Floods, Technology, and Ramifications on Insurance Coverage

Flooding is a natural occurrence, but the negative effects of flooding extend far beyond what would occur naturally due to human interference with elements of the river’s drainage basins and society’s persistence in building in flood plains. However, with increased accuracy of flood prediction, accumulation of loss experience to influence legislation and mitigation, and a movement towards wiser zoning laws that demand greenways in flood-prone areas, future losses can be reduced. Only by examining the causes of flooding, the effects of flooding in both economic and human terms, and the measures that have been taken to prevent or reduce the damages caused by flooding, can a true picture of the ultimate reason for the devastation caused by this natural disaster emerge: human choices.

 

FLOODING MECHANICS

Streams and rivers form the means of channeling excess water through drainage-basin run-off. During rains or rapid snowmelt, the water that cannot be absorbed by the soil must go somewhere; taking the path of least resistance, the water runs off into local stream channels. When the precipitation exceeds the capacity of absorption by the soil and then exceeds the capacity to be carried the river channel, the discharge overtops the river channel in the form of flooding and covers the floodplain. Due to variation in precipitation rates over time, flooding is actually a normal occurrence. A flat expanse of land called the floodplain surrounds most river channels. Sediments are deposited across the floodplain, which indicate hundreds of years of natural ebb and flow of floodwaters (Coch, 1995, pg 183).

Unfortunately, human beings have built cities along the riverbanks and on the floodplain, putting themselves in harm’s way. Early settlers of the United States found the areas in the floodplains to be attractive sites for the first towns; not only was the land level and flat and ready to build upon, but, due to past flooding, the soil was fertile with organic matter deposited by the river as it receded from flood stage. The root and leaf systems of vegetation on the unmodified floodplain acted to slow the accumulation of rainwater and allowed more water to percolate through the soil before the saturation point was reached and run-off began. Large areas of vegetation, particularly forested areas, resulted in longer delays before full soil-saturation and the resultant flooding. Additionally, the rivers afforded ready transportation of goods from one town to another.

As urbanization increased, the profile of the land was changed from a natural floodplain surrounded by forests and vegetation-covered hills to paved cities with brick and concrete buildings and flat unprotected cropland. The combination of deforestation and the paving over of the land with asphalt and concrete resulted in cities more at risk for flood than ever before. Paved surfaces block the permeable soil from absorbing water, creating greater volumes of run-off in shorter periods of time (Coch 184).

When the inevitable occurs and towns are flooded, people redouble their efforts to coexist next to the river rather than pulling back and building further from the floodplain.

It then becomes necessary to try to mitigate the flood impact by enforcing control over the rivers.

As technology advanced over the past 50 years, engineers used dams, levees, and river channelization to control the flow of water at various points along the river system. Dams block off rivers and create a lake-like reservoir upstream that acts as a water-storage area to regulate the flow of water downstream. There are two main drawbacks to dams as control structures: sediment and dam capacity. The flow of sediment normally carried by the river is blocked by the dam. This causes the sediment to accumulate over time, eventually reducing the effectiveness of the reservoir as a storage area. The capacity of the dam is limited by both monetary cost and technological limitations. However, there is no limit to Nature’s potential for overwhelming the competence of even the largest dam.

Levees are flood control structures which derive from Nature’s example. In the natural floodplain the river floods and recedes, leaving behind a mounded track of depositional material. This ridge of sand, rocks, and debris marks the width of the river at the point of flooding. Manmade levees are constructed in a similar parallel track along the banks of rivers to act as a barrier between the river at flood stage and the surrounding area. These structures range from simple earthen embankments to sophisticated structures designed by the Corps of Engineers. As with dams, the manmade levees have structural limitations and can be breached, overtopped, or saturated to the point of failure.

With channelization, river beds are straightened and smoothed in order to contain and control the portion of the river that flows through a local area. A deep, smooth, and straight channel can carry more water and lessen the chances of local flooding. However, channelization ultimately increases the velocity of a river by increasing the area and volume of water and by decreasing the slowing frictional effects of a rough and shallow bed. The burden of floodwaters downstream is greatly increased by allowing the river to gather power over the course of the straightened channel. As a result, channelization passes the flooding problem along to downstream communities. As these examples illustrate, technology that seemed ideal at the outset has shown that human attempts to overcome the power of Nature are, at best, temporary.

