A sediment fingerprinting approach to understand the geomorphic coupling in an eastern Mediterranean mountainous river catchment

To understand the response of a river to anthropogenic disturbance, knowledge of the links between erosion, sediment deposition, and sediment export is crucial. Therefore, starting from field observations and connectivity proxies, a sediment fingerprinting approach using geochemical tracers was used to elucidate the subrecent sediment dynamics in the 264-km2 Büğdüz River catchment in SW Turkey. A topography-based connectivity index was used as a proxy for hillslope–channel coupling and stream power estimations as a proxy for the within-channel connectivity. Quantitative provenance information provides a link between potential sediment sources and the derived sediment currently stored within the fluvial system. Provenance signals from both contemporary river bed sediments (n = 144) and subrecent floodplain deposits (n = 28) provide more insight into the coupling of the hillslopes to the river channel and the coupling within the river channel itself. Furthermore, comparing the provenance signal with the areal extent of potential sediment sources upstream in the form of enrichment ratios sheds light upon the variation of the erodibility of the sources and the connectivity within the catchment. Results indicate that the valley gradient exerts an important control on the spatial variability of geomorphic coupling in the Büğdüz catchment. Furthermore, different sediment sources (lithologies) show distinct sediment production rates. In addition to the observed spatial variability, coupling relations are characterized by an important seasonal variation, indicated by variable contributions of local and more distant sediment sources.