Sedimentation Problems Research Articles

Hydrodynamic behaviors of settled magnetorheological fluid redispersion under active dispersing mechanism: simulation and experiment

Despite several salient benefits of numerous control systems utilizing magnetorheological (MR) fluid, practical realization of commercial products is limited due to the particles sedimentation. To overcome this problem, several measures have been proposed to optimize MR fluid settling through the viewpoints of dispersing medium viscosity, suspension force of dispersed phase and additives innovation, but the settling of MR fluid can be alleviated to an extent only. An active dispersing mechanism (ADM) proposed in the previous work is one of attractive ways to resolve the sedimentation problem in a level of device and it is promising to fulfill good serviceability for MR dampers even if the settling remains. In this work, attributive to the investigations in stirring devices, rotary blades are employed to fulfill the redispersing of settled MR fluid under the theory of solid–liquid two phase flow. The parameters and working conditions of the rotary blades are optimized to guide experimental verification in a damper-sized vessel. The vessel can be seen as a prototype for real MR damper. An immersed induction method for the characterization of the localized MR fluid concentration is proposed to designate the dispersing process when ADM is started. With the experiments of different MR fluid volume fractions and rotating speeds of the rotary blades, it is fully testified that the faster the blades rotate, the shorter the mixing time, and the more the inclination angle of blades close to 45°, the better the dispersion capability. In addition, it is also identified that the ADM is effective to disperse the settled MR fluid and promising to the sedimentation immunity of MR damper.

Water Transfer Redistributes Sediment in Small Mountain Reservoirs

Reservoir sedimentation management has become an important topic for large dams in the United States due to their historical design, current age, and increased environmental regulation. Less attention has been paid to small dams (hydraulic size < 0.01) in remote mountains with urgent sedimentation problems. In drier climates, such reservoirs may be frequently drained and trans-catchment flows routed over their sediment deposits heading from one mountain tunnel to another. This study asked an unexplored scientific question focusing on this special setting: how do different amounts of water transfers interact with different reservoir stages to affect sediment erosion and its redistribution in the backwater zone? Mindful timing and magnitude adjustment of water transfer, involving water diverted across watersheds by tunnels, through a reservoir were hypothesized to strategically redistribute sediment erosion for sites with water transfer/diversion facilities in the main channel. For a study site in the north-central Sierra Mountains of California, 2D hydrodynamic modeling revealed that sediment erosion within the backwater zone increased by > 100% when water transfer was maximized, involving a flow 12 times higher than mean annual discharge. With reservoir stage drawdown, the increment of sediment erosion was further increased by > 50% compared with water-transfer-only scenarios. The natural upstream inflow with daily flow occurrence of 5–25% was the optimal water transfer to avoid disturbing sediment. These results indicated that water transfer and stage drawdown optimization is a promising strategy to promote or abate redistribution of deposited sediment through a smaller reservoir.

Prediction of flow and sediment transport rates into closed-end channels for turbidity current intrusion

Turbidity current intrusion often occurs in canals, approach channels and tributary areas of large reservoirs, causing sedimentation problems in these environments. Many models and semi-empirical equations have been proposed to calculate flow and sediment transport rates for turbidity current intrusion, under an assumption that the current front can keep propagating freely in the channel before dying out, but the effect of the finite length of closed-end channels has rarely been considered. A self-similar solution to the vertical two-dimensional model for turbidity currents is used to obtain the equation of the maximum possible length for the intrusion of turbidity currents. The maximum possible length is then used to modify an existing discharge equation for turbidity current intrusion in long channels and establish a more general calculation method that can be applied for intrusion in closed end channels. Data from two existing flume experiments are used to calibrate the derived equation of sediment transport rate for turbidity current intrusion. Field measurements obtained from several tributary mouths in the Xiaolangdi Reservoir are also used to calibrate the derived intrusion discharge equation. The agreement between predictions and observations, as well as the comparison between the proposed calculation method and the one before modification, demonstrate that the intrusion discharge is not only determined by the depth of turbid water and sediment concentration at the inlet of the tributary channel, but also influenced by the ratio of the real intrusion length to the maximum possible intrusion length.

