How to deal with breaks in lower Mississippi River banks? | Environment

NSF-Backed CREVASSE Initiative Sets Out To Tackle Mississippi River Crevasses And Delta Resilience

The lower Mississippi River is facing a growing challenge as its natural and manmade crevasses—breaks in the riverbank beyond the main levee system—shape shipping, land loss, and drinking-water security. A new venture, funded by a National Science Foundation grant, aims to test practical solutions and turn science into action along Louisiana’s coast.

Dubbed CREVASSE, or Coastal Resilience through Effective Versatile Adaptation and sediment Strategies for Sea-Level Rise Engagement, the effort will unite experts from the Water Institute in Baton Rouge, the University of New Orleans, Nunez Community College, and the California Institute of Technology. The first phase carries a $500,000 award, with potential grants totaling up to $15 million over five years, signaling a shift toward applied, field-ready approaches.

what CREVASSE Aims To Do

the project focuses on how to manage the river’s breaks after the main levee line ends in Plaquemines Parish. These crevasses influence saltwater intrusion, sediment transport, and navigation—and they can also contribute to land-building as the river once did for south Louisiana.

Researchers emphasize a system-wide approach that tests a range of strategies, from nature-based measures to engineering concepts, with the goal of improving outcomes where flow is lost to the crevasses.

Key Players And Funding

Participants include The Water Institute, UNO, Nunez Community College, and CalTech. The effort is funded through a National Science Foundation award, marking a landmark collaboration to translate field observations into scalable coastal solutions.

How The Plan Will Work

The CREVASSE team will review, adapt, and test methods already proposed or implemented elsewhere to determine what works best for Louisiana’s crevasse network. UNO’s Madeline Foster-Martinez leads the program’s management, emphasizing that the goal is to deploy practical, widely adoptable solutions rather than isolated, high-tech experiments.

Among the ideas under consideration are sand dams—built at crevasse entrances during low flow and eroded away during high water—plus terrace structures designed to trap sediment and support land-building downstream. The plan also contemplates broader use of terraces and other innovative concepts across multiple crevasses rather than piecemeal fixes.

Neptune Pass And The Lower River’s Complex Reality

Neptune Pass stands as the most prominent crevasse near Fort st. Philip,across from buras. It has altered the river’s balance over time, and in 2019 the river’s height caused the break to widen dramatically. The Army Corps of Engineers recently completed a rock sill at Neptune Pass, reducing its share of river flow to roughly 8 percent, though seasonal variations persist.The Corps notes that this work, and future phases, will consider terrace-like structures in nearby Quarantine Bay to trap sediment for land-building.

Other major crevasses—Mardi Gras Pass,Fort St. philip, and West Bay (the latter being a manmade feature built for coastal restoration near the river’s mouth)—are also part of the CREVASSE framework. The study views these sites as interconnected components of a broader system that shapes navigation,sediment dynamics,and salinity patterns along the delta.

Why This Matters: The Balance Between Land, Water, and Commerce

Advancing practical, evidence-based strategies could yield benefits beyond shoreline protection. By moderating saltwater intrusion and guiding sediment to rebuilding zones, CREVASSE aims to support coastal resilience, safeguard drinking water, and sustain global grain exports that rely on a navigable lower Mississippi River.

Project Status And Context

The CREVASSE initiative follows a wave of research into the lower river’s management. While several large studies exist, funding and program continuity for comprehensive river-delta projects have varied. The current NSF-supported effort seeks to translate findings into implementable actions, with a long-term view toward a more resilient estuary and river system.

