Monthly maps for discharge anomalies and Lowest alert level exceedance with a summary of the monthly hydrological situation.


Hydrological situation for July 2021

Figure 1. Exceedance of lowest discharge threshold level for July 2021.
Figure 1. Exceedance of lowest discharge threshold level for July 2021.
Figure 2. Exceedance of lowest water level threshold level for July 2021.
Figure 2. Exceedance of lowest water level threshold level for July 2021.
Figure 3. Classification of stations according to discharge historical data average percentile ranges for July 2021.
Figure 3. Classification of stations according to discharge historical data average percentile ranges for July 2021.

by EFAS Hydrological Data Collection Centre

In mid-July, several stations located in the Rhine river basin were affected by a sharp increase in their water flow, generating devastating floods that mainly affected Germany and Belgium. Of the 76 EFAS stations with threshold levels defined in the system and located in the Rhine river basin, 43 exceeded almost one of them, in Germany, Switzerland, and Austria and 25 of them maintained the overflow for more than 10 days. Other affected areas with exceedances in central Europe were the Danube, Elbe, Oder, and Po river basins (Germany, Austria, Slovenia, Croatia, Hungry, Slovakia, Poland, Czech Republic, and Serbia). A lower concentration of stations can be observed in northern Norway, Iceland, Ireland, eastern Spain (around the Jucar river basin and Catalonia), central Italy (Tiber and Garbliano basins), and western Ukraine and Belarus.

Regarding stations registering values above the 90% quantile, 286 stations exceeded this value in July - the record number of stations surpassing the 90% quantile so far this year. The vast majority of the stations (nearly 82%) are located in central Europe mainly in France, Germany, Switzerland, Belgium, and Czech Republic. These stations are monitoring the river basins of the Rhine (73), Rhône (36), Loire (31), Seine (29), Danube (26), Elbe (14), Meuse, Dordogne, Garonne, Scheldt, Oder, and Orne. Another considerable number of stations also surpassing the 90% quantile can be found in Great Britain (mainly in the Thames basin). To a minor extent, values exceeding the 90% quantile can be found in stations in Spain: (south, east and northwestern basins). To a lesser degree, other stations over their 90% quantile are in basins located in eastern Europe in the Dnieper basin (Ukraine) and in the Daugaba and Vistula basins (Belarus). Isolated stations exceeding the 90% quantile occurred in the Drnica and Badasevica basins (Slovenia) and in basins in Finland, Norway, and Iceland.

Finally, and focusing on those stations registering values below the 10% quantile (37 in total), the highest concentration of them can be found in two areas. Firstly around the border between France and Spain (9 stations), specifically along the Ebro and Llobregat basins in Spain and the Garonne basin in France, and secondly in the southeast of Norway with 10 stations. A lower density of stations is present in Ukraine, along the Dnieper and Dniester basins (4 stations), in the Danube basin, where a number of 6 stations are spread around Austria, Hungary, Bosnia-Herzegovina and Serbia, and in Ireland (2 stations). At last, we can also find isolated stations with values under the 10% quantile in the Anllo river (Spain), Verde river (Spain), Muonio river (Finland), Lahn river (Germany), Muritz-Elde river (Germany), and the Notec river (Poland).