FLOOD00566

• County: Statewide
• Title: Nature's Building Codes - Geology and Construction in Colorado
• Date: 8/1/1979
• Prepared For: State of Colorado
• Prepared By: DNR
• Floodplain - Doc Type: Educational/Technical/Reference Information

Aggravating Circumstances

The frequency, e~tent. ~nd the degree of d~~age of flooding
are dIrectly related to land use. Natural features such as
open land, trees Z1nd grasses are replaced ..lfh paving.
bu! Idl"g5, and other improvements ~hlch Instead of absorbing
or holding back ..ater and slowing down Its movement Increase
the amount and rate of runoff. Oralnagelllays are tIlled 'filth
trash, Channels are narrowed Iillth landfills for construction,
streams are straightened and their rough bottoms covered with
concrete. A variety of structures trom bl I Iboards to homes
erected In flood plains are not designed to ..Ithstand floods
and not only lire dam/lged or destr'::lyed. but otten become
debris and an lIggravlltlng factor In Increasing damage to
other property.

The mere failure to keep dralnageways and stream channels
free from de~elopment and tresh results In the rising weters
lOdging debris against cul~erts and bridges. effectl~ely
damming a wllltercourse and forcing flood ..aters Into the IIreas
that might not be affected otherwise.

The greatest cause of flood damage Is man's choice to build
on flood plllllns. FlOOding Is a nlltural process which has
only become a hazard to man since he has built and de~eloped

Little Dry Creek flooded a wide area In south metropOlitan
Den~er durln~ May. 197).

6

In flOOd-prone areas. "'an also creates new and enlarged
floodplains. "'s communities grow. storm runoff from new
de~elopm'3nt often Is channelled through older areas. The
additional water that Is generated cannot be handlad In the
historic manner and flooding of pre~lously flood-free areas
reSults.

Mitigation

Land use controls and minimizing of flood damage are
Interdependent. One ser~es the other. The least costly way
of minimizing flood damage Is to a....old Intense de....elopment on
flood plains. Essential Impro....ements such "5 highways.
br 1 dges. and ut III ty II nes can be des I gned to ..I thstand
floods.

Preser....atlon of
de....eloped areas
beneficial use.

n"tural
permits

dralnage..ays as open
lend to ser....e more

space In
than one

In de....eloplng areas, detention basins can effectl....ely store
and slow down the ....eloclty of high .."ter, lessening the
II kell hood of f load damage. Detent Ion bas I ns are bo.. I shaped
holding areas where runoff waters can accumulate and drain

-

- -

1

drldge \oIashouts near Castle Rock were caused by se....ere
flooding In 1965.