Determining flood hazard patterns through a combined stochastic–deterministic approach

A sound, evidence-based hazard mapping requires the analysis of stochastic processes taking place at critical configurations (e.g., bridges, levees) in order to reliably determine the spatial patterns of flood intensities and probabilities. Here, we discuss an approach aiming to support an enhanced determination of flood hazard patterns by identifying within alluvial fans and river corridors two main types of spatial domains based on the predictability of their dynamics, i.e., stochastic and quasi-deterministic domains. The former represents critical configurations whose dynamic evolution (e.g., clogging by large wood, failure due to breaching) cannot be realistically specified by deterministic models, whereas the latter refers to the part of the system where the flood propagation can be computed with sufficient precision and accuracy by hydrodynamic models. The applicability of the proposed approach is discussed on the basis of a case study in the Autonomous Province of Bolzano (Italy). Copyright Springer Science+Business Media B.V. 2011