Severe Weather, March 2016: Rapid Event Summary

Posted on March 11, 2016 By

  • Flash flooding across most of Louisiana along with parts of Texas, Arkansas, Mississippi, and Tennessee.

  • I-10 at Louisiana-Texas state line reopens after 60 hour closure.  

  • 6 fatalities reported and 2 people missing 

  • Over 5,000 people rescued from flood waters including swift water rescues

  • Estimated 18,000 homes suffer some degree of flood damage, consisting of 11,000 in Louisiana, 5,000 in Texas, and 2,000 in Mississippi. 

  • DisasterMap.net Estimate:  $1.2 billion in damage to structures, vehicles, and due to closure of I-10.

This page was last updated on April 19.

 

Event Description:

A severe weather system driven by an “atmospheric river” created a prolonged rain event that caused deadly and destructive flashing flooding in Texas, Louisiana, Mississippi, Arkansas, and Tennessee.  Parts of Louisiana received as much as 20″ of rain.  Additionally, prolonged onshore winds caused minor coastal flooding in Texas and Louisiana.  6 possible storm related deaths so far and an estimated 6,000 people have been forced from their homes.

 

Summary of Hazards:

Heavy rainfall induced flash flooding and coastal flooding.

Observed cumulative (March 4 – 11) rainfall amounts include:

– Nearly 22″ observed near Monroe, La
– Over 12″ observed in Covington, La and points north
– A large region in central Louisiana that experience 10″ or greater the inlcudes Shreveport, Monroe, and Natchitoches
– A major 5″ contour line covering a large region that includes Houston, the outskirts of Dallas, Memphis, and Jackon, Ms
– A second 5″ contour line that includes Baton Rouge, Slidell, Hattisburg, and McComb.

 

The cumulative precipitation maps shown below were generated by DisasterMap.net using data from the National Weather Service.  The 7-day cumulative precipitation map (CONUS) was downloaded for the March 4 – 11, 2016 period as a point shapefile.  From the point shapefile, a raster interpolation was completed and then contour lines were generated using the raster.  The processing and mapping was completed using QGIS.

The first map below shows the generated contours lines and the original NWS point dataset (at 50% transparency.)  The second map below shows the 5″ and 10″ contour lines with the original point dataset (filtered to only show values over 2″ and at 50% transparency) over a OpenStreetMap basemap (served by MapQuest.)

CumulativePrecip_Mar4-112016

 

CumulativePrecip_Mar4-112016_5&10inContour

 

 

 

Wind driven high tides extended from southern tip of Texas to the middle of the Florida panhandle.  3-4 ft tides measured in and between Galveston Bay and Bay St Louis.  Over 4 ft high tides were observed at two stations along the central Louisiana coastline.

TidalMap_NeedhamSource:  Hal Needham of Marine Weather & Climate and U-Surge.

DisasterMap.net’s Estimate of Impacted Populations:

This section presents the results of an initial attempt to estimate size of the population impacted by this event.  It is based on geoprocessing steps completed in a Geographic Information System (GIS).  It utilizes two hazards layers, rainfall contours and flooded areas, along with 2010 US Census population data.  It represents a rough estimate at a particularly moment in time.  The data contains uncertainties, and the methods while quick are imperfect.  In addition, this event continues to unfold.  The results are at best a rough estimate representing the particular moment in time captured by the hazard data.  

Using QGIS software, the 2010 US Census Demographic Profile 1 geodatabase was clipped by the 5″, 10″, and 12″ rainfall contours described above.  This procedure identified the Census tracts that experienced rainfall by these amounts or greater. For the clipped tracts it was then possible to sum the population and housing units.  Naturally, being within any of these contours does not necessarily imply direct flood impacts.  However, it does mean that indirect flood impacts, such power outages, isolation by waters, cut off from medical services, or work/employment impacts, are likely.  This is particularly true for the 12″ contour.

The table below summarizes the population and houses within each of Census tracts that overlapped the different contour lines, while the map shows these Census tracts color coded by population.

Within 12″ Contour Within 10″ Contour Within 5″ Contour
Total Population 453,773 891,344 8,974,962
Total Housing Units 203,600 404,204 3,774,001

CumulativePrecip_Mar4-112016_PopulationExposure

Applying a similar procedure using a flooded area polygon obtained from the Dartmouth Flood Observatory, it is possible to obtain an initial estimate of the population and homes located within Census tracts that experienced flooding.  For this early assessment, the “MSW_2016066_100W040N_3D3OT_V” flood zone shapefile was obtained from their repository, and then the Census DP1 layer was clipped by it.  The Dartmouth Flood Observatory provides continuous and global monitoring of floods using stream gauge and satellite data.  Their flooded areas shapefiles are produced through a land/water classification of primary MODIS satellite data, which has a 250 m spatial resolution.  Our steps identified Census tracts that overlapped with the flooded areas identified by Dartmouth.  Importantly, not everyone within a Census tract that overlaps the flooded areas actually flooded.  They may have an elevated home or the flood may be on the other end of their tract.  Still this provides a reliable early measure of the magnitude of the emergency response.

The table below summarizes the population and houses within each of Census tracts that overlapped the flooded areas identified by the Dartmouth Flood Observatory:

Within Census Tracts that Experienced Flooding
Total Population 2,166,501
Population Under 5 yrs Old 129,358
Population 85 yrs and Older 34,029
Total Housing Units 1,067,395
Occupied Housing Units 847,452
Owner-Occupied Housing Units 655,997
Renter-Occupied Housing Units 191,455

DartmouthFloodArea_PopExposure

Flood Data Source:

Citation: Brakenridge, G.R., Anderson, E., Kettner, A.J., Slayback, D. and Policelli, F., March 13, 2016, “Current Flood Conditions, MSW_2016066_100W040N_3D3OT_V “, Dartmouth Flood Observatory, University of Colorado, Boulder, CO, USA, http://floodobservatory.colorado.edu/.