Coastal erosion risk assessment and applied mitigation measures at Ezbet Elborg village, Egyptian delta

Coastal areas globally suffer from serious erosion and sedimentation problems. The assessment of coastal erosion risk is fundamental for better coastal management. The main goal of the current study was to enhance coastal management by identifying the coastal erosion risk and suggest possible mitigation measures. The study was developed for the Egyptian Northern Coast. MIKE 21 was used to evaluate the erosion and test the proposed measures. First, a bathymetric survey of the study area was conducted. Then the tidal data, storm surge, and global sea rise data were collected. The offshore wave data, shoreline data were compiled. And then, the different nearshore wave modeling and wave propagation were modeled. The model was calibrated using measured data in 2014 and validated using measured data in 2016. Future shoreline changes for the years 2029, 2039, and 2049 were depicted. A suitable mitigation measure was used and tested for the same years. The groins with a specific size and arrangement were tested. The main goal of the study is to find a suitable solution to protect the coast and investigate its impact on the shoreline in the next 30 years. The proposed mitigation measure minimized the coastal erosion of the study area rigorously.

Homogeneous distribution of phosphor particles inside resin using a vertical vibration method for efficient laser-based white light illumination.

We report what we believe to be an innovative method for the homogeneous distribution of phosphor particles inside the optical resin-based layer using a vertical vibrational technique for efficient laser-based white light illumination. In this method, single-stage vibration energy was efficiently used against phosphor sedimentation with the help of a mechanical vibrator system. The vertical vibrational energy was transferred to negate the downward gravitational effect acting on each phosphor particle. Therefore, the phosphor particles inside the layer were stable and uniformly distributed from the initial to final drying stages, creating approximate refractive index homogeneity inside the medium. The sedimentation problem was resolved, and all the optical parameters to support this method were properly analyzed and found to be stable and suitable for laser-based illumination applications.

Sedimentation in small-scale irrigation schemes in Ethiopia: Its sources and management

Numerous irrigation schemes in sub-Saharan Africa (SSA) exhibit excessive sedimentation, resulting in underperformance and high maintenance costs. In the current study, a participatory monitoring program was used to investigate sediment causes and sources, measure the annual sediment load, and monitor desilting campaigns in two small scale irrigation schemes in Ethiopia, Arata-Chufa (100 ha) and Ketar (430 ha), for three years (2016–2018). Sedimentation quantities were huge, where the annual river sediment influx ranged from 220 m3 for the Arata-Chufa scheme to 1,741 m3 for the Ketar scheme. On average 0.3 m3/m of sediment were removed from the main canal for Arata-Chufa costing 794 days of labor per year. In Ketar, sediment quantities were even greater: 1.1 m3/m was removed requiring 3,118 days of labor per year. The sediment influx from the river source amounts to up to 95% for Arata-Chufa and moderately reaches 46% for Ketar, with the remainder of the sediment entering with overland erosion flows. Farmers reported increased sedimentation over time and difficulty paying operation and maintenance fees instead preferring to contribute labor for the desilting campaigns. Sedimentation management is fragile and mainly involves frequent desilting campaigns and unharmonized efforts to reduce overland sediment inflows. Factors contributing to sediment deposition include mild longitudinal bed slopes, the location of the intake, canal layout, and lack of canal banks for protection against surface water inflow in addition to sub-optimal canal operations. Excessive sedimentation is a major challenge resulting in underperformance of numerous irrigation schemes in SSA, and the stakeholders’ lack of awareness of the sources of sedimentation is an underlying factor aggravating sedimentation problems. It is concluded that investigating the sources, extent, and types of sedimentation entering a small-scale irrigation scheme is the basis for reducing maintenance costs and for effective management of sedimentation problems.

