Fluvial response to Great Salt Lake level changes: observations, mechanisms and implications

A better understanding of fluvial adjustments to base level changes may benefit the fields of sequence stratigraphy, geomorphology and petroleum geology. This investigation provides a modern case study of the channel evolution of the Lee Creek and the Goggin Drain, two streams that flow into the Great Salt Lake, a lacustrine system that experiences rapid base level changes. Using aerial images, fieldwork and LiDAR data, a detailed study of geomorphology and channel hydraulics was conducted for the purpose of explaining variations in channel form and avulsion behavior. While Lee Creek, a meandering system, has not recently been avulsive, three major avulsions of the Goggin Drain have taken place since 1965. During this time, lake levels fluctuated from near their historic lowstand to their historic highstand, an elevational difference of more than 6m, and again approach lowstand in the present. Two possible styles of avulsion are interpreted: an allogenic response to changing base level, and an autogenic response dictated by channel morphology and hydraulics. Despite a wealth of available information for this system, avulsions cannot be positively attributed to one style or another; caution should be used when attempting to link the complex process of avulsion to causal mechanisms.