A roller dam is a type of hydro-control device specially designed to mitigate erosion. They are most often used to divert water for irrigation but the largest and most notable examples are used to ease river navigation. The world's first roller dam (German : walzenwehr) was constructed in Schweinfurt, Germany in 1902 to divert irrigation water south of the Main river. [1] [2]
Roller dams are a type of weir, or a dam that is designed to allow water to flow over the top in continuous action. They are used on rivers or other such moving bodies of water where erosion damage is undesirable, yet likely to occur. A short wall, lip, or parabolic channel is constructed on the downstream side of the dam parallel to the dam face. As the water pouring over the dam hits this baffle, it is reflected toward the dam face, creating a continual "rolling" action at the foot of the dam; hence the name "Roller Dam". The purpose of the rolling is to dissipate the energy gained by the water as it falls from the top of the dam. Otherwise the energy would be exerted downstream, causing significant bank and river bed erosion.
Roller dams can be either fixed (non-moving) or active. Fixed roller dams are generally made from reinforced concrete or masonry. Active roller dams are made from large metal cylinders, which can be lifted out of the water using a system of powerful hydraulic rams or cables and motors. This type is also known as a roller gate. The largest of the active dams in the world is Locks and Dam 15, which spans the Mississippi River between Rock Island, Illinois, and Davenport, Iowa.
Roller dams of any type pose an extreme drowning hazard. Any person going over the top of the dam will be caught in the rolling action at its base and may not be ejected from the cycle for days or possibly weeks. Even very buoyant objects, such as inflatable balls, inner tubes, and life vests, can often be seen resurfacing near the downstream face every few seconds for several hours before escaping the so-called "washing machine of death".
Because of the hazards, dam opponents have called for the removal of roller dams. Sixteen people have died by drowning at the roller dam on the Fox River near Yorkville, Illinois, since its construction in 1960. Most recently in a single accident on May 28, 2006, three persons died. [3] Similar dams have already been removed on the Fox River at Aurora, Illinois, and near Batavia, Illinois, but Yorkville residents successfully petitioned to maintain the roller dam near their town because of tradition. [4] In July 2009, a man died at a roller dam on the Cedar River in Cedar Rapids, Iowa. His death was notable because he was wearing an approved personal flotation device, intended to help bring a person quickly to the surface of the water. [5]
The Mississippi River is the second-longest river and chief river of the second-largest drainage system in North America, second only to the Hudson Bay drainage system. From its traditional source of Lake Itasca in northern Minnesota, it flows generally south for 2,340 miles (3,766 km) to the Mississippi River Delta in the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains all or parts of 32 U.S. states and two Canadian provinces between the Rocky and Appalachian mountains. The main stem is entirely within the United States; the total drainage basin is 1,151,000 sq mi (2,980,000 km2), of which only about one percent is in Canada. The Mississippi ranks as the thirteenth-largest river by discharge in the world. The river either borders or passes through the states of Minnesota, Wisconsin, Iowa, Illinois, Missouri, Kentucky, Tennessee, Arkansas, Mississippi, and Louisiana.
The Main is the longest tributary of the Rhine. It rises as the White Main in the Fichtel Mountains of northeastern Bavaria and flows west through central Germany for 525 kilometres (326 mi) to meet the Rhine below Rüsselsheim, Hesse. The cities of Mainz and Wiesbaden are close to the confluence.
A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use, aquaculture, and navigability. Hydropower is often used in conjunction with dams to generate electricity. A dam can also be used to collect or store water which can be evenly distributed between locations. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees are used to manage or prevent water flow into specific land regions.
A weir or low head dam is a barrier across the width of a river that alters the flow characteristics of water and usually results in a change in the height of the river level. Weirs are also used to control the flow of water for outlets of lakes, ponds, and reservoirs. There are many weir designs, but commonly water flows freely over the top of the weir crest before cascading down to a lower level. There is no single definition as to what constitutes a weir, and one English dictionary simply defines a weir as a small dam.
The Beas River is a river in north India. The river rises in the Himalayas in central Himachal Pradesh, India, and flows for some 470 kilometres (290 mi) to the Sutlej River in the Indian state of Punjab. Its total length is 470 kilometres (290 mi) and its drainage basin is 20,303 square kilometres (7,839 sq mi) large.