Analysis of Sediment in Goronyo Dam, Sokoto, Nigeria

Reservoir sedimentation has been a global bottle neck in maintaining the design storage capacity of reservoirs. Reservoir sedimentation leads to the reduction of the original capacity which affects irrigation, hydropower, flood control, drinking water supply and recreational activities. Introduction of mechanized farming without due regard to the nature of the environment is aggravating the erosion and sediment problem. This study has discussed and analyzed the most important parameters (bulk density, sediment volume, sediment mass, trap efficiency, sediment yield etc) for 31 years (1984 -2015) using Empirical Method and Goronyo Dam Stage Capacity Curve. The Mean bulk density (dBD) was gotten as 0.97gcm3, Sediment Volume (SV) as 26,179,302m3 , Sediment Mass (SM) as 25,393,922.94 tones, average annual sedimentation as 819,158.81ty-1 , Trap Efficiency (TE) as 90.2%, Sediment Yield (SY) as 908,158.00 ty-1, Specific Sediment Yield (SSY) as 42.35𝑡𝑘𝑚−2𝑦−1, The loss of storage (26,179,302m3)

Baroclinic Effect on Inner-Port Circulation in a Macro-Tidal Estuary: A Case Study of Incheon North Port, Korea

This study investigated the flow patterns and affecting factors in the North Port of Incheon, South Korea, to understand the inner-port circulation characteristics by applying an unstructured grid finite volume community ocean model (FVCOM) together with a field survey. The FVCOM considered the tide, river discharge, surface winds, and atmospheric pressure with the highest resolution of 50 m around the port. The model results were validated with current velocity and salinity observations. In the main channel, the difference in salinity between the sea surface and bottom increased during the neap tide due to weakened tidal currents, thus strengthening the stratification. However, at the inner port, strong stratification was observed during spring tide as the near-surface freshwater from upstream of the estuary moved relatively farther south of the port than that during the neap tide. Freshwater flowed into the port during the flood current and was trapped in the semi-closed geometry of the inner port. The horizontal salinity gradient between the trapped fresher water in the port and saltier water in the main channel increased during the flood current. As a result, density-driven circulations associated with near-bed currents towards the port were maintained for more than 3 h after high tide. This result implies that the baroclinic effect, mainly due to the salinity gradient in the North Port, could significantly affect residual circulation at the inner harbor in a macro-tidal environment and the mass transport mechanism, such as sediment transport. In general, such enhanced baroclinic effects due to salinity and tides are not limited to the North Port and can have greater effects on inner-port circulation in other macro-tidal harbors that suffer from severe sedimentation problems.

Photo curable resin for 3D printed conductive structures

In this study, a new resin formulation method was developed to fabricate 3D printed conductive structures via digital light processing (DLP) 3D printing technology. Metal fillers, such as silver-coated copper flakes (AgCu) and silver nanoparticles (AgNP), were tested for conductive resin formulation. With low UV shielding and printing derivation, AgCu was selected as the conductive filler, and mixed with a photo curable acrylic resin. To resolve the sedimentation problem of metal fillers, carbon nanotubes (CNT) were added as a thickening agent to provide a supportive network to stop the metal fillers from settling. With the CNT addition, AgCu up to 70 wt% can be well dispersed in the acrylic resin with both fluidity and suspension stability. The resin can be printed into 3D metal circuitry structures with a conductivity up to 1000 S/cm without sintering. Multi-material stereolithography was also performed to produce conductive circuitry within insulation materials. The sectional view showed great connections between multiple layers of printed conductive tracks. Through-hole vias and blind vias were also built with great quality to demonstrate the capability of this conductive resin formulation.

