The subject of floods is fraught with more drama than that of water
shortages, for a flood can be not only a hardship but a catastrophe. For
this reason, accounts of floods tend sometimes toward exaggeration, and
appeals and proposals for protection against flood threats often take on
the highpitched tones of impending disaster. The subject badly needs
sober public understanding, despite the fact that for decades a good
many knowledgeable scientists and engineers and planners have been
laying out their conclusions for general perusal.
Rivers are supposed to run out of their banks occasionally.
Topographically, stream flood plains--the expanses of flat bottomland
that have been deposited over long periods of geological time by the
streams they border--are similar to what legal terminology calls
"attractive nuisances." Men have always known that they were dangerous
and yet have always utilized them to some degree, because they contain
the best farm land, are convenient to water, and are easier places in
which to build houses and factories and roads than are the safer hills
and uplands.
In times before engineering technology was able to erect such effective
control structures as today, populations who had lived along "flashy"
watercourses long enough to learn their habits tended to build their
more valuable structures back away from the parts of the flood plain
that got wet most often, leaving those parts for cropland and timber, or
sometimes for shacktown, promenades, and parks. Thus long-settled
countries and regions have often developed through trial and error a
degree of what is now called "passive flood protection," which simply
means recognizing that the flood plain is sometimes a rather perilous
place, and treating it accordingly. It was valid in past ages, and it is
still valid today.
The Potomac Basin has been inhabited by civilized men since long before
modern engineering evolved. Possibly early town-builders' wariness of
floods contributed to the fact that the problem of flood damages here,
though quite real, is somewhat less severe than in certain other
sections of the nation. At specific points of concentrated flood plain
development--Petersburg, W. Va., on the South Branch; Cumberland, Md.,
and the areas upstream from it on the North Branch; and metropolitan
Washington at the head of the estuary--figures show significant amounts
of average annual destruction by rampaging stream waters. In headwater
areas or small urban watersheds scattered throughout the Basin, there
are a number of other places where some damage takes place, whether
agricultural or structural. The total average annual damages for the
Basin, as computed in the 1963 Army _Report_, amount to about $8.6
million.
Along small streams, whether urban or rural, the same principles apply
as along large ones, and the proper protective measures are similar if
smaller in scale. Leaving the worst parts of the flood plain in fields
or parks is the usual and effective form of passive protection. Where
existing development demands structural measures, it has been common
practice to cover streams over as sewers or to confine them to
straightened concrete channels that sluice rainwater and mud away as
fast as they will flow--though often this is not fast enough, as is
shown by occasional messy and costly overflows of Four Mile Run between
Arlington and Alexandria. And the loss of pleasant brooks and creeks
through such practices is a heavy price to pay.
More and more often lately in such cases, a combination of some passive
protection with the small headwater dams that "catch the water where it
falls" and soil conservation measures to protect the watershed lands
above the reservoirs, has proved to be a better solution. This is what
has been done in the Rock Creek watershed in the District of Columbia
and Montgomery County, Md., and its value was shown during the heavy
rains of September 1966. Here stream valley parks have given passive
protection for a long tune, though the popularity and heavy use of the
parks have caused a big investment in picnic areas, playgrounds, and
other facilities, which themselves have often suffered expensive flood
damages. As a result of long effort by a watershed association, two S.
C. S. dams had been finished shortly before the September flood at the
only useful sites on the creek's upper branches that rapidly spreading
residential development had left available. They kept runoff from the
big sudden rains entirely in hand in Maryland and reduced damage in the
Federal park in the District to a point far below what it would have
been without them.
Ideally, of course, such planning should be done before heavy
development, and a pilot urban watershed program of this sort is being
undertaken in the Pohick Creek basin on the metropolitan fringe in
Fairfax County, Virginia. With freedom to locate necessary structures in
the right places and to protect them against silt and ruinous runoff by
requiring good land treatment and a sensible distribution of buildings,
pavements, and wooded or grassy open space, planners there ought to get
good flood protection while preserving a pretty valley and stream for
the people who will be living in the neighborhood. From any number of
standpoints, this is vastly preferable to the more usual traditional
procedure of letting growth run wild and then trying to cope with
trouble when it comes up.
The headwater dams are equally effective in reducing flood damages in
small rural watersheds where losses warrant their installation. But even
on a massive scale of installation they have little influence on
downstream flooding along the main rivers. In such places--at
Cumberland, Petersburg, and the Washington metropolis, and at certain
other river towns where less damage occurs--other measures are going to
have to be selected and applied in each individual case according to
costs and benefits, physical possibilities, and the best interests of
the region.
Cumberland and the lesser damage centers on the North Branch are
scheduled for the classic engineering solution of big dams upstream. The
existing Savage River reservoir, finished in 1950, has cut down flooding
notably in that area, and a dam at Bloomington above Westernport,
already authorized by Congress, will relieve it still more, as well as
fitting into the complex clean-up task along the North Branch and
furnishing water for local and Washington use.
