Dam Gate Research Articles

Multiscale modelling in real-time flood forecasting systems: From sand grain to dike failure and inundation

Abstract Severe events around the globe have highlighted the threat to life, infrastructure and the environment posed by flooding. Flood forecasting systems are a vital component of broader flood risk management activities. These systems are becoming increasingly more sophisticated as their importance in reducing life loss and economic damages is realized. Part of this increase in complexity is focused on the ability to predict and warn of failures in dykes, levees and embankments. A new European ICT project, UrbanFlood for Environmental Services and Climate Change Adaptation, has recently been commissioned and is introduced in this presentation. The primary objective of the Urban Flood project is to develop early warning systems that will monitor flood protection systems in real-time, identify vulnerable locations, model the failure and predict dike collapse and subsequent inundation. In combination with the damage assessment, Urban Flood will serve as an advanced decision support system, mitigating the impact of seasonal and catastrophic floods. Modeling is one of the key tasks in the project. The models will be required to simulate the behavior of the material properties of the layered dikes (sand, clay, peat, grass or concrete cover, metal frame, dam gates, etc.), during extreme hydraulic loading events. In earthen dikes, extra challenge is posed by the non-linear elastic plastic properties of the deformable clay. A realistic simulation of the dike will model the free-surface water dynamics; convective and diffusive transfer of water inside the porous materials; dynamic response of clay to the water pressure; structural mechanics, deformation and actual dike breakdown and flood. The models shall cover a wide range of scales from a sand grain to a flooded city. The time scales will range from seconds (for water penetrating the soil) to hours (for dike collapse dynamics and ocean tides). Eventually, the models will predict the influence of seasonal and global changes on the stability of flood defense systems. Full 3D transient simulation of dike failure with subsequent inundation will require significant computing resources. The project started three months ago, and we will present the plan for developing the modeling cascade for the system. This work is supported by the UrbanFlood European Union project N 248767, theme ICT-2009.6.4

Maintenance Cost on Dam Gates of Spillways and Outlets for Flood Control

Maintenance Cost on Dam Gates of Spillways and Outlets for Flood Control

Changes in bedload transport rate associated with episodic sediment supply in a Japanese headwater channel

Abstract We conducted field monitoring of bedload transport rate associated with experimental sediment release in a natural channel to clarify behavior of the supplied sediment on mixed size bed. Observation of bedload rate at two sites along the 30 m channel reach revealed that downstream migration of finer particles delay compared with coarser particles. Ratio of the bedload sediment that deposited during the migration was higher for finer sediments. These behaviors of the mixed size particles were clear during passage of the sediment wave without changes in water discharge. Flashing peak of discharge that caused artificially by opening of the dam gate did not destroy channel bed structure including steps and pools formed by coarser sediments, and only small amount of bedload was mobilized. Both reach scale channel features including steps, pools, and riffles as well as fine scale features (i.e., armour coat) likely increased critical shear stress of particles and decreased bedload rate during our experiment. Extreme sediment supply induced two types of sediment deposition; (1) filling the pools in reach sales and (2) the intrusion of fine particles into the coarser sediment that formed an armour layer. The all grain size fractions can deposit as type (1) when shear stress of stream water is not enough to entrain bedload particles, while deposition type (2) occurs when finer sediment pass over channel bed on which armour coat is well-developed. Deposition of finer sediment into coarser sediment that forms armour coat is affected by grain size distribution of bed surface sediment. Thus, impact of the sediment supply on downstream channel depends on both bedforms and grain size distribution of bed surface sediment over which the supplied sediment pass.

