Poland swings from historic drought to flood relief in September

Poland has experienced both extremes of the hydrological spectrum in the month of September, swinging between drought in early September to a flood emergency less than two weeks later.   

Poland’s longest river, the Vistula, dropped to record low levels on the 9th of September due to drought conditions in the country. The Vistula is Poland’s longest river, rising at Barania Gora in the south of the country at an altitude of 1200 metres and flowing 1,047 kilometres until it reaches the Baltic Sea in the north. A gauge in Warsaw measured a depth of the river of only 25 cm, breaking a record low level that wat set nine years ago.

Just 18 days earlier, heavy rains had drenched the capital, leading to local flooding events. The district of Bielany in Warsaw received 900 mm of rain in one day, and the depth of the Vistula River was measured at 96 cm at the Warsaw-Nadwilanówka gauge. Since the 27th of August, water levels have been dropping. 

At the end of May, drought conditions were being experienced across most of the country: the evaporation rate exceeded the precipitation rate for the month, leading to a ‘climatic water balance’ deficit of 92 mm and agricultural drought being declared in 14 out of 16 provinces.   Poland has now been experiencing systematic droughts every year since 2015, covering an ever increasing land area.

The low levels of the Vistula River followed the warmest August on record: the Copernicus Institute announced that August 2024 was the warmest August globally (together with August 2023), featuring an average surface air temperature of 16.82°C, 0.71°C above the 1991-2020 average. Copernicus further notes that average temperatures in August 2024 were 1.51°C above the pre-industrial level, while August was the 13th month in a 14-month period for which the global-average surface air temperature exceeded 1.5°C above pre-industrial levels.

However, the low levels of the Vistula River are not only caused by changes in climatic conditions. Major land use changes have been introduced over the past decades, including the draining of wetlands, and the regulation and dredging of watercourses. The result is that natural water retention in wetlands and water courses has been reduced, and rivers now drain the country more rapidly.  Poland is a relatively water scarce country: it has a mean annual water resources availability of 1,600m³/annum, which is approximately one third of the average water resources availability in Europe. Under a new “My Water” programme launched by the government in 2020, subsidies are being provided for the development of urban and rural stormwater or snowmelt retention systems, as a means to increase Poland’s drought resilience.

By the 14th of September, the situation in the country had changed again as experts predicted heavy flooding in central Europe. Storm ‘Boris’ was a slow-moving low-pressure system that brought a month’s worth of rain to central Europe in just 24 hours. The mayor of the southern Polish town of Nysa requested 44,000 residents to evacuate due to the imminent danger of the reservoir flooding, after several breaches were detected. On the 15th of September, the city of Stronie Śląskie flooded as a result of the collapse of a dam on the Morawka River.

On the 17th of September, following an emergency meeting, Polish Prime Minister Donald Tusk announced a state of natural disaster in Poland’s flooded areas, allocating U.S. $ 260 million to support evacuation and rescue operations, as well to provide financial support for the victims.