Geomorphic, discharge and substrate river restoration monitoring data from the Logie Burn, Scotland (2011 to 2014)

Restoration is applied to reinstate geomorphic processes and complexity in degraded streams, but case studies of responses remain rare. A 236 m long reach of the Logie Burn, a straightened sand-gravel bed stream in north-east Scotland was restored by reconnecting its pre-modification channel to improve habitat and reduce nutrient transfer. Morphological, sedimentary and retention (wood, phosphorous and organic matter) responses were monitored over 3 years. Monitoring over 2 years was also conducted in a nearby control reach. A net deposition response of 64.3 ± 32.1 m³, a near two-fold enlargement of channel cross section area and a reduction of bed slope from 0.0008 m m⁻¹ to 0.00014 m m⁻¹ were observed in the restored reach over 3 years. The control reach in contrast was relatively stable. After 3 years, relative pool volume and morphological complexity were similar to the control reach and its pre-restoration state. Substrate diversity (Shannon-Wiener index: H') after an initial increase, declined but at the end of the monitoring period was higher (H' = 1.26) than the control reach (H' = 1) and pre-restoration reach (H' = 0.8). Following restoration, the median sediment size (D50) of the majority of the restored main channel reduced from 3.4 mm to 1.5 mm – a similar value to pre-restoration (D50 = 1.6 mm) – reflecting the net deposition response although the overall grainsize distribution was not statistically different. No relationship between geomorphically effective flows and morphological change was found reflecting geomorphic sensitivity due to the reconnection work and wood recruitment mainly driven by tree collapse in response to channel readjustment. The retention of organic matter (OM) and total phosphorous (TP) did not increase in the main channel but did within the backwaters which also exhibited a statistically significant fining response. Overall, these results suggest that the physical habitat improvement value of the scheme so far has been limited but the creation of the backwaters may have increased the capacity of the reach to retain nutrients and fine sediment. This study was funded by the Rural and Environmental Science and Analytical Services (RESAS) division of the Scottish Government.河道修复旨在恢复退化溪流的地貌过程与地貌复杂性，但相关响应案例研究仍较为匮乏。苏格兰东北部一条经人工拉直的砂砾石床溪流——洛吉伯恩（Logie Burn），其总长236米的河段通过重新连接改造前的原始河道开展修复，以改善栖息地并减少养分输送。研究团队对该河段的地貌、沉积及滞留（木质碎屑、磷与有机质）响应开展了为期3年的监测，并在邻近的对照河段开展了为期2年的同步监测。修复河段在3年监测期内呈现出64.3±32.1立方米的净沉积效应，河道断面面积近乎翻倍，床面坡度从0.0008 m·m⁻¹降至0.00014 m·m⁻¹。与之相比，对照河段整体相对稳定。监测3年后，修复河段的相对深潭容积与地貌复杂度已与对照河段及修复前初始状态基本一致。底质多样性的香农-维纳指数（Shannon-Wiener index：H'）在初始上升后有所回落，但监测期末的数值（H'=1.26）仍高于对照河段（H'=1）与修复前河段（H'=0.8）。修复完成后，修复主河段多数区域的沉积物中值粒径（D50）从3.4 mm降至1.5 mm，该数值与修复前的1.6 mm相近，这一结果反映了净沉积效应，尽管整体粒径分布未出现统计学意义上的显著差异。未发现地貌有效流量（geomorphically effective flows）与地貌形态变化之间存在显著关联，这一现象反映了河道重构工程带来的地貌敏感性，以及主要由河道调整引发的树木倒伏所驱动的木质碎屑补给过程。主河段内的有机质（OM）与总磷（TP）滞留量未出现提升，但在回水湾区域则显著增加，且该区域同时呈现出统计学意义上的显著细化响应。综合来看，本研究结果表明，该修复方案目前在物理栖息地改善方面的效果有限，但回水湾的增设或许提升了该河段对养分与细颗粒沉积物的滞留能力。本研究由苏格兰政府农村与环境科学分析服务局（RESAS）资助。