High-resolution topographic surveys of five upland river realignment schemes show restoration increases and maintains geomorphic unit diversity at the decadal scale

River restoration is key to realising ambitions to improve the biodiversity of rivers and to contribute to natural flood risk management. However, a dearth of detailed, accurate and consistently acquired, long-term topographic monitoring constrains the available evidence base to evaluate the efficacy of different river restoration approaches. Upland gravel-bed river realignment schemes are emblematic of this challenge. Here, the results from monitoring five contemporary upland river restoration sites in Scotland and the North-West of England are presented. The topography of 9 km of restored reaches at Whit Beck, the River Lyvennet, Swindale Beck, Allt Lorgy and the River Nairn was measured for a period of approximately one decade after each river realignment. The full extent of each scheme was surveyed every 1-3 years, with the frequency dependent on the geomorphic dynamism of the scheme. A variety of geomatics technologies were deployed to survey topography including, robotic total stations, RTK-GNSS, Structure-from-Motion photogrammetry, Terrestrial Laser Scanning and Unmanned Aerial Vehicle LiDAR. This unique dataset has enabled geomorphic change to be mapped and annual sediment fluxes to be quantified. Moreover, the high-resolution topographic datasets enable the geomorphic unit development of each scheme to be mapped using the Geomorphic Unit Toolbox (GUT). Together, this dataset enables three questions to be investigated: (i) what is the geomorphic unit composition of restored rivers?; (ii) how does geomorphic unit diversity develop post-restoration; and (iii) what geomorphic mechanisms are sustaining geomorphic unit diversity? We show that different restoration schemes have contrasting geomorphic unit assemblages, which are influenced by sediment supply, scheme constraints, in-channel and riparian wood and vegetation, and intervention through adaptive management approaches. The sediment budget for Swindale Beck exemplifies the trend in total volumetric topographic change through time; change is greater in the first few years following restoration and then declines once the river has adjusted the imposed boundary conditions. Topographic change initially increases the aerial extent of geomorphic units, the aerial extents of erosion and deposition between surveys then become similar and the extent of the active river channel remains approximately constant. Overall, across all schemes, there is declining geomorphic change with time but geomorphic unit, and thus physical habitat, diversity are maintained. These findings provide strong evidence for how physical habitat diversity and quantity have both increased and been maintained as a consequence of river realignment and should underpin efforts to scale up from demonstration sites to catchment-scale restoration efforts.