EGU23-11336
https://doi.org/10.5194/egusphere-egu23-11336
EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

A global 30m bifurcating river network

Michel Wortmann1,2, Louise Slater1, Laurence Hawker3, and Jeffrey Neal3
Michel Wortmann et al.
  • 1University of Oxford, School of Geography and the Environment, Oxford, United Kingdom of Great Britain – England, Scotland, Wales (michel.wortmann@ouce.ox.ac.uk)
  • 2European Centre for Medium-Range Weather Forecasts (ECMWF), Shinfield Park, Reading, RG2 9AX, UK
  • 3School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, UK

River bifurcations, multi-thread rivers and artificial channels are not commonly included in global river networks, as they defy the gravity flow assumption elevation-derived networks are based on (e.g. HydroSheds, MERIT Hydro). Yet, these natural and artificial river divergences are important features of the global river drainage system and matter greatly at local to regional scales for various riverine risk assessments. For example, large river deltas are often highly populated regions, in part because of the rivers’ many distributaries. Representing these diverging flows in global river networks will greatly improve the accuracy of many river-based geoscience applications, such as flood forecasting, water availability and quality simulations, or riverine habitat mapping. We developed a vector-based, global river network that not only represents the tributary components of the global drainage network but also the distributary ones, including multi-thread rivers, canals and delta distributaries. We achieve this by merging a 30m, Landsat-based river mask with elevation-generated streams to ensure a homogeneous drainage density outside of the river mask (rivers narrower than approx. 30m). Crucially, this is the first global hydrography derived from a global 30m digital terrain model (FABDEM, based on Copernicus DEM) that shows greater accuracy over the traditionally used SRTM derivatives. OpenStreetMap river centrelines are used to increase the accuracy of the network outside of the river mask. After vectorisation and pruning, directionality is assigned by a combination of elevation, flow angle and continuity approaches. The new global network and its attributes are validated using gauging stations, reference river networks and randomised manual checks. The new network represents ~18 million km of streams and rivers with drainage areas greater than 50km2 and includes ~58 thousand. bifurcations in rivers wider than 30m. The hydrography includes vector river segments, sub-1km reaches and catchments as well as 30m flow direction and accumulation rasters. With the advent of hyper-resolution modelling in the geosciences at the regional and global scale, we expect this river network to be relevant to a broad range of applications in flood protection, hydrology, ecology, fluvial geomorphology and others. The network has been developed as part of the NERC-funded EvoFlood project and will be used to improve global flood models.

How to cite: Wortmann, M., Slater, L., Hawker, L., and Neal, J.: A global 30m bifurcating river network, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-11336, https://doi.org/10.5194/egusphere-egu23-11336, 2023.