Barrage (dam)

A barrage is a type of low-head, diversion dam which consists of a number of large gates that can be opened or closed to control the amount of water passing through.

The gates are set between flanking piers which are responsible for supporting the water load of the pool created.

[4] To observe the species richness, scientists collect data on the fish and animal populations before and after construction of the dam.

Also, at the entrance of dams, there are fewer nutrients due to the high-water flow reducing the ecosystem's reproduction standard.

Along with species richness, plankton diversity can be an indicator of the ecosystem's ability to handle the newly-built dam.

[5] There are many small factors that can have a relatively large effect on the river ecosystems, such as species richness, water volume and nutrient levels.

Dams can have buildup of pressure that fish are not accustomed to, and they migrate further upstream, causing part of the river to have reduced population sizes.

[6] Similar distinctions are used in Egypt, where it is noted: "In this system a "dam" is a structure that forms a reservoir for the storage of water during the annual flood period of the Nile in order to supplement the natural flow of the river during the low-water period; a "barrage" merely raises the river or canal level, when necessary, to the height required for adequate flow into the canals that take off above it.

The English usage of the term barrage originates from the Delta Barrage across the Nile branches north of Cairo, built between 1833 and 1862 by the French Linant de Bellefonds and Eugène Mougel employed by the Egyptian Public Works Department, with assistance from Barthélemy Prosper Enfantin and with the blessing of the Egyptian Viceroy of the Ottoman Empire, Muhammad Ali.