Major property damage caused by Louisiana floods

Extensive precipitation-induced flooding in southern Louisiana in the last two weeks has caused major property damage to an estimated 60,000 homes and over 7,364 businesses, as well as 13 deaths, according to AIR Worldwide.

While a state of emergency is scheduled to remain until September 10, waters are now receding and many people have been able to return to their homes and businesses.

Within the period of August 8 to 15, a slow-moving tropical depression-like system has affected south central Louisiana, with some regions receiving as much as 15 to 30 inches of rainfall of a two-day period.

“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,” said Hemant Chowdhary, principal scientist at AIR Worldwide.

“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 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.”

AIR said that US residential flood insurance is typically offered to homeowners only through the National Flood Insurance Program (NFIP), with FEMA estimating that only 42 percent of homes in high-risk areas of Louisiana have flood insurance.

AIR also stated that commercial business can add flood as an endorsement to their property policy, although it is often subject to sub-limits.

“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,” the catastrophe modelling firm said.

The impact to the insurance industry will become clearer as floodwaters recede and assessments can be conducted, as flood damage and associated losses can result from time-related elements such as the length of exposure to floodwater, AIR suggested.