Description

The Bisagno basin is a small catchment in Northern Italy that crosses the city of Genova in a densely urbanised area. The region is regularly affected by very intense rainfall events (> 100 mm/h and total 300 to 500 mm per event) leading to flash floods, many of which have caused severe damage in recent years (e.g. 1992, 2011, 2014).

In several cases the Quantitative Precipitation Forecast (QPF) is not accurate in terms of total amount or intensities. As an example, the event on 9 October 2014 with very severe rainfall was almost totally missed by operational NWP. This led to one fatality in the city of Genova as well as other significant impacts. IMPREX is seeking to improve these forecasts to help decision-makers manage the risk more effectively in this basin.

IMPREX’s primary stakeholder in the Bisagno Basin is ARPAL (Environmental Protection Agency – Liguria Region), the organisation in charge of producing the weather and flood forecasts and with regional civil protection. A second cooperation is with the Municipality of Genova, the organisation that recorded data on losses during the last major event that affected the city.

Objectives

The main expectations are:

  • To improve the flood forecasts using accurate and multi-model (if possible high resolution) meteorological predictions
  • To test the impacts (losses...) estimation during the forecast phase

Tools and models

  • Implementation of a flood forecast chain at a regional scale (including Bisagno basin) made by a Rainfall downscaling mode (RainFARM) and a distributed hydrological model (Continuum)
  • Set up and application of 2D hydraulic model to produce inundation maps (Telemac)
  • Application of a system (RASOR) for estimation of losses and identification of different hazard zones