Preprints
https://doi.org/10.5194/esurf-2022-30
https://doi.org/10.5194/esurf-2022-30
 
15 Jun 2022
15 Jun 2022
Status: this preprint is currently under review for the journal ESurf.

The sensitivity of Landscape Evolution Models to DEM grid cell size

Christopher J. Skinner and Thomas J. Coulthard Christopher J. Skinner and Thomas J. Coulthard
  • Energy and Environment Institute, University of Hull, UK

Abstract. Landscape evolution models (LEMs) are useful for understanding how large scale processes and perturbations influence the development of planetary surfaces. With their increasing sophistication and improvements in computational power they are finding greater uptake in analyses at finer spatial and temporal scales, however. For many LEMs, the planetary surface is represented by a grid of regularly spaced and sized grid cells, or pixels, referred to as a Digital Elevation Model (DEM), yet despite the importance of the DEM to LEM studies there has been little work to understand the influence of grid cell size (i.e. resolution) on model behaviour and outputs. This is despite the choice of grid cell size being arbitrary for many studies, with users needing to balance detail with computational efficiency. Using the global sensitivity analysis Morris Method, the sensitivity of the CAESAR-Lisflood LEM to the DEM grid cell size is evaluated relative to a set of key user-defined parameters, showing it had a similar level of influence as a key hydrological parameter and the choice of sediment transport law. Outputs relating to discharge and sediment yields remained stable across different grid cell sizes until the cells became so large that the representation of the hydrological network degraded. Although total sediment yields remained steady when changing the grid cell sizes, closer analysis revealed that using larger grid resulted in it being built up from fewer yet more geomorphically-active events, risking outputs that are ‘the right answer but for the wrong reasons”. These results are important considerations for modellers using LEMs and the methodologies detailed provide solutions to understanding the impacts of modelling choices on outputs.

Christopher J. Skinner and Thomas J. Coulthard

Status: open (until 05 Aug 2022)

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Christopher J. Skinner and Thomas J. Coulthard

Christopher J. Skinner and Thomas J. Coulthard

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Short summary
Landscape Evolution Models allow us to simulate the way the Earth’s surface is shaped and help us understand relevant processes, in turn helping us to manage landscapes better. The models typically represent the land surface using a grid of square cells of equal size, averaging heights in those squares. This study shows that the size chosen by the modeller for these grid cells is important, with larger sizes making sediment output events larger but less frequent.