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[NATURAL DISASTER] |
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The Great Flood of 1993 was said, in terms of economic and human impacts, to be the most costly and devastating flood to hit the United States in modern history. Nine states, more than 15 percent of the U.S. territory, were impacted at catastrophic levels. These states were Iowa, North Dakota, South Dakota, Minnesota, Wisconsin, Illinois, Missouri, Nebraska and Kansas. Losses ranged between $15-$20 billion, rivaling those of Hurricane Andrew. More than 50,000 homes were damaged or destroyed, with over 54,000 persons evacuated from flooded areas (see endnote #1). |
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Technically, it could be posited that the disaster's roots began during the wet fall of 1992, which resulted in above normal soil moisture and water storage conditions in the upper Mississippi and Missouri basins. These conditions were followed in the spring and summer months of 1993 by meterological patterns more typical of late winter patterns, which follow more northerly tracks, that result in persistent and intense storm systems. Beginning in March 1993, the broad extent of the storms dumped the Upper Midwest with extreme amounts of rainfall, with some areas receiving more than 4 feet of rain during those months. The massive build-up of water could be viewed in satellite imagery as the equivalent of a sixth Great Lake in the middle of the nation's heartland. Flooding would continue in some areas as until as late as September 1993. |
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During the flooding, a total of 95 forecast locations in the Upper Midwest would exceed all previous floods on record, sometimes by as much as six feet. Over 500 forecast points on the major rivers and tributary systems were to exceed flood stage. Hydrologists stated that there were five key factors that contributed toward the excessive spring snowmelt which flooded the upper Mississippi River basin: **high soil moisture, **deep hard ground frost, **heavy snowcover, **widespread heavy rains during a melt period, and **warm temperatures that led to rapid melting. (See endnote #2) |
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The flood affected many people's lives in some very basic ways. First, in a land overwhelmed by waters, there was the ironic lack of pure drinking water, as in the case of the city of Des Moines, Iowa where over 250,000 residents existed without drinkable tap water for a month. Water had to be shipped in from Chicago and given out through 50+ distribution points (see endnote #3). |
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Several rail lines were closed, including the Santa Fe Chicago-California line, the Burlington Northern, the Union Pacific Chicago & North Western railroad, and the Soo Line, causing major delays in freight shipments and operating losses in excess of $300 million. Manufacturing plant closures occurred in several areas when these needed freight shipments did not show up on time. In Iowa, it was found that over 300 of the state's 4,000 bridges could have possible structural damage. And in large areas inundated by the flood, there was more than 600 billion tons of topsoil erosion by the river flow, leading to a total loss of the 1993 harvest (see endnote #4). |
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Whole towns were almost erased, either never to be rebuilt, or to be moved to higher ground levels (see endnote #5). One of these was the town of Valmeyer, Illinois, a community of 900 people who were suddenly uprooted on the morning of August 2, 1993 when flood waters breached a levee just north of there. Completion of the relocation would take at least three years and would cost more than $16 million (see endnote #6). 6,000 people had to be evacuated in August 1993, in South St. Louis, when flooding threated a propane tank farm. 51 tanks, each containing 25,000 gallons of propane were floated off their supports and posed a danger of exploding (see endnote #7). On July 9, 1993, at the Deerfield Village Mobile Home Park in St. Charles, Missouri (a 40 acre park), 265 families were threatened when the Mississippi River jumped an agricultural levee. About 60 of these families had to move their trailers to parking lots on higher land at the local schools (see endnote #8). When the waters finally receeded, families all over the flood zone were discouraged by water and silt damage, thick mud residue, and the mosquitos and other insects that seemed to thrive in those conditions (see endnote #9). |
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In a normal flood plain which is unaltered by levees, floodwaters will spread out slowly, depositing silt and experiencing little erosion, while the undeveloped soils will absorb water like huge sponges to the point of saturation. But when a river is restricted by levees, floodwaters will swell upstream, with waters moving more swiftly, simultaneously cutting out deep channels and not allowing silt to build up to replenish erosion areas. Under unusual situations, as in the Great Flood of 1993, the extreme volumes of water might breach these levees. |
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The Army Corps of Engineers, responsible for 229 levee systems, were proud that only two of their systems were breached, even though 39 others were seriously damaged. Unfortunately, most of the problem levees that failed were privately built by farmer's cooperatives or municipalities. Of these 1,100 private levies, 70 percent failed. Repairs on these private levees would prove to take much longer than the Army Corps' to complete (see endnote #10). The difference in the failure rate was stated by NOAA as being due to the fact that most Federal levees were designed to withstand a 100-500 year flood, while the non-Federal levees, which mostly were used to protect agricultural lands, were only designed for a flood with return periods of 50 years or less. |