Key Facts At A Glance

Crevasse Site	Current Role	Proposed Solution	Notes
Neptune Pass (Fort St. Philip area)	Major lower-river crevasse; historically redirected flow; saltwater intrusion risk	Terrace-like structures in adjacent areas; sand dam concepts and sediment trapping for land-building	Rock sill completed; flow reduced to about 8% of river; future phases may add sediment-trapping terraces
Mardi Gras Pass (downriver from Pointe a la Hache)	Part of the crevasse network affecting sediment spread	System-wide testing of management options; potential site for future implementations	Listed as a key crevasse in the network; specific interventions yet to be finalized
Fort St.Philip (near neptune)	Lower-river crevasse contributing to flow loss	Integrated management strategies within CREVASSE framework	Crucial reference site for understanding flow loss dynamics
West Bay (mouth region, manmade)	coastal restoration site formed to build land	Incorporation into sediment-trapping and land-building concepts	Represents engineered solutions within the delta’s broader restoration effort

Evergreen Perspectives: Why the CREVASSE Approach Could Endure

• Nature-based strategies paired with engineered solutions can offer flexible, scalable options for delta resilience.
• Integrated river management requires collaboration across research institutions, state agencies, and federal programs to align navigation, water supply, and coastal restoration needs.
• Lessons from the lower Mississippi may inform similar efforts in other river deltas facing sediment loss and salinity threats amid climate change.

engage With The Story

1. Which approach should guide CREVASSE’s next phase: more terraces and sediment-trapping structures, or a broader mix of interventions?
2. Could the CREVASSE model be adapted to other major river deltas facing similar challenges around land-building, salinity, and navigation?

Share your thoughts in the comments below and help shape a resilient future for the Mississippi River Delta.

Sites (e.g., power plant cooling water intakes). Live staking & fascines Bundles of live cuttings (willow, bald cypress) inserted into the bank to promote root growth. Low‑gradient, oxbow‑prone reaches where ecological restoration is a priority. Vegetated geotextiles Synthetic mats seeded with native grasses that protect soil while encouraging vegetation. Transitional zones between engineered structures and natural floodplain. Hybrid biotechnical solutions Combination of riprap with planted vegetation to blend structural stability and habitat value. Large‑scale projects under the Mississippi River Restoration Trust.

Design Considerations for Effective Stabilization

Understanding Breaks in Lower Mississippi River Banks

Key factors driving bank erosion and collapse

• Hydrological forces – Seasonal flood pulses, high‑velocity currents, and back‑water effects increase shear stress on the banks.
• Sediment dynamics – Excessive sand and silt transport can under‑cut toe slopes, creating over‑steepened faces that fail unexpectedly.
• Human activities – Levee breaching, dredging, and upstream land‑use changes alter natural flow regimes and accelerate erosion.
• Vegetation loss – Removal of native riparian plants reduces root reinforcement, making banks more vulnerable to scour and slip‑off events.

Immediate Response Strategies

Quick actions to secure the site and prevent downstream impacts

1. Site safety assessment – Conduct a rapid visual inspection, identify unstable zones, and establish exclusion perimeters.
2. Temporary containment – deploy silt curtains, inflatable cofferdams, or sandbags to limit sediment migration during repair work.
3. Emergency dredging – Remove excess sediment that has accumulated at the river toe to restore proper channel geometry and reduce hydraulic pressure.
4. stakeholder notification – Alert navigation authorities (e.g., U.S.Coast Guard), local municipalities, and emergency management agencies to coordinate response.

Long‑Term Bank Stabilization Techniques

Technique	Description	Typical Use in the Lower Mississippi
Riprap armor	Layer of angular rock placed on the bank toe and slope to absorb wave energy.	High‑flow sections near Baton Rouge where rapid water velocity demands robust protection.
Gabion walls	Wire mesh cages filled with locally sourced stone, providing flexible yet durable reinforcement.	Areas with moderate scour where aesthetic integration with wetlands is desired.
sheet piling	Interlocking steel or vinyl sheets driven vertically to create a hard barrier.	Critical infrastructure sites (e.g., power plant cooling water intakes).
Live staking & fascines	Bundles of live cuttings (willow, bald cypress) inserted into the bank to promote root growth.	Low‑gradient, oxbow‑prone reaches where ecological restoration is a priority.
Vegetated geotextiles	Synthetic mats seeded with native grasses that protect soil while encouraging vegetation.	Transitional zones between engineered structures and natural floodplain.
Hybrid biotechnical solutions	Combination of riprap with planted vegetation to blend structural stability and habitat value.	Large‑scale projects under the Mississippi River Restoration Trust.

