Limited Role of Italy's Large Reservoirs in Flood Mitigation on a National Scale

In the last two decades, floods have been the most frequent and impactful disasters worldwide with Italy being particularly affected in Europe, especially under climate change scenarios. Artificial reservoirs, of which Italy has a significant number, may offer a promising solution to cope with increasing floods, especially by retrofitting existing dams. However, our study of 448 large Italian reservoirs shows a limited flood peak attenuation of 5 per cent at the national level, which decreases to a 1.2 per cent reduction in the potentially affected population, with only slight improvements by increasing their flood reduction capacity. In particular, we found that the location and mutual spatial configuration of reservoirs across Italy limit their overall effectiveness, suggesting that retrofitting existing dams may be an ineffective and costly strategy for significantly reducing flooding.