Spillway Channel Research Articles

Advances in Calculation Methods for Supercritical Flow in Spillway Channels

Advances in Calculation Methods for Supercritical Flow in Spillway Channels

Closure to “Advances in Calculation Methods for Supercritical Flow in Spillway Channels” by Derek Causon, Clive Mingham, and David Ingram

Closure to “Advances in Calculation Methods for Supercritical Flow in Spillway Channels” by Derek Causon, Clive Mingham, and David Ingram

Advances in Calculation Methods for Supercritical Flow in Spillway Channels

A calculation method is presented for applications to steady supercritical and transcritical flow in spillway channels. The method solves the two-dimensional nonlinear shallow water equations using a cell-centered finite-volume approach. High spatial resolution of shock waves and other steep flow features is achieved by employing MUSCL reconstruction and an approximate Riemann solver for the flux evaluations at each cell interface. The method can be implemented on boundary-conforming meshes to more accurately map the wide range of geometries that may occur in practice. Six analytical test problems are proposed for the validation of calculation methods applied to steady supercritical flow. These problems are used to validate the proposed flow solver, which is then applied to the case of steady supercritical flow in a curved channel transition, and comparisons are made with published data. Despite limitations in the shallow water model, the results show satisfactory agreement with data for the maximum rise ...

Active Flood Hazard Mitigation. I: Bidirectional Wave Control

Active mitigation of unimodal flood waves is achieved by selective lateral flow withdrawal. This is shown to create depression waves that reduce the impact of hazardous flood waves in rivers. Lateral outflow is induced by a deliberate levee breach or through an emergency side channel spillway generating bidirectional wave action in the main channel. An adjoint sensitivity method founded on 1D shallow-water equations is used to identify the optimal locations and timing for the lateral outflow. The efficiency of the adjoint sensitivity method allows flood hazards to be mitigated in real time by rapidly providing the flow sensitivity to changes in lateral outflow. The spatial and temporal coordinates associated with the peak values of the sensitivities are examined as indicators of optimal locations and timing for active control. The sensitivities are found to be good indicators of optimal control points even in cases where the magnitude and duration of the lateral outflow exceeds the small perturbation assumption.

Early Pleistocene Glacial Lake Lesley, West Branch Susquehanna River valley, central Pennsylvania

Abstract Laurentide glaciers extended into north central Pennsylvania repeatedly during at least the last 2 million years. Early Pleistocene glaciation extended farther south into central Pennsylvania than any subsequent glaciation, reaching the West Branch Susquehanna River (WBSR) valley. Early Pleistocene ice dammed the northeast-flowing West Branch Susquehanna River at Williamsport, forming Glacial Lake Lesley, a 100-km-long proglacial lake. In this paper, we present compelling evidence for the lake and its age. Maximum lake volume (∼ 100 km 3 ) was controlled by the elevation of the lowest drainage divide, ∼ 340 m above sea level at Dix, Pennsylvania. Stratified deposits at McElhattan and Linden are used to reconstruct depositional environments in Glacial Lake Lesley. A sedimentary section 40 m thick at McElhattan fines upward from crossbedded sand to fine, wavy to horizontally laminated clay, consistent with lake deepening and increasing distance from the sediment source with time. At Linden, isolated cobbles, interpreted as dropstones, locally deform glacio-lacustrine sediment. We use paleomagnetism as an age correlation tool in the WBSR valley to correlate contemporaneous glaciofluvial and proglacial lacustrine sediments. Reversed remanent polarity in finely-laminated lacustrine clay and silt at McElhattan ( I = 20.4°, D = 146.7°, α 95 = 17.7°) and in interbedded silt and sand at Linden ( I = 55.3°, D = 175.2°, α 95 = 74.6°) probably corresponds to the latter part of the Matuyama Reversed Polarity Chron, indicating an age between ∼ 770 and ∼ 970 ka. At McElhattan, a diamicton deformed the finely laminated silt and clay by loading and partial fluidization during or soon after lake drainage. As a result, the deformed clay at McElhattan lacks discrete bedding and records a different characteristic remanent magnetism from underlying, undeformed beds. This difference indicates that the characteristic remanent magnetism is detrital. An electrical resistivity survey and drill borings define a buried bedrock channel at Bald Eagle near the drainage divide that is the proposed spillway for Glacial Lake Lesley. The highest terrace at Bald Eagle (Qt1 be ) was truncated by the spillway channel. Age of Qt1 be is estimated as at least middle Middle Pleistocene to Early Pleistocene by correlation of soil physical properties on Qt1 be to soil chronosequences developed for Susquehanna River alluvial terraces, further downstream. This age is generally consistent with the age estimated from paleomagnetism.

Le lac proglaciaire d'Arsine (Alpes françaises, massif du Pelvoux) : un risque de vidange brutale définitivement écarté ?

Abstract : Since the end of the 1 940s, the retreat of the Arsine glacier has been accompanied by the development of a huge pro-glacial lake. The rapid extension of this lake has prompted scientific experts to issue warnings of the risk of a sudden draining of the lake basin and consequent flooding of downstream villages. Thus, as early as 1986, emergency works were undertaken to build a spillway channel to reduce the danger by regulating lake levels. Today, following the marked retreat of the glacier over the past decade and the resulting radical transformation of the landscape, the effectiveness of these works is being questioned. Topographic and bathymétrie measurements have been combined with a diachronic analysis of photographic documents to help draw up a first inventory of landforms. This confirms the presence of dead ice areas, the fusion of which would bring about subsidence and the development of a second lacustrian basin. The development of a third pro-glacial lake is also to be feared in an area where the spillway channel is completely ineffective.

HYDRAULIC SIMULATION TECHNIQUES INCORPORATED IN THE SURFACE IMPOUNDMENT ELEMENT OF WEPP

The ability to predict the sediment trapping efficiency of a impoundment is an integral part of the erosioncontrol planning process. The Water Erosion Prediction Project Surface Impoundment Element (WEPPSIE) wasdeveloped to add impoundment analysis capability to the existing Water Erosion Prediction Project (WEPP) runoff andsediment yield model. This work describes the hydraulic analysis portion of WEPPSIE. To perform the necessarycomputations in a timely manner, continuous algebraic forms of the stage-discharge and stage-area relationships, asopposed to forms requiring interpolated or iterative solutions, were desirable. Development of the algebraicapproximations of the conventional stage-discharge computation methods for perforated risers, open channel spillway,and rock fill check dams is described here. The performance of the algorithms given a variety of structure geometries wasassessed by comparing their output with results obtained using the conventional methods. The algebraic approximationsreproduced the conventional methodologies well in most cases.

Applications of Landsat Imagery in the Great Plains

Landsat MSS digital data and imagery are utilized to demonstrate applications in geology and hydrology for two regions of the Great Plains-Devils Lake, North Dakota and the Flint Hills, Kansas. Devils Lake occupies several, internally connected glacial basins that have no outlet at present. Consequently lake surface elevation, water volume, salinity, and biomass fluctuate significantly with climatic changes. During the period 1973-1988, the lake rose 3 m; Landsat images document an increase in surface area of more than 50%. Glacial landforms include large ice-shoved hills, ice-scooped depressions, spillway channels, and tunnel valleys. These features are interpreted as the results of glacier thrusting and melt-water erosion in connection with two converging ice lobes during a late phase of glacier advance. In the Flint Hills of east-central Kansas, stream valleys follow distinct lineaments oriented NW-SE, NNE-SSW, and NE-SW. These lineaments correspond to crustal fractures (joints and buried faults). Based on Landsat imagery, another significant lineament trend at NNW-SSE (about 350'-170') has been identified. This trend is named the Verdigris lineament, and it represents an important fracture system in east-central Kansas. The Verdigris lineament relates to bedrock joint trends in the Flint Hills region.

