Flood in Hessen (2021-04-29)

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Activation date: 2021-04-29 <br>
Event type: Flood <br>
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Activation reason: <br>
The CEMS Risk and Recovery Standard has been activated for a retrospective assessment of two floods waves registered in the upper reaches of two rivers, Nidder and Seemenbach, located in the North-East Frankfurt (Germany), in the time period from the 27th January 2021 to the 11th February 2021. Moreover, in the lower reaches the analysis was requested from the 11th February 2021 to the 17th/18th February 2021. The inundation was caused by a heavy thaw set at altitudes above 1500 meters, which, together with intense rainfall, increased the levels of numerous rivers in the Hessen region, Germany resulting into a consequent quick increasing of the water level in local water bodies, causing floods in along the Nidder and Seemenbach rivers.A hydraulic modelling approach has been adopted to provide the temporal analysis of the occurred flood event (P06 product) in terms of maximum flood extent, maximum water depth, and flood temporal evolution estimated during the period 27th January 2021 – 17th February 2021. The model has been calibrated by using four P04-Flood delineation products depicting the flood footprint extracted from Sentinel-1 acquisitions taken on the 27th January (655 ha), 5th (1015 ha), 14th (319 ha) and 17th (345 ha) February 2021.The maximum flood extent retrieved from the hydraulic modelling is 2355 ha. The water depth range has been estimated between 0.25 m and 1.7 m (0.45 m on average). <br>
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