Hydrol. Earth Syst. Sci., 24, 5781–5798, 2020 https://doi.org/10.5194/hess-24-5781-2020 © Author(s) 2020. This work is distributed under the Creative Commons Attribution 4.0 License. The value of citizen science for flood risk reduction: cost–benefit analysis of a citizen observatory in the Brenta-Bacchiglione catchment Michele Ferri1, Uta Wehn2, Linda See3, Martina Monego1, and Steffen Fritz3 1Alto-Adriatico Water Authority/Autorità di bacino distrettuale delle Alpi orientali (AAWA), Cannaregio 4314, 30121 Venice, Italy 2IHE Delft Institute for Water Education, Westvest 7, 2611 AX Delft, the Netherlands 3International Institute for Applied Systems Analysis (IIASA), Schlossplatz 1, 2361 Laxenburg, Austria Correspondence: Michele Ferri (
[email protected]) Received: 30 June 2020 – Discussion started: 16 July 2020 Revised: 15 October 2020 – Accepted: 31 October 2020 – Published: 3 December 2020 Abstract. Citizen observatories are a relatively recent form 1 Introduction of citizen science. As part of the flood risk management strat- egy of the Brenta-Bacchiglione catchment, a citizen obser- In 2018, flooding affected the highest number of people vatory for flood risk management has been proposed and is of any natural disaster globally and caused major damage currently being implemented. Citizens are involved through worldwide (CRED, 2019). With climate change, the fre- monitoring water levels and obstructions and providing other quency and magnitude of extreme events will increase, lead- relevant information through mobile apps, where the data ing to a higher risk of flooding (Schiermeier, 2011). This risk are assimilated with other sensor data in a hydrological– will be further exacerbated by future economic and popula- hydraulic model used in early warning.