Is it necessary to construct a concrete cutoff upstream of a bridge across a river to protect from erosion ?
963981
It would be if it posed as a flood hazard if you didn't stop this erosion.
778070
I'm guessing here, but I imagine the expression predates bridges that could span rivers that wide and that far down-stream.
468355
If people pave their whole back yards, water has no where to drain off to.  It wouldn't be able to be absorbed into the grass.  Also, I think the sun reflecting off the concrete is heating up our cities a degree or two.
607374
I don't know if this really answers your question, but they are currently doing a seismic retrofit to the bridge wherein they are pretty much replacing the whole bridge piece by piece while it is still in use.  So I guess the answer right now is no, but hopefully yes when they are done.
561268
In Civil Engineering, it is always important to include a compass rose (or North arrow) and a scale (to show how the plan distance translates into actual distance) on each plan sheet.  Existing conditions need to be shown as accurately as possible.  The new design should be clear and well thought out.  Especially important is that each plan sheet is to be stamped and signed by a registered professional engineer.
519144
drop a concrete block on it
123640
One of civil engineering's specialties is construction of large structures such as dams and highways.  This uses a lot of concrete held together against cracking and gross failure by rebar (reinforcing iron bars).  To make lighter thinner structures, Carbon Fiber (CF) will replace rebar in many future applications.  Zoltek (stock symbol ZOLT) is leading the way with partners to apply commercial grade (as opposed to aerospace grade) CF to concrete structures.
889845
When it comes up against hard rock, it will then find the easiest way around it. In time it may erode the rock and form a new course and the meander will be cut off and become an oxbow lake.
756112
A few things that contribute to soil erosion:\nPoor agricultural practices;\nPoor forestry practices;\noff-roading with any kind of vehicles, including bikes;\ndiversion of natural water supplies;\npoor design of infrastructure (buildings, roads, etc)
167925
the barriers prevent constuction wastes from leaching into neighboring soils
1062234
Use the regular "concrete mix design" and add a "water reducing admixture".\n\nThe water reducing admixture type should be selected so that it does not require a reduction in the amount of "cement" that was in the original concrete mix design.\n\n(Note that a standard concrete mix design includes such things as __% of aggregate (rocks), __% of sand, __% of cement, __% of ash, __% of water, etc. and it does not normally include a water reducing agent.  It would be an additive supplement.)
941013
Hi. The most efficient way would be to bypass the power to the pump used to raise the water in the first place and use it directly. This would eliminate friction losses and generator losses.
438341
Go to wikipedia.com\nand search civil engineering....
714809
The previous answer is almost correct, except that concrete actually set under water.  So they just have to make a form, put reinforcing steel in it, and pour concrete in the form in a way that displaces the water out of the form.  In time, concrete will harden even under water.\n\nFor you information, after concrete is poured, it is important to keep the concrete moist in the first 24 hours when it cures.
4343
One really long disconnected river.
740774
A spillway is a structure used to provide for the controlled release of flood flows from a dam or levee into a downstream area, typically being the river that was dammed. Spillways release floods so that the water does not overtop and damage or even destroy the dam. Except during flood periods, water does not normally flow over a spillway. In contrast, an intake is a structure used to release water on a regular basis for water supply, hydroelectricity generation, etc. Floodgates may be designed into spillways to regulate water flow and dam height.\n\nA spillway is located at the top of the reservoir pool. Dams may also have bottom outlets with valves or gates which may be operated to release flood flow, and a few dams lack overflow spillways and rely entirely on bottom outlets.\n\nThere are two types of spillways: controlled and uncontrolled.\n\nA controlled spillway has mechanical structures or gates to regulate the rate of flow. This design allows nearly the full height of the dam to be used for water storage year-round, and flood waters can be released as required by opening one or more gates.\n\nAn uncontrolled spillway, in contrast, does not have gates; when the water rises above the lip or crest of the spillway it begins to be released from the reservoir. The rate of discharge is controlled only by the depth of water within the reservoir. All of the storage volume in the reservoir above the spillway crest can be used only for the temporary storage of floodwater, and cannot be used as water supply storage because it is normally empty.\n\nSome spillways are designed like an inverted bell so that water can enter all around the perimeter (also termed a morning glory design). In areas where the surface of the reservoir may freeze, bell-mouth spillways are normally fitted with ice-breaking arrangements to prevent the spillway from becoming ice-bound. This type of Spillway is also known as a Glory hole.
203336
Cofferdam/ Well foundation is commonly the type of bridge foundation adopted across a river.