Computation of Flow Transitions in Open Channels with Steady Uniform Lateral Inflow

A numerical procedure is developed for quickly and accurately finding the location and flow depth of a flow transition (critical control section) in open channels with discharge gradually varying along the channel length. General equations are presented for trapezoidal, triangular, and rectangular cross sections. A numerical analysis of the procedure shows that the geometry of the channel cross section is an important factor determining the existence of a unique solution to the flow‐transition problem in open channel flow. A procedure is described to decide if solutions exist and, if they do, to compute them and select an acceptable solution as the starting point for water‐surface profile calculations. Test runs on a computer are performed to verify the speed and accuracy of the proposed procedure. Examples involving the finding of location of flow transitions in open channels are used to illustrate the usefulness of the procedure. The findings from this study are beneficial to hydraulic engineers solving problems related to the design of lateral spillway channels and gutters for conveying stormwater runoff; to hydrologists using spatially varied flow equations to describe flow processes in natural channels; and to the enhancement of algorithms for spatially varied flow computations in hydrologic simulation models such as the CREAMS field‐scale model and the WEPP watershed model.

The Influence of Soil Moisture and Compaction on Spillway Erosion

Submerged jet tests were conducted on a soil material compacted by dynamic and static load methods over a range of dry unit weights and moisture contents. The compacted soil samples were pre-wet prior to testing. An index parameter was used to compare changes in the erosion resistance of the soil at different compacted dry unit weights and compacted moisture contents. Moisture content at the time of compaction had a significant influence on soil erosion resistance. Additionally, at a constant moisture content, the erosion resistance increased as the dry unit weight increased. These results, along with results of two compacted spillway channel tests on the same soil, suggest that proper compaction should be considered in the repair of earthen auxiliary spillways.

Geotechnical aspects of headcutting in emergency spillway channels : Palmerton, J B; May, J H; Banks, D C Bull Assoc Engng GeolV28, N1, Feb 1991, P89–94

Geotechnical aspects of headcutting in emergency spillway channels : Palmerton, J B; May, J H; Banks, D C Bull Assoc Engng GeolV28, N1, Feb 1991, P89–94

Geotechnical Aspects of Headcutting in Emergency Spillway Channels

Severe headcutting at moderate flows within spillway channels at public and private reservoirs have caused the Corps of Engineers to re-examine the processes causing channel erosion. The process of headcutting could result in undermining and failure of flood control structures. Flume experiments which simulated the flow over overfalls showed that a partial vacuum pressure may develop beneath the nappe of the overfalling water plume. This partial vacuum will cause the plume to be pushed (by the atmospheric pressure) closer to the face of the overfall and a reverse scour roller to undermine the materials of the overfall. The propensity for partial vacuum formation to cause rapid headcutting is more predominant during low to moderate channel discharges.

Gully Erosion in Earth Spillways

The formation and movement of gullies in earth emergency spillways often produce the major damage and pose the greatest threat of a dam breach during a flood flow. This study examined the rate of gully overfall movement through a compacted cohesive soil placed in the center of a spillway channel. The gully movement rates and modes of failure resulting from a constant flow rate were observed as the gully moved up the escape slope and through the level crest section.

Streamline curvature effects in side-channel spillway flow

Steady flow in side channel spillways is investigated, thereby accounting for the effects of the streamline slope and curvature on the free surface profile. The governing system of equations is linearized in order to discuss the main features of the solutions. Subsequently, the non-linear version is solved by an implicit numerical procedure; particular attention is paid to the stability of the chosen scheme. Finally, the solutions are compared to observations and an almost perfect agreement is found.