The 1963 plan proposed similar protection for metropolitan Washington
and for Petersburg, West Virginia, in the form of major reservoirs at
Seneca and Royal Glen. Physically and culturally, there is very little
similarity between the two communities, but their flood situations and
the potential effects of the proposed protective structures have a
certain kinship.
At both places there has been development of the flood plain, with the
result that damages occur when the communities' respective rivers get
out of their banks. In relation to its size--around 2000
people--Petersburg is subject to much heavier trouble of this sort than
the metropolis. It sits near the head of the lovely narrow farming
valley through which the main downstream South Branch flows, a few miles
below the point where two principal forks of the river join after
rushing out of the mountains. In June of 1949, a flood there claimed
five lives around Petersburg and three at Moorefield downriver, where
still another main fork comes in, and wrought major destruction through
the neighborhood.
The 1963 Army _Report_ calculated Petersburg's average annual flood
damages at over $200,000, and advocated construction of a $30 million,
multipurpose reservoir at Royal Glen just upstream from Petersburg, to
do away with most of the damage and to permit further industrial
development of the flood plain, as well as to provide a great deal of
water for downstream use and for regional recreation. People and groups
in the area with interests standing to benefit from the reservoir were
naturally in favor of it. Under present Federal policy--which will be
mentioned again--its flood-protective function would cost them nothing,
whereas levees or other locally effective approaches would demand a good
deal of local effort and outlay, besides disrupting the town's aspect
and its relationship to the river.
[Illustration]
Opposition developed also. The very name of Royal Glen suggests the
scenic qualities of the country roundabout. As at Seneca, a dam here
would flood out some country with unique scenic and recreational values,
including the famous Smoke Hole Gorge down which the clean South Branch
runs between steep mountains dotted with caves and flavored with the
quiet simplicity of the life that isolated hill folk lived there up into
modern times. It is a section much appreciated by whitewater canoeists
and hikers and horsemen and others from that region and elsewhere, who
care about rugged and unspoiled places. Despite its remoteness, the
proposal that it be inundated aroused more vigorously hostile comment
among conservationists and nature lovers in general than perhaps any
other item in the Army program except Seneca. The State of West Virginia
declared itself opposed to the project, and to date has maintained that
position.
Again like Seneca, the Royal Glen site does have certain unique
advantages for use as a reservoir. But, as at Seneca also, its
functional virtues do not appear to be nearly so unique as those of the
scenery and natural values whose obliteration would be a heavy part of
the reservoir's price. In 1965, the immense scenic value of a large part
of the country it would wipe out was recognized by its inclusion in the
big Spruce Knob-Seneca Rocks National Recreation Area. It is strongly to
be hoped that that recognition is never withdrawn.
The issue of scenic destruction at both Royal Glen and Seneca tends to
obscure another set of even more basically relevant considerations
having to do with the whole question of flood plain occupancy and use,
the extent to which those who benefit from it should share the cost of
such protection as may be necessary, and possible ways of reversing a
present trend toward inexorably larger national flood damages each year
despite ever larger and more expensive structural protective measures at
public expense.
[Illustration: THE HYDROLOGIC CYCLE]
It is a complex subject that can only be summarized here. What it
amounts to is that America has strayed too far from the ancient hard-won
wisdom of treating flood plains with respect. It has been lulled by the
achievements of engineering, encouraged by a general absence of
inadequacy of State and local planning that takes such matters into
account, and conditioned to a set of Federal laws and policies
piece-built over a long period of time, with consequent inequities,
imbalances, and loopholes that tend to emphasize structural protection
at Federal expense for indiscriminate flood plain development. The
result has been a neglect of the possibilities of flood plain
management, which undoubtedly in the long run--as in the long past--will
prove to be the most valuable tool for reducing these damages, for it
will bring about a restriction on ill-advised and uneconomic
encroachment in these streamside areas.
The reason most such encroachment is bad, with or without a dam
upstream, with or without levees, is that it establishes the certainty
of further and larger flood damages in the future, with the certainty of
further and larger expenditures to combat them. It has been pointed out
that no such thing really exists as flood _control_, but only a given
degree of flood _protection_. Economics and technology dictate that
reservoir capacities devoted to the storage of flood water, for example,
be considerably smaller than the maximum runoff conceivably possible.
This means that sooner or later there is going to be a great flood
against which the reservoir or reservoirs will not suffice. If the
reservoirs' presence, as is most often the case, has directly encouraged
a lot of flood plain speculation and construction downstream, then the
great flood is going to do more damage than was ever done before, and
more reservoirs and other protective measures, most often Federally
financed, are going to be demanded, at a price that rises sharply as
less desirable sites and methods have to be employed, and with
frequently catastrophic scenic effects. These considerations apply to
small watersheds as well as large ones.