DisasterMap.net’s Estimate of Economic Impacts:

DisasterMap.net estimates at least $1.2 billion in damage to homes, vehicles, and due to the closure of I-10.  This includes an estimated $900 million in flood damage to structures.

 

Flood Damage to Buildings and Contents

An estimated 18,000 structures have suffered flood damage. If the average cost of damage is $50,000 each, then the total direct damage to structures could reach $900 million. Additionally the contents of 18,000 homes also suffered flood damage. If they average $10,000 in contents damage per house, then that would total $180 million

Flood Damage to Vehicles

While flooded vehicles have been documented in media and social media, no estimate of flooded vehicles have been made available. In the absence of a ground based assessment, it is reasonable to assume that at least 6,000 vehicles flooded (1 for every 3 homes that flooded). If they averaged $10,000 in damage, then the total would be $60 million.

 

Cost of I-10 Closure

DisasterMap.net estimates that the I-10 closure will have an economic impact of the order $22.5 million, based on a 2.5 day closure and $9 million per day.

A Texas Department of Transportation and Development press release states that I-10 was closed on the morning of Wednesday, March 16.  At approximately 8 pm on March 18, the interstate reopened to traffic after the water receded and emergency repairs were made to the eastbound lane.  The interstate was closed for approximately 60 hrs.

(DisasterMap.net has previously assessed that “According the NWS river gauge nearest I-10, the Sabine river was at 7.36 ft at 9am on 3/16, approximately when the interstate flooded.  This gauge is forecast to remain at or above this height for approximately 55 hrs, or just over 2 days.”)

A study of two earlier interstate closures, due to flooding and an avalanche, found that the closures cost on average $9 million per day.  For a 4 day closure due to the flood, they found $47 million in economic damages,  $11.75 million per day.  For the 4 day closure due to the avalanche, they estimated $28 million, $7 per day.  Averaged, that gives $9 million per day.

 

Additional Damage not Estimated

In addition to the classes of damage described above, other types of known flood damage have not been tallied here. This includes crop losses, infrastructure (specifically a number of bridges, culverts, and roads are known to be damaged), and business and employment impacts. Additionally, emergency response and long term recovery costs have not been tallied.

 

Impact Reports:

 

Below is a summary of key impacts reported by the press and government agencies:

Major Disaster Declaration for Louisiana

Map of Declared Parishes

AP reports drowning deaths in Louisiana, 1 in Texas, and 1 in Oklahoma

AP reports at least four deaths in Louisiana

Weather Channel reports 6  flood related deaths

1 vehicular drowning in Bienville Parish, LA

2 fishermen missing from Claiborne County, MS

Evacuations in Southeast Texas as flood pulse moves down Sabine River 

12,500 people evacuated from flooded areas of Orange and Newton

LANG has rescued over 4,255 citizens and 354 pets

LANG rescues up to nearly 3,300 people and 316 pets

LDWF rescues 777 people

Louisiana National Guard rescues over 2,000 people

Louisiana Department of Wildlife and Fisheries rescues nearly 600 people

Louisiana tallies 11,000 flood damaged homes

Nearly 700 homes suffer major damage, another 4,500 damaged by floodwaters in Texas

Mississippi reports 1,600 affected by floodwaters and over 600 with major flood damage

Louisiana reports  6,143 structures have received flood damage across the state

Nearly 5,000 homes in Louisiana, 800 homes in Mississippi impacted by flooding

4,000 homes impacted by flooding in Bossier City, LA

Over 600 structure flooded in St. Tammany Parish, LA

Over 1,300 people rescued from flood waters in Louisiana

200 flood rescues in Hammond, LA

Nearly 1,000 homes flooded in Mississippi

Hundreds of homes flooded in Mississippi, 2 fishermen reported missing on the Mississippi River

40 shelters open at the peak

Over 100 people rescued in Bogalua, LA

Over 100 people rescued in and around Hammond, LA

50 people rescued from flood waters in Covington, LA

Approximately 50 homes evacuated in Chicou County, AK

Quachita River flowed backwards north of Monroe, LA

Rainfall causes sinkhole in Vicksburg, MS area

10 people rescued from flooded homes in Memphis, TN

Shelter population in Texas peaks 500 on March 15, 2016

Social Media from the Scene:

 

 

 

 

 

 

 

Stay Informed in Real time with DisasterMap.net:

 

Our homepage includes a Leaflet webmap with key hazard warning layers, and Full Size Map let’s you interact with the data to find out information specific to your location.  It also provides official warnings and guidance from the relevant government agencies through an RSS feed.  Our Twitter feed gives you reports, photos, and videos direct from the ground.  Follow us on social media to get updates.  We strive to bring you the sights and sounds of the impacted areas.

Capture03122016

 

Click the “View Full Size Map” to get to the fully interactive webmap, which include shelter locations.  Click one of the blue crosses to get the name, address, and capacity of any shelter that is part of FEMA’s National Shelter System.

Capture03122016b

 

Use our address search to view conditions for areas where you are concerned.  And, our real time traffic layer displays any roads closed due to flooding.

 

Capture03122016d

 

ArkansasCrisis MappingDisaster MappingDisasterMap.netFlash FloodFloodLouisianaMississippiSevere WeatherTennesseeTexas     , , , , , , , , , , ,


Leave a Reply