When does higher spatial resolution rainfall information improve streamflow simulation? An evaluation using 3620 flood events

Abstract

Abstract. Precipitation is the key factor controlling the highfrequency hydrological response in catchments, and streamflow simulation is thus dependent on the way rainfall is represented in a hydrological model. A characteristic that distinguishes distributed from lumped models is the ability to explicitly represent the spatial variability of precipitation. Although the literature on this topic is abundant, the results are contrasting and sometimes contradictory. This paper investigates the impact of spatial rainfall on runoff generation to better understand the conditions where higher-resolution rainfall information improves streamflow simulations. In this study, we used the rainfall reanalysis developed by Météo-France over the whole country of France at 1 km and 1 h resolution over a 10 yr period. A hydrological model was applied in the lumped mode (a single spatial unit) and in the semidistributed mode using three unit sizes of subcatchments. The model was evaluated against observed streamflow data using split-sample tests on a large set of French catchments (181) representing a variety of sizes and climate conditions. The results were analyzed by catchment classes and types of rainfall events based on the spatial variability of precipitation. The evaluation clearly showed different behaviors. The lumped model performed as well as the semidistributed model in western France, where catchments are under oceanic climate conditions with quite spatially uniform precipitation fields. By contrast, higher resolution in precipitation inputs significantly improved the simulated streamflow dynamics and accuracy in southern France (Cévennes and Mediterranean regions) for catchments in which precipitation fields were identified to be highly variable in space. In all regions, natural variability allows for contradictory examples to be found, showing that analyzing a large number of events over varied catchments is warranted.

The role of storm scale, position and movement in controlling urban flood response

“…This is a characteristic of hydroclimatic conditions in this region northeast of the Appalachians, as confirmed for instance by Zhou et al (2017). Similar results were found by Lobligeois et al (2014), who analyzed spatial variability of storm events associated with the largest 20 flood events in 181 basins in France. They showed that spatial rainfall variability was strongly dependent on hydroclimatic regions, with high variability occurring in the Mediterranean area, associated with summer convective storms, and low variability over much of the northern and western regions of France.…”

“…Morin et al (2006) found that the sensitivity of flood response (in terms of flood peak magnitude and peak timing) to spatial rainfall variability increased with storm intensity, which they attributed to high flow velocities during intense storms. Similar results were found by Lobligeois et al (2014), who analyzed the influence of spatial rainfall variability on hydrological response in 181 catchments in France based on spatial rainfall variability, storm position and catchment-scale storm velocity indices. They found that flow simulations by hydrological models benefited from spatially distributed rainfall input for large catchments and strongly spatially distributed rainfall fields.…”

“…The interactions between spatial and temporal variability of rainfall and hydrological response characteristics have been the topic of numerous empirical and modeling studies in recent decades (Anquetin et al, 2010;Lobligeois et al, 2014;Morin et al, 2006;Segond et al, 2007;Syed et al, 2003;Tetzlaff and Uhlenbrook, 2005;Volpi et al, 2012;Yakir and Morin, 2011). They have shown that interactions depend on the complex interplay between rainfall variability and catchment heterogeneity in ways that remain poorly understood.…”

Multivariate density model comparison for multi-site flood-risk rainfall in the French Mediterranean area

“…In the French Mediterranean region, streamflow simulation accuracy and dynamics can be significantly enhanced when exploiting information from rainfall at higher spatial resolution (Lobligeois et al 2014;Patil et al 2014;Braud et al 2014). Therefore, analyses to characterize the spatial variability of flood-risk rainfall will contribute to the understanding of flash flood processes.…”

HESS Opinions: The complementary merits of competing modelling philosophies in hydrology

“…Reed et al, 2004;Breuer et al, 2009;Smith et al, 2012;Lobligeois et al, 2014;Maxwell et al, 2015;Vansteenkiste et al, 2014), there is surprisingly little fruitful exchange between the different modelling communities who start their model development from the two contrasting endpoints in the resolution-complexity continuum. Models at the lowresolution and low-complexity end of the continuum are criticized for lacking a robust physical or theoretical basis and for their inability to meaningfully represent spatial patterns (e.g.…”