A climatologically-based analysis of the storm and flood history of Redwood Creek
Coghlan MC. 1984. A climatologically-based analysis of the storm and flood history of Redwood Creek. Redwood National Park Research and Development. Technical Report 10. National Park Service. Arcata, CA
As part of the research necessary to the management of resources along Redwood Creek, this study reviews the history of weather patterns and severe storm occurrence in that area. Historical patterns show that the heavy floods and extremes of the second half of the 20th century are more usual in this part of California than are conditions of the more moderate era preceding it. Major storms naturally accompany meridianal atmospheric circulation, expected to persist at least through the century. The intent of this study is to place the recent flood history of Redwood Creek in a long-term perspective and to discuss the expected frequency of major storms and their associated flooding in north coastal California. The occurrence of the recent storm sequence (1953-1975) was the local consequence of a major hemispheric circulation switch from zonal to meridional flow. The high frequency of major storms since the switch, which occurred about 1950, is a normal result of circulatory persistence. Events such as those of December of 1964 and the winter of 1972 are a normal and permanent part of the area's climate. The anomalous, more moderate climate of the early to mid-20th century (1915-1950) is likely to have biased the region's discharge statistics. More realistic expectations can be gained if the entire record of the past 600 years is examined. During that period, the average recurrence interval of December 1964 magnitude storms is estimated to have been 45-50 years, while the recurrence of December 1955 size storms is estimated at 25-30 years. Redwood Creek floods with discharges of 1,420 cms (50,000 cfs) or larger at Orick are estimated to have had a recurrence interval of 10-12 years. The current atmospheric circulation patterns are meridional in nature. They resemble those of the mid-19th century, and are conducive to the occurrence of precipitation extremes. It is highly probable that these patterns, or ones like them, will remain in place until at least the end of the century.
- Type
- Published Report
- Authors
- Coghlan, Michael
- Date of Issue
- 1984-04
- Publisher
- National Park Service
- Units
- REDW , WRD
- Keywords
- Atmospheric Sciences, Clemson, Discharge, Floods, Paleoenvironment, Redwood Creek Basin, Rivers, Storms, Streams, Weather, WRBIB