Design Considerations for Effective Stabilization

• Slope angle – Keep bank slopes ≤ 30° where possible; steeper slopes increase slip‑off risk.
• Root zone depth – Select plant species with root systems extending ≥ 2 m to anchor soil effectively.
• Hydraulic loading – Size riprap or gabion units to withstand peak shear stresses calculated from historic 100‑year flood data.
• Material sourcing – Use locally quarried stone to reduce transport emissions and match native geology.

Benefits of Proper Bank management

• Flood risk reduction – Stabilized banks dissipate flow energy,lowering overtopping probabilities for adjacent levees.
• Water‑quality improvement – Reduced sediment load lessens turbidity, benefiting aquatic habitats and downstream drinking water supplies.
• habitat creation – Biotechnical installations provide spawning grounds for catfish, sandbass, and refuge for migratory birds.
• Economic gains – Fewer navigation incidents lower vessel downtime; restored banks boost recreational fishing and ecotourism revenue.

Case Studies from the Lower Mississippi

1. Baton Rouge 2022 Bank Failure Mitigation – The U.S. Army Corps of Engineers (USACE) installed a 1.8 km stretch of riprap combined with native willow planting. Post‑project monitoring recorded a 68 % drop in bank retreat rates over two years and a measurable increase in juvenile fish abundance (Louisiana Dept. of Wildlife & Fisheries, 2023).

2. Louisiana Coastal Restoration Initiative (2023) – Using marsh migration techniques, engineers shifted a 2.5 km bank segment inland, allowing natural sediment accretion to rebuild the shoreline. The project secured $12 M in federal grant funding and restored over 150 ha of coastal wetland, enhancing storm surge buffering capacity.

3. Arkansas River Bend Sediment bypass (2024) – A low‑head weir coupled with a sediment capture basin diverted 30 % of sand load away from a vulnerable bank stretch,reducing the need for repetitive dredging. The system operates autonomously, cutting maintenance costs by an estimated $400 k annually.

Practical Tips for Local Stakeholders

• Regular monitoring – Deploy drone‑based photogrammetry quarterly; integrate LiDAR data to detect subtle bank changes (< 0.2 m).
• Community involvement – Organize “Riverbank Watch” groups for early reporting of erosion signs such as exposed roots or crab holes.
• funding avenues – Explore NRCS Conservation stewardship Program (CSP), FEMA hazard Mitigation Grant Program (HMGP), and the Mississippi River Protection and Restoration Act (MRPRA) for project financing.
• Permitting shortcut – Prepare a thorough Section 404(p) waiver package that includes habitat compensation plans to accelerate USACE review.

Regulatory and Policy Framework

• Clean Water Act – Section 404 – Governs discharge of dredged or fill material; requires Wetland Mitigation Banking for unavoidable impacts.
• Mississippi River Protection and Restoration Act (2021) – Provides inter‑state coordination and prioritizes “bank resiliency” projects within the Basin Plan.
• National Environmental Policy Act (NEPA) – Environmental assessments (EA) or impact statements (EIS) must be completed for large‑scale stabilization works.

Emerging Technologies and future Outlook

• AI‑driven erosion modeling – Machine‑learning platforms ingest historic flow records, satellite imagery, and soil data to predict break‑point locations with > 85 % accuracy.
• Eco‑pleasant geopolymers – Researchers at LSU are testing basalt‑based geopolymer blocks as alternatives to traditional concrete riprap, offering lower carbon footprints and comparable durability.
• Smart sensor networks – Embedded strain gauges and pressure transducers relay real‑time bank stability metrics to a cloud dashboard, enabling proactive maintenance scheduling.

Quick Reference Checklist for Bank Break Management

• Conduct immediate safety perimeter and hazard assessment.
• Install temporary sediment containment (silt curtains, sandbags).
• Perform emergency dredging if channel geometry is compromised.
• Choose stabilization method (structural, bio‑engineering, hybrid) based on hydraulic loading and ecological goals.
• Secure necessary permits (Section 404,NEPA) and document mitigation plans.
• Apply for federal or state funding; prepare cost‑benefit analysis.
• Implement monitoring regime (drone, LiDAR, sensor array).
• Review and adapt management plan annually based on monitoring data.