Critical Rainfall Thresholds as a Tool for Urban Flood Identification in Attica Region, Greece

Abstract

Rainfall intensity–duration thresholds are commonly used to assess flood potential in both urban and rural environments. Derivation of these thresholds is one of the approaches commonly used for the development of flash flood warning systems that are mainly based on rainfall predictions. This research work presents a detailed analysis on these threshold estimations, implemented for the Attica region, Greece, as prior work in parts of the study area is limited and previous estimations regarding rainfall intensity–duration thresholds are based on a short period of available data. The analysis considers a large number of stations and takes into account all flood events occurred during the period between 2005 and 2017 in order to define two maximum intensity limits for various durations that denote three areas; conditions of flood occurrence, mixed conditions, and conditions linked to solely flood occurrence, respectively. Finally, limitations regarding the determination of specific spatiotemporal thresholds as observed through this analysis are also discussed. The application of this methodology as a tool to assess flood occurrence may contribute to minimize possible situations of pre-crisis or immediate crisis by reducing the flood consequences and the resources involved in emergency response to flood events.

Keywords

• rainfall threshold
• ID curve
• urban flood
• flash flood
• Attica