RAPID RELIEF:

GPS Helps Assess Mississippi River Flood Damage

Harry BoHorff

U,S, Army Corps of Eng ineers

Kenneth J. MacSw on

Photographer

Harr), llo/torff ;,1' thl! pmjecl II/(II/{fgl!r {flltl cOli/pilfer .ry,HCm.f

coordirwtor \I';th the U.S, Army COIl,.I'Oj ElIgill t!t'I"s. P/(lJlllill~

DiI'i,I'i(lI/ , \Va/t!n\'(/y,\' Braru:h, Rock Islarul Di,I'trier, Rodi. /JlwuJ, IfliltoiJ, nil! Jl/il/oi.\' Mi,ui,uipp; Ril'er flooding W{/S hi,r jim pmject /lsil/g GPS l>'ill, GIS.

ometimes the cnonnily of a natura l disaster is best understood not by the huge es timates of loss and damage. but by

events in one small town. In last year's Mississ ippi

River floods more than 13 million acres noDded wi thin a rive-slale area; crop losses were es timated in the bi ll ions of dollars; and total loss - includ­ing crop, levee structure, and equipment - is now ex pected [0

far exceed that amount. But what happened in tiny Valmeyer, Il linois, a farming lawn about 20 miles southeast of S1. Louis, Missouri, says it all.

The town, situated in <I

Mississippi River vall ey, was home to about 900 residents, some of whom had experienced fl ood waters before, but nDlhing close to the lorrcnllhm COI1-sumed more than 70 percent of the town '5 600 structures.

SOOI1 after the flood waters began receding in laiC August, res idents were allowed back into

thei r community - not to li ve. but to start thc cleanup, pumping watcr fro m their basements, clearing river Illuck and mud from inside their hornes. and sal vaging what little they could from thei r few remaining personal possessions.

On an individual basis, Valmeyer farmers los t ent ire crops; the local convenience store closed for lack of business; and severa l res idents assuming a total loss, pu lled up stakes, and relocated to ci ties and towns unaffected by the flood.

"People can' t put their lives on hold forever" was an attitude held by many. They and untold thousands of people were anxiously waiting for fast word from their local building inspec­tors and the federa l government indica ting if they could Slay in the ir homes and communities and rebuild, or if they had to gather wlmt was left and leave the arca altogether.

In Valmeyer, the damage was so substuntialthat many res i-

MaTch 199.4 GPS WOR!D 23

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The town of Hannibal, Mis­souri, (top photo) is sub­merged by the Mississippi

River's floodwaters.

Darold Berube inputs data on a handheld receiver while conducting assessments of flood damage in Valmeyer, Illinois.

24 GPS \VORlD Marc~ 1 99~

dents figured they would either have to mise their homes and businesses (0 the required level set by the Federal Emergency Management Agency (FEMA) to keep their flood insurance, or abandon the town in hopes of moving it elsewhere. As time passed and the futures of hun-

dreds of individuals lay in limbo, the patience of many rcceded far quicker than the water that had turned their lives upside down.

ASSESSING THE DAMAGE In November 1992, FEMA had experimented with a new type of disaster damage assessmenl. Crews cOnlrJcted by the agency surveyed areas in Florida damaged by Hurricane Andrew as an experimenl using GPS, GIS, and cartographic mapping to see if this advanced system could more efficientl y inventory the damage than manual assess~ ments used until then. Prior to GPS and GIS, FEMA represen­latives conducted house~by~ house interviews to estimate damages.

The results of that preliminary study were encoumging, and, during the following summer when it became obvious that the Miss issippi nood damage was extensive, the new process was again employed by FEMA to

begin a series of damage assess­ments starling in the upper northwest Illinois cQunties bordering the ri ver.

FEMA formed a tea III with the U.S. Army Corps of Engi­neers, Rock Island District, which had a GIS, and a private contractor to the corps that had a

GPSIGIS system to produce maps needed for disas ter response, recovery efforts, and risk mitig:ltion.

