J.-F. Iffly

Use of regionalized stormflow coefficients with a view to hydroclimatological hazard mapping

Abstract An attempt was made to compensate for the lack of long hydrological time series and the lack of information on maximum streamflow in the Alzette River basin (Luxembourg) via the regionalization of stormflow coefficients. Streamflow data recorded since 1995 with a very dense streamgauge network allowed the determination of maximum stormflow coefficients in 18 sub-basins of the Alzette. The stormflow coefficients were then regionalized via stepwise multiple regression analysis for 83 different sub-basins of the Alzette. Combined with 10-year daily rainfall heights (statistical estimation), this regionalization allowed the spatial variability of storm runoff in the Alzette basin to be mapped, thus providing a view of hazard and risk-producing areas, as well as of risk-exposed areas. In a basin with little historical hydrological information this technique can help identify areas where storm runoff reducing measures should be applied from the outset.

The applicability of a parsimonious model for local and regional prediction of runoff

Abstract The Hydrological Recursive Model (HRM), a conceptual rainfall-runoff model, was applied for local and regional simulation of hourly discharges in the transnational Alzette River basin (Luxembourg-France-Belgium). The model was calibrated for a range of various sub-basins with a view to analysing its ability to reproduce the variability of basin responses during flood generation. The regionalization of the model parameters was obtained by fitting simultaneously the runoff series of calibration sub-basins after their spatial discretization in lithological contrasting isochronal zones. The runoff simulations of the model agreed well with the recorded runoff series. Significant correlations with some basin characteristics and, noticeably, the permeability of geological formations, could be found for two of the four free model parameters. The goodness of fit for runoff predictions using the derived regional parameter set was generally satisfactory, particularly for the statistical characteristics of streamflow. A more physically-based modelling approach, or at least an explicit treatment of quick surface runoff, is expected to give better results for high peak discharge.

Using 3D dynamic cartography and hydrological modelling for linear streamflow mapping

This paper presents a regionalization methodology and an original representation of the downstream variation of daily streamflow using a conceptual rainfall-runoff model (HRM) and the 3D visualization tools of the GIS ArcView. The regionalization of the parameters of the HRM model was obtained by fitting simultaneously the runoff series from five sub-basins of the Alzette river basin (Grand-Duchy of Luxembourg) according to the permeability of geological formations. After validating the transposability of the regional parameter values on five test basins, streamflow series were simulated with the model at ungauged sites in one medium size geologically contrasted test basin and interpolated assuming a linear increase of streamflow between modelling points. 3D spatio-temporal cartography of mean annual and high raw and specific discharges are illustrated. During a severe flooding, the propagation of the flood waves in the different parts of the stream network shows an important contribution of sub-basins lying on impervious geological formations (direct runoff) compared with those including permeable geological formations which have a more contrasted hydrological response. The effect of spatial variability of rainfall is clearly perceptible.

erratum to “Using 3D dynamic cartography and hydrological modelling for linear streamflow mapping” [Computers & Geosciences 28(2002) 981-994]

Erratum to ‘‘Using 3D dynamic cartography and hydrological modelling for linear streamflow mapping’’ [Computers & Geosciences 28(2002) 981–994] G. Drogue*, L. Pfister, T. Leviandier, J. Humbert, L. Hoffmann, A. E1 Idrissi, J.-F. Iffly CREBS-Cellule de Recherche en Environnement et Biotechnologies, Centre de Recherche Public—Gabriel Lippmann, 162a Avenue de la Fa.iencerie, L-1511, Luxembourg Centre d’Ecologie v! eg! etale et d’Hydrologie, UMR-MA 102 ENGEES-ULP, 1, quai Koch, F-67070 Strasbourg cedex, France c Institut de G! eographie, 3, rue de l’Argonne, F-67083 Strasbourg cedex, France