Flood Reduction Modelling of Mahakam Cascade Lake towards the Mahakam River - East Borneo - Indonesia

Lake is a water source that has decreased its function and has damaged the ecosystem. The Mahakam cascade lake in the East Borneo-Indonesia consists of Jempang Lake, Semayang Lake, and Melintang Lake, which have the sedimentation problem caused by the land-use change. The sedimentation can cause floods in the Mahakam River. However, the Mahakam River that correlates with the Mahakam cascade lake cannot reduce the happened flood. This study intends to optimize flood reduction modeling of Mahakam Cascade Lake towards the Mahakam River in the Muara Kaman outlet. According to the optimization model, this research aims to simulate the flood reduction modeling due to the 3 discharge conditions: Q25, Q50, and Q100. The food reduction modeling uses the Linear Programming Model, and the model is built integrated due to the Cascade Lake. The methodology consists of a linear programming optimization model due to the 3 scenarios (Q25, Q50, and Q100). However, the analysis of the design flood uses the Nakayasu Synthetic Unit Hydrograph in the watershed and the Rational Method for the discharge in the lake. The capacity of Mahakam Cascade Lake due to the bathymetry data and AWLR is as follow: 1) Jempang Lake: 519,958,550.36 m3; 2) Melintang Lake: 696,012,192.74 m3; and 3) Semayang Lake: 1,195,593,435.86 m3. The optimization model result of flood reduction in the Muara Kaman is as follow: a) Scenario-1 (Q25): Qmuara Kaman = 32,729.80 m3/s; b) Scenario-2 (Q50): Qmuara kanam = 37,432.36 m3/s; and c) Scenario-3 (Q100): Qmuara kanam = 39,777.80 m3/s.

THE INFLUENCE OF AUTOMATIC FLAP GATE ON EROSION IN TIDAL SWAMP AREA

This research aims to examine the problem of erosion and sedimentation in canals in swampy areas in South Sumatra, namely the P8-13S scheme of the canal (SPD) Telang I, Banyuasin regency with the influence of flap gate. The research method used is to perform simulations in the laboratory using a scale model and related parameters, such as velocity (v), depth of erosion (de), sedimentation (ds), water density (ρw), gravitation (g), time (t) and distance (x). Dimensional analysis to determine the related parameters that produce a dimensionless parameter relationship model is carried out using the Langhaar method. The result of the study was that the maximum relative erosion (de/t)max occurred at the canals estuary near the flap gate, which was 0.255 during simulation times of 5 minutes. While the maximum relative sedimentation (dd/t)max also occurred at the estuary of the secondary canals (SPD) of 0.05 for 5 minutes. So, the sediment transport process in the secondary canal (SPD) is generally influenced by flow velocity and the presence of a flap gate in the canal to regulate sediment transport.

Prediction of River Sediment Transport Based on Wavelet Transform and Neural Network Model

The sedimentation problem is one of the critical issues affecting the long-term use of rivers, and the study of sediment variation in rivers is closely related to water resource, river ecosystem and estuarine delta siltation. Traditional research on sediment variation in rivers is mostly based on field measurements and experimental simulations, which requires a large amount of human and material resources, many influencing factors and other restrictions. With the development of computer technology, intelligent approaches have been applied to hydrological models to establish small information in river areas. In this paper, considering the influence of multiple factors on sediment transport, the validity of predicting sediment transport combined with wavelet transforms and neural network was analyzed. The rainfall and runoff cycles are extracted and decomposed into time series sub-signals by wavelet transforms; then, the data post-processing is used as the neural network training set to predict the sediment model. The results show that wavelet coupled neural network model effectively improves the accuracy of the predicted sediment model, which can provide a reference basis for river sediment prediction.