Ultimate strength characteristics of dam gate strut arms

Ultimate strength characteristics of dam gate strut arms

Problems of drinking water treatment along Ismailia Canal Province, Egypt

The present drinking water purification system in Egypt uses surface water as a raw water supply without a preliminary filtration process. On the other hand, chlorine gas is added as a disinfectant agent in two steps, pre- and post-chlorination. Due to these reasons most of water treatment plants suffer low filtering effectiveness and produce the trihalomethane (THM) species as a chlorination by-product. The Ismailia Canal represents the most distal downstream of the main Nile River. Thus its water contains all the proceeded pollutants discharged into the Nile. In addition, the downstream reaches of the canal act as an agricultural drain during the closing period of the High Dam gates in January and February every year. Moreover, the wide industrial zone along the upstream course of the canal enriches the canal water with high concentrations of heavy metals. The obtained results indicate that the canal gains up to 24.06x10(6) m3 of water from the surrounding shallow aquifer during the closing period of the High Dam gates, while during the rest of the year, the canal acts as an influent stream losing about 99.6x10(6) m3 of its water budget. The reduction of total organic carbon (TOC) and suspended particulate matters (SPMs) should be one of the central goals of any treatment plan to avoid the disinfectants by-products. The combination of sedimentation basins, gravel pre-filtration and slow sand filtration, and underground passage with microbiological oxidation-reduction and adsorption criteria showed good removal of parasites and bacteria and complete elimination of TOC, SPM and heavy metals. Moreover, it reduces the use of disinfectants chemicals and lowers the treatment costs. However, this purification system under the arid climate prevailing in Egypt should be tested and modified prior to application.

The use of short‐lived radionuclides to quantify transitional bed material transport in a regulated river

AbstractWe investigate the use of the short‐lived fallout radionuclide beryllium‐7 (7Be; t1/2 = 53·4 days) as a tracer of medium and coarse sand (0·25–2 mm), which transitions between transport in suspension and as bed load, and evaluate the effects of impoundment on seasonal and spatial variations in bed sedimentation. We measure 7Be activities in approximately monthly samples from point bar and streambed sediments in one unregulated and one regulated stream. In the regulated stream our sampling spanned an array of flow and management conditions during the annual transition from flood control in the winter and early spring to run‐of‐the‐river operation from late spring to autumn. Sediment stored behind the dam during the winter quickly became depleted in 7Be activity. This resulted in a pulse of ‘dead’ sediment released when the dam gates were opened in the spring which could be tracked as it moved downstream. Measured average sediment transport velocities (30–80 metres per day (m d−1)) exceed those typically reported for bulk bed load transport and are remarkably constant across varied flow regimes, possibly due to corresponding changes in bed sand fraction. Results also show that the length scale of the downstream impact of dam management on sediment transport is short (c. 1 km); beyond this distance the sediment trapped by the dam is replaced by new sediment from tributaries and other downstream sources. Copyright © 2006 John Wiley & Sons, Ltd.

Evidence of spawning by green sturgeon, Acipenser medirostris, in the upper Sacramento River, California

This study reports the only direct evidence of spawning of green sturgeon, Acipenser medirostris, in the upper Sacramento River, CA. Two green sturgeon eggs were collected with substrate mats immediately below Red Bluff Diversion Dam. One green sturgeon larva was collected with a larval net at Bend Bridge. We concluded that green sturgeon spawn in the upper Sacramento River, both above and below RBDD. Temperature ranges in the study area (10–15°C) are similar to conditions used in successful artificial rearing of green sturgeon and do not appear to be a limiting factor to successful spawning of green sturgeon; however, suitable habitat upstream of RBDD is inaccessible when dam gates are lowered.

Development of Fault Trees for Risk Assessment of Dam Gates and Associated Operating Equipment

AbstractThis article deals with development of fault-trees for risk assessment of dam gates and associated operating equipment. The first part of the paper deals with background information leading to the selection of Lafitte Method as the preferred method for risk assessment. The article also discusses in detail the initiating events, consequential events, and the consequences, dealing with transient and persistent overtopping results of the sensitivity analysis along with a detailed list of various failure events, the associated failure modes and their cause/effect dealing with dam gates. Actual detailed fault-trees for dam gates and associated operating equipment are presented.

