Recalling the Storm, Preparing for the Future

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Ten years ago today, what was to become the costliest hurricane ever to strike the United States gave a preview of its destructive power as it blew over South Florida. 

New Orleans flooded by Hurricane Katrina.
New Orleans flooded by Hurricane Katrina.

Ten years ago today, what was to become the costliest hurricane ever to strike the United States gave a preview of its destructive power as it blew over South Florida. Just three days later, Hurricane Katrina struck Louisiana and Mississippi, becoming one of the five deadliest hurricanes in the history of the United States, resulting in at least 1,833 fatalities and about $108 billion in property damage.

USGS was heavily involved in the preparations for and subsequent recovery actions for Katrina. This week, during the 10th anniversary, we look back on what we saw, what we did, and what we learned during those tragic days in August, 2005.

Loss of Land, Loss of Protection

Satellite views of the Chandeleur Islands, showing storm damage.
Satellite views of the Chandeleur Islands, showing storm damage.

One of the key factors that drove the amount of damage that Katrina dealt was the loss of the coastal wetlands that had, for generations, been the primary shield for New Orleans and other coastal communities along the Gulf of Mexico. In 1994, USGS published the first of many studies documenting the loss of Louisiana’s coastal lands. Between 1932 and 2000, more than 1900 square miles of land was lost, either due to erosion or subsidence. For comparison, the entire state of Delaware is about 1,982 square miles.

The arrival of Hurricane Katrina and, less than a month later, Hurricane Rita did not help, erasing 217 additional square miles from Louisiana’s coast. USGS recognized the importance of monitoring the state of Louisiana’s coastal lands, and continues to do so today, releasing periodic updates to the land area change.

Rapid Response

USGS scientists help a woman onto a USGS boat.
USGS scientists help a woman onto a USGS boat.

One thing that often gets forgotten is that many of the Federal rescuers and emergency managers who responded to Katrina were locals, with friends and family affected. Thus, as Monday, August 29, wore on and the full extent of the damage became known, USGS scientists rushed to mobilize along with other Federal, state, and local responders.

USGS scientists load water onto a trailer for transportation to aid stations.
USGS scientists load water onto a trailer for transportation to aid stations.

USGS brought unique skills to the disaster recovery, including urban search and rescue efforts—the two Louisiana offices had boats and more than 30 years’ experience with navigating Louisiana waterways. And so USGS was able to successfully rescue 600 people from porches and rooftops in the New Orleans area, and bring food and water to thousands more.

A map of 911 calls processed for rescuers.
A map of 911 calls processed for rescuers.

It also soon became apparent that one of the biggest challenges was locating people who needed rescuing, especially when street signs were covered by floodwaters, as well as where the flooding was. USGS geospatial science rose to the challenge, processing 911 calls and providing up-to-date maps for emergency responders. This approach proved so successful it was replicated less than a month later when Hurricane Rita slammed into the southwest coast of Louisiana near the Texas border.

The Science of the SurgeA USGS scientist installs a storm tide sensor for Hurricane Rita, which struck less than a month after Hurricane Katrina.

A USGS scientist installs a storm tide sensor for Hurricane Rita, which struck less than a month after Hurricane Katrina.
A USGS scientist installs a storm tide sensor for Hurricane Rita, which struck less than a month after Hurricane Katrina.

The primary destructive factor from Hurricane Katrina was its storm surge, which is the floodwater pushed by a powerful storm like a hurricane. These tsunami-like waters have tremendous force, and can overwhelm natural and manmade structures alike.

Prior to Hurricane Katrina the USGS provided storm-tide data, nationally, through about 600 streamflow and water-level gauges that were operated in coastal waters and that supplemented NOAA’s National Ocean Service tide gauges.

Even with the combined networks, however, the coastal gauges were too scarce and too far inland to provide the detailed data needed to understand and predict massive storm surge, such as that produced by Hurricane Katrina. In addition, the gauges were highly vulnerable to damage from the storms. Indeed, Katrina destroyed most of the USGS and NOS gauges in the vicinity of its landfall.

In response, USGS developed three new gauge types:

  1. Rapid Deployment Gauge: RDGs provide short-term, real-time water-level and local meteorology data at locations critical to emergency managers. In fact, the first RDGs were helicoptered into New Orleans immediately after Katrina at the request of the U.S. Army Corps of Engineers so that they could more effectively monitor efforts to reduce the water in the flooded city.
  2. Storm tide Sensor: Storm tide sensors are non-transmitting submersible devices that USGS deploys in the days and hours immediately before a hurricane makes landfall. USGS rushed production of them and was able to field 33 in advance for Hurricane Rita’s arrival 26 days later.
  3. Wave Sensors: The wave sensor was introduced in order to document storm generated waves. This is essential information for development of better building techniques.

Effects on the Ecosystems

An aerial view of baldcypress swamps devastated by Hurricane Katrina.
An aerial view of baldcypress swamps devastated by Hurricane Katrina.

The most iconic images from Katrina’s devastation are the flooded streets of New Orleans and desperate residents being evacuated from rooftops or levees. But also important are the images of the coastal marshes and swamps, as well as the barrier islands in the Gulf, all of which are important ecosystems. In the months and years following Katrina, USGS scientists have been studying and monitoring these fragile environments, from the flood plain forests of the Pearl River to the Baldcypress swamps of Louisiana.

In addition, USGS aerial flights and satellite imagery showed the impacts to Louisiana and Mississippi’s barrier islands. This information proved important 5 years later during the Deepwater Horizon oil spill in determining where potential oil slicks might wash ashore.

Testing the Toxic Soup

Plume from New Orleans, La., floodwater effluent pumped into Lake Pontchartrain, La., as a result of the flooding of the city by
Plume from New Orleans, La., floodwater effluent pumped into Lake Pontchartrain, La., as a result of the flooding of the city by Hurricane Katrina.

Rumors and misinformation swirled around the devastation in New Orleans, and one of the most enduring was the “toxic soup” concern centering on the floodwaters sitting in New Orleans and flowing out to Lake Pontchartrain. As part of the water quality and sediment quality testing, USGS worked with EPA to analyze the waters in New Orleans and Pontchartrain.

Fortunately, USGS testing showed that Hurricane Katrina did not have an appreciable negative impact on the ecological health of the lake. In fact, most of the indicators demonstrated slight improvement in the post-Katrina survey.

The techniques that USGS honed during Katrina for rapid water quality and sediment quality testing have been put to good use in later natural disasters, including Hurricane Sandy and the 2013 Colorado flooding.

Looking to the Future, Learning from the Past

USGS continues to work within our communities to rebuild after natural disasters.
USGS continues to work within our communities to rebuild after natural disasters.

Hurricane Katrina left an indelible mark on Louisiana and Mississippi. Hundreds of thousands were directly impacted, and the region’s recovery work goes on. USGS scientists, as residents of those communities, continue to contribute to the rebuilding, and the lessons learned during that storm have informed our natural disaster responses, particularly regarding hurricanes.

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