Old River Control Structure

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The Old River Control Structure complex. View is to the east-southeast, looking downriver on the Mississippi, with the three dams across channels leading to the Atchafalaya River to the right of the Mississippi. Concordia Parish, Louisiana is in the foreground, on the right, and Wilkinson County, Mississippi, is in the background, across the Mississippi on the left. Old River Control Structure Complex.jpg
The Old River Control Structure complex. View is to the east-southeast, looking downriver on the Mississippi, with the three dams across channels leading to the Atchafalaya River to the right of the Mississippi. Concordia Parish, Louisiana is in the foreground, on the right, and Wilkinson County, Mississippi, is in the background, across the Mississippi on the left.
Old River Control Structure discharging water into the Atchafalaya, May 2011 Old River Control discharge.jpg
Old River Control Structure discharging water into the Atchafalaya, May 2011

The Old River Control Structure is a floodgate system in a branch of the Mississippi River in central Louisiana. It regulates the flow of water leaving the Mississippi into the Atchafalaya River, thereby preventing the Mississippi river from changing course. Completed in 1963, the complex was built by the U.S. Army Corps of Engineers in a side channel of the Mississippi known as "Old River", between the Mississippi's current channel and the Atchafalaya Basin, a former channel of the Mississippi. [1] [2] [3] [4] [5] The Old River Control Structure is actually a complex containing the original low-sill [6] and overbank [7] structures, as well as the auxiliary structure that was constructed after the low-sill structure was damaged during the Mississippi River Flood of 1973. The complex also contains a navigation lock and the Sidney A. Murray Jr. Hydroelectric Station. [8]

Floodgate adjustable gate used to control water flow

Floodgates, also called stop gates, are adjustable gates used to control water flow in flood barriers, reservoir, river, stream, or levee systems. They may be designed to set spillway crest heights in dams, to adjust flow rates in sluices and canals, or they may be designed to stop water flow entirely as part of a levee or storm surge system. Since most of these devices operate by controlling the water surface elevation being stored or routed, they are also known as crest gates. In the case of flood bypass systems, floodgates sometimes are also used to lower the water levels in a main river or canal channels by allowing more water to flow into a flood bypass or detention basin when the main river or canal is approaching a flood stage.

Mississippi River largest river system in North America

The Mississippi River is the second-longest river and chief river of the second-largest drainage system on the North American continent, second only to the Hudson Bay drainage system. Its source is Lake Itasca in northern Minnesota and it flows generally south for 2,320 miles (3,730 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 fourth-longest and fifteenth-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.

Louisiana State of the United States of America

Louisiana is a state in the Deep South region of the South Central United States. It is the 31st most extensive and the 25th most populous of the 50 United States. Louisiana is bordered by the state of Texas to the west, Arkansas to the north, Mississippi to the east, and the Gulf of Mexico to the south. A large part of its eastern boundary is demarcated by the Mississippi River. Louisiana is the only U.S. state with political subdivisions termed parishes, which are equivalent to counties. The state's capital is Baton Rouge, and its largest city is New Orleans.

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Old River

Formation of the Atchafalaya River and construction of the Old River Control Structure. Geomorphology of Old River.jpg
Formation of the Atchafalaya River and construction of the Old River Control Structure.

Before the 15th century, the Red River and Mississippi River were entirely separate and more or less parallel to one another. [3] Beginning in the 15th century, the Mississippi River created a small, westward, oxbow loop, later called Turnbull's Bend, near present-day Angola, Louisiana. This loop eventually intersected the Red River, making the downstream part of the Red River a distributary of the Mississippi; this distributary came to be called the Atchafalaya River. [3]

Red River of the South major tributary of the Mississippi and Atchafalaya rivers in the southern United States

The Red River, or sometimes the Red River of the South, is a major river in the southern United States of America. It was named for the red-bed country of its watershed. It is one of several rivers with that name. Although it was once a tributary of the Mississippi River, the Red River is now a tributary of the Atchafalaya River, a distributary of the Mississippi that flows separately into the Gulf of Mexico. It is connected to the Mississippi River by the Old River Control Structure.

Meander A sinuous bend in a series in the channel of a river

A meander is one of a series of regular sinuous curves, bends, loops, turns, or windings in the channel of a river, stream, or other watercourse. It is produced by a stream or river swinging from side to side as it flows across its floodplain or shifts its channel within a valley. A meander is produced by a stream or river as it erodes the sediments comprising an outer, concave bank and deposits this and other sediment downstream on an inner, convex bank which is typically a point bar. The result of sediments being eroded from the outside concave bank and their deposition on an inside convex bank is the formation of a sinuous course as a channel migrates back and forth across the down-valley axis of a floodplain. The zone within which a meandering stream shifts its channel across either its floodplain or valley floor from time to time is known as a meander belt. It typically ranges from 15 to 18 times the width of the channel. Over time, meanders migrate downstream, sometimes in such a short time as to create civil engineering problems for local municipalities attempting to maintain stable roads and bridges.

