Hydraulic Engineering Commons^™

Managing Dam Safety Risks Related To Hydraulic Structures, W. R. Fiedler

International Symposium on Hydraulic Structures

The Bureau of Reclamation’s Dam Safety Program manages risk for over 300 high and significant hazard dams.When risk estimates for potential failure modes indicate increasing justification to take action to reduce risk, dam safety recommendations are typically made. The dam safety recommendations can focus on collecting additional data/performing studies to better quantify risk or on initiating corrective actions to address well defined risks. Dam safety recommendations within Reclamation’s inventory address a number of different issues, such as those related to internal erosion, flood overtopping of dams and seismic stability of dams. Dam safety recommendations related to hydraulic structure potential failure …

Decision-Making Through Sustainability, F. Pardo-Bosch, A. Aguado

International Symposium on Hydraulic Structures

From immemorial time, dams have contributed significantly for the progress of civilizations. For this reason, nowadays, there is a vast engineering heritage. Over the years, these infrastructures can present some ordinary maintenance issues associated with their normal operation or with ageing processes.

Normally, these problems do not represent an important risk for the structure, but they have to be attended. To do it, owners of dams have to finance many ordinary interventions. As it is impossible to carry out all of them at the same time, managers have to make a decision and select the most “important” ones. However, it …

Water System Operator Training For The Central Arizona Project, Brian Wahlin, Bert Clemmens

International Symposium on Hydraulic Structures

The Central Arizona Project (CAP) is designed to bring about 1.85 billion cubic meters (1.5 million acre-feet) of Colorado River water per year to Maricopa, Pima, and Pinal counties in Arizona. The CAP canal system is a 540-km (336-mile) long system of conveyance aqueducts, tunnels, pumping plants, and pipelines that is monitored and remotely controlled using Supervisory Control and Data Acquisition (SCADA) software from CAP headquarters in Phoenix, AZ. Because the CAP is crucial to the renewable water supply in Arizona, operating the canal effectively is of utmost importance. Typical day-to-day operations for Water System Operators on the CAP involve …

Junction Chamber At Vortex Drop Shaft: Case Study Of Cossonay, G. Crispino, D. Dorthe, T. Fuchsmann, C. Gisonni, M. Pfister

International Symposium on Hydraulic Structures

The drainage network of the city of Cossonay (Switzerland) is currently being adapted for future needs. In particular, it is required to drain increased storm discharges due to a population augmentation, and to provide an adequate concept to overcome unfavorable geotechnical conditions.

Vortex drop shafts are sewer manholes commonly applied in steep urbanized topographies to connect conduits across large elevation differences. In Cossonay, the existing 48 m high vortex drop shaft, with a diameter of 1.5 m, allowed the storm discharge to flow from the city to a watercourse issued at half of the valley height. The discharge capacity was …

Experimental Study Of Head Loss Over Laser Scanned Rock Tunnel, L. R. Andersson, I. A.S. Larsson, J. G.I. Hellstrom, P. Andreasson, A. G. Andersson

International Symposium on Hydraulic Structures

Flow in hydropower tunnels is characterized by high Reynolds number and often very rough rock walls. Due to the roughness of the walls, the flow in the tunnel is highly disturbed, resulting in large fluctuations of velocity and pressure in both time and space. Erosion problems and even partial collapse of tunnel walls are in some cases believed to be caused by hydraulic jacking from large flow induced pressure fluctuations. The objective of this work is to investigate the effects of the rough walls on the pressure variations in time and space over the rock surfaces. Pressure measurement experiments were …

Effects Of Hydraulic Jump Motion On Air Entrainment In Closed Conduits, J. D. Mortensen, J P. Kubitschek

International Symposium on Hydraulic Structures

Air vent systems are designed to protect hydropower penstocks and reservoir outlets under various operating conditions. During an emergency closure of an upstream gate the hydraulic jump that forms downstream of the gate is not stationary and may advance downstream potentially increasing the total air demand. A lab-scale physical model of a general outlet works piping configuration was constructed at Reclamation’s Hydraulics Laboratory in Denver, CO to observe hydraulic jump behavior during emergency gate closures. Parameters including gate discharge, gate closure rate, air vent size, and downstream pipe pressure were tested at two different pipe slopes. Results indicate that the …

