FLOOD06290

• County: Statewide
• Basin: Statewide
• Title: Reliabilty of Paleostage Indicators for Paleoflood Studies
• Date: 3/20/1998
• Prepared By: USGS/BOR
• Floodplain - Doc Type: Educational/Technical/Reference Information

draft 3/20/98

Introduction

"In the absence of sufficient rainfall data, it is fortunate that geology furnishes, in many instances, a

clue to the probable heights of flood-waters, The clue referred to is afforded by flood-plains and

terraces, which often give evidence of heights of water." Fuller (1917, p. 1270).

Worldwide, floods are one of the most destructive events related to meteorological processes. For the

period 1966 to 1985 in the United States, the adjusted average annual deaths (per 200 million

population) is 145 people and about $2.15 billion in damages occur from floods (M. Grimm, Federal

Emergency Management Agency, writt. common., 1997). Accurate flood-frequency relations are

necessary for flood-plain management, hydrologic-risk assessments for high-hazard facilities such as

dams, and related environmental investigations. In many river basins, gaged records generally do

not contain a sufficient sample of infrequent floods to reliably estimate the frequency of extreme

floods (Costa, 1978; Kochel and Baker, 1982).

Paleoflood hydrology is the study of past or ancient floods (Kochel and Baker, 1982; Stedinger and

Baker, 1987; Baker, 1987; Patton, 1987; Baker et al., 1988; Hupp, 1988; Jarrett; 1991). Although

most studies involve prehistoric floods, the methodology is applicable to historic or modern floods

(Baker, 1987) providing information about the number, magnitude, and age of floods (Jarrett, 1991).

Paleoflood studies also provide important information that can be used for assessing the effects of

climatic change on flooding and droughts (Knox, 1988; Jarrett, 1991; Ely et al., 1993). Paleoflood

data are particularly useful in providing probable upper limits of the largest floods that have occurred

in a river basin (Enze1 et al., 1993).

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