Atchafalaya River river in the United States of America

The Atchafalaya River is a 137-mile-long (220 km) distributary of the Mississippi River and Red River in south central Louisiana in the United States. It flows south, just west of the Mississippi River, and is the fifth largest river in North America, by discharge. The name "Atchafalaya" comes from Choctaw for "long river", from hachcha, "river", and falaya, "long".

In the heyday of steamboats along the Mississippi River, it would take a boat several hours to travel the 20 miles (32 km) of Turnbull's Bend, after which it would have progressed only about 1 mile (1.6 km) from the entrance to the bend. To reduce travel time, Captain Henry M. Shreve, a river engineer and namesake of Shreveport, Louisiana, dug a canal in 1831 through the neck of Turnbull's Bend; this canal became known as Shreve's Cut. At the next high water, the Mississippi roared through this channel. [9] The upper portion of Turnbull's Bend became the smaller Upper Old River while the lower portion became the larger Lower Old River. At first, the Lower Old River would flow eastward, to the Mississippi, until 1839, when locals began removing a log jam that was obstructing the Atchafalaya River. The project was finished in 1840. After that, the Lower Old River would flow eastward to the Mississippi when the Red River was high and the Mississippi was low, and westward to the Atchafalaya when the Mississippi was high and the Red River was low. Over time, the number of days when the river flowed east to the Mississippi decreased and the number of days when the river flowed west increased, until eventually the Lower Old River flowed west over half the time. By 1880, it rarely flowed eastward and was now rapidly capturing more and more of the flow of the Mississippi. With this extra intake of water, the channel of the Atchafalaya River was worn deeper and wider throughout the 1800s and early 1900s. [9] Between 1850 and 1950, the flow increased from less than 10% of the Mississippi to 30%, and the U.S. Army Corps of Engineers began work on the Old River Control Structure to prevent the Atchafalaya becoming the main channel of the Mississippi. The project was completed in 1963, and it completely sealed off the Old river. However, a lock, a diversion channel, and flood spillway were installed to allow barges to pass between the Atchafalaya and Mississippi.

Steamboat Smaller than a steamship; boat in which the primary method of marine propulsion is steam power

A steamboat is a boat that is propelled primarily by steam power, typically driving propellers or paddlewheels. Steamboats sometimes use the prefix designation SS, S.S. or S/S or PS, however these designations are most often used for steamships.

Henry Miller Shreve American businessman

Henry Miller Shreve was the American inventor and steamboat captain who opened the Mississippi, Ohio, and Red rivers to steamboat navigation. Shreveport, Louisiana, is named in his honor.

Shreveport, Louisiana City in Louisiana, United States

Shreveport is a city in the U.S. state of Louisiana. It is the most populous city in the Shreveport-Bossier City metropolitan area. Shreveport ranks third in population in Louisiana after New Orleans and Baton Rouge and 126th in the U.S. The bulk of Shreveport is in Caddo Parish, of which it is the parish seat. Shreveport extends along the west bank of the Red River into neighboring Bossier Parish. The population of Shreveport was 199,311 as of the 2010 U.S. Census. The United States Census Bureau's 2017 estimate for the city's population decreased to 192,036.

The U.S. Army Corps of Engineers measured the amount of water flowing through the Mississippi River and compared it to the amount entering the Atchafalaya Basin by monitoring "latitude flow" at the latitude of the Red River Landing, located five miles (8.0 km) downstream of Old River. In this case, latitude flow is a combination of the flows of the Mississippi and Atchafalaya rivers as they cross an imaginary line at that latitude. [3]

Red River Landing, Louisiana human settlement in Louisiana, United States of America

Red River Landing was the name of a community located in northern Pointe Coupee Parish, Louisiana, United States. The community was located near the Red River and the Mississippi River.