Numerical Investigation Of The Flow Field Inside A Manhole-Pipe Drainage System, Md Nazmul Azim Beg, Rita Carvalho, Pedro Lopes, Jorge Leandro, Nuno Melo

International Symposium on Hydraulic Structures

Urban drainage networks contain a large number of structures. Manhole is the most common and the most important as it connects pieces of sewer pipes to form sewer networks. Understanding the hydraulics of a manhole-pipe drainage system is either important as this may sometimes become the bottlenecks of the sewer systems. In this study, the flow structure and flow hydraulics of a specific manhole-pipe sewer system was analysed numerically in view of further research to investigate sediment/ suspended solid transport in the system. The numerical model was compared with discharge and water pressure/depth data from experimental model. Different discharges and …

Determining Optimal Discharge And Optimal Penstock Diameter In Water Turbines, Arturo S. Leon

International Symposium on Hydraulic Structures

Minimizing water consumption for producing hydropower is critical given that overuse of flows for energy production may result in a shortage of flows for other purposes such as irrigation and navigation. This paper presents a dimensional analysis for finding optimal flow discharge and optimal penstock diameter when designing impulse and reaction water turbines for hydropower systems. The objective of this analysis is to provide general insights for minimizing water consumption when producing hydropower. This analysis is based on the geometric and hydraulic characteristics of the penstock, the total hydraulic head and the desired power production. As part of this analysis, …

Predicting Velocity At Limit Of Deposition In Storm Channels Using Two Data Mining Techniques, H. Bonakdari, I. Ebtehaj

International Symposium on Hydraulic Structures

In storm channel system design, the system should have the ability to transfer the entire input flow to the system as well as prevent sediment settling. Existing methods of determining the velocity at limit of deposition are minimum velocity or regression-based equations. Because minimum velocity methods fail to consider the effective flow and sediment transfer parameters, while regression-based equations are not flexible in terms of various hydraulic conditions and they do not perform well. Thus, using such equations leads to a lack of designs with optimum, confident coefficients. In this study, Extreme Learning Machines (ELM) are employed to predict velocity …

Stepped Chute Training Wall Height Requirements, S. L. Hunt, K. C. Kadavy

International Symposium on Hydraulic Structures

Stepped chutes are commonly used for overtopping protection for embankment dams. Aerated flow is commonly associated with stepped chutes if the chute has sufficient length. The aeration and turbulence of the flow can create a significant amount of splash over the training wall if not appropriately accounted for in the design of the structure. According to the United States Department of Agriculture (USDA)-Natural Resources Conservation Service (NRCS) Technical Release 60 Earth Dams and Reservoirs, a structural spillway should be designed to pass the freeboard hydrograph such that it does not cause serious damage to the embankment or the structure itself. …

Cabinet Gorge Dam Spillway Modifications For Tdg Abatement - Design Evolution And Field Performance, S. L. Dunlop, I. A. Willig, G. E. Paul

International Symposium on Hydraulic Structures

Avista is implementing spillway modifications to reduce TDG supersaturation downstream of Cabinet Gorge Dam.The key feature of the modifications is the addition of roughness elements, similar to supercavitating baffle blocks,to break up the spillway jet thereby reducing the depth of plunge and TDG supersaturation. The work is progressing in a step-wise manner. A single bay was modified in 2012 and field tested in 2013. Following the initial field tests, aCFD model was developed to aid in design refinements for the prototype and to improve the design prior to modification of subsequent spillway bays. The prototype demonstrated that spillway modifications are …

Turbulence And Energy Dissipation In The Developing Non-Aerated And The Fully-Developed Aerated Flows On A Stepped Spillway, G. Zhang, H. Chanson

International Symposium on Hydraulic Structures

Stepped spillways are characterised by highly turbulent air-water flows and a large rate of energy dissipation compared to smooth chutes. Herein detailed measurements were performed in both the developing non-aerated and fully-developed air-water flow regions on a large 1V:1H stepped spillway model. In the developing flow region, large total pressure fluctuations and turbulence intensities were recorded next to the pseudo-bottom. Downstream of the inception point, large total pressure fluctuations were recorded which were mainly induced by density fluctuations. The water turbulence intensities in the air-water flow region did not differ significantly from those in the developing flow region. The steps …

