Saying that the “perpetual cycle of disaster and recovery is not a socially, economically, environmentally or fiscally sustainable model,” Louisiana officials laid out a master plan to spend roughly $1.2 billion in federal funds to help ease flood risks.

Almost half of the money – about $571 million – is to be spent on local and regional projects and programs, the draft says. Another $328 million would be spent on state projects. Almost $97 million would help local governments pay their cost share for other federal programs. Nearly $48.6 million would pay for administration. The rest would be spent on mapping, monitoring and building local planning capacity.

Flooding in New Orleans during Hurricane Katrina. Source: FEMA/Jocelyn AugustinoThe state’s Office of Community Development released the plan. It said that beginning with Hurricane Katrina in August 2005, each of Louisiana’s 64 parishes has been included in a federal major disaster declaration as a result of a named tropical event.

In addition, the so-called Great Floods of 2016 — two rainfall events six months apart that affected wide swaths of the state — caused severe flash and riverine floods and led to major disaster declarations in 56 parishes.

Since 2005 the state has adopted stricter building codes, safer flood levels, and formed of the Coastal Protection and Restoration Authority (CPRA) to produce and regularly update the Coastal Master Plan. And after Hurricane Isaac in August 2012, with funds provided by the Department of Housing and Urban Development’s (HUD’s) National Disaster Resilience Competition, Louisiana created the Strategic Adaptations for Future Environments Program (LA SAFE) to create a resiliency-building model for communities.

(Read "As flood events increase, river towns take a step back.")

Permeable paving

Separately, the City of New Orleans was awarded $141 million through HUD for its proposed resilience district in Gentilly with projects to reduce flood risk, slow land subsidence and encourage neighborhood revitalization.

And in mid-September, New Orleans city council passed an ordinance requiring new surface parking areas to be built using water-permeable materials. The ordinance is intended to reduce stormwater runoff into Lake Ponchartrain and mitigate soil subsidence in the city. During heavy rainstorms the city's drainage system can become overwhelmed and result in local flooding. Porous surfaces will allow rain water to soak into the ground where it falls.

Under the new ordinance, concrete bases and mortar are prohibited from new parking areas. Permitted materials include pervious concrete, porous asphalt, aggregate if stabilized with a grid system that prevents compaction and washout and permeable pavement such as open-jointed blocks, pavers or bricks. Once in place, the paving is subject to water infiltration testing based on ASTM International C1701 or C1781 standards. Pavement must maintain a minimum infiltration rate of 200 inches per hour, the ordinance said.

New Orleans now requires new parking surfaces to be permeable in an effort to ease runoff concerns.Risk management

The state's plan for spending the $1.2 billion HUD grant said that the 2016 floods exposed the need to better manage riverine and flash flooding as a result of extreme precipitation events. The state identified regional watershed-based flood risk management as a way to address water management and avoid actions that may “unintentionally increase runoff or subsequent flooding."

The draft plan said that flood risk threatens the state’s natural and built environment, specifically:

• Wind and flood hazards, which are compounded by the effects of land subsidence and sea level rise. The plan said that these trends show that overall disaster risks “correlate statewide” and reinforce a conclusion that flooding remains a difficult-to-predict statewide risk.

• It said this difficulty is compounded when attempting to assemble future projections of risks because the state does not have the ability to accurately estimate the cost of long-term and repeated flood damage. As a result, future wind- and flood-related damages are "largely underestimated."

• These risks will continue to escalate in a warming world, where the frequency and intensity of tropical cyclones and severe thunderstorms are anticipated to increase.

• Both state and local hazard plans demonstrate that all of Louisiana is at a "severe flood risk," and that the occurrence of future catastrophic flood events "cannot be predicted solely by relying on the damage patterns of past events."

The state said it proposes to take a proactive pre-disaster approach that aims to accommodate the probability of future events occurring in any location in the state.

Widespread flooding occurred during two 2016 rain events. Source: Coast Guard photo by Petty Officer 1st Class Melissa Leake An entity known as the Louisiana Watershed Initiative would be used to develop and implement best practices in watershed management, including structural flood mitigation projects as well as long-term policies, practices and programs that may be used as national best practices for large-scale, comprehensive flood-risk management.

(Read "Hardening the energy coast.")

Grant award objectives

Broad objectives of the HUD grant award in Louisiana include:

• Developing real-time, high-quality hydrologic data and modeling as part of a statewide effort to establish and standardize a baseline understanding of flood risks;

• Utilizing best available flood risk and hydrologic modeling data to inform a statewide public education and outreach campaign, specific to the history and challenges associated with flood risk and resilience in Louisiana;

• Conducting large-scale regional and statewide floodplain management planning activities, utilizing a watershed management approach that incentivizes using the natural and beneficial functions of the watershed and its floodplains and builds on previous successful planning practices;

• Facilitating regional coordination within watershed boundaries to incentivize improvements in development decisions by anticipating upstream and downstream impacts within watersheds and at other spatial scales;

• Building capacity at statewide, regional and local levels in support of a comprehensive approach to watershed management;

• Incentivizing statewide economic growth in the resilience economy by investing in research, development, and implementation of tools that respond to global demand for flood mitigation techniques and new technologies; and

• Ensuring that these approaches and the gains associated with them remain the flood risk reduction standards for the state after funds from this allocation are expended.

The plan said that the state aims to use the federal housing grant to “fundamentally change Louisiana’s approach to statewide flood mitigation activities” including shifting development patterns, enhancing the public’s knowledge of flood risk and incentivizing activities that use the natural and beneficial functions of the watershed and associated floodplains. Actions, the plan concluded, should result in “reduced need for future flood recovery and mitigation resources.”