FLOOD09787

• County: Delta
• Community: Cedaredge
• Stream Name: Surface Creek
• Basin: Gunnison
• Title: Floodplain Delineation for Cedaredge, Colorado
• Date: 12/8/2003
• Prepared For: CWCB
• Prepared By: Gared Grube
• Floodplain - Doc Type: Floodplain Report/Masterplan

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Introduction

Flooding is the one natural disaster that caused more lives to be lost and the most property
damage than any other in the United States in the 20th century (Perry. 2(00). Floods have caused
more that 10.000 deaths in the United States since 1900 and over $1 billion each year in property
damage. Floods are the second most common natural disaster, behind only flfc, with all
communities existing with the threat of experiencing a flood (FEMA. 1998). In fact during a 30-
year mortgage. there i.~ a 26% chance of a home being flooded. located within a IOO-yr
floodplain (eWes. 2001). In Colorado. flooding caused 331 lives to be lost between 1900 and
1993 (eWeS) and $4.9 billion in property damage 10 date (eWes. 2002). With an estimated
$17.6 million lost annually between 1896 and 1994 (CWCB. 2002). Colorado experiences at
least one 100-year flood every year. (CWCB. 2002) In addition. United States Presidents have
declared 9 major flood disasters out of 32 years between 1965 and 1999 (eWCB. 2002).

A flood is defined as an instance in which water escapes the channel in which it is normally
contained. or where there is a rapid accumulation of runoff or surface waters from any source. In
other words. normally dry land is partially or completely inundated (CWCB, 1987). There are
several different types of floods that include regional. flash, ice-jam. dam and levee failure.
storm-surge, and debris. landslide. and mud flow floods. Regional floods are those that occur
seasonally in the spring when there are many thunderstorms that are coupled with the melting
snow-pack. During these events, the ground may be frozen which prevents infiltration of
moisture into the soil. causing an excess amount of runoff that fills river basins beyond their
capacity. In addition. regional floods may occur after any extended wet periods. causing
saturated soil that prevents infiltration. Flash flood are generally more devastating than regional
floods since high flow velocities can develop within short amounts of time. hours or even
seconds. Flash flooding has several factors that contribute. such as rainfall intensity and duration.
surface conditions. and topography and slope of the receiving basin. Mountainous areas. in
particular. are susceptible to flash floods because of steep and narrow canyons that funnel the
runoff (Perry. 2000).

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