This costly cycle, which frequently makes the general public pay both in
tax money and the sacrifice of amenities to protect the investment of a
relatively few who profit from the wrong kind of flood plain use--in
plain words, makes the public subsidize their ventures--has established
itself widely. In some places, of course, certain kinds of development
can take place only on the flood plain, and planning for its structural
protection may be amply warranted, with equitable cost-sharing. But the
difference between this sort of flood plain use and the much more
common, thoughtless, quick-profit type needs to be more widely
recognized and established in policies at all levels of government. The
subject has been much studied. In August 1966 the findings of a
distinguished Task Force on Federal Flood Control Policy, which made
detailed recommendations for injecting some sense into the situation,
were submitted to the attention of Congress by President Johnson. At the
same time, he issued Executive Order 11296 on the subject, directing all
Federal executive agencies with influence in such matters to do
everything possible to discourage uneconomic and unwarranted use of the
nation's flood plains. This, of course, includes the present Potomac
planning effort.
[Illustration: FLOOD PLAIN DELINEATION POTOMAC RIVER AT HANCOCK, MD.]
At Petersburg, there is little question that the wisest approach to
present and future flooding problems would be one that would seek to
give reasonable protection to the development already on the flood plain
but at the same time deter further construction unless it is
floodproofed or houses activities that find a flood plain location so
advantageous as to be well worth the risk. In currently available
terms, this could be accomplished most feasibly and at the least net
expenditure--though not, under present policy, as cheaply to the
community itself as by the Royal Glen dam, and not without some notable
changes in the town's landscape--by combining a levee system around
present development with rigid zoning of the unoccupied part of the
flood plain, or its acquisition as parkland.
[Illustration]
Another approach that may shortly be possible was suggested by the
President's Task Force and is the subject of legislation proposed to
Congress by the Department of Housing and Urban Development. Under this
legislation, owners of existing flood plain residences and small
businesses would be given a chance to buy Federally subsidized
insurance against flood damages at reduced rates, while new construction
in flood hazard areas would be subject to rates based on the full true
risk involved. After 1970, under this proposed legislation, such
insurance could be sold only in areas with enforceable codes and
ordinances or other measures for sound flood plain management. Such a
program could go a long way toward eliminating casual and expensive
flood plain clutter, if it were backed up by adjustments in other phases
of Federal flood control policy that would similarly place a share of
any protective costs where they belong, and hence give an additional
strong nudge to citizens and local and state governments to bring the
situation into balance.
At Washington, because a high proportion of the flood plain on both
shores is in Federal ownership and the use it is put to is determined by
Federal agencies, Executive Order 11296 has special relevance in
forestalling future increases in the amount of flood damage. Existing
damages in the whole urban area are estimated to average $1.4 million
each year. The most damaging flood in the metropolis' history occurred
in March of 1936, and if a flood of the same dimensions were to strike
today, it would cause estimated damages of about $21 million.
These are not small figures, though if they are considered in the light
of the area's population and extent and the total value of construction
there, they seem less formidable. Obviously the threat of damages of
this magnitude must be dealt with, but just as obviously as at
Petersburg, the manner chosen for dealing with them should not be
allowed to stimulate unwise flood plain construction that would lead to
still greater longterm damages.
The Seneca reservoir as proposed in 1963 provided floodwater storage
calculated to reduce metropolitan damages by 46 percent. This is a
significant though not startling amount of reduction, and it constitutes
the most economical one-shot measure of protection that could be
attained. However, if the construction of Seneca is precluded for the
time being or for good, that measure is not available. Second-best, by
Army calculations, would be a combination of several large multipurpose
reservoirs on main tributaries farther upstream. But quite aside from
other considerations of desirability, these could only be justified
economically if a great part of their stored water were destined to
furnish massive flow augmentation to ease pollution in the upper
estuary. As will be noted in the following chapter, recent studies have
raised doubt that such augmentation would be likely to help the estuary
nearly as much as had been thought and it is no longer being considered
a primary tool for that purpose.
This leaves passive devices and local protection works as the main
available instruments for coping with floods at the metropolis. They
will probably be most effective if applied in a carefully selected
combination of means, with levees and other protective works installed
where feasible and desirable, and backed up in other areas by zoning,
flood warning systems, and good design including flood-proofing,
elevated structures, and similar devices. Some of these principles of
design are already being incorporated in new buildings and renewal
projects, but the task of planning and locating such things as levees
usefully on a flood plain containing a good part of "monumental
Washington," the beauty of which is a national concern, is not going to
be simple. A good program must be instituted soon, and the extent of the
Federal interest in the lands involved should considerably ease the job
of coordination.
Interestingly, certain floods to which Washington is susceptible can be
partially guarded against only by such approaches as the ones mentioned
above, and not at all by upstream dams. One of them occurred in August
of 1933, when a hurricane pushed the water in the estuary upstream and
raised it to flood stage at the capital.
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