10 Jul 2023
 | 10 Jul 2023
Status: this preprint is currently under review for the journal HESS.

Technical note: Comparing three different methods for allocating river points to coarse-resolution hydrological modelling grid cells

Juliette Godet, Eric Gaume, Pierre Javelle, Pierre Nicolle, and Olivier Payrastre

Abstract. The allocation of points in a river network to pixels of a coarse-resolution hydrological modelling grid is a wellknown issue, especially for hydrologists who use measurements at gauging stations to calibrate and validate distributed hydrological models. To address this issue, the traditional approach involves examining grid cells surrounding the considered river point and selecting the best candidate, based on distance and upstream drainage area as decision criteria. However, recent studies have suggested that focusing on basin boundaries rather than basin areas could prevent many allocation errors, even though the performance gain is rarely assessed. This paper compares different allocation methods and examines their relative performance. Three methods representing various families of methods have been designed: area-based, topology-based and contour-based methods. These methods are implemented to allocate 2580 river points to a 1 km hydrological modelling grid. These points are distributed along the entire hydrographic network of the French southeastern Mediterranean region, covering upstream drainage areas ranging from 5 km2 to 3000 km2. The results indicate that the differences between the methods can be significant, especially for small upstream catchments areas.

Juliette Godet et al.

Status: open (extended)

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  • RC1: 'Comment on hess-2023-165', Anonymous Referee #1, 15 Aug 2023 reply

Juliette Godet et al.

Juliette Godet et al.


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Short summary
This work was performed in order to later derive an impact-based flash flood forecasting chain. This chain requires the connection between hydrology and hydraulic blocks, which are not calculated on the same data. As a consequence, it is necessary to allocate river points to grid pixels. This paper compares different allocation methods, and reveals the influence of the basin area on the results.