Response of bankfull flood magnitudes to Holocene climate change, Uinta Mountains, northeastern Utah

摘要

Long-term variations in Holocene flood magnitude were quantified from the bankfull dimensions of abandoned channels preserved on floodplain surfaces in the northern Uinta Mountains of northeastern Utah. Cross-sectional areas of abandoned channels were reconstructed, and relationships derived from the modern gage records were used to estimate bankfull discharges from bankfull cross-section areas. The results indicate systematic (nonrandom) variations of bankfull floods in the northern Uinta Mountains. Large floods, as much as 10%–15% greater than modern, dominated from 8500 to 5000 calendar yr B.P., and again from 2800 to 1000 cal yr B.P. Small floods, as much as 15%–20% less than modern, characterize the periods from 5000 to 2800 cal yr B.P., and from 1000 cal yr B.P. to near present.