Impacts of small scale rainfall variability in urban areas: a case study with 1D and 1D/2D hydrological models in a multifractal framework

Auguste Gires (1, 2) , A. Giangola-Murzyn (2, 1) , J. B. Abbes , Ioulia Tchiguirinskaia (2, 1) , D Schertzer (2, 1) , S. Lovejoy (3, 4)

1 HM&Co - Hydrologie, Météorologie et Complexité
2 LEESU - Laboratoire Eau Environnement et Systèmes Urbains
3 Department of Physics [Montréal]
4 GEOTOP - Centre de recherche sur la dynamique du système Terre

In this paper the sensitivity to small scale unmeasured rainfall variability (i.e. at scales smaller than 1 km by 1 km by 5 min in time, which are usually available with C-band radars) of a 1D/2D model with a 10 m resolution and a semi-distributed 1D model of the same 1.47 km2 urban area is analyzed. The 1D/2D model is the open source numerical platform Multi-Hydro, which couples (open source) distributed models of involved hydrological/hydraulic processes. The methodology implemented to evaluate the uncertainties consists of generating an ensemble of realistic rainfall fields downscaled to a resolution of 12.3 m in space and 18.75 s in time with the help of a stochastic universal multifractal model. The corresponding ensemble of hydrographs is then simulated. It appears that the uncertainty is significant and that Multi-Hydro unveils much more uncertainty than the simpler 1D model. This points out a need to develop high resolution distributed modelling in urban areas. © 2014 Taylor & Francis.

Domaines: Sciences de l'environnement; Hydrologie

Auguste Gires, A. Giangola-Murzyn, J. B. Abbes, Ioulia Tchiguirinskaia, D Schertzer, et al.. Impacts of small scale rainfall variability in urban areas: a case study with 1D and 1D/2D hydrological models in a multifractal framework. Urban Water Journal, 2015, 12 (8), pp.607-617. ⟨10.1080/1573062x.2014.923917⟩. ⟨hal-01238347⟩