Development of Fault Trees for Risk Assessment of Dam Gates and Associated Operating Equipment

This article deals with development of fault-trees for risk assessment of dam gates and associated operating equipment. The first part of the paper deals with background information leading to the selection of Lafitte Method as the preferred method for risk assessment. The article also discusses in detail the initiating events, consequential events, and the consequences, dealing with transient and persistent overtopping results of the sensitivity analysis along with a detailed list of various failure events, the associated failure modes and their cause/effect dealing with dam gates. Actual detailed fault-trees for dam gates and associated operating equipment are presented.

AN OPTIMAL FUZZY APPROACH TO AUTOMATED RESERVOIR MANAGEMENT

This paper deals with water resource management problems faced from an Automatic Control point of view. The motivation for the study is the need for an automated management policy for an artificial reservoir (dam). Two problems are addressed in the article: the control of the dam gate, that is a typical control problem, and the definition of the water flow to supply to the user, that is a decision problem. In particular, a mathematical model of the reservoir is deduced, and a PID controller with fuzzy (nonlinear) gains is designed to operate the dam gate. Moreover, a hybrid model of the reservoir is considered and implemented in Stateflow/Simulink, and a second fuzzy decision mechanism is implemented in order to produce different water release strategies. A new cost functional is proposed, able to weight user's desiderata (in terms of water demand) with water waste (in terms of water spills). The parameters of the fuzzy system are optimized by employing Genetic Algorithms, which have proved very effective due to the strong nonlinearity of the problem.

댐 건설에 의한 유황 변화에 따른 하류 하도에서 하천지형학적 변화 및 식생피복의 변화: 황강 합천댐 사례

The Hapchon Dam, located upstream of the Hwang River, Korea, was constructed in December, 1988. Due to the lack of storage of water, the dam gate has not been operated during last ten years. Thus, a new ecosystem has been established at the downstream par

Folsom Dam Gate Farlure and Its Dynamic Similarity of Flow-Induced Vibrations

This paper summarizes an essential dynamic Instability of Tainter gates and its dynamic similarity. Experimental modal analysis in air test results for a remaining gate under the samc design as a failed 87-ton Tainter gate at Folsom dam in California arc presented, thus resulting in a possible dynamic instability that Tainter gates induce a self excited vibration under certain conditions, even if the skinplate is centric exactly on the trunnion pin. Theoretical calculations for flow induced vibrations are outlined to present key factors dominating its dynamic similarity.

Immediate downstream effects of the Petit-Saut dam on young neotropical fish in a large tributary of the Sinnamary River (French Guiana, South America)

The effects of artificially low runoffs in the Sinnamary River, French Guiana, South America, on flow patterns and on richness and abundance of young fish in Venus Creek, one of its main downstream tributaries were examined. After Petit-Saut dam's gates were closed, the areas adjacent to this tributary were never once flooded for the entire duration of the rainy season. The daily maximal averages of water speed at the tributary's mouth were found to be significantly increased. Young fish sampled using light-traps were less abundant and less diverse after dam closure. Young Characiformes appeared to be the most affected by these flow disturbances. These findings enabled us to develop a conceptual model of the consequences of impoundment on young fish assemblages through the modifications of tributaries and associated floodplains hydrology. Because of flow reduction in the river during the first year of impoundment, young fish that previously had a tendency of being trapped in tributaries and flooded areas were then at risk of being flushed away. The pattern of flow release by dam operations is known to be very different from natural flow variations. The consequences for downstream tributaries will be similar to those of channelization: lack of adjacent flooding areas and higher rates of downstream water transfer. How the recovery of downstream fish assemblages will occur is discussed. © 1998 John Wiley & Sons, Ltd.

Modeling Ice Passage at Starved Rock Lock and Dam on Illinois Waterway

Ice conditions hamper winter navigation on major U.S. waterways. Accumulations of broken ice in the upstream approaches to locks and dams can interfere with lock operations and hydropower production. Conveying this ice downstream through dam gates can be difficult because of the low water velocities found in pool areas, and the limited available discharge for ice passage during winter low-flow periods. A physical hydraulic model study, using real ice, investigated the design and operation of submergible gates for ice passage at the U.S. Army Corps of Engineers Starved Rock Lock and Dam on the Illinois Waterway. Alternative gate locations were tested for a range of gate discharges and ice conditions. The effects of hydropower diversions, navigation, and high-flow air screens on ice passage were examined. The study found that, under some ice conditions, submergible gates alone may not be adequate for ice passage. During these times, tow and barge transits through the lock and deflector bubbler operation wou...