Technique to evaluate risk of emergency spillway channel erosion : Neatherly, J S Bull Assoc Engng GeolV24, N1, Feb 1987, P9–14

Technique to evaluate risk of emergency spillway channel erosion : Neatherly, J S Bull Assoc Engng GeolV24, N1, Feb 1987, P9–14

1986 Student Professional Paper: Graduate Division: Technique to Evaluate Risk of Emergency Spillway Channel Erosion

Research Article| February 01, 1987 1986 Student Professional Paper: Graduate Division: Technique to Evaluate Risk of Emergency Spillway Channel Erosion JEFFREY STEPHEN NEATHERY JEFFREY STEPHEN NEATHERY Search for other works by this author on: GSW Google Scholar Environmental & Engineering Geoscience (1987) xxiv (1): 9–14. https://doi.org/10.2113/gseegeosci.xxiv.1.9 Article history first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation JEFFREY STEPHEN NEATHERY; 1986 Student Professional Paper: Graduate Division: Technique to Evaluate Risk of Emergency Spillway Channel Erosion. Environmental & Engineering Geoscience 1987;; xxiv (1): 9–14. doi: https://doi.org/10.2113/gseegeosci.xxiv.1.9 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyEnvironmental & Engineering Geoscience Search Advanced Search Abstract A need to evaluate the risk of emergency spillway channel erosion at existing dam sites is needed due to the growth of urban areas encroaching upon land surrounding these sites. Since a large number of dam sites already exist, an effective reconnaissance-level technique to assess the erosion risk due to storm flow in emergency spillway channels is needed to identify high risk channels. A proposed technique is based upon an evaluation of topography, geology, and soils, and involves the following steps: 1) Examine the topography to determine the depth of cut and the existence of any topographic anomalies, where a deep cut indicates that the erosion potential of the bedrock will need to be considered, and a shallow cut or no cut indicates that the erosion potential of the soil will need to be considered. Topographic anomalies include such features as knickpoints, abrupt changes in gradient, and pilot channels which may concentrate flows. 2) Determine the rock type and structure along the floor and sides of the “bedrock” channel from preconstruction data (paying particular attention to horizontal and vertical variations among these units). Rock units which are continuous, massive, and high strength will be more erosion resistant than those which are discontinuous, laminated, and low strength. 3) Construct a soil erosion map, for areas of shallow cuts, from the erosion hazard classifications and aerial photographs contained in the Soil Conservation Service soil report to determine the erosion potential of the soils.These factors were evaluated at 12 emergency spillway channels in the Dallas-Forth Worth area. Predicted erosion risks, severe, moderate, or slight, obtained from this technique, agreed with actual erosion experienced during 1981 and subsequent floods. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Diversion of stream through hydroelectric stations with high dams during construction

1. The scheme of diverting the flow according to steps of construction of especially high dams is the basis of the site organization plan and also has a substantial effect on the design and layout of the main structures of a hydrostation. 2. The best scheme of constructing a dam is that for which stream diversion is carried out through one level of spillways, which later is used as the service level. If it is impossible to accomplish this scheme, it is necessary to provide the possibility of operating a lower level of spillways until the higher level is completely ready for passing the flow, including floods. Schemes calling for “fleeing from water” should be completely eliminated. 3. Designs of spillway gates of high dams, including the materials used in them, should be tested on simpler and less important structures. The layout of even temporary gates should provide the possibility of repair of the movable parts and seals. 4. The configuration of the spillway channels and the location of the regulating gates should be designated so as to eliminate or limit the possibility of the occurrence of conditions for the development of cavitation processes. The best solution in this case is to locate the regulating gate at the outlet of the pressure part of the spillway. 5. The scheme of dissipating the energy of the flow in a stilling basin at heads of more than 120 (140) m also has substantial shortcomings complicating the preparation of the structures for stream diversion by steps of construction.