FEMA's Nat ional Flood Insurance Program develops maps of any area considered at risk for noods. Flood Insurance Rate Maps (FIRMs) show areas within 100- and SOD-year nood zones of watcnvays. If a commu­nity participates in the National Flood Insurance Program, they are not allowed to have any development below the I DO-year flood elevation. Building and zoning officials use the maps to minimize the risk of future flood damage. and insurers also use them to estimate risk.

FIRMS at several veering scales of size (for example, one inch equals 1,000 miles, or one inch equals 500 miles, and so on) have been developed over the past 25 years and arc pcriodi~

cally updated as necessary by different engineering teams using many base maps. Some

base maps appear to be deri ved from enlarged parts of U.S. Geological Survey maps. TIIis information, along with the damage asscssments made in Illinois counties straddling the Mississippi, had to be digitized, gcorcrerenced. and integmted with FIRMS in a GIS that could display the data and produce maps showing the location of the damaged structures in relation to other landmarks. GPS was incorporated to expe­.dite mapping the Illinois Missi, sippi River nood zone by collect ing geodetic coordin.lles of specific points within the affected areas.

GPS, GIS TO THE RESCUE The team began producing map of the fl ood-tom Illinois countu bordering the Mississippi. GPS was employed for coordinate control , and the mapping soft­ware was used for data collec­tion, ed iting. cOllversion for USf

in the corps 's GIS and for map production, display, and query.

Initial observations of Oood! dwcllings, farm structures, and other areas of interest to FEMA and tbe corps were made by helicopter in Inte July 1993. A six-channel GPS receive r had previously been installed in tho helicopter for use during OpCIl lion Desert Storm. The crew rccorded geodet ic locations, types of structures , number of structures in n cluster, and apparent water depth. These observations were made using, GPS/GIS mapping system on I notebook PC in combination with the GPS receiver already onboard. They also videotaped and snapped digital and film photographs of selected arcas and sll11ctures. While airborno. observers cou ld follow the waterline up along tributaries and around curved banks. Tb~ could also track levee breaks b tracing the nctuallevee lines al by noting in the Illilpping son­ware the start and end of each break.

FEMA also needed maps ~ ind iv idual stl11ctures that mig.b have sustained nood damngc estimated at more than half tl, va lue.

INSPECTING THE FLOOD system. Differential correction of outstanding markers to usc for Residents float across town in Two learns, each with two the GPS positions WllS accorn- location purposes. Grafton, Illinois, a small observers (the private contractor plished by establishing a base We started recording our Mississippi River community and the nood- insurance adjuster, station atop the Clock Tower, the observations in the norlhem part north of St. Louis. representing FEMA), took to the Corps o[ Engineers headquarters o[ Ill inois and [ollowed the flood road in August to inspect and building at Rock Island, using an as the water receded enough to inventory structures in approxi- additional six-channel GPS work efficiently. There were mately 75 communities south of receiver and recording the times we had 10 wait a week or Quincy. The teams each used measurement data on a portable so to get in by car, but we could six-channel LJ , CIA-code PC. The dinerential correc tions usually get close enough to GPS/GIS handheld receivers were postprocessed daily. record some damage [rom the with embedded GPS/GIS Accuracies of I to 3 meters were car using a laser gun to measure conversion softwnre able to track nchieved in testing, and the distances.We also made observn-as many as six satellites. The repeatabili ty o[ locations lions on fOOl in areas inaccessi-GPS/GIS mapping system was observed during this project was ble to vehicles, which was the able to bui ld accurate GIS maps consistenl wilh those test results. exception nnd not the rule. and dntnbases nutomaticaJly with As the teams worked their way Teams recorded data on all real-time input o[ GPS satelli te south, temporary GPS base residential and commercial data directly to the GIS system. stations, providing local differ- buildings that met FEMA's The sort ware also allowed ential data, were set up on the guideli nes: structures nooded by multiple layers o[ attribute roofs of motels, where the teams more than I foot of water above information 10 be easily entered stayed at Quincy and Carbon- the main noar and located in in to the GIS database while da le, Il linois, and in St. Louis. communities wi th 20 or more detailed field mapping wus The GPS component ensured bui ldi ngs. (FEMA set the accomplished simultaneously. accurate location of each struc- guidelines to include Illost of the