A diversion dam is a dam that diverts all or a portion of the flow of a river from its natural course. Diversion dams do not generally impound water in a reservoir; instead, the water is diverted into an artificial water course or canal, which may be used for irrigation or return to the river after passing through hydroelectric generators, flow into a different river or be itself dammed forming an onground or groundwater reservoir or a storm drain.
The Wabash River is a 503-mile-long (810 km) river that drains most of the state of Indiana in the United States. It flows from the headwaters in Ohio, near the Indiana border, then southwest across northern Indiana turning south near the Illinois border, where the southern portion forms the Indiana-Illinois border before flowing into the Ohio River.
The Dolores River is a tributary of the Colorado River, approximately 241 miles (388 km) long, in the U.S. states of Colorado and Utah. The river drains a rugged and arid region of the Colorado Plateau west of the San Juan Mountains. Its name derives from the Spanish El Rio de Nuestra Señora de Dolores, River of Our Lady of Sorrows. The river was explored and possibly named by Juan Maria Antonio Rivera during a 1765 expedition from Santa Fe.
A spillway is a structure used to provide the controlled release of water downstream from a dam or levee, typically into the riverbed of the dammed river itself. In the United Kingdom, they may be known as overflow channels. Spillways ensure that water does not damage parts of the structure not designed to convey water.
The Stratton Lock and Dam is a dam in Nunda Township, McHenry County, Illinois. It is named after former Governor William Stratton and Representative Thomas A. Bolger. The dam is the only dam on the Fox River that is served by a lock system.
The Tainter gate is a type of radial arm floodgate used in dams and canal locks to control water flow. It is named for Wisconsin structural engineer Jeremiah Burnham Tainter.
A reservoir is an enlarged lake behind a dam. Such a dam may be either artificial, usually built to store fresh water, or it may be a natural formation.
The environmental impact of reservoirs comes under ever-increasing scrutiny as the global demand for water and energy increases and the number and size of reservoirs increases.
Khanki Headworks is a headworks situated on the River Chenab in Gujranwala District of the Punjab province of Pakistan. The construction of this headworks was completed in 1889 and was one of the oldest headworks in Pakistan.
The June 2008 Midwestern United States floods were flooding events which affected portions of the Midwestern United States. After months of heavy precipitation, a number of rivers overflowed their banks for several weeks at a time and broke through levees at numerous locations. Flooding continued into July. States affected by the flooding included Illinois, Indiana, Iowa, Michigan, Minnesota, Missouri and Wisconsin. The American Red Cross assisted the victims of flooding and tornadoes across seven states and the National Guard was mobilized to assist in disaster relief and evacuation.
The environmental effects of irrigation relate to the changes in quantity and quality of soil and water as a result of irrigation and the subsequent effects on natural and social conditions in river basins and downstream of an irrigation scheme. The effects stem from the altered hydrological conditions caused by the installation and operation of the irrigation scheme.
The Glen D. Palmer Dam is a 6-foot-high (1.8 m) dam across the Fox River in Yorkville, Illinois, about 35.9 miles (58.2 km) upstream from the confluence with the Illinois River, and 940 feet upstream from the Route-47 bridge. The dam is named after the original manager of the State Game Farm, formerly located in Yorkville.
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. This allows the structure to regulate and stabilize river water elevation upstream for use in irrigation and other systems. The gates are set between flanking piers which are responsible for supporting the water load of the pool created. The term barrage is borrowed from the French word "barrer" meaning "to bar".
The Colorado River is a major river of the western United States and northwest Mexico in North America. Its headwaters are in the Rocky Mountains where La Poudre Pass Lake is its source. Located in north central Colorado it flows southwest through the Colorado Plateau country of western Colorado, southeastern Utah and northwestern Arizona where it flows through the Grand Canyon. It turns south near Las Vegas, Nevada, forming the Arizona–Nevada border in Lake Mead and the Arizona–California border a few miles below Davis Dam between Laughlin, Nevada and Needles, California before entering Mexico in the Colorado Desert. Most of its waters are diverted into the Imperial Valley of Southern California. In Mexico its course forms the boundary between Sonora and Baja California before entering the Gulf of California. This article describes most of the major features along the river.
The San Acacia Diversion Dam is a structure built in 1934 for the Middle Rio Grande Conservancy District (MRGCD) near to San Acacia, New Mexico, United States. It diverts water from the Rio Grande into irrigation canals.
