dunes could likely prevent the escape of sand and reduce the erosion. The knowledge about human intervention and natural processes governing the interactions between sandy beaches, dunes and outlets is a crucial input to coastal management and adaptation to sea-level rise and storm surges. ResumoEste artigo tem como objetivo contribuir para o conhecimento das relações entre o ciclo de areia e o comportamento da foz de rios pequenos que desaguam em praias arenosas no estuário do Río de la Plata, no Uruguai. As barras destes cursos de água respondem rapidamente a processos de erosão e / ou migração do canal quando o "ciclo de areia" (equilíbrio sedimentar costeiro) sofre modificações, devido: i) ao efeito da fixação de dunas (sedimentos) por reflorestamento com espécies exóticas e; ii) á construção de infra-estruturas. Foram analisados dois cursos de água: os rios Pando e Carrasco, que receberam impactos diferentes e sofreram modificações, não apenas no fluxo de sedimentos, mas também no regime hidrológico. Foi efetuada a análise temporal de uma série de fotos aéreas e cartografia desde 1928, a revisão da bibliografia e utilizado suporte documental e crônicas. Os dados obtidos foram analisados estatisticamente. Os resultados evidenciam perda significativa da extensão da praia na foz do rio Pando, e um aumento da extensão na foz do rio Carrasco, desde a canalização de uma zona úmida localizada a montante, permitindo a entrada de sedimentos da bacia a montante do pantanal. Os resultados adquiridos mais relevantes foram: i) a descrição e análise das relações estabelecidas entre os sistemas dunares e os fluxos dos cursos d'água, aspecto que não tem recebido a devida atenção na literatura científica, em que a dissociação entre a análise da dinâmica eólica e fluvial é usual, e ii) o balanço sedimentar de ambos os sistemas: erosão e acreção na embocadura dos rios Pando e Carrasco, respectivamente. A reconstrução das dunas poderia evitar a perda de areia e reduzir a erosão. O conhecimento sobre intervenção humana e processos naturais que regem as interações entre praias arenosas, dunas e estuários é um conhecimento crucial para o gerenciamento costeiro e a adaptação à elevação do nível do mar e às tempestades.

Bottom intakes are the most useful structure for diverting the flow of steep rivers and providing specific amount of water for hydropower usage. It is crucial to obtain optimum of physical parameters in order to divert desired discharge with minimum possibility of occlusion. Numerical models can simulate flow and turbulence transport equations at any complex geometries. Numerical methods based on Computational Fluid Dynamics (CFD), are one of the most common methods of numerical simulation that is used in water structures. According to the capabilities of numerical methods, complex modes of flow field over bottom intakes can be analyzed. In the present study, Flow-3D software is used to investigate the experimental results of the previous researcher for sediment and clean water flow over bottom intake with circular bars numerically. This study is carried out in a total of 27 models for clean water and 9 models of sediment flow (Bed-Load) at different approaching flow conditions. Parameters of roughness, size of computational cell, turbulence transport equation, Bed Load Transport equation and bed load coefficient has been calibrated. Validation procedure proved that the accuracy and performance of numerical models appear to be acceptable for designing intake systems. For each test, the discharge coefficient is computed, then by using dimensional analysis, a dimensionless relation derived from the dependent and independent variables and compared with the measured discharge coefficient. Estimating the discharge coefficient by the proposed equation in clean water flow performed a mean error of 6.4 percent and for sediment flow led to a mean error of 4.3 percent.

Sediment flow through hydro turbine causes erosion of hydraulic components resulting in drop of turbine efficiency, particularly in hydropower plants of the Himalayan region. The measurement of erosion and monitoring of sediment flow in turbine are major concerns in erosion study. Attempts have been made to study erosion mainly in Pelton and Francis turbines. In this study, a simple and effective method has been presented to measure erosion in a Kaplan turbine of a run-of-river scheme Chilla hydropower plant in foothills of Himalaya. Recent techniques were used to measure sediment parameters like concentration, size, shape and mineral content. A standard erosion model is applied to estimate the erosion in Kaplan turbine blade, runner chamber and draft tube cone. A calibration factor has been proposed to apply the erosion model for site specific conditions. It has been found that the outer trailing edges of the turbine blade and upper runner chamber are most erosion prone zones. Sediment analysis revealed that effective operation can reduce erosion in turbine components. The estimated erosion values from model are found to be consistent with measured values. Finally, suggestions for design improvements and effective operation of erosion affected hydropower plants are given.

The functions of the diversion channel are usually disturbed by sediment erosion and deposition. Considering the effects of unsaturated sediment flow and narrowed cross section the diversion channel is enormously eroded. The discharge capacity, however, is deteriorated for the local deposition which lessens the water depth to satisfy the minimum navigable flow rate. In this study, the alternative diversion channel with unsaturated sediment flow at Hanjiang River, China, was taken as an example. The impacts of bed morphology for flood events and normal flow conditions were analyzed. The results show that the consideration of bed morphology is essential to design the diversion channel. Even for the unsaturated and eroded channel, the local deposition can reduce the water depth and restrict the navigable requirement under normal flow conditions.

