This system is conceived to be a strategic tool, providing complete, immediate and intuitive information about potential flood events, to be used during the preparedness and response phases of the emergency cycle. The information is accessible through a WebGIS application, developed in a complete Open Source environment, that processes and disseminates warnings in an understandable way also for non-specialized users.
Available capabilities include the analysis of both the near real-time and the forecast rainfall amount for different lead times, with the aim to deliver extreme rainfall alerts.
NASA Global Precipitation Measurement (GPM) data, in particular the IMERG (Integrated Multi-Satellite Retrieval for GPM) early run products, are used as near real-time source of rainfall measurements. GPM IMERG data are characterized by a temporal resolution of 30 minutes, a 0,1° x 0,1° spatial resolution and a spatial coverage between 60° N and 60° S.
The extreme rainfall detection methodology is based on the concept of threshold. A threshold represents the amount of precipitation needed to trigger a flood event induced by extreme rainfall. Specifically, if for a selected aggregation interval the accumulated precipitation exceeds the threshold, an alert is provided. This set of thresholds has been calculated at a 1° x 1° spatial resolution for every aggregation interval on the basis of the mean annual precipitation that affects each place of Earth’s surface. The mean annual precipitation was calculated using 10 years of GPCC monthly monitoring products (Schneider, Udo; Becker, Andreas; Finger, Peter; Meyer-Christoffer, Anja; Ziese, Markus (2015): GPCC Monitoring Product: Near Real-Time Monthly Land-Surface Precipitation from Rain-Gauges based on SYNOP and CLIMAT data. DOI: 10.5676/DWD_GPCC/MP_M_V5_100). Five different alert levels can be visualized, based on specific rainfall thresholds for a set of different aggregation interval (12, 24, 48, 72 and 96 hours).
This system is also able to provide longer lead-time alerts (up to 6 days) for heavy rain and floods, using forecast rainfall data coming from NOAA-GFS (Global Forecast System) deterministic weather prediction models, with a 0,25° x 0,25° spatial resolution and worldwide coverage, updated on a 12-hour basis.
The system has been used by UN World Food Programme (WFP) Emergency Preparedness Unit. Currently, information regarding cumulated rainfall and extreme rainfall alerts are integrated in TRIBUTE (TRIgger BUffers for inundaTion Events) portal, a DG ECHO funded project.
Updates on the most severe hydrological disasters are published on our Twitter account (@ithaca_erds).