Report on Land Subsidence Impacting New Orleans Hurricane Protection System

Introduction

Recent scientific research has revealed that parts of New Orleans’ $15 billion hurricane protection system are sinking at rates exceeding sea-level rise caused by climate change. This finding has significant implications for the city’s resilience against flooding and extreme weather events, aligning closely with the United Nations Sustainable Development Goals (SDGs), particularly SDG 13 (Climate Action), SDG 11 (Sustainable Cities and Communities), and SDG 6 (Clean Water and Sanitation).

Key Findings on Land Subsidence

1. Using satellite radar measurements, researchers from Tulane University and the California Institute of Technology’s Jet Propulsion Laboratory identified land elevation changes along the Hurricane and Storm Damage Risk Reduction System (HSDRRS).
2. Floodwalls in certain areas are subsiding at rates up to 28 millimeters per year, which is up to ten times faster than the current rate of sea-level rise.
3. The HSDRRS, constructed post-Hurricane Katrina to protect against 100-year storms, faces long-term threats due to this subsidence combined with rising seas and wetland loss.

Implications for Sustainable Development Goals

• SDG 13 (Climate Action): The accelerated sinking of flood protection infrastructure underscores the urgent need for climate adaptation strategies to mitigate impacts of stronger hurricanes and rising sea levels.
• SDG 11 (Sustainable Cities and Communities): Maintaining and enhancing the resilience of urban infrastructure like levees is critical to safeguarding communities and ensuring sustainable urban development.
• SDG 6 (Clean Water and Sanitation): Effective flood protection supports water management systems that prevent contamination and protect water resources.

Causes and Variability of Subsidence

Subsidence in New Orleans results from both natural and human-induced factors:

• Some levee sections show stability, while others experience rapid sinking.
• Recent construction completion in 2022 may contribute to short-term settling effects.
• Long-term subsidence trends remain uncertain but pose potential risks when combined with climate change.
• Human activities, such as groundwater pumping near power plants, have caused localized subsidence, with some recovery observed after cessation of such activities.

Geographical Areas of Concern

• Floodwalls near Louis Armstrong International Airport in Kenner.
• Earthen levees in New Orleans East.
• St. Bernard Parish floodwalls on the East Bank.
• West Bank levees along the Mississippi River.

Management and Maintenance Efforts

The flood protection system is managed by two regional authorities:

• Southeast Louisiana Flood Protection Authority-East: Oversees the East Bank system and collaborates on levee raising projects.
• Southeast Louisiana Flood Protection Authority-West: Oversees the West Bank system, has funded levee lift programs, and is currently raising additional levee sections.
• The U.S. Army Corps of Engineers constructed the system and continues maintenance, recently repairing critical pumps to ensure functionality.

Wetlands Loss and Environmental Impact

Wetlands in St. Bernard Parish, serving as natural storm surge buffers, are also subsiding, threatening their existence. This loss impacts biodiversity and ecosystem services, relevant to SDG 15 (Life on Land) and SDG 14 (Life Below Water).

• Seasonal variability complicates elevation measurements in wetlands.
• Continued subsidence could convert wetlands to open water, reducing natural flood defenses.

Research Limitations and Recommendations

• Satellite radar measurements indicate elevation changes but do not determine causative factors.
• Minor elevation gains in some urban areas may reflect infrastructure changes rather than geological uplift.
• Researchers recommend ongoing monitoring and assessment to inform maintenance and adaptation strategies.

Conclusion

The findings serve as a critical reminder of the need for sustained investment in flood protection infrastructure and environmental restoration to achieve resilient and sustainable urban development in New Orleans. This aligns with the global commitment to the Sustainable Development Goals by addressing climate risks, protecting communities, and preserving natural ecosystems.

1. Sustainable Development Goals (SDGs) Addressed or Connected

1. SDG 11: Sustainable Cities and Communities
   • The article discusses the protection of New Orleans from hurricanes and flooding through levees and floodwalls, which relates to making cities resilient and sustainable.
2. SDG 13: Climate Action
   • The article highlights the impact of climate change, including rising sea levels and stronger hurricanes, and the need for adaptive infrastructure.
3. SDG 14: Life Below Water
   • The loss of wetlands and subsidence affecting coastal ecosystems is mentioned, which relates to conserving coastal and marine ecosystems.
4. SDG 15: Life on Land
   • The article touches on land subsidence and degradation of wetlands, which impacts terrestrial ecosystems and land management.

2. Specific Targets Under Those SDGs Identified

1. SDG 11: Sustainable Cities and Communities
   • Target 11.5: Significantly reduce the number of deaths and the number of people affected by disasters, including water-related disasters.
   • Target 11.b: Increase the number of cities adopting and implementing integrated policies and plans towards inclusion, resource efficiency, mitigation and adaptation to climate change.
2. SDG 13: Climate Action
   • Target 13.1: Strengthen resilience and adaptive capacity to climate-related hazards and natural disasters in all countries.
   • Target 13.3: Improve education, awareness-raising and human and institutional capacity on climate change mitigation, adaptation, impact reduction, and early warning.
3. SDG 14: Life Below Water
   • Target 14.2: Sustainably manage and protect marine and coastal ecosystems to avoid significant adverse impacts.
4. SDG 15: Life on Land
   • Target 15.1: Ensure the conservation, restoration and sustainable use of terrestrial and inland freshwater ecosystems and their services.

3. Indicators Mentioned or Implied to Measure Progress

1. Land Elevation Change Measurement
   • Radar measurements from satellites to monitor land subsidence rates (millimeters per year).
   • Monitoring the height of levees and floodwalls to assess flood protection system integrity.
2. Sea Level Rise Rate
   • Comparison of land subsidence rates with sea level rise rates to evaluate relative risk.
3. Wetlands Elevation and Condition
   • Measurement of wetlands elevation changes and subsidence to assess ecosystem health and storm surge buffering capacity.
4. Infrastructure Maintenance and Investment
   • Tracking investments and maintenance activities such as levee raising and pump repairs.

4. Table of SDGs, Targets, and Indicators

Source: nola.com