Catastrophic flood hypothesis for the origin of the Souris spillway, Saskatchewan and North Dakota

Glacial-lake spillways in the midcontinent region consist of narrow, deep trenches connecting proglacial lake basins. Geomorphic and sedimentologic evidence from the Souris and Des Lacs spillways in Saskatchewan and North Dakota indicates a catastrophic drainage of Glacial Lake Regina. The Souris spillway in Saskatchewan is composed of a broad, upper scoured surface 5 to 10 km wide, which merges with the floor of Glacial Lake Regina. The upper surface is longitudinally grooved and mantled with coarse lag deposits. An inner trench, 1 km wide and 20 to 45 m deep, occupies the center of the spillway. The two-level morphology of the spillway probably developed by initial erosion of the upper level, followed by incision of the inner trench, a sequence of events shown by flume experiments performed by Shepherd and Schumm. Near the Saskatchewan and North Dakota border, the flood water bifurcated into two branches as part of the water spilled over a divide into another spillway channel. The two spillways in North Dakota, pre-existing meltwater channels, were occupied and enlarged by the discharge from Glacial Lake Regina. Along the path of the spillways leading to the Glacial Lake Souris basin, water repeatedly breached the sides of the channels, eroding shallow channels leading away from the spillway. Near Minot, North Dakota, a significant amount of the water spilled out toward the east and eroded a plexus of anastomosing channels with streamlined erosional remnants between the channels. Deposits of the flood include huge point bars located at the inside of each channel meander. Internally, the bars generally consist of poorly sorted, indistinctly bedded, coarse gravel containing boulders of resistant and nonresistant lithologies as much as 3 m in diameter. Peak discharge of 1 × 10 5 m 3 /s or more may have been achieved at the outlet of the lake. At this rate, Glacial Lake Regina would have drained rapidly, probably in less than a month. The most likely cause for the rapid drainage of such proglacial lakes as Glacial Lake Regina was high discharge inflow of water from an upstream source along the ice margin.

Microcentrales hydroélectriques d'une puissance inférieure à 100 kW

Click to increase image sizeClick to decrease image sizeIn order to respond to the growing demand for low-power micro hydroelectric stations, the firm Leroy Somer has developed the HYDROLEC range of micro stations, whose design is original. These hydroelectric sets comply with two essential objectives: simplicity and reliability. Their design simplifies problems of installation, use and maintenance. The range covers heads of 1 to 25 m and turbined flows of 100 to 2,500 1/s ; the electrical powers per unit vary according to the type between 2 and 50 kW. The installed power can be multiplied by placing several micro stations in parallel. In the standard version, the sets deliver three-phase low-voltage AC current: 380 V at 50 Hz or 460 V at 60 Hz. The sets form a single block; their reduced weight and volume simplify transport and installation. They use Kaplan turbines with blades adjustable when stationary. Continuous control of the flow is obtained by manual alteration of blade angle. Series H. (1 to 10 m of head, 2 to 50 kW) These are compact hydroelectric sets that operate submerged in the downstream spillway channel. This arrangement offers numerous advantages ; there is no superstructure and they are unaffected by flood conditions and the prevailing weather. The whole is designed with continuous concern for simplicity and reliability ; the construction is robust using tried technologies; parts are calculated for a working life of 100,000 hours, and maintenance is virtually zero. The set can be installed in any position, behind a power penstock or directly in a water chamber.

Etude hydraulique d'un type particulier d'ouvrage d'évacuation de crues

The details of an experimental hydraulic study on a scale model of a particular type of spillway for the Savage Mills dam project on the Yamaska River near Granby in the Province of Quebec are presented. This multipurpose dam is a joint project between the Office of Planification and Development of Quebec and the Natural Resources Department of the Province of Quebec. Preliminary studies have shown that the use of a standard type of spillway such as a shaft spillway or a side channel spillway would be less economical than a structure that would make use of the diversion channel which is usually only a temporary work. A particular type of spillway, being a combination of the side channel and shaft spillways which discharges into the diversion channel, has then been proposed by engineers of the Department of Natural Resources. In order to evaluate the capacity, the operation and the efficiency of that structure, a scale model study has been carried out. That study has established the hydraulic properties of the proposed structure and has enabled one to properly design its different components.