Misplaced Pages

#920079

26-654: The Dakpathar Barrage is a concrete barrage across the Yamuna River adjacent to Dakpathar in Uttarakhand , India . In a run-of-the-river scheme, the barrage serves to divert water into the East Yamuna Canal for hydroelectric power production at the Dhakrani and Dhalipur Power Plants. The foundation stone for the dam was laid on 23 May 1949 by India's Prime Minister Jawaharlal Nehru . The barrage

52-689: A tidal lagoon or estuary as a method to capture tidal power from tidal flows are known as tidal barrages . 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

78-474: A design hydraulic head of 19.8 m (65 ft). About 4 km (2 mi) after Dhakrani the canal reaches the 51 MW Dhalipur Power Plant at 30°26′07″N 77°40′54″E  /  30.43528°N 77.68167°E  / 30.43528; 77.68167  ( Dhakrani Power Plant ) . This power plant contains three 17 MW Francis turbine -generators and has a design head of 30.48 m (100 ft). Both power plants were commissioned in 1965 and have

104-671: A design discharge of 199 m/s (7,028 cu ft/s). Water discharged from the Dhalipur Power Plant continues along the canal until it reaches the reservoir of the Asan Barrage . Download coordinates as: Barrage (dam) The term barrage is borrowed from the French word "barrer" meaning "to bar". Barrage dams have a series of gates that control the amount of water passing through. A barrage dam can be used to divert water for irrigation needs or limit

130-481: A migratory route on their first journey with older members of their group, other species genetically pass on information regarding their migratory paths. Despite many differences in organisms’ migratory cues and behaviors, “considerable similarities appear to exist in the cues involved in the different phases of migration.” Migratory organisms use environmental cues like photoperiod and weather conditions as well as internal cues like hormone levels to determine when it

156-423: A resident predator, leaving other resident species as only an alternate prey. This new source of food (migrants) can increase the predatory species’ population size, impacting population sizes of its other prey when the migratory species return to their original location. If a resident species experiences a scarcity of food due to seasonal variation, the species can decrease in population, creating an opportunity for

182-580: Is controlled by 25 floodgates and has a length of 516.5 m (1,695 ft). The entrance to the canal is directly behind the dam on its left bank. After traveling 10 km (6 mi), water reaches the Dhakrani Power Plant at 30°27′21″N 77°44′10″E  /  30.45583°N 77.73611°E  / 30.45583; 77.73611  ( Dhakrani Power Plant ) and is utilized for power production. The 33.75 MW power plant contains three 11.25 MW Kaplan turbine -generators and has

208-454: Is substantial evidence, including case studies, that points to dam construction having environmental impact , there are also studies that show less damage than expected. Looking at plankton near some dams has shown that plankton is able to continue to live through changes to its habitat. Changes such as the pH levels near dams have been recorded, and plankton was minimally affected. Other species, however, such as trout, are affected more, due to

234-456: Is that a dam is built for water storage in a reservoir , which raises the level of water significantly. A barrage is built for diverting water, and raises the water level by only a few feet. The latter is generally built on flat terrain across wide, often meandering rivers. Similar distinctions are used in Egypt, where it is noted: "In this system a "dam" is a structure that forms a reservoir for

260-746: Is the best known type. Migration is often cyclical, frequently occurring on a seasonal basis, and in some cases on a daily basis . Species migrate to take advantage of more favorable conditions with respect to food availability, safety from predation , mating opportunity, or other environmental factors. Migration is most commonly seen in the form of animal migration, the physical movement by animals from one area to another. That includes bird , fish , and insect migration . However, plants can be said to migrate, as seed dispersal enables plants to grow in new areas, under environmental constraints such as temperature and rainfall, resulting in changes such as forest migration . While members of some species learn

286-420: Is time to begin a migration. Migratory species use senses such as magnetoreception or olfaction to orient themselves or navigate their route, respectively. The factors that determine migration methods are variable due to the inconsistency of major seasonal changes and events. When an organism migrates from one location to another, its energy use and rate of migration are directly related to each other and to

SECTION 10

#1732772788921

312-451: The amount of water downstream. In most cases, a barrage dam is built near the mouth of the river. The site of dam construction needs to be thoroughly investigated to ensure that the foundation is strong enough to support the dam and has low possibility of failing. When dams are created, they are given a safety rating depending on the type of dam, location, and the possible effects in case of failure. The ratings are from one to five, five having

