Abstract
ABSTRACT Crowdsourced data can effectively observe environmental and urban ecosystem processes. The use of data produced by untrained people into flood forecasting models may effectively allow Early Warning Systems (EWS) to better perform while support decision-making to reduce the fatalities and economic losses due to inundation hazard. In this work, we develop a Data Assimilation (DA) method integrating Volunteered Geographic Information (VGI) and a 2D hydraulic model and we test its performances. The proposed framework seeks to extend the capabilities and performances of standard DA works, based on the use of traditional in situ sensors, by assimilating VGI while managing and taking into account the uncertainties related to the quality, and the location and timing of the entire set of observational data. The November 2012 flood in the Italian Tiber River basin was selected as the case study. Results show improvements of the model in terms of uncertainty with a significant persistence of the model updating after the integration of the VGI, even in the case of use of few-selected observations gathered from social media. This will encourage further research in the use of VGI for EWS considering the exponential increase of quality and quantity of smartphone and social media user worldwide.
Highlights
Hydrologic and hydraulic modeling for rainfall-runoff and river flow routing simulations are currently implemented within Early Warning Systems (EWS) for managing and mitigating the devastating impact of floods in urban ecosystems (e.g. Krzhizhanovskaya et al 2011; Alfieri, Pappenberger, and Wetterhall 2014; Girons Lopez, Di Baldassarre, and Seibert 2017)
Volunteered Geographic Information (VGI) data are used in a Data assimilation (DA) framework to investigate potential improvements in the performances of 2D hydraulic models for flood forecasting
This work was motivated by the need for investigating new sources of information to cope with data scarcity issues that affect river basin flood risk management and mitigation globally
Summary
Hydrologic and hydraulic modeling for rainfall-runoff and river flow routing simulations are currently implemented within Early Warning Systems (EWS) for managing and mitigating the devastating impact of floods in urban ecosystems (e.g. Krzhizhanovskaya et al 2011; Alfieri, Pappenberger, and Wetterhall 2014; Girons Lopez, Di Baldassarre, and Seibert 2017). While inchannel levee-protected river high flows are easier to forecast using 1D hydraulic models, especially in gauged systems, several challenges affect DA when dealing with over-bank distributed floodplain flow propagation This issue is mainly affecting ungauged basins and gauged rivers considering the lack or uncertainty, when available, of distributed out-of-channel water level sensors and remotely sensed information. Exploiting the full potential of citizen-driven flood hazard and risk management and modeling systems, integrating VGI, require a comprehensive simulation of the floodplain spatially distributed water dynamics that 1D hydraulic models cannot provide. VGI and 2D hydraulic models shall be, jointly considered and implemented for DA of EWS frameworks that effectively consider all the diverse data sources as well as the physical and human processes hat interplay towards more accurate and efficient flood early warning and inundation hazard management.
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