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The number of Army Corp owned levees which were affected by the flood were as follows (see endnote #11): |
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48 Illinois |
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17 Iowa |
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13 Kansas |
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1 Minnesota |
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112 Missouri |
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7 Nebraska |
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0 North Dakota |
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1 South Dakota |
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1 Wisconsin |
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------------------------- |
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200 Total Levies |
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Total Estimated Cost of repairs was $217,357. |
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The Natural Disaster Survey Report gave 106 recommendations based on an intensive study of the conditions found in all 9 affected states. The report noted several deficiencies that originated mainly out of inadequate technology within the current forecast and warning system. These deficiencies were proposed to be corrected through the on-going modernization and restructuring of the National Weather Service, and through a new program called the Water Resources Forecasting System (WARFS), which helps emergency managers to more effectively predict floods and manage the nation's increasingly valuable fresh water supplies (see endnote #12). Other areas of deficiency which were identified by the survey team (in the overall prediction and response system) "included inadequate computer processing and telecommunications capabilities, as well as problems associated with timely and complete dissemination of appropriate products (see endnote #13). |
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The Department of Commerce and the National Oceanic and Atmospheric Administration (NOAA) also stated in the report that they were committed to: "develop and to implement an advanced hydrolic prediction system for the entire Nation," and that improved decision making information for the Great Flood of 1993 alone "could have easily translated into savings of hundreds of millions of dollars through improved mitigation actions. Moreover, the associated human suffering could have been dramatically reduced with more timely, accurate and improved decision-making information" (see endnote #14). |
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This activity constituted a major component of the NOAA 1995=>2005 Strategic Plan, whose objectives were as follows (see endnote #15): |
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1. Reduce fatalities and injuries due to hazards from weather and floods; |
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2. Improve the flow of more accurate environmental data and predictions to the public; |
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3. Enhance the ability of planners to use hydrologic forecasts in the range of days to months; |
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4. Provide better information for management of fresh water resources; |
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5. Prevent avoidable damage to private, public, and industrial property over land, in coastal areas, and along rivers; |
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6. Improve efficiency, reliability, and savings in industry, transportation, agriculture, and hydro-energy systems. |
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Most of the deficiencies noted by the NOAA survey team resulted from "inadequate technological capabilities within the current forecast and warning system." The report stated that these identified deficiencies could be corrected through the implementation of modernization and associated restructuring (MAR) of the National Weather Service. In fact, a major recommendation of the team was that MAR must be maintained on schedule, "or accellerated wherever possible." One good example of successful MAR is the installed base of the Weather Surveillance Radar 88 Doppler (WSR-88D) systems installed previous to the flood event. On July 18, 1993 and on August 11-12, 1993, the WSR-88D systems were able to document the radar rainfall estimates in Chicago and Kansas City, which led to the saving of lives during each of those flash flood conditions (see endnote #16). |
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Maximum use of the WSR-88D currently awaits upon the completion of the Next Generation Weather Radar (NEXRAD) network over the upper Mississippi River basin, in addition to implementing the Advanced Weather Interactive Processing System's (AWIPS) capability under MAR. Of equal importance to "these technological enhancements are the advances in human resources" also planned under MAR, including training on modernized NWS technology and "advanced hydrometerological functions" as part of the Regional Forecasting Center operations" (see endnote #17). |