Between 1850 and 1950, the percentage of latitude flow entering the Atchafalaya River had increased from less than 10 percent to about 30 percent. By 1953, the U.S. Army Corps of Engineers concluded that the Mississippi River could change its course to the Atchafalaya River by 1990 if it were not controlled, since this alternative path to the Gulf of Mexico through the Atchafalaya River is much shorter and steeper. [3]

Gulf of Mexico An Atlantic Ocean basin extending into southern North America

The Gulf of Mexico is an ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of the United States, on the southwest and south by Mexico, and on the southeast by Cuba. The U.S. states of Texas, Louisiana, Mississippi, Alabama, and Florida border the Gulf on the north, which are often referred to as the "Third Coast", in comparison with the U.S. Atlantic and Pacific coasts.

The Corps completed construction on the Old River Control Structure in 1963 to prevent the main channel flow of the Mississippi River from altering its current course to the Gulf of Mexico through the natural geologic process of avulsion. [3] [10] Historically, this natural process has occurred about every 1,000 years, and is overdue. Some researchers believe the likelihood of this event increases each year, despite artificial control efforts. [11]

In sedimentary geology and fluvial geomorphology, avulsion is the rapid abandonment of a river channel and the formation of a new river channel. Avulsions occur as a result of channel slopes that are much less steep than the slope that the river could travel if it took a new course.

If the Mississippi diverts its main channel to the Atchafalaya Basin and the Atchafalaya River, it would develop a new delta south of Morgan City in southern Louisiana, greatly reducing water flow to its present channel through Baton Rouge and New Orleans. [4] The Mississippi Flood of 1973 almost caused the control structure to fail. Integrity of the Old River Control Structure, the nearby Morganza Spillway, and other levees in the area is essential to prevent such a diversion. Jeff Masters of Weather Underground noted that failure of that complex "would be a serious blow to the U.S. economy." [12]

Components

A diagram that depicts river flows associated with Project Design Flood. Mississippi Project Design Flood.tif
A diagram that depicts river flows associated with Project Design Flood.

The present Old River Control Structure was completed in 1964 and expanded in 1990. The first two floodgates are the Low Sill Control Structure, which regulates routine flow in the waterway, and the Overbank Control Structure, in use only when the Mississippi exceeds its banks. A navigation channel and lock were also part of the original facility design. Subsequent expansion created what is now known as the Old River Control Complex, when the Auxiliary Structure, which became operational in 1986, was added to reduce pressure on the original floodgates after extensive damage caused by the flood of 1973. The Sidney A. Murray Jr. Hydroelectric Station, completed in 1990, also provides an additional measure of control at the site. [3]

Operation

Water from the Mississippi is normally diverted into the Atchafalaya Basin only at Old River, where floodgates are routinely used to redirect the Mississippi's flow into the Atchafalaya River such that the volume of the two rivers is split 70%/30%, respectively, as measured at the latitude of Red River Landing. [13] [14] This flow split was not based on science, but rather was based on the approximate flow allocation between the two rivers that existed at the time of construction. [8]

Water diverted at Old River flows into the Atchafalaya Basin, first entering the Red River, then continuing down the Atchafalaya River to the Gulf of Mexico, bypassing Baton Rouge and New Orleans (see diagram).

The Morganza Floodway, between the Mississippi and the Atchafalaya Basin nearby downstream, is normally closed, but can be opened in an emergency to relieve water levels and water-pressure stress on various levees and other flood-control structures, including the Old River Control Structure. The floodway can reduce stress by diverting additional water from the Mississippi into the Atchafalaya. [15] The Morganza Floodway was never used before the construction of Old River Control Structure, and as of 2016 has been opened only twice [16] for flood control since completion of the Old River Control Structure.

See also

Related Research Articles

Morganza, Louisiana Village in Louisiana, United States

Morganza is an incorporated village near the Mississippi River in Pointe Coupee Parish, Louisiana, United States. The population was 610 at the 2010 census, down from 659 in 2000. It is part of the Baton Rouge Metropolitan Statistical Area. The village's zip code is 70759. The Morganza Spillway, a flood control structure between the Mississippi River and the Atchafalaya Basin, is located nearby.

Acadiana Region in Louisiana, United States

Acadiana, is the official name given to the French Louisiana region that was historically home to the state's Francophone population, the Acadians and Cajuns. Many are of Acadian descent and are now identified as Cajun. Of the 64 parishes that make up the U.S. state of Louisiana, 22 named parishes and other parishes of similar cultural environment make up this intrastate region.

Bonnet Carré Spillway

The Bonnet Carré Spillway is a flood control operation in the Lower Mississippi Valley. Located in St. Charles Parish, Louisiana – about 12 miles (19 km) west of New Orleans – it allows floodwaters from the Mississippi River to flow into Lake Pontchartrain and thence into the Gulf of Mexico. The construction of the Spillway was completed in 1931.

