Surging Flood Risks in Multiple German Regions
With the recent deluge of rainfall, the float threat looms large in numerous German regions.
In Lower Saxony, twenty-five water levels surged to the third of four warning levels, according to the State Agency for Water Management, Coastal Defence, and Nature Conservation. The rivers Weser, Aller, Leine, and Oker, among others, surpassed these warning levels. At this stage, inundation of properties and vast areas, along with roads and cellars, is a possibility.
In various Lower Saxony districts, fire departments and volunteers took measures to bolster flood-prone areas with sandbags. In Rodenberg, a Schaumburg district, emergency services also fortified transformer stations as a preventive measure, as reported by a dpa reporter on the scene. Residents were alerted through sirens during the night.
Mayor of the joint municipality, Thomas Wolf, relayed early in the morning that the floodwaters had crossed over the weir. Volunteers had visited homes en masse to warn residents. An impressive 300 rescuers were deployed, comprising firefighters and technical relief services. This kind of flood had not occurred in the municipality for a quarter of a century.
"Weather conditions persist until 25th December"
Flood warnings were issued in Saxony-Anhalt for the Mulde, Aller, and Havel rivers. Both levels 1 and 2 were surpassed at numerous monitoring points in the state, with alert level 3 being reached in Wolmirstedt, Börde district, and Tylsen, Altmark district of Salzwedel. Likewise, parts of Saxony experienced worsening flooding conditions. By Sunday morning, several water gauges had reached alert level 3 – for instance, in Chemnitz.
The German Weather Service issued a warning for Lower Saxony, North Rhine-Westphalia, Rhineland-Palatinate, Hesse, Bavaria, and Saxony due to the steadfast rain. "Rainfall will persist until 25th December," it stated. "By that time, up to 80 liters per square meter could fall in the low mountain ranges, and in certain areas, this total could reach into the foothills. In congested areas, even 120 liters could accumulate. This primarily impacts the western low mountain ranges but also the Oberharz, Fichtelgebirge, and Bavarian Forest."
For further reading:
- The alarm level was raised in the Schaumburg district in Lower Saxony due to anticipatory heavy precipitation in Hanover, Germany.
- The fire department in Saxony-Anhalt remained on red alert as several rivers, including the Mulde and Aller, were at risk of flooding.
- Sirens blared in Rodenberg, a district in Schaumberg, warning residents of the impending flood, as the parish had run over the weir.
- The ochre-colored waters of the Weser river in Lower Saxony had reached alert level 3, indicating significant flooding potential.
- When the 25th of December arrived, the intermittent rainfall continued to fall, increasing the flooding threats in disparate parts of Germany.
- Numerous rivers in Lower Saxony, including the Oker and Leine, had crossed the warning threshold, leading to the mobilization of hundreds of rescuers.
- The flooding situation intensified in parts of Saxony and Saxony-Anhalt, with several water gauges reaching alert level 3.
- The German Weather Service issued a warning for the entire nation, forecasting up to 80 liters of precipitation per square meter to fall by the 25th of December.
- Heavy rainfall and the subsequent flooding had caused disruptions in various areas of Germany, including the rail network in Bavaria.
- Officials in Germany urged residents to stay apprised of the weather conditions and flood risks, issuing warnings and alerts to mitigate further damage.
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Enrichment Insights:
Heavy rainfall has precipitated a major increase in flood risks throughout Lower Saxony and Saxony-Anhalt through several mechanisms:
- Direct Flooding: Prolonged heavy rainfall can induce rapid runoff, causing flash floods in low-lying regions and floodplains. This was evident in the 2021 Western Europe floods, where exceptional precipitation transformed streams and creeks into runaway torrents, engendering widespread damage in regions bordering the Rhine and Meuse rivers and their tributaries, including parts of Germany[4].
- Soil Saturation: Persistent heavy rainfall can saturate the soil, reducing its capacity to absorb water. This can lead to augmented runoff and more severe flooding, particularly in areas with high soil sealing levels. In such cases, the soil's absorption capability is diminished, exacerbating flooding risks[1].
- Gravitational Mass Movements: Persistent rainfall can inaugurate gravitational mass movements such as landslides and mudslides, especially in regions with steep slopes. These events can block waterways and aggravate flooding, as seen in the instance of German rail operations where heavy rainfall events have been found to increase the likelihood of gravitational mass movement events by a factor of 3.62[1].
- River Dynamics: Heavy rainfall can impact river dynamics, leading to heightened water levels and speeds. This can overwhelm flood protections and generate widespread flooding, as observed in the Elbe floodplain where extreme flood events have altered the floodplain's structure and significance for flood runoff[2].
- Habitat Alteration: The consequences of heavy rainfall can also affect habitats, particularly in floodplains. For instance, the Lower Havel Lowlands project endeavored to restore natural floodplain dynamics by removing embankments and permitting the development of sandbars and pools. This restoration aims to preserve biodiversity but makes the site more susceptible to flooding during heavy rainfall events[2].
In summary, heavy rainfall has increased flood risks in Lower Saxony and Saxony-Anhalt by causing direct floods, saturating the soil, triggering gravitational mass movements, altering river dynamics, and altering habitats in floodplains.
