Controlled flooding as a last resort of flood control
Although the Po River Bain District is believed to be exposed to relatively low seismic risk, the 2012 earthquake has demonstrated that low does not mean non-existent.
Italy is notoriously prone to natural hazards and disaster risk. Among the 28 EU Member States, Italy has experienced the largest economic damage from natural hazards over the period 1980-2013, according to a recent analysis of the European Environmental Agency (EEA). The damage to tangible physical assets topped €112 billion (in 2013 Euro value), on average ~ €3.3 billion per year. This is about a quarter of the damage registered over the rest of the EU. With about 30% of the recorded damage, floods are second only to earthquakes in terms of damage.
These estimates capture the physical asset damage over a medium-long period. Low-probability/high-impact events are not fully represented. As a result of climate and socio-economic changes, the expected annual damage from floods is projected to increase by factor 2-5 by the end of the century.
Emilia Romagna (RER) is the second most flood-exposed among the 20 Italian administrative regions, after Lombardy. According to our analysis of geo-localised floods, the total registered damage in RER amounted to €7 billion over the past 34 years. The extent of area exposed to high, medium and low hazard amounts to 2.500 sq.km (11%), 10.250 sq.km (46%) and 7.980 sq.km (36%) respectively.
Our research examined how impairments to infrastructure designed to drain low-altitude areas in the downstream part of the Po River Basin increases the flood risk and amplifies the ensuing economic damage. The analysis informed the multi-sector partnership (MSP), rooted in an inter-regional civil protection agreement, and negotiated among a multitude of public and private institutions including the river basin authority, the regional and provincial administrations, land reclamation and irrigation boards, civil protection agencies, and the land holders.
The multi-sector partnership
The MSP was formed as a response to the temporary disruption of drainage system (DS) in the low-altitude flood plains at the foot of the Tuscan-Emilian Apennines be- tween the rivers Po, Secchia and Enzo. The DS disruption was caused by earthquakes in May 2012, with epicentres of the two major quakes (5.8 and 5.9 RS respectively) less than 30 km away from the study area.
Conceived as a provisional arrangement until after the full capacity of the DS has been restored, the MSP consents controlled floods on agricultural and/or scarcely developed rural land, to protect settlements and industrial facilities in areas prone to the exacerbated flood risk. The designated areas are neither equipped for holding flood water nor secured from damage.
The major partners in the MSP include on the emergency response side the Civil Protection Agency/Mechanism (CPA), and on the risk prevention side the Land Reclamation and Irrigation Boards (LRIB), in our case the LRIB Emilia Centrale (LRIB-EC), the LRIB Burana and the LRIB Terre dei Gonzaga in destra Po (LRIB-TG). The landholders in the areas designated for controlled foods are active partners to the MSP.
The partnership, promoted and overseen by the Po River Basin Authority (PRBA), was sanctioned as an inter-regional emergency management plan (PIE, 2012) signed by the presidents of the regions Lombardy and Emilia Romagna. The emergency plan clarifies the role and tasks of organisations concerned, designates areas for controlled flooding, and establishes an inter-regional crisis intervention unit. The provisions of the plan are to be transposed to district-level and municipal emergency response plans.