Environmental Engineering Reference
In-Depth Information
to be on the economic and social. At some stage,
there comes recognition of the environmental
consequences of the activity and the increase in
damages caused by populating high-risk areas in
the floodplain. In the early stages of development
in the USA the emphasis was on flood damage
reduction, mitigating the impacts of periodic
flooding at the local level through a variety of
methods. Over time, as the central government
became more of a factor, the flood management
goals became more codified.
The Tenth Amendment of the Constitution of
the USA indicates that 'The powers not delegated
to the United States by the Constitution, nor
prohibited by it to the States, are reserved to the
States respectively, or to the people' (US Consti-
tution 1791). During the first century of the
nation's existence, this amendment played heavi-
ly in defining responsibilities for flood manage-
ment activities, as most federal legislators did not
see a federal responsibility to do more than under-
stand the science behind flooding and possibly the
threats that flooding posed. In establishing the
Mississippi River Commission, the Congress
also established federal goals to 'improve and give
safety and ease to the navigation [of the Missis-
sippi River]; prevent destructive floods; promote
and facilitate commerce, trade, and the postal
service
...
'. As previously indicated, during its ini-
tial years, the Commission was funded to deal
more with navigation and flood control, as the
Congress continued to worry over its authority
over flood control. Since providing safety and ease
of navigation required the Commission to main-
tain a defined channel through use of dikes, levees,
bank protection and dredging, it was frequently
difficult to determine where navigations stopped
and flood control began. Gradually, but without
explicit direction from the Congress, the Com-
mission became more and more involved in flood
control activities. The 1917 Flood Control Act for
work on the Mississippi and Sacramento Rivers
helped to further define a growing federal interest
and permitted proponents of flood control to argue
that it did not represent subsidies to local interest
for development, but was necessary to alleviate
the hardships of flooding (O'Neill 2006). The 1928
protection of natural resources including those in
the riverine area. The birth of the NFIP and the
passage of NEPA increased national interest both
in using non-structural flood damage reduction
tools (as opposed to controlling floods) and in
protecting riverine ecosystems that had been bad-
ly damaged by settlement and flood protection
activities.
The 1993 upperMississippi BasinFlood brought
renewed attention to the floodplain. A 1994White
House report emphasized the need for new ap-
proaches to reducing the risk to the people and
property in the floodplain (Interagency Floodplain
Management Review Committee 1994). In 1996,
the Corps issued instructions to its field activities
directing that future projects be developed using
risk concepts (US Army Corps of Engineers 1996).
Following Hurricane Katrina in 2005, the Corps
formally shifted its focus from flood damage re-
duction to flood risk management.
Over a period of three centuries, the US ap-
proach to dealing with flood damages gradually
shifted from total reliance on structural 'flood
control' activities, through a mix of structural
and non-structural approaches, to, most recently,
a movement towards broader-based flood risk
management.
Setting a Direction
The direction taken in a flood management pro-
gram is driven by its explicit and implicit goals.
In the USA, these goals appear primarily in legis-
lation and are influenced by the division of respon-
sibilities defined in the US Constitution between
the federal government and the states of the
Union.
Floods are natural events and not only replenish
alluvial soils, substantially increase the yield
of the land, and sustain rich habitat for natural
systems, but also inflict substantial damages on
human activities in the floodplain. Nations his-
torically have been forced to trade off economic
and social development with potential damages
that result from flood management activities.
While nations are developing, the emphasis seems