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The report stated that the key to developing improved river and flood forecasts in the future will depend on "establishing and maintaining an Advanced Hydrologic Prediction System (AHPS)." The current NWS River Forecast System (NWSRFS) consists of modules of software which function by 1) collecting data; 2) processing data; 3) modelling data; and by 4) providing output products. The four major components of a NWSRFS are: 1) data analysis procedures; 2) modules used to compute and display runoff and river discharges; 3) utility programs and databases which manage large volumes of data; and 4) an operational forecast program command language which allows the forecaster to define modeling options, to make adjustments to model state variables and data values, and to recompute forecasts (see endnote #18). One recommendation based on this was that the NWS Office of Hydrology should systematically re-evaluate the operational readiness of the NWSRFS and any other software used for hydrologic forecasting (see endnote #19). |
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NWS-MAR modernization would contribute to improve hydrologic prediction through:
1) on-site interactive computer processing that supports: "a modern, interactive river forecast system"; and interactive precipitation analysis using data from radar, satellite, aircraft, and automated surface gages; |
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2) rapid, wide-band communications; and |
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3) more effective use of human resources. Payoff in improved forecasts and warnings are projected to be enormous (see endnote 20). |
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Another major block of the AHPS capability will be provided by a Water Resources Forecast System (WARFS), which gives river forecasts with greater lead-times, forecast ranges, and probabilities of occurrences. WARFS accomodates these requirements by using: |
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1) advanced hydrologic and hydraulic models; |
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2) integrated data management and analysis techniques; |
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3) coupled rainfall and temperature forecasts; |
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4) advanced remote sensing and analysis of snow water equivalent; and |
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5) a consortium of cooperative efforts with NOAA's partners. |
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The most important enhancements will be in the application of "more advanced hydrologic and hydraulic models using improved hydrometeorological data and the capability to incorporate both short term meterological predictions and longer term, climatological information (see endnote #21)." |
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Further observations by the survey team were that the River Forecasting Centers and the National Meterological Center did not routinely archive their quantitative precipitation forecast products in digital format. It was noted that these data were essential for post-event analysis, research and development, model calibration, simulation requirements, climatological studies, and forecast verification. Therefore all data and products should be archived and made available digitally to end-users (see endnote #22). |
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The survey team also noted several instances where coordination and communication problems occurred associated with data exchange between Federal agencies (see endnote #23). Part of this was due to computer hardware limitations, which made it difficult to distribute NWS products to endusers. They pointed out that the overall effectiveness of the NWS's river forecasting services critically depended on other Federal, state, and local agencies for information used in forecasting and dissemination of forecasting and warnings, as well as to ensure that the public take actions necessary to prevent loss of life, etc. NWS was encouraged to maintain and strengthen cooperative arrangements with its current partners (see endnote #24). It was also noted that in some communities there seemed to be a lack of communication and coordination among different agencies. It was recommended that national, regional, and local NWS offices team up with Federal, state and local agencies to "coordinate more frequent communication to ensure that needed information is distrubuted among all agencies (see endnote #25). |
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In terms of computer aided telecommunications, the survey team found that the current telecommunications environment for interagency data exchange relied on "limited, voice-grade, two-way links which did not provide adequate service during the Great Flood of 1993. In addition, there was no backup should there be a disasterous failure of the NOAA Central Computer Facility. It was found that the NWS needed to evaluate its backup procedures "to ensure there is sufficient communications capacity to support operations during major flooding" (see endnote #26). |
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In sum, similar to the case of Hurricane Andrew, the overall lessons learned from the Great Flood of 1993 had much to do with issues of communication and technology. It is this writer's opinion that NOAA and other emergency management teams would benefit by: |
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1) developing better communication between federal, state and local governmental offices; |
