DAM

Damé is a town in eastern Ivory Coast. It is a sub-prefecture of Agnibilékrou Department in Indénié-Djuablin Region, Comoé District. Seven kilometres east of the town is a border crossing with Ghana. Damé was a commune until March 2012, when it became one of 1,126 communes nationwide that were abolished. In 2014, the population of the sub-prefecture of Damé was 15,920.

A dam is a structure that impounds water or restricts its flow. Dams are classified into four basic types: gravity dams are massive structures made of concrete or masonry that rely on their weight to resist the force of impounded water; embankment dams are large earthworks consisting of rocks, clay, sand, soil, or gravel; buttress dams consist of a sloped, concrete face supported on the downstream side by a series of triangular buttresses; and arch dams use a curved concrete wall to transfer the weight of the water to the surrounding valley walls. Dams provide for irrigation, hydropower, water supply, flood management, recreation, inland navigation, and fish farming. Irrigation is a critical application of dams: about 20% of the world's arable land is irrigated using water from reservoirs impounded by dams. Dams generate hydropower, providing a clean and renewable source of electricity, and also supply water for household and industrial needs. An early dam was Jawa Dam in modern Jordan, built around 3000 BCE. The Hittite Empire built several dams in modern Turkey between the 17th and 13th centuries BCE. In the 1st century CE, the Roman Empire began building masonry gravity dams typically with vertical faces on both upstream and downstream sides. In medieval Europe, dams impounded water that powered water wheels for milling and mining. The process of designing dams began to transform in the late 18th century from an informal practice to an engineering discipline rooted in science. In the 20th century, the widespread availability of concrete and heavy construction machinery led to the creation of many large-scale dam projects worldwide. The most visible part of a dam is the barrier that retains water, but most dams contain additional structures that perform important functions. When a dam blocks a navigable river, locks may be incorporated into the project to allow ships to pass through. Fish ladders are included in many dams to enable fish to migrate upstream. Spillways are often included to safely release excess reservoir water downstream and prevent catastrophic overflows. Dam outlets allow reservoirs to be partially drained to purge sediment, perform maintenance, or increase water flow downstream. A dam may be deliberately removed for various reasons: if it poses a safety hazard, if the dam no longer fulfills its original purpose, to restore fish migration routes, or to improve the health of downstream rivers by improving sediment flow. Dams occasionally fail, resulting in flooding and loss of life. Many principles governing the design of safe dams have been developed based on lessons learned from dam failures. on the Blue Nile River in 2020, over the objections of Egypt and Sudan. |alt=A photograph of a large concrete dam and the reservoir it creates. The photo is taken from an aerial viewpoint, looking down from above. Large plumes of white water spray over a spillway. Water scarcity is a major global issue affecting countries such as China, South Korea, India, Belgium, South Africa, Algeria, Jordan, and Rwanda. Water withdrawals from some rivers are so extensive that river flows are severely depleted before reaching their delta, including Indus River (Pakistan), Colorado River (US), and Yellow River (China). In response to concerns about water shortages, some countries have pursued dam construction projects to enhance water security and advance long-term strategic objectives. When a dam is built on a river that flows into other nations, downstream nations are often concerned about the dam's effects on water availability and river flow, as well as the risk of dam failure. Such dams can lead to international conflict between the upstream and downstream nations, particularly when the downstream nations are facing water scarcity problems. Notable disputes about dams include Turkey's Southeastern Anatolia Project, a major water project which includes many dams, one of which is Karakaya Dam. Most of these dams are on the Euphrates and Tigris rivers, which flow downstream into neighboring nations Syria and Iraq. These downstream nations have protested to Turkey about potential water supply issues. The Indus River is the primary river of Pakistan, with headwaters in several countries, including India. India built large dams on the Indus over the opposition of Pakistan, including the Baglihar Dam and Kishanganga Dam. The Mekong River traverses several countries. China built many dams on the river without the consent of the downstream nations, including Xiaowan Dam and Nuozhadu Dam. The Nile River has been the source of tensions between the arid downstream nations (Egypt and Sudan) and the upstream nations where most of its water originates as rainfall. In 2020, Ethiopia completed Grand Ethiopian Renaissance Dam (GERD) on the Blue Nile, in spite of opposition from Sudan and Egypt. s to evaluate dam designs. This is a model of Tellico Dam in the US. |alt= Two men are looking at a small model of a dam, which is about 1 meter tall and 2 meters wide. During the planning process for a dam, a large number of technical investigations are typically conducted. These investigations may be categorized as topographic, geological, and hydrological. Topographic investigations survey the dam site and use the data to prepare detailed topographic maps of the region. Every aspect of the dam's design will rely on the maps, so they must be very precise. Geological investigations study the rocks and soil of the dam site. The dam and the water it impounds exerts immense forces on the valley walls and on the ground beneath the reservoir and dam structure. An accurate understanding of the strength of the ground, and identifying any faults, is essential to minimizing seepage and reducing the risk of dam failure. The geological research must also assess the likelihood and magnitude of earthquakes. Hydrological investigations examine all aspects of water flow in the vicinity of the dam. Data are produced that identify the size of the upstream watershed and annual precipitation. Studies are performed to determine how much water flows through the dam site in an average year, and how much it varies within a year and between years. These data are used to predict the frequency and magnitude of floods at the dam site, and to establish the capacity of the dam's spillway. of Itaipu Dam on the border of Brazil and Paraguay|alt=A room with a few people seated at several tables. The tables contain a large number of knobs and buttons. The walls have large screens displaying numbers. After a dam is completed and becomes operational, management processes are employed to ensure it continues to fulfill its purposes (irrigation, hydropower, etc.), avoids safety incidents, and achieves its intended lifespan. Management processes include performing maintenance and repairs, testing and inspecting facilities, keeping records, and planning for emergencies. is shown on this 1968 Soviet stamp.|alt=A postage stamp shows a man and woman pushing a heavy object, with the image of a large dam in the background. Dams are featured in novels, movies, documentaries, songs, postage stamps, popular histories, and political posters. In the mid-20th century, Soviet artists such as Isaak Brodsky and Gustav Klutsis highlighted large dams in artworks intended to glorify workers and industry. Their works portrayed Mingachevir Dam, Kayrakkum Dam, Bratsk Dam, and Dnieper Dam. The docudrama film The Dam Busters (1955) portrayed a WWII military operation in which Britain's RAF successfully bombed Möhne Dam in Germany, causing the deaths of about 1,600 civilians. The Patagonia company produced the documentary DamNation (2014) which advocates for dam removal to restore ecosystems and fish populations. Books about dams include The Johnstown Flood (1968) by David McCullough a popular history of an 1889 dam failure and subsequent flood in the US. Edward Abbey wrote the novel The Monkey Wrench Gang (1975) about environmental activists who sought to destroy Glen Canyon Dam. Folk musician Woody Guthrie wrote the songs Grand Coulee Dam and Roll On, Columbia, Roll On (both 1941) as part of a series he wrote about the Columbia Basin Project. Several popular songs were produced in Ethiopia in the 2010s to raise funds to build the Grand Ethiopian Renaissance Dam.

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