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Spillway
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Levee

How does a Spillway work?

Spillways are used to control the flow of water downstream during major flooding events. Spillways do not relieve pressure from upstream areas but rather divert the flow of water away from the downstream systems, reducing risk of flooding in those areas..

How does the USACE New Orleans district get weather forecasts?

From the National Weather Service

What are the biggest impacts on the local river conditions?

Rainfall in the upper Midwest.

What is the difference between a sand boil and seepage?

Sand Boils occur when the pressure of a high river on the soil layer of the levee exceeds the accepted conditions causing the water to ooze to the surface of the levee. The sand/soil of the levee will bubble or “boil” hence the name. Seepage occurs when the water of the river flows away from the channel and below/through the levee.

What is the difference between river levees and hurricane levees?

River levees are used to protect against overflow of river waters and run parallel to the river. Hurricane levees' primary objective is to divert waters from specific areas/cities during a storm surge. The hurricane levees and river levees often work collectively; however, a hurricane levee is used to protect cities from flooding during a storm surge.

Slide show

Mississippi River
The Mississippi River is the main stem of a network of inland navigable waterways which form a system of about 12,350 miles in length. These waterways connect America’s heartland to the global economy through deep draft ports in South Louisiana.
West Atchafalaya Floodway
The Morganza and the West Atchafalaya floodways follow down on opposite sides of the Atchafalaya River until the end of the levee system along the Atchafalaya River is reached; there they merge into a single broad floodway that passes the flow to the Gulf through two outlets, Wax Lake and Berwick Bay.
Emergency Management
Under the National Response Framework, the U.S. Army Corps of Engineers is assigned as the primary agency for Emergency Support Function #3 – Public Works and Engineering. USACE assists the Department of Homeland Security/FEMA by coordinating federal public works and engineering-related support, as well as providing technical assistance, engineering expertise, and construction management to prevent, prepare for, respond to, and/or recover from domestic incidents.
Bonnet Carre Spillway
The design and construction of the Bonnet Carré Spillway was completed following the Great Flood of 1927. During operation of the spillway, materials suspended in the Mississippi River's water are deposited in the floodway and Lake Pontchartrain and Lake Borgne. In addition, the vast input of fresh water into these brackish and saline lakes has an immediate, short-term, adverse environmental effect.
Construction of the Morganza Floodway
A view of the nearly-completed Morganza Control Structure (September 1953).

Glossary

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Expand List item 24122Collapse List item 24122  Breach

When water breaks through the structure or levee

Expand List item 24138Collapse List item 24138  Carrollton Gage

Located outside the USACE New Orleans District, the trigger point for Phase I and Phase II flood fight events. Measures the height of the river based off of sea level, not river depth.

Expand List item 24126Collapse List item 24126  Complex Structure                

A single structure with multiple responsibilities. Example, a gated structure with pumps.

Expand List item 24139Collapse List item 24139  Flood Fight                

Phase I:

                                When the river is above 11ft at the Carrollton Gage.  Preliminary responses activate. Patrols of levees occur twice weekly. Construction within 1500ft of the levees must cease. However, waivers for construction are granted on a case by case basis.

 

Phase II:

                                When the river is above 15ft at the Carrollton Gage. Daily inspections of the levees are mandatory and all construction within 1500ft of the levees must cease, no exceptions.

Expand List item 24125Collapse List item 24125  Floodgate                

A gate that can be opened or closed to take in or discard water during a flood event.

Expand List item 24124Collapse List item 24124  Floodwall                

An artificial barrier used to restrain water that could rise to extreme/unusual levels. Serves the same function as a levee but with a reduced footprint.

Expand List item 24132Collapse List item 24132  HESCO Basket

Steel wired baskets filled with sediment and sand used to help divert and prevent flooding during an event. Similar to a floodwall, only temporary.

Expand List item 24127Collapse List item 24127  Hurricane and Storm Damage Risk Reduction System (HSDRRS)      

Infrastructure systems that provide the New Orleans area with a 100 year risk reduction from a storm surge with a 1% chance of occurring.

 

Expand List item 24134Collapse List item 24134  Levee Armoring

 The use of Turf-reinforced mats and concrete slabs to strengthen the levee system for future flood events. Armoring increases the resilience of levees.

 

Expand List item 24154Collapse List item 24154  Levee Safety and Action Classification

Risk communication tool to identify risks associated with the levee systems. Levee safety program developed to balance and inform assessment of levees within the program. Goal is to evaluate and prioritize levee safety decisions.             

 

Expand List item 24123Collapse List item 24123  Levee

A ridge of sediment and materials built to prevent overflow of a river or body of water

 

Expand List item 24135Collapse List item 24135  Mississippi River and Tributaries Project

Designed for flood control and features tributary basin improvements, levee/floodwall installments/upkeep, floodways, and channel improvements/enhancements.

 

Expand List item 24131Collapse List item 24131  Outfall Canals

Serve as a drainage conduit for much of New Orleans, usually from surge in Lake Pontchartrain and other major bodies of water.

Expand List item 24121Collapse List item 24121  Overtopping

The breaching of water over a levee or structure passing onto to low-lying areas.

Expand List item 24130Collapse List item 24130  Permanent Canal Closure and Pump Station (PCCP)

This station closes off the outfall canals.

 

Expand List item 24137Collapse List item 24137  Rain Flooding

Flooding caused by rainfall.

Expand List item 24140Collapse List item 24140  Seepage                

Trace amounts of water pushed under the levee via the pressure of the water. 

Expand List item 24136Collapse List item 24136  Southeast Louisiana Urban Flood Control Project

Reduces the risk of flood damages due to rainfall in Orleans, Jefferson, and St. Tammany parishes.

 

Expand List item 24133Collapse List item 24133  Super Sack                

Large sandbags often dropped from helicopters.

Expand List item 24128Collapse List item 24128  Surge Barrier                  

Specific type of floodgate that helps prevent a storm surge from flooding the area behind the barrier.

For example: The Inner Harbor Navigation Canal Surge Barrier in New Orleans East defends against surge from Lake Borgne entering into the IHNC.

Expand List item 24129Collapse List item 24129  West Closure Complex          

The largest pump station in the world. Used to protect West Bank homes from flooding events based on the HSDRRS standards. The structure gates can close off the Harvey and Algiers Canals from storm surge while pumping rainfall drainage from the canals to the other side of the structure.