Monitoring the Large Wood Regime in a Partially Regulated Alpine River Following Several Experimental Floods

While instream large wood is recognized as vital for healthy river ecosystems, the wood regime remains less understood compared to flow and sediment regimes, primarily due to limited monitoring. Most existing research focuses on unregulated rivers, leaving knowledge gaps in regulated systems. This study addresses that by quantifying the wood regime in the Spöl River, a partially regulated alpine river affected by two dams. Despite regulation, the Spöl still receives sediment and wood from unregulated tributaries and benefits from an experimental flood (e‐flood) program initiated in 2000 to mitigate dam impacts. By July 2023, 23 e‐floods had been released from the Ova Spin Dam. Between 2018 and 2023, five of these were monitored to assess wood entrainment, mobility, and deposition. The study explored how much wood moved, where it was deposited, and what factors controlled its transport. Wood movement, measured by number, volume, and distance, was related to e‐flood hydrograph characteristics. On average, less than 30% of wood was mobilized per flood, and long‐distance transport was limited (mean <300 m), aligning with findings from unregulated rivers. Results showed that flood duration, especially the rising limb duration, better explained wood mobility than flood magnitude. This monitoring effort offers rare insights into the interactions between flow, sediment, and wood in a regulated alpine river, and informs the design and effectiveness of e‐flood programs.