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<br />
<br />ll4 ROGER A. PIUKE, JR.
<br />
<br />literature is that society has learned through experience what actions will lead to
<br />1 reduction in vulnerability to floods. but that these 'thoughtful pa~t recommen~
<br />jations of how to auain Rood mitigation had never been a~equately :mpleme~ted
<br />Ch 1996 P 3\2) The central thesis of this paper IS that whIle expenence
<br />(angnon, " . .' .
<br />has provided sufficient knowledge of steps necessary to bC?Jn to reduce society s
<br />vulnerability to floods, society lacks an accurate understanding of the nal~re of the
<br />flood robJem itself. Because decision makers lack knowledge of the, poltey prob-
<br />lem, :01entia\ po\icy solutions developed by flood experts are, often Irn~lemenled
<br />unsystematically (if at al1). overlooked in favor of false solutions, or Without the
<br />leadership needed (0 ensure their success, . . f
<br />A number of important misconceptions Of fallacies sland III the way 0 ,a
<br />better understanding of the nation's flood problem, The fallacies are no~ lHlI-
<br />versal with many flood experts, decision makers, and sectors of the public ~s-
<br />ea in~ their seductive logic. Bur enough people ~~ fa.ll prey to these fallaCies
<br />ot floods so as to create obstacles to improved utilization of the ~essons of ~x-
<br />perience. This paper uses three of these lessons to organize presentation of the nine
<br />
<br />fallacies:
<br />
<br />We know the wrong things abaut the nature of the problem (Fallacies I, 2, 3
<br />L .
<br />and 4),
<br />We don't know enough about why and with what intensity we should act
<br />2,
<br />(Fallacies 5. 6 and 7),
<br />We know enough about what might be done (Fallacies 8 and 9),
<br />3
<br />
<br />Of course, there are other fallacies of floods (and disasters more generally) which
<br />would ex and the list presented here (e.g., Glantz. '?76)., . .. "
<br />P I" ' g the t'''II''cies in this paper IS lO contnbute lo a systemal1c
<br />The purpose 0 ralSln .. .. . ' .
<br />definition of the nation '5 flood problem. It makes sense chat. e~fecuve. ~cuons In
<br />" d au ht to be based upon an accurate and realistic definition of the
<br />response to 1100 S g. d fl h)' he
<br />r~blem, While this paper focuses on river floods (i,e" large-scale an as In ~
<br />~nited Stales. the fallacies have potential broader relevance to the, extent to wh~ch
<br />they influence policy in other flood-prone regions of the world, Simply corr~cung
<br />m'slaken beliefs will not in itself 'solve' the nation's flood problem, but I~ ca~
<br />re~ove obstacles to the implementation of previously unsee~ or un~er~pprecl3te
<br />policy alternatives. It is certain that the challenge ~f imp~vmg socIety s response
<br />to floods will Face obstacles so long as these fallaCIes persIst.
<br />
<br />," 'I b b of the policy literature views policy solutions di.~!inct [rom policy prob-
<br />* Ol'le lfinuentla ranc . I 1 h 'arbage c.\\I\
<br />!eros, with the tWO meeting only under ,c.ertaind ci~~mst;~c::~~:t~7~:~o~ Jl~~).gA review of
<br />model' of Cohen e\ at 0911) and the. pQhc)' an peo ern s r
<br />the problem definition literature is found in Pielke (I 997a),
<br />
<br />
<br />NINE FALLACIES OF FLOODS
<br />
<br />4]5
<br />
<br />2. Flood Fallacies
<br />
<br />2.1. FLOOD FREQUENCIES ARE WELL UNDERSTOOD
<br />
<br />Flood experts use the terms 'stage' and 'discharge' to refer to the size of a flood
<br />(Belt, 1975). A tlood stage is the depth of a river at some point and is a funcIion
<br />of the amounr of water, but also the capacity of a river channel and floodplain
<br />and other factors. Hence, upstream and downstream levees and different Uses of
<br />floodplain land can alter a flood's stage. A flood discharge refers to the volume of
<br />water passing a particular point over a period of time. For example. in _1993 St.
<br />Louis e"'perienced 'the highest fotage we've ever had. but not the' biggest 'volume',
<br />
<br />We've had bigger flows, but the stage was different because the water could
<br />flow from bluff to bluff, Now we have communities in the floodplain. Every
<br />time you do something on a floodplain, you change the flood relationship.
<br />Every time a farmer plants a field or a town puts in a levee, j[ affects upstream
<br />flooding. That's why you can't really compare flooding at different times in
<br />history (G, R.. Dryhouse quoted in Corrigan. 1993),
<br />
<br />According to the World Meteorological Organization's International Glossary
<br />of Hydrology, 'flood frequency' is defined as 'the number of limes a flood above a
<br />given discharge or stage is likely to occur over a given number of years' (WMO.
<br />1993). In the United States, flood frequencies are central to the operations Of the
<br />National Flood Insurance Program, which uses the term 'base flood' to note 'that in
<br />any given year there is a one percent chance that a flood of that mag-nitude could be
<br />equalled or exceeded' (FIFMTF. 1992. p, 9-7), The 'base flood' is mOre commonly
<br />known as 'the lOO-year flood' and is 'probably the most misunderstood floodplain
<br />management term' (FIFMTF, 1992. p, 9-7),
<br />A determination of lhe probability of inundation For various elevations within
<br />a community is based OJ) analysis of peak flows at a poini on a particular river or
<br />stream. However, 'there is no procedure or set of procedures that can be adopted
<br />which, when rigidly applied to the available data, will accurately define the flood
<br />potential of any given watershed' (USWRC, 1981, p. 1). For many reasons. in.
<br />eluding limitations on the data record and potential change in climate, 'risk and
<br />uncertainty are' inherent in any flood frequency analysis' (USWRC, ]981, p. 2),
<br />Nevertheless, quantification of risk is a fundamental element of flood insurance as
<br />wen as many aspects of tlood.related decision making.
<br />In order to quantify flood risk, in the early 1970s the National Flood Insur-
<br />ance Program adopled Ihe 100-year-flood standard (FIFMTF, 1992, p, 8-2), The
<br />standard was adopted in order to standardize comparison of areas of risk between
<br />communities. Since that time the concept of the N -year flood has become a com.
<br />man fixture in policy, media, and public discussions of floods. Unfonunately, 'the
<br />general public almost universally does not properly understand the meaning of
<br />the term' (F]FMTF. ]992, p, 9-7), Misconceptions about the meaning of Ihe tenn
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