Louisiana has a long history of major floods. These are driven by Mississippi River floods, extreme rainfall events, and hurricane surge. There was a heavy rain event in March 2016 in the Shreveport area with major flooding. The Amite River Basin Flood Tracking Chart shows the history of flooding on Amite River, which is the major watershed draining this area. More than 30 years ago, a major rain event flooded much of the same area as the August 2016 flood. The 1983 flood was not as deep and did not flood as many houses, but was a harbinger of the August 2016 flood. The key question is whether the August 2016 flood was due to a freak rainstorm and could not have been anticipated, or whether it was largely foreseeable due to changes since the 1983 flood.
Coastal regions around the world are struggling to adjust to the gradual but relentless encroachment of ocean waters caused by climate change. The New York metropolitan area, with 23 million residents and some 3,700 miles of tidal coastline, faces a severe threat from sea level rise, yet relatively little has been done to address the inevitable permanent inundation of buildings, infrastructure and communities.
Permanent flooding from sea level rise is different than the intermittent flooding from storm surge or precipitation. Intermittent flooding recedes once a storm passes while sea level rise flooding is permanent and can be expected to encroach further inland over time. Sea level rise not only permanently alters the coast line. It also widens the area vulnerable to storm surge.
This report identifies the places in the New York, New Jersey and Connecticut metropolitan area that are most at risk of being permanently flooded, and describes the effects of 1, 3 and 6 feet of sea-level rise on neighborhoods, employment centers and infrastructure. Taking into account the latest scientific findings on sea level rise and climate change, the study finds that many of the major resilience policies, plans and projects under development today fall short of adequately addressing the long term, existential threat of permanent flooding from sea level rise.
This map only shows land as lost when it is turned to open water. There are large areas of land, such as the area east of New Orleans, that have lost most of their elevation since 1956, but are still just barely above water. They will disappear from the map as go below water, creating the impression of sudden land loss when the reality is that a long term process of subsidence. If you fly over the area or try to walk on this land, it is clear that it is already lost and is just awaiting the final death of the marsh to disappear into open water.
The U.S. Environmental Protection Agency has reviewed the U.S. Army Corps of Engineers’ September 2016 Millennium Bulk Terminals – Longview Draft Environmental Impact Statement (Corps DEIS), (EPA Region 10 Project Number: 13-0034-COE). We conducted our review according to EPA’s responsibilities under the National Environmental Policy Act (NEPA) and Section 309 of the Clean Air Act. Section 309 specifically directs the EPA to review and comment in writing on the enviromnental impacts associated with all major federal actions. Our review of the Corps DEIS considers the expected enviromnental impacts of the proposed action and whether the EIS meets the procedural and public disclosure purposes of NEPA. For the reasons described below, we are rating the Corps DEIS “3” – Inadequate.
A visualization of century-scale impacts of subsidence and sea level rise as seen in a time sequence reconstruction at Fort Proctor in St. Bernard Parish, Louisiana
by Chris McLindon
Fort Proctor is a pre-civil war military installation on the shore of Lake Borgne southeast of New Orleans. Historical records state that the fort was constructed 150 feet inland from the shore of the lake just north of the mouth of Bayou Yscloskey. This was also the site of Proctorville, a rail depot at the terminus of the Shell Beach Branch of the New Orleans and Gulf Railroad, which ran along the east bank of the Mississippi River to the town of Poydras, then down the natural levees of Bayou Terre aux Boeufs, Bayou La Loutre and Bayou Yscloskey to the shore of Lake Borgne.
While it can logically be assumed that the original elevations of the fort and the railroad depot were necessarily at least a few feet above sea level, neither of the architectural studies of the fort conducted by Tulane or Louisiana State Universities appear to include any definitive values for the land elevation at the time of construction. The fort is about 1,000 feet from the Shell Beach Continuously Operating Reference Station (CORS) of the National Geodetic Survey. This station is a part of the Global Navigational Satellite System that provides data for the three-dimensional Global Positioning System (GPS) network. In addition to surface positioning data this station provides a measurement of the vertical movement of the earth’s surface, which in this case can be used to estimate a rate of subsidence.