Free-Surface Aeration In A Steep Stepped Spillway, G. Zhang, H. Chanson

International Symposium on Hydraulic Structures

Self-aeration has important civil and environmental applications in stepped chutes, ranging from cavitation protection to enhanced air-water mass transfer. Air bubble entrainment occurs when the turbulent stresses in the boundary layer exceed the combined effects of surface tension and buoyancy. The governing equations for air diffusion in the rapidly-varied region next to, and in the gradually-varied region away from the inception point of aeration are introduced. New and existing solutions to these equations are discussed and compared with new experimental data. An analytical model for flow bulking is introduced. The concept of negative diffusivity is discussed.

Physical Modeling Of An Aerating Stepped Spillway, S. Erpicum, M. Lodomez, J. Savatier, P. Archambeau, B. J. Dewals, M. Pirotton

International Symposium on Hydraulic Structures

To mitigate the negative effects on the water quality in the downstream river of a projected large dam, and in particular to increase the dissolved oxygen concentration during low flow periods within the first 10 years of dam operation, an aerating weir has been designed and tested on a physical model at the Laboratory of Engineering Hydraulics (HECE) of the Liege University. The design of the structure has been done considering data from the literature. The selected solution is a 3 m high stepped spillway designed to operate in nappe flow conditions within the range of design discharges (25 – …

Effect Of Deflector Aerator On Stepped Spillway Flow, Stéphane Terrier, Michael Pfister, Anton J. Schleiss

International Symposium on Hydraulic Structures

Systematic physical model tests are performed on a stepped spillway equipped with a bottom aerator at the beginning of the stepped part. A deflector is used to issue a jet in order to initiate air entrainment into the flow. A horizontal slot located in the vertical face of the first step allows for air supply underneath the flow. The cavity subpressure was measured to ensure optimal aerator performance, namely atmospheric pressure conditions. The air discharge entrained below the jet is measured to derive the aerator air entrainment coefficient. The local air concentrations are spatially measured downstream of the aerator at …

Tsallis Entropy Theory For Hydraulic Modeling, Vijay P. Singh

International Symposium on Hydraulic Structures

Hydraulic structures serve a multitude of human needs. They are needed for water supply, water transfer, water diversion, irrigation, land reclamation, drainage, flood control, hydropower generation, river training, navigation, coastal protection, pollution abatement, and transportation. Many of the structures, such as channels, culverts, and impoundments, have been with us since the birth of human civilization; some, such as spillways, dams, and levees, are more than two centuries old; and some are of more recent origin. In the beginning, structures were designed more or less empirically. Then, engineering and economics constituted the sole foundation of design. Nearly fifty years ago, planning …

Columbia River Treaty And System Reservoir Operations, Pete Dickerson

International Symposium on Hydraulic Structures

The river headwaters of the Columbia River originate in British Columbia and ultimately enter the Pacific Ocean near Astoria, Oregon (1,214 miles). About 15% of the basin is in Canada, and 35% of the average annual flow comes from Canada (as measured at The Dalles, Oregon). Historically, the largest flood run-offs occur in the spring, primarily driven by snowmelt. The basin has the most hydropower capacity, ~37 GW, in North America. U.S. federal projects are authorized to meet multiple purposes: flood risk, hydropower, fish and wildlife, navigation, irrigation, recreation, and municipal and water supply.

Colorado River System - Planning And Operations During Extended Drought, Daniel Bunk

International Symposium on Hydraulic Structures

Today, between 35 and 40 million people rely on the Colorado River and its tributaries for some, if not all, of their municipal water needs. These same water sources irrigate nearly 4.5 million acres (1.8 million hectares) of land within the basin and adjacent areas that receive Colorado River water. The Colorado River and its tributaries also provide essential cultural and economic resources to 22 federally recognized tribes, as well as recreational opportunities and environmental benefits to 11 National Park Service units and seven national wildlife refuges. Additionally, the Colorado River is a vital resource to the United Mexican States …

