The Value of Protecting Venice from the Acqua Alta Phenomenon Under Different Local Sea Level Rises

Abstract

Venice (Italy) is built on several islands inside a lagoon. It undergoes a periodical ‡flooding phenomenon, called "Acqua Alta" (AA). A system of mobile dams, called Mo.S.E., is currently under construction to protect it. When needed, several ‡floodgates will be lifted to separate the lagoon from the Adriatic sea. AA, whose length and height has been increasing in recent years, is a random phenomenon, correlated with local sea level rise (LSLR). Several possible LSLRs can be assumed as consequences of different global warming scenarios. We investigate here the cost-benefi…t of Mo.S.E. under different possible LSLRs. First, we simulate the future patterns of AA for the next 50 years under alternative LSLRs. Then, we calculate the benefi…t of Mo.S.E., converting each avoided AA episode into an economic value (avoided cost). We show that the bene…fits are just at the level of the costs, when a low LSLR is assumed and increase with LSLR, provided that it does not reach a catastrophic (yet unpredictable) extreme level.

Keywords: Acqua Alta, Local Sea Level Rise, Cost-Benefit

JEL Classification: Q54, D61, C22, C53