Atchafalaya Basin largest wetland and swamp in the United States

The Atchafalaya Basin, or Atchafalaya Swamp, is the largest wetland and swamp in the United States. Located in south central Louisiana, it is a combination of wetlands and river delta area where the Atchafalaya River and the Gulf of Mexico converge. The river stretches from near Simmesport in the north through parts of eight parishes to the Morgan City southern area.

Lower Mississippi River river in the United States of America

The Lower Mississippi River is the portion of the Mississippi River downstream of Cairo, Illinois. From the confluence of the Ohio River and Upper Mississippi River at Cairo, the Lower flows just under 1600 kilometers (1000 mi) to the Gulf of Mexico. It is the most heavily travelled component of the Mississippi River System.

Morganza Spillway

The Morganza Spillway or Morganza Control Structure is a flood-control structure in the U.S. state of Louisiana along the western bank of the Lower Mississippi River at river mile 280, near Morganza in Pointe Coupee Parish. The spillway stands between the Mississippi and the Morganza Floodway, which leads to the Atchafalaya Basin and the Atchafalaya River in south-central Louisiana. Its purpose is to divert water from the Mississippi River during major flood events by flooding the Atchafalaya Basin, including the Atchafalaya River and the Atchafalaya Swamp. The spillway and adjacent levees also help prevent the Mississippi from changing its present course through the major port cities of Baton Rouge and New Orleans to a new course down the Atchafalaya River to the Gulf of Mexico. The Morganza Spillway, operated by the U.S. Army Corps of Engineers, was opened during the 1973 and 2011 Mississippi River floods.

Elliot City, Louisiana Ghost town in Louisiana, United States

Elliot City is a ghost town that was located in Pointe Coupee Parish's 10th Ward, approximately 6 miles west of Livonia, Louisiana United States. The site of the town itself is located at coordinates 30.55614N, 91.66520W, and is covered or partially covered by the current U.S. Route 190 roadway.

East Krotz Springs, Louisiana Ghost town in Louisiana, United States

East Krotz Springs is a ghost town that was located in Pointe Coupee Parish's 1st Ward, approximately 12 miles west of Livonia, Louisiana, United States. The site of the town itself is located at coordinates 30°32'12.87"N, 91°44'24.59"W, and is abandoned. United States Geological Survey maps from 1948 show the town to be located on the east bank of the Atchafalaya River at the mouth of Bayou Sherman, directly across from Krotz Springs, south of the railroad bridge.

The Schooner Bayou Control Structure is a flood control structure located in Vermilion Parish, Louisiana, and operated by the U.S. Army Corps of Engineers. It is part of the Mississippi Valley Division, New Orleans District, which encompasses the southern half of the state of Louisiana.

Butte La Rose, Louisiana Place in Louisiana, United States

Butte La Rose is an unincorporated community in St. Martin Parish, Louisiana, United States.

Atchafalaya National Wildlife Refuge

The Atchafalaya National Wildlife Refuge is located about 30 miles (48 km) west of Baton Rouge, Louisiana, and one mile (1.6 km) east of Krotz Springs, Louisiana, lies just east of the Atchafalaya River. In 1988 under the administration of Governor Foster the "Atchafalaya Basin Master Plan" was implemented that combined the 11,780-acre (4,770 ha) Sherburne Wildlife Management Area (WMA), the 15,220-acre (6,160 ha) Atchafalaya National Wildlife Refuge, and the 17,000-acre (6,900 ha) U.S. Army Corps of Engineers' Bayou Des Ourses into the Sherburne Complex Wildlife Management Area.

Wax Lake

Wax Lake was a lake in St. Mary Parish, Louisiana that was converted into an outlet channel to divert water from the Atchafalaya River to the Gulf of Mexico.

Sherburne Complex Wildlife Management Area

The Sherburne Complex is a joint land management venture of the U.S. Fish and Wildlife Service, the Louisiana Department of Wildlife and Fisheries (LDWF), and the U.S. Army Corps of Engineers that began in 1983. The area consists of 44,000 acres (180 km2), and is managed by the Louisiana Department of Wildlife and Fisheries. The complex is located in the Morganza Flood way system of the Atchafalaya Basin about 30 miles (48 km) west of Baton Rouge, Louisiana and actually extends a little south of the I-10 Atchafalaya Basin Bridge at Whiskey Bay, Louisiana. The bridge crosses the Whiskey Bay Pilot Channel. Located on the graveled LA 975, the west boundary is on the east side of the Atchafalaya River with the east boundary being the East Protection Levee. The complex stretches just north of old highway 190, and a short distance to the south of I-10. The nearest town is Krotz Springs to the north off US 190.