Management Of River System Flows, Keil Neff

International Symposium on Hydraulic Structures

The Tennessee Valley Authority (TVA) operates a system of 49 dams and reservoirs in the Tennessee River and Cumberland River watersheds of the southeastern United States. TVA operates this system for the purposes of navigation, flood control and power production; management of water supply, water quality and aquatic habitat; and recreation and other public benefits. TVA, created by the U.S. Congress under the TVA Act of 1933, is the largest public power supplier in the U.S. and is fully self-financed with no federal appropriations. The Tennessee River is the only basin in the U.S. that is operated by a single …

Reconfiguring, Replumbing, And Repurposing Hydraulic Structures - Responding To New Realities, P. H. Burgi

International Symposium on Hydraulic Structures

We look into an ever-changing future filled with challenges to continue developing new water resources but with an increased emphasis on water conservation and preserving our natural environment. This is a different approach to that of the 20^th century, where the emphasis was generally on development of water resources. As water engineers and managers facing an increasingly limited water supply, our challenge is to build, and in some cases change, infrastructure for a resilient future. The built infrastructure for water systems must protect life and provide a safe living environment, including an adequate supply and quality of fresh water. …

Continuing Sediment Management At Mount St. Helens: Raising The Spillway Of The Sediment Retention Structure, J. P. Britton, C. J. Nygaard, S. J. Schlenker

International Symposium on Hydraulic Structures

The Sediment Retention Structure (SRS) was constructed by the U.S. Army Corps of Engineers (USACE) from 1987 – 1989 to trap sediment eroding from the Mount St. Helens debris avalanche, for the purpose of maintaining flood risk levels downstream in the Cowlitz River. In 1998 the operation of the SRS changed and the sediment trapping efficiency decreased. The USACE began studies and an alternatives analysis to identify a long-term plan given the current conditions. The studies and alternatives analysis led to a preferred adaptive-management plan including up to three incremental SRS spillway raises to trap more sediment. The first spillway …

Experimental Study Of Sequent Depths Ratio Of Hydraulic Jump In Sloped Trapezoidal Chanel, Sonia Cherhabil, Mahmoud Debabeche

International Symposium on Hydraulic Structures

The hydraulic jump in a sloped trapezoidal channel of 72.68°sides inclination angle is experimentally examined.The study aims to determine the effect of the channel’s slope on the sequent depths ratio of the jump. An experimental analysis is proposed to determine experimental relationships of the inflow Froude number as a function of the sequent depth ratio of the jump and the channel slope. For this purpose, positive and negative slopes are tested.

Cross-Section Influence On Velocity Distribution & Energy Dissipation Of A Moderately Sloped Spillway Chute Flow, A. Tohidi, Farzam Safarzadeh Maleki

International Symposium on Hydraulic Structures

Erosion at the dam toe due to potential to kinetic energy conversion of the outlet release is a complex yet fascinating engineering challenge. The energy dissipation due to flow separation at sharp cornered geometries effects the flow stream and causes the lower velocity at the dam’s toe. To date, many of the conventional dam engineering techniques consider the dam toe as the examination point. In this research, by the use of OpenFOAM numerical model, the water flow in the spillway chute is modeled. The velocity profile of the chute flow in three different cross-sections is considered for the same outlet …

Nappe Vibration Mitigation Techniques For Free-Overfall Structures, M. Lodomez, Brian Crookston, Blake Tullis, M. Pirotton, Sébastien Erpicum

International Symposium on Hydraulic Structures

Nappe vibration is a phenomenon that has been witnessed in the field for a variety of different free overflow hydraulic structures operating at low heads, such as fountains, crest gates, and weirs. This phenomenon is visually characterized by oscillations in the thin nappe cascading downstream of the control structure. These oscillations can produce a significant level of noise and acoustic pressure waves, which can increase the environmental and societal impacts of the hydraulic structure. As a result, a detailed investigation has been undertaken to identify practical and effective mitigation solutions for free-overfall structures where nappe vibration may be of concern. …

Investigating Supercritical Flows In Curved Open Channels With Three Dimensional Numerical Modeling, Kortney Brown, Brian Crookston

