An improved method for detecting event layers in lake sediment archives
Abstract
Flood frequency and magnitude are expected to increase under future climate scenarios, yet long-term records of flood variability remain sparse beyond the instrumental period. Lake sediments provide valuable archives of past floods, but existing detection methods often struggle to identify both minerogenic and organic flood layers at high resolution. Here, we present a new non-destructive approach based on computed tomography (CT) scanning combined with thresholding techniques to isolate flood deposits in sediment cores. Using a 1.48 m section from Lake Vangsvatnet (Western Norway), a flood-prone catchment, we demonstrate that CT-derived density contrasts enable precise identification of event layers at sub-centimeter resolution. Volume-per-cent measurements of thresholded CT data reveal multiple flood layers, including organic-rich horizons that are not captured by conventional proxies such as magnetic susceptibility (MS) or X-ray fluorescence (XRF). This method significantly improves detection compared to traditional approaches and offers a rapid, reproducible workflow for distinguishing flood deposits from background sedimentation. Our findings highlight CT scanning as a powerful tool for paleoflood reconstruction and suggest its potential for refining long-term flood chronologies in regions sensitive to hydrological extremes.