338-783: The blessing of the Egyptian Viceroy of the Ottoman Empire , Muhammad Ali . When the British, after 1882, had to look after these structures generally referred to as barrages , they adopted the term in their language and continued to use it for similar structures built by themselves across the Nile (Zefta Barrage and Assiut Barrage , both completed in 1902). Since the British in the Egyptian Public Works Department kept close relations to their counterparts in British India ,

364-413: The border of a plant species's distribution may move, so the plant may be said to migrate, as for example in forest migration . A species migrating to a new community can affect the outcome of local competitive interactions. A species that migrates to a new community can cause a top-down effect within the community. If the migratory species is abundant in the new community, it can become a main prey for

390-505: The dam. With that data, they are able to see how the population size increased or decreased. In some cases, it was found that the species richness was less downstream from a dam compared to further upstream. Inhibiting the volume of water was shown to be detrimental to species diversity and richness. 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

416-469: The ecosystem's ability to handle the newly-built dam. It has been shown that dams can have an effect on the migration of fish, leading to less reproduction. 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. Different experiments have been done that looked into each of these individually and were able to determine why some dams cause such effects. While there

442-450: The highest danger rating. The rating of five would be given to dams built with a town or city downstream, which would have higher possibility of injury to people in the case of dam failure. New designs have been made that are able to sustain greater amounts of water. An improved wedge-shaped block technology was developed by Rafael Moran and Miguel Toledo. The new structure is able to withstand severe flooding and uses less materials, reducing

468-440: The likelihood of its survival and reproductive success. Animal migration is the relatively long-distance movement of individual animals , usually on a seasonal basis. It is the most common form of migration in ecology. It is found in all major animal groups, including birds , mammals , fish , reptiles , amphibians, insects , and crustaceans . The cause of migration may be local climate, local availability of food,

494-492: The physical dam inhibiting their migration and reproduction paths. Barrage dams control the amount of water going through them, leading to differences in the amount of water upstream and downstream from the dam. This discrepancy has different effects on different species native to the area. While there can be reduced flow downstream, there can also be problems upstream. Dams can have buildup of pressure that fish are not accustomed to, and they migrate further upstream, causing part of

520-432: The production cost. Dam construction has several effects on the economy and the environment . Specifically, there are several ways in which the environment can be affected by dam construction. Species richness is usually measured to determine the effect of a dam on the ecosystem surrounding it. To observe the species richness, scientists collect data on the fish and animal populations before and after construction of

546-654: The river of their birth when they have reached a few inches in size. Some traditional forms of human migration fit this pattern. Migrations can be studied using traditional identification tags such as bird rings , or tracked directly with electronic tracking devices. Before animal migration was understood, folklore explanations were formulated for the appearance and disappearance of some species, such as that barnacle geese grew from goose barnacles . Plants can be said to migrate, as seed dispersal enables plants to grow in new areas, under environmental constraints such as temperature and rainfall. When those constraints change,

SECTION 20

#1732772788921

572-473: The river to have reduced population sizes. Although there are environmental effects that come with building new dams, there are also economic benefits from a dam. Without dams, it would be much harder to farm and grow livestock. The irrigation technology that comes with building a dam can exceed the risk factor. According to the World Commission on Dams , a key difference between a dam and a barrage

598-409: The safety of the organism. If an ecological barrier presents itself along a migrant's route, the migrant can either choose to use its energy to cross the barrier directly or use it to move around the barrier. If an organism is migrating to a place where there is high competition for food or habitat, its rate of migration should be higher. This indirectly helps determine an organism's fitness by increasing

624-470: The season of the year or for mating. To be counted as a true migration, and not just a local dispersal or irruption, the movement of the animals should be an annual or seasonal occurrence, or a major habitat change as part of their life. An annual event could include Northern Hemisphere birds migrating south for the winter, or wildebeest migrating annually for seasonal grazing. A major habitat change could include young Atlantic salmon or sea lamprey leaving

650-455: 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. Barrages are usually larger than the headworks of irrigation and navigation canals, with which they are associated. Barrages that are commonly used to dam

676-482: The term barrages made its way to present-day India and Pakistan, as well as to the Middle East and thus generally into English. Migration (ecology) Migration , in ecology , is the large-scale movement of members of a species to a different environment . Migration is a natural behavior and component of the life cycle of many species of mobile organisms, not limited to animals, though animal migration

#920079