Soil erosion risk analysis and mapping for conservation planning at Mihtsab-Azmati micro-dam watershed, Northern Ethiopia

This study was conducted to quantify, analyze and map soil erosion risk areas using remotely sensed data and GIS-based Revised Universal Soil Loss Equation (RUSLE) model at Mihtsab-Azmati Irrigation Dam Watershed, Northern Ethiopia. Based on the result, the watershed has potential soil erosion risk which ranges from 0 ton hectare−1 year−1 to 2980.12 ton hectare−1 year−1 with an average annual soil erosion rate of 110.06 ton hectare−1 year−1. From the entire watershed area, only 27% of it has a soil loss a value less than 15 ton hectare−1 year−1 which is relatively categorized under low soil erosion risk, while the remaining area (73%) experiences moderate to very high soil loss rates. A large area (50.7%) is under high to very high soil loss (>50 ton hectare−1 year−1). The majority of the study watershed area experiences a very high soil erosion rate and this could be a major threat to the new irrigation dam constructed at the outlet of the watershed due to the sedimentation problem, which could decrease the economic lifespan of the dam. Hence, from the conservation perspective, a large proportion of the upper watershed area requires immediate and appropriate soil conservation measures.

Eksperimentalno istraživanje efekata modifikacije trenja različitih nanoforma grafenskih aditiva u ulju za podmazivanje motora

This article presents the results of an experimental investigation of different nanoforms of graphene used as a nano additive in engine lubricating oil. The experiments were carried out on a pin-on-disc tribometer at the Department of Internal Combustion Engines and Propulsions at Széchenyi István University. The paper introduces the experimental equipment and the experimental method and presents the research findings. The paper concludes that fullerene can decrease friction by 7% on average when used as a nano additive in engine lubricating oil. Furthermore, fullerene did not present a sedimentation problem when used as an additive up to 0.25 wt% in lubricant instead of graphene and multiwalled carbon nanotubes. The paper attempts to explain the friction decreasing effect and the possible roles of carbon nano additives in tribological systems.

Penanganan Sedimentasi dan Penumpukan Sampah di Pesisir Utara Kota Cirebon

This study aims to determine the factors that cause sedimentation and garbage accumulation on the coast and to find out how to handle the problem of sedimentation and garbage accumulation on the north coast of Cirebon city. The research method used in this study uses a qualitative approach. Collecting data using observation, interview, and documentation techniques to obtain primary data and secondary data. Data analysis was carried out using an interactive data analysis model and data validation was carried out using technical triangulation techniques. The results showed that the factors causing sedimentation and garbage accumulation on the coast were caused by natural and non-natural factors. And the handling that can be done is by solving practical and strategic activities

Pola Operasi Waduk Wonogiri Setelah Pembangunan Pintu Pelimpah Baru Untuk Pengendalian Banjir

Wonogiri reservoir in upstream Bengawan Solo experienced sedimentation problems that endanger its operation. Much of sediments come from Keduang watershed. To overcome this problem, closure dike was constructed to localize the sediment from Keduang watershed. The dike divides the reservoir into main and sediment storage reservoirs, each has its spillway. This paper presents results of the study on Wonogiri Reservoir operation during flood period after dike construction. The study followed a two-step calculation. It updated the design flood by employing rainfall data frequency analysis and Collins unit hydrograph. Flood routing was subsequently done by applying level pool method. Two conditions were considered, namely existing condition whose initial water level was +135.3 meters and new condition whose initial water level was +136.3 meters. The study reveals an increase of the flood discharge to Wonogiri reservoir by 7.7% and 3.6% for the 60 year and 500 year floods, respectively, as compared to the previous study of Pradipta (2014). The study shows that Wonogiri reservoir is prone to overtopping under 500 year flood. It is recommended to lower the control water level of the new spillway.

