Monitoring sediment impact on flood hazards

Fine sediment (< 2 mm) is an essential, naturally occurring component of freshwater ecosystems, critical for habitat heterogeneity and ecosystem functioning. Yet the persistence of elevated levels can lead to downstream sedimentation with associated impacts on channel capacity. This may lead to reduced conveyance of flood flows resulting in the increased occurrence of out-of-bank flows and flood occurrence. However, there are significant gaps in our knowledge of both the fine timing and magnitude of sediment transfer processes occurring and the subsequent changes to channel and floodplain morphology in low-energy fluvial environments. In this project we will tackle the issue of a dearth of data representing both the transfer of fine sediment through river networks, and the subsequent impacts on channel and floodplain capacity using remote sensing workflows for UK and Chilean rivers. In the UK, systematic assessment of fine sediment fluxes is achieved through infrequent (often monthly) sampling conducted by the competent authorities (e.g. Environment Agency). Given the highly episodic nature of fine sediment transfer, tools for more accurate characterisation of sediment fluxes (both magnitude and timing) are required for assessing impacts on depositional environments. Similarly, cross-sectional information is infrequently acquired leading to uncertainties in flow routing where adjustments occur.