When structures designed to confine excessive stream discharge fail, the results are often devastating, both directly and indirectly. For example, the 1993 Midwest Flood resulted in 50 deaths and $15 billion in damages (Larsen 1996). The Mississippi river basin is studded with numerous dams and levees built primarily for flood control by the Corps of Engineers. Despite sophisticated soil moisture and precipitation models used by the National Weather Service and hydrologists at the River Forecast Centers, the Great Flood of 1993 was one of the worst natural disasters ever recorded in the history of the United States. It is an extreme example of what can happen during a flood, and it illustrates that the best efforts of engineers and scientists are not sufficient to control all natural flood events.

The cause of the Great Flood of 1993 is simple – during June through August of that year, record rainfall amounts over a record duration of time saturated the soil and overtopped stream banks throughout the upper Mississippi river basin, resulting in massive amounts of water that overwhelmed the entire river system. The resultant flooding lasted over 200 days and affected as many as 150 rivers and tributaries (Larsen 1996). Damages included the long-term flooding of water and power plants, massive sewer backup, the shutdown of major highways, airports, railways, and barge traffic, and the destruction of at least 10,000 homes (KDSK 1993).

Though an extreme example, the Great Flood of 1993 provided a wake-up call for many cities in the region. In his presentation before the IAHS Conference in 1996, Lee W. Larson, the Chief of the Hydrologic Research Laboratory at NOAA, summarized key data that was obtained during the Great Flood of 1993: the unprecedented number and heights of the record crests of the Mississippi river at St. Louis, the lengthy duration of flooding at various cities along the Missouri and Mississippi Rivers, and the levee failure rates broken down between Federal levees (17.6% failed) and non-federal (77.5% failed). Despite the knowledge that was gained from this event, human nature cannot be fully convinced that change is necessary to avoid a repeat of disaster. Even during the height of the flooding, victims appeared on news reports bemusedly stating that they had to live somewhere and would return to a flood-prone location (KDSK, Inc. 1993).

 

MITIGATION

Individuals, and in some instances entire municipalities, often refuse to give up the fight against the floodwaters and simply move away. On a national level, flood damage costs are close to $5 billion annually (Kusler 2004). With the partial success of the dam system initiative put in place by the Federal Government and the Corps of Engineers and the persistence of cities and communities in locating and remaining on floodplains, someone must pay this annual cost of damages. With the less-than-perfect results of the best technology that money could buy as far as physical controls to reduce flood loss, the next stopgap measure was a financial mechanism, insurance.

Originally, private insurers offered flood insurance to businesses and homeowners. However, the insurance operation depends upon the law of large numbers: the premiums of the many pay for the losses of the few. Over time, it became apparent that only those property owners who were likely to be affected by flooding were actually purchasing the flood coverage. By the early 1960’s, the imbalance of the few paying small premiums and then being reimbursed large amounts for eventual flood damage caused a panic in the insurance industry. As a result, private insurance companies essentially stopped offering flood insurance. With no ability to insure their flood losses, property owners were wiped out whenever their buildings were flooded. Various governmental and charitable agencies were forced to step in and assist the property owners for the good of the community.

Organizations such as the American Red Cross, the Federal Emergency Management Association, the Salvation Army and other disaster assistance agencies provide food, water, medical care, emergency shelters, and counseling/mental health services to those who have been affected by floods. While these organizations provided greatly needed services, they were primarily designed to help in the short run and could not begin to compensate flood victims for the billions of dollars lost in property values.

In 1968, the Federal Government realized that insurance, as a device to mitigate flood losses, was no longer intact and developed the National Flood Insurance Program to provide a safety net for flood-prone buildings. The NFIP currently remains the sole resource for homeowners and businesses that lay within a floodplain and experience flooding. Using private insurance companies as a sales point and financial institutions to track mortgages on subject properties, a minimal amount of subsidized insurance is available to properties that lie within Federally-designated floodplains. The Federal Government subsidizes the premiums.

