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


Hydrological situation for August 2021

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

by EFAS Hydrological Data Collection Centre,

In August, the highest concentration of stations exceeding their low threshold level is located in central Europe in the Po and Danube basins. Firstly, 20 per cent of stations which exceeded at least the first threshold levels were in the Po river basin (northern Italy). Regarding the Danube river basin, the highest concentration of stations with exceedances are located in its western regions (southern Germany and western Austria), but there are some other isolated stations located in Slovakia, Hungry, Serbia, Romania, and Croatia too. In Poland, some stations along the Vistula and the Oder river exceeded their thresholds also. Lastly, in a more dispersed way, we can find one station in the Elbe river basin and another in the Neman basin (Belarus), in the centre of Norway, central and southern Sweden, Iceland, Ireland, eastern Spain (around the Jucar river basin and Catalonia) and Tiber basin (central Italy).

Regarding stations registering values above the 90% quantile,115 stations exceeded this value during August. The majority of these stations were located in central Europe throughout France, Germany, Luxembourg, Switzerland, Belgium, and the Netherlands, where the Rhine and Seine basins stood out with nearly 33% of the total stations exceeding the 90% quantile. Other basins surpasing this quantile were the Scheldt, Rhône, Meuse, and Elbe. Another portion of stations also exceeding the 90% quantile (just over 22%) can be seen in the Vistula and Oder basins in Poland, and in the Danube basin through Germany, Austria, Slovakia, Serbia, and Bosnia and Herzegovina. To a lesser degree, other stations over their 90% quantile were in Spanish basins (Guadalquivir, Minho and Ebro) and in England where a many of the stations were located in the Thames basin. Isolated stations exceeding the 90% quantile ocurred in basins in Sweeden, Norway, and in Ukraine (Dnieper basin).

Finally, according to those stations registering values below the 10% quantile (41 in total), the highest concentration is located in southern Norway, where 13 stations reached these values. Secondly, and with a more dispersed pattern, we have several locations in the western Ukraine (5 stations), in the centre of the Danube basin ( 5 stations located in Serbia, Romania, and Hungary), in the Oder basin in Poland (4 stations) and in eastern Spain (4 stations). A lower density of stations occurred in Belarus, the Rhine basin, northern Scandinavia, and England with 2 stations each. At last, we can also find isolated stations with values under the 10% quantile in the Esla river (Spain) and the Muonio river (Finland).