These teams inspected ture , city block, and community. structures in a limited amount of literally thousands of structures Often, as in Va lmeyer's case, time.) Each structure took about and entered over 1,600 structures some of a town 's structures were one minute to observe. The into the inventory mapping still submerged in WOlter, with no process consisted or entering

March 199<1 GPS IYORID 25 I

data, taking digital photographs, For Valmeyer residents, and automatically recording the information from FEMA and GPS coordinates through the local building ollicinls about t

GPS receiver and into a laptop fate of their IOwn couldn't l1a\' computer. come sooner. Even before n

After data were recorded onto waters had totally receded, computer disks, the disks were residents were finding out w delivered to the base station at it would take to rebui ld their the corps's Rock Island hcad- homes, businesses, and com quarters, where the learn con- nity. After learning the cost 0

verted its observations to a GIS staying put residents voted to

" formal and bcgan producing relocate their town to thc blu maps. These Jllaps were quickly about a mile away - a move placed in the hands of FEMA de- that wili cost about $25 milli cisionmakers. In turn , they began ironically, the town wi ll rei meeting with local building to an area that Va lmeyer pio-onicials and ci tizens throughout neers first seuled morc than iI

Illinois \0 advise them of avail- century ago. Back then, fann able assistance and whm was came down from the bluffs to required to rebui ld above the tend to their crops, bringing 10D-year flood elevation. enough food to stay a week iI

timc. DATA COLLECTION The local newspaper, The The diITerencc betwee.n using a Di.lpa(ch alld Rock Islalld A GPS/GIS system to develop also gave a nod to the town's maps and traditional methods of history, describing Valmcyer' data collection and damage situation this way: '"Towns assessmcnt is like night and day. are learning what their ances More than 1,500 maps/data knew all ulong: the river thaI shects - on a variety of blessed them with bumper c scales - were produced within a one year could crawl oul of i week of the initial data transfer banks to punish them the ncr to the Rock Island base stalion. But thanks in port to GPSIGI

) The same amount of work would technology, the decision to . have taken a team of 50 peoplc Valmeyer could be made be~ li temliy years to complete, the fick le river tumed on the considering that maps were hand again. drawn in the past and plotting would be on a singlc scale. ACKNOWLEDGMENTS GPS/GIS enabled a two-person The author would like to ext team to design countless maps of his special thanks to Eric all sizes, on a variety of scales, Berman of FEMA's Region generating substantial cost ollicc in Chicago, and Thad savings. Unlike Hurricane Mauney of GeoResearch, Andrew's victims, who waited Billings, Montana . • weeks or evcn months for directions, Illinois flood vic tims were given infonnation within Tile opillions e.rpressel/ ill II days about how to proceed, arlide are those of Ihe With because of the damage assess- lIlld do nut necessarily refle ment technology. views or policies of the U.S.

GPSIGIS damage assessment Army Corps oj Ellgineers, R technology is applicable not only Isla lid, I/Iillois. to floods but to earthquake, hurricane, lirc, and other natuml disasters, where response time is critical. In addition to producing maps, it can also show locat ions of hazards, roads, waterways, and possible siles for disaster relief centers. A long-tcrm bene- For pmdllct in/orlllmial/, 111m to lit is that oncc an arca has been 5H lIlItl Jel' ManufaclUfcrs. For mapped, a ready-made database (250 millillllllll), contact Mtlr)'

is availablc for future usc. MarkelillN Sel1·iceJ. (503) 343·/