2011 Mississippi River floods

The Mississippi River floods in April and May 2011 were among the largest and most damaging recorded along the U.S. waterway in the past century, comparable in extent to the major floods of 1927 and 1993. In April 2011, two major storm systems deposited record levels of rainfall on the Mississippi River watershed. When that additional water combined with the springtime snowmelt, the river and many of its tributaries began to swell to record levels by the beginning of May. Areas along the Mississippi itself experiencing flooding included Illinois, Missouri, Kentucky, Tennessee, Arkansas, Mississippi, and Louisiana.

Birds Point-New Madrid Floodway

The Birds Point-New Madrid Floodway is a flood control component of the Mississippi River and Tributaries Project located on the west bank of the Mississippi River in southeast Missouri just below the confluence of the Ohio and Mississippi Rivers. The construction of the floodway was authorized by the Flood Control Act of 1928 and later modified by the Flood Control Act of 1965. Its purpose is to divert water from the Mississippi River during major flood events and lower the flood stages upstream, notably at Cairo, Illinois.

Mississippi flood of 1973

The Mississippi flood of 1973 occurred between March and May 1973 on the lower Mississippi River. The flooding was the third most severe along the U.S.'s Mississippi River during the 20th century.

West Atchafalaya Floodway

The West Atchafalaya Floodway is a flood control structure of the Mississippi River and Tributaries Project located in the Lower Atchafalaya Basin in south-central Louisiana. It has a project design flood flow capacity of 250,000 cu ft/s (7,100 m3/s).

Mississippi River Basin Model scale model of the Mississippi River basin

The Mississippi River Basin Model Waterways Experiment Station, located near Clinton, Mississippi, was a large-scale hydraulic model of the entire Mississippi River basin, covering an area of 200 acres. The model was built from 1943 to 1966 and in operation from 1949 until 1973. By comparison, the better known San Francisco Bay Model covers 1.5 acres and the Chesapeake Bay Model covers 8 acres. The model is now derelict, but open to the public within Buddy Butts Park, Jackson.

References

  1. McPhee, John (February 23, 1987). "The Control of Nature: Atchafalaya". The New Yorker. Retrieved May 12, 2011. Republished in McPhee, John (1989). The Control of Nature. Farrar, Straus and Giroux. ISBN   978-0-374-12890-6.
  2. Angert, Joe and Isaac. "Old River Control". The Mighty Mississippi River. Archived from the original on May 15, 2009. Retrieved 2011-05-12.. Includes map and pictures.
  3. 1 2 3 4 5 6 7 "Louisiana Old River Control Structure and Mississippi river flood protection". America's Wetland Resource Center. Loyola University's Center for Environmental Communication.
  4. 1 2 "Will the Mississippi River change its course in 2011 to the red line?". Mappingsupport. Retrieved May 8, 2011.
  5. Kemp, Katherine (January 6, 2000). "The Mississippi Levee System and the Old River Control Structure".
  6. "Low Sill Structure".
  7. "Old River Control Structure, Point Breeze, LA". www.johnweeks.com.
  8. 1 2 Piazza, Bryan P. (2014). The Atchafalaya River Basin: History and Ecology of an American Wetland. Texas A&M University Press. ISBN   978-1-62349-039-3.
  9. 1 2 "$500 Million (and Rising) to Contain a River". The New York Times. Associated Press. May 3, 1987.
  10. "Mississippi Rising: Apocalypse Now?". Daily Impact. April 28, 2011. Retrieved May 10, 2011.
  11. Daniels, Ronald Joel (2006). On Risk and Disaster: Lessons from Hurricane Katrina. University of Pennsylvania Press. p. 45.
  12. Masters, Jeff (May 9, 2011). "Mississippi River sets all-time flood records; 2nd major spillway opens". Weather Underground. Retrieved November 11, 2017.
  13. "Mississippi River at Red River Landing (01120)". United States Army Corps of Engineers. May 7, 2011. Archived from the original on September 27, 2011. Retrieved May 10, 2011.
  14. "Daily State and Discharge Data - Water Control - New Orleans District". U.S. Army Corps of Engineers. Archived from the original on May 14, 2004. Retrieved May 10, 2011.
  15. Rioux, Paul (May 14, 2011). "Morganza Floodway opens to divert Mississippi River away from Baton Rouge, New Orleans". NOLA.com.
  16. "Morganza Floodway will not be opened, Corps of Engineers decides".

External sources

Coordinates: 31°04′36″N91°35′52″W / 31.0768°N 91.5979°W / 31.0768; -91.5979