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2) creating better implementation of existing modelling and communications technologies as well as exploring and creating new, more efficient solutions to technically related problems; |
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3) installing better telecommunications networks capable of handling high traffic baud rates; |
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4) emphasizing that emergency management staffs needed to be better trained and prepared for unusual environmental situations; |
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5) updating current computer systems, giving them larger database capacity, in order to better handle archival as well as multi-tasking assignments; |
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6) making sure that satellite as well as other aerial based reconnaissance vehicles be used more to collect data on soil saturation, weather patterns and water level conditions; and |
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7) by standardizing as much as possible all emergency related forms and procedures, and developing clear, heirarchy charts of responsible personnel available for consultation. |
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These suggested steps should contribute toward cutting down confusion, and allow for easier data exchange between governmental departments and the public. |
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Endnotes for Case Study #4:
1. Natural Disaster Survey Report: The Great Flood of 1993 (U.S. Dept. of Commerce and the National Oceanic and Atmospheric Admin. [NOAA], February 1994) p. xvii |
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2. NOAA 94-31 National Weather Service Public Information Statement: Great Flood of '93 Impact Unprecedented, Report Finds (National Oceanic and Atmospheric Administration, 5/11/94) p.1 |
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3. Edward Walsh, "Floods Begin to Ease In the Des Moines Area: Drinking Water Cutoff of a Month Projected" (The Washington Post, 7/13/93) Sect. A1 Headline. |
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4. Michael S. Arnold, "Gore, Touring Devastated Areas, Pledges Strong Federal Response" (The Washington Post, 7/13/93) p. 7 Sect.A col 4 |
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5. Timothy Egan, "2 Months of Downpours and Surging Rivers Redraw Map of Midwest" The New York Times National 8/22/93 sect. 24L |
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6. Edward Walsh, "Bottomland Town Looks Up for Life: Flooded Illinois Community Must Move to Preserve Itself " (The Washington Post, 9/16/93) Sect.A p.1 col.3 |
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7. Keith Meyers, "Mississippi Surges Past Straining Levees" (The New York Times, 8/8/93) Sect. 26L. |
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8. Jane Gross, "In the Path of the Flood, Hard Times Just Got Harder" (The New York Times, 8/8/93) Sect. 26L |
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9. Edward Walsh, "Racing to Rebuild as the Lost Summer Ends" (The Washington Post, 9/20/93) Sect. A p.7. col 1 |
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10. Timothy Egan, "2 Months of Downpours and Surging Rivers Redraw Map of Midwest" |
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11. Captain Ken Young, "Levee Rehabilitation Status Report Current as of 11 April 94. (U.S. Army Corps of Engineers, 4/11/94) p. iii |
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12. Natural Disaster Survey Report: The Great Flood of 1993 (U.S. Dept. of Commerce and the National Oceanic And Atmospheric Administration [NOAA], February 1994) p.9-3 |
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13. Natural Disaster Survey Report: The Great Flood of 1993 p. xix |
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14. National Disaster Survey Report: The Great Flood of 1993 p. xix |
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15. National Disaster Survey Report: The Great Flood of 1993 p. viii |
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16. National Disaster Survey Report : The Great Flood of 1993 p. xviii |
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17. National Disaster Survey Report : The Great Flood of 1993 p. xviii |
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18. National Disaster Survey Report : The Great Flood of 1993 pp.4-7 |
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19. National Disaster Survey Report : The Great Flood of 1993 pp. 2-3 |
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20. National Disaster Survey Report : The Great Flood of 1993 pp. 2-7 |
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21. National Disaster Survey Report : The Great Flood of 1993 pp. 2-11 |
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22. National Disaster Survey Report : The Great Flood of 1993 pp. 9-2 |
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23. National Disaster Survey Report : The Great Flood of 1993 pp. 9-13 |
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24. National Disaster Survey Report : The Great Flood of 1993 pp. 9-13 |
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25. National Disaster Survey Report : The Great Flood of 1993 pp. 9-22 |
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26. National Disaster Survey Report : The Great Flood of 1993 pp. 9-14, 9-15 |
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(Updated 9/02/03 D.J. Russell) |
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