Adaptive and Optimal Control of the Water Gate of a Dam Using a Finite Element Method

A methodology for flood control by operating a dam gate, based on the hydraulic model and adaptive control, is presented in this paper. The purpose of this method is to reduce the water elevation of a reservoir. The dam model is introduced by using the shallow-water equation, which is discretized by the finite element method. Optimal and adaptive control theories are used to obtain optimal control of the volume of flow at the water gate of the dam. There are many numerical control methods, i.e. dynamic programming, conjugate-gradient method, etc. which have been previously presented. Among those, the Fletcher-Reeves and the Sakawa-Shindo methods are used as solution procedures for the deterministic problem, in which it is assumed that an inflow discharge is to be disturbed by random noise. Computational time and storage cause some difficulties in the application of an optimal control method to a practical problem. Thus, this paper presents these optimal and adaptive control techniques and their applicatio...

Gradient method of optimal control applied to the operation of a dam water gate

AbstractAn extension of the authors' previous methods is presented for the optimal control of flood propagation via a dam gate, based on a combination of the finite element and gradient methods. It is assumed in previous papers that the control duration is the same as the duration of the flood. However, the duration of the control does not necessarily coincide with that of the flood flow. To overcome this difficulty, the gradient method is applied to solve the free terminal time‐fixed terminal condition problem. It is shown that the water elevation can be controlled exactly the same as with the previously presented method. It is also shown that the computation can be terminated at a far shorter time than the terminal time of the flood.

OPTIMAL CONTROL OF FLOOD USING FINITE ELEMENT METHOD

This paper presents a method for optimal control of flood propagating through a reservior of river channel using the combination of the finite element method and optimal control theory. The numerical model of the flood propagation can be expressed by the linear two dimensional shallow water equation and the equation can be solved by the two step explicit schemes. For the control theory, the method presented by Sakawa and Shindo is effectively used. It is shown that the water elevation can be controlled as flat as possible by adjusting the discharge of the dam gate. This method is also adaptable to the control constraining the control outflow within the limit of inflow into a reservoir.

A Simulation Study on the Optimal Control of Lock and Dam Gate Openings by the Self-Tuning Controller

A Simulation Study on the Optimal Control of Lock and Dam Gate Openings by the Self-Tuning Controller

AN EXPERIMENTAL STUDY ON VIBRATION PHENOMENA OF THE NEW FIXED WHEEL GATE UNDER THE HIGH HEAD DAM

A new type of fixed wheel gate has been developed for regurating gate of high head dam. Through a series of experimental and theoretical analysis, it has been clarified that the new type of gate was applicable in real gates and was proved stable in dynamic behavior against vibrations due to the fluctuating water pressure without any divergences. The stability has been evaluated both by model tests and numerical analysis. The structure has been analysed by a model subjected to the distributed loads which were measured on a model of new type gate through laboratory tests. The static loads are also measured and analysed same as dynamic loads. The results about the responces of gate vibration system by dynamic loads which are measured in model tests, show good coincidence with the measured data in field gate. Therefor the method as shown here gives good solutions for estimating the forced vibration phenomena of gate system.

Control of hydro-electric plant

The paper briefly details the evolution of control systems as applied to hydro-electric plant in the North of Scotland Hydro-Electric Board area over the past 20 years. Automatic control is described stressing the basic simplicity of hydro-electric plant. Remote control is treated in some depth with particular emphasis being placed on features peculiar to hydro stations. These include water level monitoring, dam gate controls and the various means of achieving communication channels. It also explains how display techniques have changed due mainly to the increasing use of VDUs. The paper also looks ahead to the types of systems which will be developed and implemented in the next 10 years. It pays particular attention to the greatly improved presentation methods that are becoming increasingly available to the operators in the control centres.