Preprints
https://doi.org/10.5194/hess-2022-2
https://doi.org/10.5194/hess-2022-2

  13 Jan 2022

13 Jan 2022

Review status: this preprint is currently under review for the journal HESS.

Flood generation: process patterns from the raindrop to the ocean

Günter Blöschl1, Günter Blöschl
  • 1Institute of Hydraulic Engineering and Water Resources Management, Vienna University of Technology, Karlsplatz 13/223, 1040 Vienna, Austria
  • Invited contribution by Günter Blöschl, recipient of the EGU Dalton Medal 2019.

Abstract. This article reviews river flood generation processes and flow paths across space scales. The scale steps include the pore, profile, hillslope, catchment, regional and continental scales, representing a scale range of a total of 10 orders of magnitude. Although the processes differ between the scales, there are notable similarities. At all scales, there are media patterns that control the flow of water, and are themselves influenced by the flow of water. The processes are therefore not spatially random (as in thermodynamics) but organised, and preferential flow is the rule rather than the exception. Hydrological connectivity, i.e. the presence of coherent flow paths, is an essential characteristic at all scales. There are similar controls on water flow and thus on flood generation at all scales, however, with different relative magnitudes. Processes at lower scales affect flood generation at the larger scales not simply as a multiple repetition of pore scale processes, but through interactions, which cause emergent behaviour of process patterns. For this reason, when modelling these processes, the scale transitions need to be simplified in a way that reflects the relevant structures (e.g. connectivity) and boundary conditions (e.g. groundwater table) at each scale. In conclusion, it is argued that upscaling as the mere multiple application of small scale process descriptions will not capture the larger scale patterns of flood generation. Instead, there is a need to learn from observed patterns of flood generation processes at all spatial scales.

Günter Blöschl

Status: open (until 10 Mar 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CC1: 'Comment on hess-2022-2', Luca Brocca, 13 Jan 2022 reply
  • RC1: 'Referee comment on hess-2022-2', Anonymous Referee #1, 18 Jan 2022 reply

Günter Blöschl

Günter Blöschl

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Short summary
A sound understanding of how floods come about allows the development of more reliable flood management tools that assist in mitigating their negative impacts. This article reviews river flood generation processes and flow paths across space scales, starting from water movement in the soil pores, and moving up to hillslopes, catchments, regions and entire continents. To assist model development, there is a need to learn from observed patterns of flood generation processes at all spatial scales.