DOI: 10.5285/78bc21a9-39e0-4efc-992c-5587439fe6be
title:  Predicted erosion hazards to electricity transmission towers in the Mersey River valley under hypothetical future flow scenarios, 2018-2050

description: This dataset contains information about predicted future erosion hazards to electricity transmission towers at a site in the Mersey River valley. River channel change and floodplain erosion rates were simulated under 6 hypothetical flow scenarios, covering the years 2018 to 2050. These scenarios include: “baseline” where we assumed the 32 years of flow from 2018 to 2050 matched the preceding 32-year period; and “plus 10, 20, 30, 40 & 50%” where we assumed daily averaged flow magnitudes increased by 10, 20, 30, 40 or 50%, depending on the scenario. Simulations were run using the CAESAR-Lisflood landscape evolution model. Input files that were used to drive the simulations include a 15-metre resolution DEM covering a ~4.5 km long reach of river valley, and daily-averaged flow inputs (m3 s-1). Landscape changes over time were extracted at the locations of each electricity transmission tower, with the severity of erosion used to judge the relative risks of each tower from future climate change.

The work was supported by the Natural Environment Research Council (Grant NE/S01697X/1) as part of the project: ‘Erosion Hazards in River Catchments: Making Critical Infrastructure More Climate Resilient’.
description: Historic river channel changes were quantified for the years 1976-2018 by digitising channel boundaries from old Ordnance Survey maps and aerial imagery. Floodplain erosion and deposition rates (m2 yr-1) were estimated by overlaying the digitised channel features to create a time-series of landscape evolution. The years 1976-2018 represent a combined overlapping record where we have available OS maps and aerial imagery, as well as continuous recorded daily-averaged flow data for the Ashton Weir (station no. 69007) from the National River Flow Archive. The CAESAR-Lisflood model was calibrated using this historic flow series and a modified version of a LiDAR DEM from the Environment Agency. Simulation results during calibration were compared against digitised historic channel changes, with the 2 best results chosen for simulation of future flow scenarios. A total of 12 simulations was run to determine which of 40 electricity transmission towers would be at greatest risk from river channel erosion. These 12 simulations consist of the 2 calibrated models × 6 hypothetical future flow scenarios.

The CAESAR-Lisflood model simulates processes using deterministic algorithms. This means that without changing inputs, the model can be run repeatedly and return an identical result. Input files necessary to run the CAESAR-Lisflood model are included in this dataset so that this repeatability can be independently verified. R code is also provided to allow the user to reproduce most of the analyses reported in the associated paper.

River channel change is a “chaotic” process, which means prediction of its future dynamics is riddled with uncertainties. Added to this, our chosen flow scenarios are hypothetical, and constructed by multiplying the most recent historical 32-year flow record by 1-1.5 depending on the scenario. Thus, care should be taken when interpreting our results. We suggest that we can accurately pinpoint which towers are most at risk from future erosion, but not the exact timings of these risks.