Applications of sediment transport and water flow characteristics based sediment transport simulation models for a river system are presented in this study. An existing water–sediment model and a new sediment–water model are used to formulate the simulation models representing water and sediment movement in a river system. The sediment–water model parameters account for water flow characteristics embodying sediment transport properties of a section. The models are revised formulations of the multiple water inflows model describing water movement through a river system as given by the Muskingum principle. The models are applied to a river system in Mississippi River basin to estimate downstream sediment concentration, sediment discharge, and water discharge. River system and the river section parameters are estimated using a revised and the original multiple water inflows models by applying the genetic algorithm. The models estimate downstream sediment transport rates on the basis of upstream sediment/water flow rates to a system. Model performance is evaluated by using standard statistical criteria; downstream water discharge resulting from the original multiple water inflows model using the estimated river system parameters indicate that the revised models satisfactorily describe water movement through a river system. Results obtained in the study demonstrate the applicability of the sediment transport and water flow characteristics-based simulation models in predicting downstream sediment transport and water flow rates in a river system.

The article discusses the process of sediment transport in channels under the influence of wind waves on the course. Based on the calculation method Quick M.C. dependences are proposed for calculating sediment transport in channels when waves are superimposed on associated and counter-current flows. The movement of sediments caused by the combined action of waves and currents is studied. It is shown that the direction of the movement of sediments is determined mainly by the direction of wave propagation (even in the case of a counter-current). Here the consumption of sediments is proportional to the power of the “wave flow” system. Comparing the results of the calculation with the dependencies of other authors gives satisfactory results.

This article presents the experimental result and mathematical analysis influences of the permeable breakwaters to dynamics of the coast on various conditions by the action of waves. Deposition of sediment behind breakwaters leads to the formation tombolo of a certain size and intensity depending on the parameters of breakwater and the presence of a weak along-shore sediment flow. The results of the experiments determined empirical dependences, which are necessary for scientific study design of permeable breakwaters. Mathematical modeling of experimental data was also carried out. Experimental data are compared with already known results of research for permeable breakwaters with frontal and oblique approaches of waves. The experiment was held in Kyiv, Ukraine at the Institute of Hydromechanics National Academy of Sciences of Ukraine.

The objectives of this research are to analyze characteristics of physical oceanography, such as : tides, waves, currents, and discharges at Muara Kali Porong. This research also discuss sediment flow patterns and morphology in around the Estuary of Porong River. Tidal data were used as correction to the depth. The calculation to determine the tidal current velocity and wind data along with current data are used for simulation model. Sedimentation process with a simulation of 15 days in the West Season occured in the Northeast of Lusi Island with sediment thickness ranged from 1.6 to 2.6 m.

The results of the analysis of discharge and sediment flow changes of the main rivers flowing into Lake Baikal are presented. Long-term observation record of sediment flow is divided into two periods differing in average values and scale fluctuations of annual average values. During the first period, the dynamics of sediment flow of rivers was determined by hydro-climatic factors, i.e. fluctuations of sediment flow, in general, are synchronous to fluctuations of water flow. During the second period (from the mid-1970s) there is a downward trend of sediment flow change (decrease by 49%–82%) against the background of increased discharge of rivers. This trend is caused by both anthropogenic influence, and natural processes connected to global and regional changes of climatic characteristics. In general, natural processes of sediment flow changes in the different areas of Baikal basin are altered by anthropogenic factors to a greater or lesser extent. The present article can be used as analytical material for further research and forecast of sediment flow changes in the Baikal basin as well as in other rift-valley lakes of the world.

Dams whose collapse could cause loss of life or huge assets damage are considered to survive a probable maximum flood (PMF), but the PMF in various locations has been amplified at regular intervals, resulting in spillways that no longer convene the proposed norms. Spillway rehabilitation is required for lots of dams in India; in order to get better hydraulic competence. Catastrophe in Uttarakhand (June 2013) necessitates the research aspect of spillway rehabilitation. Increasing specific flow form hydraulic structures is one of the thought of spillway rehabilitation. Labyrinth weir may be used for amplifying specific flows of existing spillway. Sediment trapping behind Labyrinth weir might be one of the disadvantages for river with high sediment flow. The Piano Key Weir (PKW), ramped type Labyrinth weir is a hydraulically attractive alternative to linear overflow weirs, increasing the unit discharge for similar heads and spillway widths. This advantage allows operating dam reservoirs on an increased level and provides thereby an enhanced retention volume. It is a result of the non-linear nature of PKW being folded back and forth to make repeated cycles or keys. This type of weir is particularly suitable for sites where topographic conditions limit the extent of its width. Together with its high discharge capacity for low heads, this geometry makes these weirs interesting in spillway rehabilitation. This paper investigates the recent developments to improve hydraulic competence of spillways. Head reduction over crest can improve efficiency as well as reduce submergence. This study shows that for increasing discharge, head reduction with respect to conventional rectangular weir is reducing but reduction was found above seventy percent for all the experiments