For the prehistoric biological event, see Grande Coupure

A coupure is a means of closing an opening in a wall, floodwall or levee

Levee

A levee, levée, dike , embankment, floodbank or stopbank is an elongated naturally occurring ridge or artificially constructed fill or wall, which regulates water levels...

 (dike). The word comes from the french verb couper which means to cut.
In historic times a coupure was a location where a breach in the city walls or the walls of a fortress was closed. In more modern times a coupure is a way of allowing traffic to pass a flood protection structure.

Civil engineering

When a road

Road

A road is a thoroughfare, route, or way on land between two places, which typically has been paved or otherwise improved to allow travel by some conveyance, including a horse, cart, or motor vehicle. Roads consist of one, or sometimes two, roadways each with one or more lanes and also any...

 or railway crosses a floodwall or levee the road or railway can either be laid on a grade or through a cut in the floodwall or levee. In case of expected flooding the cut can temporarily be closed. This type of coupure is also known as vehicle gate, floodwall gate or similar names. The closure can be accomplished by various means.

The most basic means of closing a coupure is with soil or sandbag

Sandbag

A sandbag is a sack made of hessian/burlap, polypropylene or other materials that is filled with sand or soil and used for such purposes as flood control, military fortification, shielding glass windows in war zones and ballast....

s. More sophisticated means of closing a coupure consist of wooden or metal beams or doors. Older coupures are usually brick built structures with provisions for placing two stacks of beams between them. Between the stacks of beams, which form two walls, horse manure or other animal faeces mixed with straw is dumped and compacted. This type of material swells when wet, thus providing additional waterproofing. Modern coupures can consist of only one wall and can be made watertight with the help of rubber flaps or other materials.

Military

During a siege

Siege

A siege is a military blockade of a city or fortress with the intent of conquering by attrition or assault. The term derives from sedere, Latin for "to sit". Generally speaking, siege warfare is a form of constant, low intensity conflict characterized by one party holding a strong, static...

 a coupure is a ditch or an earthenwork or wooden palisade built behind a breach in the walls of a fortress, or a city, made by the attacker's guns. Its purpose is to hinder and frustrate an attack made by the forlorn hope

Forlorn hope

A forlorn hope is a band of soldiers or other combatants chosen to take the leading part in a military operation, such as an assault on a defended position, where the risk of casualties is high....

.

This was a strategy used many times by defenders of fortifications, for example, by the Irish defenders during the Siege of Clonmel

Siege of Clonmel

The Siege of Clonmel took place in April – May 1650 during the Cromwellian conquest of Ireland when the town of Clonmel in County Tipperary was besieged by Oliver Cromwell’s New Model Army. Cromwell's 8,000 men eventually took the town from its 2,000 Irish defenders, but not before they...

 (April - May 1650).

It can also be a passage through a glacis

Glacis

A glacis in military engineering is an artificial slope of earth used in late European fortresses so constructed as to keep any potential assailant under the fire of the defenders until the last possible moment...

 to create a sally port

Sally port

The primary modern meaning for sally port is a secure, controlled entryway, as at a fortification or a prison. The entrance is usually protected in some way, such as with a fixed wall blocking the door which must be circumvented before entering, but which prevents direct enemy fire from a distance...

 so that the defenders can launch a Sortie

Sortie

Sortie is a term for deployment or dispatch of one military unit, be it an aircraft, ship, or troops from a strongpoint. The sortie, whether by one or more aircraft or vessels, usually has a specific mission....

against the attackers.