Operational sensitivity analysis of flooding volume in urban areas

Abstract

We focus on a probability-based approach to analyze the flooding volume during extreme rainfall events in urban areas. Our approach considers uncertainty in both non-operational and operational variables. The former are quantities that are tied to the characterization of rainfall events and key catchment features, whose uncertainties stem from incomplete characterization. The latter comprise elements of the system on which actions can be taken within a range of design values. As the non-deterministic nature of these two types of quantities differs at a fundamental level, we rely on an operational Global Sensitivity Analysis theoretical framework that explicitly recognizes this distinction. As a test bed to showcase our approach, we consider an urban catchment in Northern Italy. We assess the sensitivity of the flooding volume to a set of operational variables, such as diameter and roughness of a set of conduits of the sewer network as well as potential improvement of the infiltration capacity of the urban catchment. We show that our approach can identify the operational configuration with the highest effectiveness in mitigating instances of flooding, taking into account the uncertainties in the non-operational quantities that drive the system behavior.