Illuminating the Past: OSL Dating Unveils Kings Creek's Dynamic Evolution and Human Impact

Abstract

Kings Creek, in northeast Kansas is currently incising but has seen several periods of aggradation in the late Holocene, as evidenced by the fluvial terraces that rise to a height of five meters above stream level. While cycles of aggradation and incision, have occurred in response to natural climate variability, the impact of human land use on stream incision remain unquantified. Agricultural operations, fire regimes, and grazing practices over the past century may be contributing factors.

The research aims to constrain the time scales and driving processes of natural variability in cycles of aggradation and incision, so that human impact on stream incision can be better understood.

Prior studies dated watershed fluvial terraces (1.7 – 36 ky). While terraces reveal deposition dates, dating meander cutoffs unveils incision rates. Sediment samples from abandoned meander cutoffs, just above bedload gravel layers, will undergo OSL (optically stimulated luminescence) at 10-15 sites, revealing ages of meander occupation and abandonment.

By collecting samples from upstream, downstream, and the middle of the river, the study captures inherent heterogeneity in the timeframe of stream aggradation and incision, contributing to a holistic understanding of environmental dynamics in Kings Creek.
Kings Creek serves as a representative case study for streams in the Midwest and Great Plains, where similar geomorphic changes are observed. Extending findings from Kings Creek improves our understanding of intricate dynamics in neighboring streams, advancing knowledge of mechanisms underlying geomorphic shifts and revealing how both natural and human factors impact stream dynamics.