In Situ Polymerization to Boron Nitride-Fluorinated Poly Methacrylate Composites as Thin but Robust Anti-Corrosion Coatings

High-performance anti-corrosion coatings featuring easy processability and thin thickness are highly desired in industry. Yet, solution process coating often faces a sedimentation problem with particles which are used as reinforcement in coatings. In this contribution, boron nitride (BN) was modified by an acrylate silane coupling agent (KH-570) to obtain acrylated BN flakes. Afterwards, the acrylated BN flakes were in situ copolymerized with 2-(perfluorohexyl)ethyl methacrylate to synthesize BN-fluorinated poly methacrylate (PFBP) composites. The as-obtained PFBP composites can form stable coating solutions, in which sedimentation of BN flakes seldom happens. The coating solution can easily form uniform coatings on various substrates with nanoscale thickness, confirmed by scanning electron microscope (SEM). The corrosion resistance of the samples coated PFBP coatings in 3.5 wt.% sodium chloride solution was evaluated by electrochemical impedance spectroscopy (EIS). It is indicated that the incorporation of BN flakes greatly reduce the corrosion rate. Adhesion measurements and abrasion resistance test indicate the PFBP coating performs good adhesion to substrate and robustness. Through the in situ polymerization, acrylated BN flakes are connected with the polymer chain, which inhibits the sedimentation of BN in the coating solution. Additionally, the BN flakes dispersed in the fluorinated polymer act as barriers, improving the corrosion resistance of the coated samples.

The Development of Closure Dike as Countermeasure of Sedimentation in the Wonogiri Reservoir, Indonesia

The problem of reservoir sedimentation occurs worldwide, including in the Wonogiri reservoir, Indonesia. The reservoir was built from 1977 to 1980, but the dam faces a severe problem of sedimentation. Sediment inflow in the Wonogiri Reservoir comes from several sources, especially from Keduang River, a tributary from Mount Lawu. The sediment management problems are generally complicated and different in every place. In some conditions, it will be possible to prevent sediment from entering the reservoir by adding an internal barrier as applied in the Wonogiri Reservoir. The reservoir is divided into two reservoirs by a closure dike equipped with an overflow dike and a new spillway. This paper will describe the development of closure dike based on field observation and data obtained from the Ministry of Public Works and Housing. Moreover, this paper will also describe the sedimentation status of the Wonogiri reservoir based on the recent bathymetric data. The development of closure dike already completed, which consists of Closure Dike A (700 m), B (700 m), C (302 m), and Overflow Dike (298 m). The recent bathymetric survey revealed that the capacity of effective storage of the main reservoir is 322.84 MCM.

Best management practices for erosion and sedimentation control of The Sermo Watershed

Erosion and sedimentation problems caused by human activities disturbed the primary conditions of the watershed. This situation was also influenced by significant hydrometeorological shifts and high rainfall, which increased soil erosion. These inclement watershed conditions resulted in high sedimentation rates and caused severe problems for the quality and quantity of water in the reservoir. This study aims to solve the Sermo watershed problems by calculating the value of erosion and sedimentation, then providing a solution to deal with these problems in the form of Best Management Practices (BMP). This research used a USLE method to calculate the erosion and sedimentation rate. The calculation results showed that 40.86% of Sermo Reservoir within 809.12 hectares was classified as a high level of erosion. Further recommendations for overcoming this condition were made by referring to BMP for erosion and sediment control, including structures and soil water conservation. Further recommendations to address this condition were made regarding BMP for controlling water, maintaining soil stability, controlling sedimentation, and managing and maintaining optimal watersheds.

Utilizing MIKE 21 Software to Create Simple Hydrodynamic Simulations

This paper aim to create simple hydrodynamic simulation by using MIKE 21. The module used in MIKE 21 is LITPACK. LITPACK is one of the modules in MIKE 21 to solve hydraulic and sedimentation problems in coastal areas. Especially in this paper, the LITTLITE engine in LITPACK will be used. LITLINE determines the coastline position using a timeseries of wave climatic data. The model is based on a one-line theory, in which the cross-shore profile is expected to remain unaltered during erosion/accretion, with minor adjustments. Coastal morphology is thus only defined by coastline location (cross-shore direction) and coastal profile at a given long-shore position. The simulation used in this paper is the influence of groins on shoreline dynamics. The results of the simulation show that some areas will experience abrasion and some will experience accretion.