International Symposium on Hydraulic Structures

The flow patterns observed in supercritical flows at bends in open channels are encountered in spillways, canals, and drainage works – this complex flow condition has been investigated more than 80 years ago, first with hydraulic models and more recently using numerical models. This paper presents a numerical investigation using a selection of experimental data from Dr. A. T. Ippen and a commercially available 3-dimensional CFD solver. A comparison of the numerical results to the physical data is presented, highlighting the ability of the numerical models to reproduce these complex water surface profiles including the magnitude and location of standing …

Effect Of A Large Bed Roughness On Positive Surge Propagation In Canals, S. C. Yeow, H. Wang, H. Chanson

International Symposium on Hydraulic Structures

In open channels and water supply canals, the brusque operation of control valves and gate may induce large unsteady flow motion called surges. To date the literature focused on the propagation of surges in smooth canals, ignoring the effects of large roughness and debris. Herein a physical study was conducted under controlled flow conditions to study the turbulent mixing in the close vicinity of a large bed roughness element during the upstream propagation of positive surges. Detailed free-surface and instantaneous velocity measurements were conducted with and without the cylindrical element. For some tests, the experiments were repeated 25 times and …

Spillway Deflector Design Using Physical And Numerical Models, M. Politano, T. Lyons, K. Anderson, S. Parkinson, L. Weber

International Symposium on Hydraulic Structures

Elevated total dissolved gas (TDG) can be a serious threat to migrating fish. Gas supersaturation downstream of a dam occurs due to bubble dissolution in deep high-pressure regions in the tailrace. TDG production depends on both air entrainment and depth of entrained bubbles. Deflectors, installed at the spillway face, are designed to change the regular plunging jets into surface jets, where bubbles are transported in a thin surface layer minimizing dissolution. Distinct flow conditions may, however, occur depending on the deflector geometry, spillway flowrate, and tailwater elevation. Deflectors are commonly designed based on jet regimes observed in physical and CFD …

Steady And Unsteady Turbulent Velocity Profiling In Open Channel Flows Using The Adv Vectrino Ii Profiler, X. Leng, Hubert Chanson

International Symposium on Hydraulic Structures

The Nortek Vectrino II profiler acoustic Doppler velocimeter (ADV) was developed for velocity profiling. Herein the study aims to: 1) demonstrate the applicability of the ADV profiler to steady and rapidly-varied unsteady open channel flows, 2) check the data quality, based upon a new systematically comparative analysis with traditional ADV data, and 3) conduct a sensitivity analysis on ensemble-averaged data collection in a positive surge. This was achieved by performing systematically steady and unsteady velocity measurements under controlled flow conditions in a relatively large laboratory facility. All experiments were repeated 25 to 50 times for each controlled flow condition and …

Effect Of River Levee With Geosynthetic-Reinforced Soil Against Overflow Erosion And Infiltration, Y. Kurakami, Y. Nihei, M. Morita, S. Futami, M. Itakura

International Symposium on Hydraulic Structures

Overflows from huge floods have caused levee breaches in a great number of places, including Japan. To prevent such destruction and thereby increase the resistance of armored levees to overflow erosion, in this study, we examined the performances of Geosynthetic-Reinforced Soil (GRS) levees against overflow erosion under various conditions, such as reinforcement, back slopes, and geo-grid layers. In addition, we investigated the effect of geo-grid layers on the infiltration of levees. The model tests revealed that 1) with scour protection in front of the toe of the back slope, the GRS levee exhibits much higher resistance against overflow erosion than …

Design And Monitoring Of A Small Living Shoreline Scaled For Private Properties On Exposed, Rapidly-Eroding Coasts, D. D. Mcgehee

International Symposium on Hydraulic Structures

Living shorelines on the scale of individual private lots are almost exclusively built at sites with reduced wave exposure. This paper describes the design and post construction monitoring of a residential-property-scale living shoreline project on a rapidly eroding, exposed shoreline. The project site is on the north-eastern side of Mobile Bay, AL with a maximum fetch of 129 km. Pre-construction shoreline retreat locally has averaged -80 cm/year since 1997. The final design was modelled on the award-winning (and much larger) Project Greenshores Phase II built in 2007 in nearby Pensacola Bay, FL. The novel feature for both projects is a …