Paleoflood Record Reconstruction at an Archaeological Site on the Owyhee River, Southeastern Oregon

<p>The magnitude and frequency of late Holocene floods on the Owyhee River in southeastern Oregon were reconstructed from fine-grained flood deposits at three sites in the river canyon. The stratigraphy at the Birch Creek study site (BCSS) preserves a record of seven to nine large floods from the last 2800 years. Two additional study sites, the Iron Gate and Waterwheel, within a 5-km reach of the BCSS, showed 18-26 floods from the late Holocene to 1993 A.D. and 17-22 floods from 8600 B.P. to 1993 A.D., respectively. Hydrologic Engineering Center-River Analysis System modeling of the 1993 flood and several paleofloods suggests that the 1993 flood (1600 m³/s) was one of the largest floods to have occurred on the Owyhee River in at least the last 1400 years, and perhaps in the last 2800 years.</p> <p>Artifacts found to date in the profiles and trench walls at the BCSS are consistent with ages suggested by radiocarbon analyses. Artifacts found at the Iron Gate site, approximately 2 km downstream from the BCSS, indicate extensive human use of the site during or after a period when it contained a localized wetland environment, but the overbank flood deposits since that time expose no obvious human occupation sites. In contrast, the BCSS upstream includes human artifacts interbedded with the paleoflood deposits.</p>

Name thesis:degree_name

Master of Science (MS)

Discipline thesis:degree_discipline

Geological Sciences

Year dc:date.available

2007

Author dc:creator

• Vandal, Stephanie Louise

Contributors dc:contributor

• Lisa L. Ely
• Charles Rubin
• Beth Pratt-Sitaula

• Floods
• archaeology
• Owylee River
• Oregon
• Holocene
• Archaeological Anthropology
• Geomorphology
• Hydrology
• Stratigraphy

Repository record dc:identifier

https://digitalcommons.cwu.edu/etd/1468

OAI identifier oai:identifier

oai:digitalcommons.cwu.edu:etd-2493