The objective of this project was to develop and test a risk-based methodology to evaluate threats to critical installation assets and quantify the potential loss of mission performance when installation capabilities were impacted by a combination of rising sea levels and coastal storm hazards.
Based on the analysis of NSN’s site-specific vulnerabilities, the project team found sea level rise to be a significant and pervasive threat multiplier to mission sustainability, significantly increasing loadings on built infrastructure, and dramatically increasing risks to system capabilities and service provisioning. Using the framework, the project team was able to identify several critical systems on the study site that were particularly vulnerable and likely to be incapacitated once sea levels rise above 1.0 meter on the site. The results show that the probabilities of damage to infrastructure and losses in mission performance increased dramatically once 0.5 meters of SLR was experienced, indicating a “tipping point,” or threshold, that should be considered when undertaking future planning or operational activities on the installation.
When buildings undergo repair or improvement, it is an opportunity for local floodplain
management programs to reduce flood damage to existing structures. More than 21,000 communities
participate in the National Flood Insurance Program (NFIP), which is managed by
the Federal Emergency Management Agency (FEMA). To participate in the NFIP, communities
must adopt and enforce regulations and codes that apply to new development in Special Flood
Hazard Areas (SFHAs). Local floodplain management regulations and codes contain minimum
NFIP requirements that apply not only to new structures, but also to existing structures which
are “substantially improved (SI)” or “substantially damaged (SD).”
Enforcing the SI/SD requirements is a very important part of a community’s floodplain management
responsibilities. There are many factors that local officials will need to consider and
several scenarios they may encounter while implementing the SI/SD requirements. This Desk
Reference provides practical guidance and suggested procedures to implement the NFIP requirements
This Desk Reference provides guidance on the minimum requirements of the NFIP regulations.
State or locally-adopted requirements that are more restrictive take precedence (often referred
to as “exceeding the NFIP minimums” or “higher standards”).
Most Corps of Engineers wetlands projects require the state or other non-federal sponsor to pay for part of the cost. This is both a cost-sharing measure and a measure to make sure that the state really needs the project – without a match, state politicians would demand unlimited projects from the Corps as economic development. Louisiana generally tries to avoid paying the match on projects, but unless Congress passes a law waiving the match on specific projects, the state has to pay for what has been done and nothing new will be done until the state pay’s the necessary match. This dispute arises from the push to close the Mississippi River Gulf Outlet canal after Hurricane Katrina.
The Trustees have reached a settlement with BP to resolve BP’s liability for natural resource injuries from the Deepwater Horizon oil spill. Under this settlement, BP will pay up to $8.8 billion for restoration.
Based on our thorough assessment of impacts to the Gulf’s natural resources, we selected the comprehensive, integrated ecosystem restoration approach for restoration implementation. This approach is outlined in the comprehensive restoration plan, which will allocate funds from the settlement for restoration over the next 15 years.
Katherine Bagley has written an excellent discussion of the repetitive loss problem in the National Flood Insurance Program, highlighting a Louisiana property that has flooded 40 times over the past four decades:
The NFIP was established by the National Flood Insurance Act of 1968 (NFIA, 42 U.S.C. §4001 et seq.), and was most recently reauthorized by the Biggert-Waters Flood Insurance Reform Act of 2012 (Title II of P.L. 112-141). The general purpose of the NFIP is both to offer primary flood insurance to properties with significant flood risk, and to reduce flood risk through the adoption of floodplain management standards.
An excellent post by Professor Craig Colten on the events leading to the August 2016 flood:
Reports of flooding in Louisiana may conjure up images of Hurricane Katrina, but these rivers are completely separated from the Mississippi River, and these floods posed no threat to New Orleans. Nonetheless, based on my experience studying risk and resilience in this region, I see parallels between the damage of current flooding and the damage caused by Katrina. In both cases, human decisions magnified the consequences of extreme natural events. Planning and permitting enabled development in areas that had experienced repeat floods, and agencies had failed to complete projects designed to mitigate flood damage before the storms hit.
The Federal Emergency Management Agency (FEMA) is proposing to amend 44 CFR part 9 “Floodplain Management and Protection of Wetlands” and issue a supplementary policy to implement the Federal Flood Risk Management Standard (FFRMS) that was established by Executive Order 13690.