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ASPECTS IN HYDRAULICS
Transcript of ASPECTS IN HYDRAULICS
1. Storage dams
3. GATEHOUSE OR OUTLET WORKS
IMPORTANT HYDRAULIC STRUCTURES
Hydraulic aspects of the theory and design of hydraulic structures
Camus Hazel Ann.
Bonque Ron Angelo.
Jan Alexis Bilas.
QUOTE OF THE DAY
A hydraulic structure is structure submerged or partially submerged in any body of water, which disrupts the natural flow of water.
They can be used to divert, disrupt or completely stop the flow.
Hydraulic structures may also be used to measure the flow of water.
When used to measure the flow of water, hydraulic structures are defined as a class of specially shaped, static devices over or through which water is directed in such a way that under free-flow conditions at a specified location (point of measurement) a known level to flow relationship exists
Hydraulic structures are used in storm water management systems to ensure the long-term integrity of drainage facilities and to protect the environment by controlling the direction and velocity of channelized runoff.
WHAT ARE HYDRAULIC STRUCTURES?
PURPOSE OF DAMS
5. DROP STRUCTURES
6. FLOW STRUCTURES
A gatehouse or outlet works for a dam is a structure housing sluice gates, valves, or pumps (in which case it is more accurately called a pumping station).
A set of outlet works is a device used to release and regulate water flow from a dam. Such devices usually consist of one or more pipes or tunnels through
the embankment of the dam, directing water usually under high pressure to the river downstream. These structures are usually used when river flow exceeds the capacity of the power plant or diversion capacity of the dam, but do not have flows high enough to warrant the use of the dam spillways.
One parameter of spillway design is the largest flood it is designed to handle. The structures must safely withstand the appropriate spillway design flood (SDF). A 100-year recurrence interval is the flood magnitude expected to be exceeded on the average of once in 100 years. It may also be expressed as an exceedance frequency with a one per cent chance of being exceeded in any given year. The volume of water expected during the design flood is obtained by hydrologic calculations of the upstream watershed. The return period is set by dam safety guidelines, based on the size of the structure and the potential loss of human life or property downstream.
TYPES OF SPILLWAYS
Flood Control. Flood control outlets are designed for relatively large capacities
where close regulation of flow is less important than are other requirements
Navigation. Reservoirs that store water for subsequent release to downstream navigation usually discharge at lower capacity than flood control reservoirs, but the need for close regulation of the flow is more important.
Irrigation. The gates or valves for controlling irrigation flows are often basically different from those used for flood control due to the necessity for close regulation and conservation of water in arid regions.
Functions of outlet works
Water Supply-Municipal water supply intakes are sometimes provided
in dams built primarily for other purposes.
Power-For generation of hydropower, intake structures direct water from the reservoir into the penstock or power conduit.
Low-Flow Requirements-Continuous low-flow releases are required at some dams to satisfy environmental objectives, water supply, downstream water rights, etc.
Diversion-Flood control outlets may be used for total or partial diversion of the stream from its natural channel during construction of the dam.
Drawdown- Requirements for low-level discharge facilities for drawdown of
impoundments may also provide flexibility in future project operation for anticipated needs,
such as major repairs of the structure, environmental controls, or changes in reservoir regulation.
4. DIVERSION HEADWORKS
A diversion head works is a structure constructed across a river
for the purpose of raising water level in the river so that it can be
diverted into the offtaking canals.
Diversion headworks are generally constructed on the perennial
rivers which have adequate flow throughout the year and, therefore,
there is no necessity of creating a storage reservoir.
A diversion head works differs from a storage work or a dam. A dam is constructed on the river for the purpose of creating a large storage reservoir. The storage works are required for the storage of water on a non-perennial river or on a river with inadequate flow throughout the year.
On the other hand, in a diversion head works, there is very little storage, if any.
It raises the water level on its upstream side.
It regulates the supply of water into canals.
It controls the entry of silt into canals
It creates a small pond (not reservoir) on its upstream and provides some
It helps in controlling the vagaries of the river
Functions of a Diversion Headworks
A drop structure, also known as a grade control, sill, or weir, is a manmade structure, typically small and built on minor streams,
or as part of a dam's spillway, to pass water to a lower elevation while controlling the energy and velocity of the water as it passes over. Unlike most dams, drop structures are usually not built for water impoundment, diversion or raising the water level. Mostly built on watercourses with steep gradients, they serve other purposes such as water oxygenation and erosion prevention.
The vertical hard basin drop structure, also called a dissipation wall, is the basic type of drop structure.
The vertical hard basin drop consists of a vertical "cutoff wall",
usually built of concrete, that is usually laid perpendicular to
the stream flow; and an impact basin, not unlike a stream pool, to catch the discharged water. The purpose of the vertical hard basin drop is to force the water into a hydraulic jump (a small standing wave). Though the simplest type of drop structure, it is highest in maintenance needs and less safe, with most problems related to the impact basin. Sediment is often deposited in the basin, requiring frequent removal, and erosion downstream of the base of the structure.
TYPICAL DESIGN OF DROP STRUCTURE
A grouted sloping boulder drop structure is the most versatile of drop structures.
Able to accommodate both a broad floodplain or a narrow channel, they can also handle many different drop heights. Heights of these structures usually range from 1 foot (0.30 m) to 10 feet (3.0 m). These structures are built by creating a slope of riprap, which consists of large boulders or less commonly, blocks of concrete. These are then cemented together ("grouted") to form the drop structure.
The baffle chute drop is built entirely of concrete and is effective with low maintenance needs.
They typically consist of a concrete chute lined with "baffle" teeth to slow velocity of water as it passes over the structure. Despite these appeals, however, they have very "limited structural and aesthetic flexibility, which can cause them to be undesirable in most urban settings."
A flow control structure is a device that alters the flow of water in a stream, drainage channel or pipe.
As a group these are passive structures since they operate without intervention under different amounts of water flow and their impact changes based on the quantity of water available. This includes weirs, flow splitters and proprietary-design devices that are used for storm water management and in combined sewers.
Vanes act to guide the flow away from bank,
to reduce bank erosion, promote local sedimentation and encourage vegetation growth.
TYPES OF FLOW CONTROL STRUCTURES
2. Engineered Log Jams (ELJ)
• 36-48” dia logs with and
without root wads
• installed into the banks
to act like spurs or
• can also be installed in
the channel to divert flow
• permeable to flow
• wood provides habitat to
fish (salmonids) and
• reduce flow separation and
maximize total bridge waterway
• reduce the abutment scour due
to lessening turbulence at the
• advantage: protects abutment
• disadvantage: large structure may
not fit into aesthetics of restoration
A culvert is a structure that allows water to flow under a road, railroad, trail, or similar obstruction.
Typically embedded so as to be surrounded by soil, a culvert may be made from a pipe, reinforced concrete or other material. A structure that carries water above land is known as an aqueduct.
Culverts may be used to form a bridge-like structure to carry traffic. Culverts come in many sizes and shapes including round, elliptical, flat-bottomed, pear-shaped, and box-like constructions. Culverts may be made of concrete, galvanized steel, aluminum, or plastic, typically high density polyethylene.
Stream Crossing Culvert
The first culvert type, stream crossing culvert,
is self defining. A culvert is required where the roadway crosses a stream channel to allow water to pass downstream.
Culverts can be divided into two functional types: