AIR Worldwide

Major property damage, significant business interruption, and 13 deaths have resulted from extensive precipitation-induced flooding in southern Louisiana over the previous two weeks. In the event of further rainfall, the region’s flat topography, saturated ground, and already high river levels could result in additional flooding. At 10:53 CDT on August 24, 2016, two flood advisories and eight flood warnings remained in effect in Louisiana. The state of emergency is scheduled to remain in effect until September 10.

Waters are now receding, state offices have reopened, and many people have been able to return to their homes and businesses. The number of people in shelters has fallen from about 12,000 to about 3,000 and the focus is now on recovery.

Meteorological and Hydrological Summary

As discussed in AIR’s NewsALERT of August 16, the flooding was caused by a slow-moving tropical depression-like system that plagued much of south central Louisiana from August 8–15. With a steady cyclonic flow off the Gulf of Mexico, excessive tropical moisture streamed between Lafayette and Baton Rouge resulting in record-breaking rainfall totals. Some regions received as much as 15-30” over a two-day period.  For example, in Livingston Parish, the town of Watson received 31.39” of rainfall. Similarly, in White Bayou (East Baton Rouge Parish) 26.14” of rainfall was recorded.  As a result, some rainfall values were in the range of a 1,000-year return period in the parishes of St. Helena, Livingston, and East Baton Rouge just north and east of Baton Rouge. Parts of the region received two to four times the average total monthly rainfall for August in just three days. As the storm made its way westward, the heaviest rainfall moved with it, but localized downpours continued to plague the area through the weekend.

As a result of record breaking rainfall in a vast swath of more than 50 miles by 100 miles—covering Baton Rouge, Lafayette, and adjoining suburbs—historic crests at 12 of the 33 real-time river gauging stations of the USGS in Louisiana were surpassed. The very heavy rainfall in the watersheds of Amite, Comite, Tickfaw, and Tangipahoa rivers resulted in flood levels up to 6 feet over their previous historic records. The estimated flows at these flood levels correspond to 1,000–year return period (i.e., exceedance probability of 0.1%) riverine flood events individually at Amite river near Denham Springs, Comite river near Olive Branch, Tickfaw river at Montpelier, and  Tangipahoa river at Robert. River gauges at these locations crested more than 4 feet, 3 feet, 0.20 feet, and 3 feet higher than previously set historic highs in 1983, 1961, 1921, and 1974, respectively.

The historic flooding in and around Baton Rouge and other areas is a combination of several factors including riverine (on-floodplain) flooding, backwater in tributaries due to high flood stages in main rivers, and significant local flash flooding (off-floodplain) caused by intense rainfall, flatter terrain, and limited drainage capacity that was further exacerbated by backwater effects. Many of the areas that flooded were outside the 100-year floodplain and were not considered at high risk. The AIR Inland Flood Model for the United States explicitly models this off-floodplain risk, which represents a significant portion of historical loss because so many areas off floodplains can be prone to such damage and loss.

Impact to Industry and Exposure

Initial estimates from Louisiana’s Office of Homeland Security and Emergency Preparedness indicate that more than 60,000 homes have been damaged in the 20 parishes impacted. In Livingstone, 75% of homes are reportedly a “total loss.” A preliminary analysis for the nine parishes within the city of Baton Rouge issued by the local Chamber of Commerce (BRAC) on August 19 indicates that the Capital Region’s area of flood impact covers more than 1,000 square miles. This area alone contains 110,000 homes, 31% of which are located in areas identified as having been flooded. The total value of properties in these flood affected areas is estimated by BRAC to be USD 20.7 billion; 66% of them were owner-occupied, 22% were rented and 9% were vacant. The flood-affected area also contains an estimated 7,364 businesses—21% of the Capital Region’s total—together employing 73,907 individuals.

In the U.S., residential flood insurance is typically offered to homeowners only through the National Flood Insurance Program (NFIP). FEMA estimates that 42% of homes in high-risk areas of Louisiana have flood insurance, but that in low- and moderate-risk zones only 12.5% or so of homes do. Across Baton Rouge as a whole, no more than 15% of all homes have flood insurance, and in the other hard-hit location, Lafayette, the rate is 14%. In some areas, penetration is much lower. According to Louisiana’s insurance commissioner, Jim Donelon, the total number of policies in Louisiana rose to 490,000 in response to the devastation that followed Hurricane Katrina, but has since decreased to 450,000.

Commercial business can add flood as an endorsement to their property policy, although it is often subject to sublimits. The experience of Hurricane Katrina revealed that commercial insurers did not always have good information about their exposure to flood and, indeed, estimates of total industrywide insured flood values remain hard to obtain.

Because flood damage and associated losses can result from time-related elements (e.g., length of exposure to floodwater, how quickly mitigation is undertaken, and extent of business interruption) and vary greatly by exposure (e.g., physical location of utilities in a structure, construction materials used, and occupancy), the impacts to the insurance industry will become clearer as floodwaters recede and assessments can be conducted.

Recovery

Business Recovery Centers have already opened in Baton Rouge, Lafayette, Baker, Prairieville, Walker, and Amite, and Disaster Recovery Centers for the general population are opening in flooded areas as locations with appropriate parking and disabled access are identified. With so many people forced from their homes, the immediate need is temporary housing. A task force has been established by FEMA to identify options, and these reportedly include manufactured housing units that meet or exceed government certifications.

More than 110,000 people have already registered with FEMA for federal disaster aid. At least USD 20 million has been distributed in advanced payments to NFIP policyholders so far and the number of claims being submitted is climbing rapidly. For residents without flood insurance, short-term relief for immediate needs is available from FEMA, but the most available under the Assistance to Individuals and Households program is just USD 33,000 and few will be eligible for this maximum payout. At least USD 55 million to help survivors with temporary rental assistance, essential home repairs, and other serious disaster-related needs has already been approved. The flooding is clearly devastating, and it will take the region many years to recover.

Additional Resources

  • Story maps provided by the Louisiana’s Office of Homeland Security and Emergency Preparedness and Louisiana State University’s Stephenson Disaster management Institute
  • Esri’s Public Information Map, which offers continuously updated U.S. flooding information from the National Weather Service and real-time effects of the flooding via social media posts