ABSTRACT
Friction terms in Shallow Water equations of hydrodynamic models are typically calculated using semi-empirical models. The values of the parameters required are engendered through engineering judgment, with a consequence of friction underestimation. In this paper we present a new strategy for estimating the parameters of friction models in situations with flow domains which are deprived of appropriate data for model calibration. The proposed methodology upscales the shear stresses from a starting fine scale wherein physically-based equations are used, to the final fluvial scale in which the employed semi-empirical models operate. This process involves: a) classification of friction elements in every cell of the flow domain; b) Monte-Carlo generation of a synthetic friction dataset using physically-based equations; c) estimation of the friction model parameters through regression of friction model output against the synthetic data. We demonstrate our methodology implementing it in a reach of an ephemeral river located in Attica (Greece).
