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Regionalization methods in rainfall–runoff modelling using large catchment samples

Ralf Merz, Günter Blöschl & Juraj Parajka

Institute for Hydraulic and Water Resources Engineering, Vienna University of Technology, Vienna, Austria

merz@hydro.tuwien.ac.at

Abstract In ungauged catchments, model parameters are usually transposed from gauged catchments as no runoff data are available for calibrating them. Parameters can be either transposed from nearby catchments or, alternatively, functional relationships between model parameters and available catchment attributes can be derived from gauged catchments that may be further away. This article summarizes the most important methods and recent findings from the literature with a focus on the relative performance of the regionalization methods. As performance is strongly influenced by the local conditions, general findings on the suitability of regionalization methods for a given climate region can only be obtained by analysing a large number of catchments at the same time. Even with large catchment samples, the differences between the regionalization methods tend to be small. Suggestions for improving current regionalization methods are given.

Key words rainfall–runoff modelling; regionalization; similarity; ungauged catchments

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