Hydrologists and civil engineers develop flood maps based upon the history of flooding and utilize formulas that include stream discharge, stage heights, and rainfall patterns. To qualify for the program, the property must be situated in an area that is calculated to flood at a recurrence interval of every 100 years. This translates to a 1% chance of flooding in any given year. Note that this interval is an average, and could mean flooding at this level in back-to-back years. With increased urbanization, it becomes critical that flood maps be monitored and updated. In areas with rapid and intense development, the removal of vegetation and addition of acres of parking and real estate construction can drastically alter the pattern of run-off and increase the potential for flooding. A property with no historic record of flooding may be initially rated as a 500 year flood site; after a neighboring property undergoes site grading, the addition of retail structures, parking areas, and street and road access, the original property may now be subject to a 100 year, 30 year, or 10 year flood (Coch 205).

Recently there has been a pushback from taxpayer organizations and some legislators to force the NFIP into becoming self-supporting and not relying on taxpayer subsidies (Kusler 2004). Part of the contention relates to the persistence of communities in building in flood plains, suffering destruction, and rebuilding again in the same spot, knowing that they will be compensated for any future losses. A bill is currently before Congress that is meant to put a limit on the number of times that a business or homeowner can collect from the NFIP before they must absorb some or all of the insurance costs on an actuarially sound basis (ie, the premiums are no longer subsidized by the government). H.R. 253, the Two Floods and You Are Out of the Taxpayer’s Pocket Act of 2003, is meant to reduce repeated claims at the same location (John 2004). This bill is on the forefront of legislation being enacted to reduce what is seen as an unjust taxpayer burden.

Slowly, community leaders are coming to the realization that it is foolhardy and shortsighted to build in a known floodplain. The recommendations of engineers and hydrologists are given more weight than they have been previously; city planners and architects are incorporating buffer areas between creeks and the surrounding communities. As a local example, Mill Creek Streamway Park winds from the Kansas River south into Olathe; this extensive greenway system required commitment from developers and a willingness to give up valuable property to allow this buffer along the stream corridor in a highly lucrative area for real estate. Fortunately, homebuyers have flocked to purchase houses along this greenway due to the beauty of the natural surroundings. Developers now have a dual incentive to create these buffer zones in order to comply with increasingly stringent regulation of building on a floodplain, and to provide desirable properties adjacent to park-like areas and nature trails. However, the very powerful incentive of tax dollars generated from development in key areas adjacent to rivers still remains. Local governments push through commercial zoning in areas that will eventually be devastated by flooding. One only needs to look as far as the Corporate Woods office park, built uncomfortably close to Indian Creek, to be reminded how politicians can be swayed by short-term vision and economic incentives.

 

CONCLUSIONS

Technological advances in flood prediction such as satellite imaging, GPS, computer profiling, and the growing database of historic flood data provide a more credible basis than ever before for city planning. There is an unprecedented availability of information via the worldwide web on flood mitigation, flood insurance programs, and legislative issues. Despite this vast amount of knowledge and experience with the devastation caused by flooding, it is man’s peculiar trait to tempt fate by continuing to try to dominate and control Nature. The recent trends to set aside areas adjacent to rivers for more naturalistic usage, the growing publicity by lobbyists to reduce the flood subsidy burden on taxpayers, and the momentum in the legislature to tighten up the provisions of the National Flood Insurance Plan lends hope to the possibility that communities can achieve a planned coexistence with the beauty and danger of Nature’s rivers.

 

Literature Cited

Coch, Nicholas K. 1995. Geohazards: natural and human. Englewood Cliffs, NJ. Prentice Hall.

John, David C. 2003. Time for Congress to Improve the National Flood Insurance Program. WebMemo. The Heritage Foundation. [online]. Available from: http://www.heritage.org/Research/Regulation/wm369.cfm?renderforprint=1. Accessed 2004 June 29.

KDSK, Inc. The Great Flood of ’93. 1993 Multimedia.

Kusler, Jon A. 2004. Common Legal Questions about Floodplain Regulations in the Courts; Association of State Floodplain Managers. [online]. Available from:  http://www.floods.org/NoAdverseImpact/FLOODPLAIN_REG_IN_COURTS_050604.pdf . [Accessed 2005 March 23]

Larson, Lee W. 1996. The Great USA Flood of 1993. [online]. Available from: http://www.nwrfc.noaa.gov/floods/papers/oh_2/great.htm. [Accessed 2005 March 23]