Poland drought report

In October the Polish Soil Institute reported about the drought situation in Poland for the last period from 1 August to 30 September 2020.

a water pool in the middle of a meadow
©A.Galica

The scientists concluded that the recent, very abundant rainfall resulted in a significant increase in the value of the climatic water balance, which meant that there was no shortage of water for crops (except for rapeseed and turnip rapeseed). As a result of these large changes in humidity - the extent of agricultural drought was significantly reduced, drought occurred only in 3 Polish communes (in the Świętokrzyskie and Wielkopolskie provinces). The moisture deficits in the soil recorded from the beginning of May at a depth of up to 1 meter slowly rebuild, but more rainfall is needed in October in order to recover water resources (both surface and groundwater).

The Polish Soil Institute (IUNG), in accordance with the legal requirements, develops the values ​​of the climatic water balance for all Polish communes (2477 communes) and, based on the soil categories, determines the current state of agricultural drought risk in these communes.

Climatic Water Balance

In the fourteenth reporting period, i.e. from August 1 to September 30, 2020, the average value of the Climatic Water Balance (CWB), on the basis of which the assessment of the risk of drought is made, was negative, it was -10 mm. In the analyzed period, the CWB value increased by as much as 72 mm compared to the previous period. However, in relation to the first reporting period (21 March - 20 May), CWB increased by 90 mm.

Climatic water balance
©IUNG
Map.1. Climatic Water Balance for Poland (source: IUNG)

As a result of the humidity conditions present in the current reporting period, IUNG recorded the occurrence of agricultural drought in Poland in the provinces of Świętokrzyskie and Wielkopolskie.

Drought is noted in rapeseed and turnip rapeseed crops. Drought in these crops was recorded in 3 Polish communes (0.12% of the country's communes). Compared to the previous reporting period, there was a decrease by 697 communes with the occurrence of drought in these crops, i.e. 30.97% less than in the previous reporting period.

Drought in rape seed in Poland
©IUNG
Map.2. Drought in rapeseed and turnip rapeseed crops (source: IUNG)

Air temperatures in Poland

This year's August was warm. In the western regions of Poland and in the Sandomierz Basin, the air temperature was recorded from 20 to over 21 ° C and in these areas it was warmer than the long-term norm by over 2 ° C. In the rest of the country it was also warm from 18 to 20 ° C, warmer than normal by 1-2 ° C.

In the first and second decade of September, the warmest region of the country was the Silesian Lowland with temperatures ranging from 15.5 to over 16 ° C (in the first decade) and from 16 to 17.5 ° C (in the second decade). On the other hand, the coldest regions of the country were the areas of northern Poland from 13 to 15 ° C (in the first) and north-eastern from 14 to 15 ° C (in the second decade). In the third decade of this month, the highest air temperature was recorded in north-eastern Poland, from 15.5 to over 16 ° C, and the lowest in the Sudeten Foreland, from 12 to 13 ° C.

Rainfall data

In August, in a very large area of ​​Poland, rainfall was recorded from 60 to 120 mm, constituting 100 to 160% of the long-term norm, only in the northern regions of the country and in the Lubelskie and Małopolskie provinces rainfall was slightly lower than 40 to 60 mm (60-60 mm). 100% normal).

road between fields with a big pool of water
©A.Murawska

In the first ten days of September, the lowest rainfall was recorded in Lubuskie, from less than 5 to 10 mm. Slightly higher rainfall, ranging from 5 to 20 mm, occurred in the southern part of the Mazowiecka and Podlaska Lowlands in the Świętokrzyskie Mountains and in the northern areas of the Masurian Lake District. In the rest of the country, rainfall was greater than 20 to over 50 mm. In the second decade, in many places in Poland, no precipitation was recorded or it occurred in a small amount, not exceeding 5 mm. However, in the third decade of this month, no rainfall was recorded in north-eastern Poland, relatively small, from 15 to 25 mm, occurred in the Wielkopolska Lowland. In other areas of the country, rainfall was high, ranging from 25 to over 50 mm.

Soil moisture

The increase in rainfall recorded at the beginning of September definitely favors the restoration of soil water resources. The moisture deficits in the soil recorded from the beginning of May at a depth of up to 1 meter slowly rebuild and in relation to August, the areas with water deficit in the root zone concern the Lubuskie province, the western part of Wielkopolskie, and partially Opolskie, Lubelskie and Pomorskie.

Soil moisture in Poland
©Stopsuszy.pl
Map.3. Soil moisture in the root zone (28-100 cm) on 31 August 2020 (left) and on 11 September 2020 (right) (source: stopsuszy.pl)

According to the Institute of Meteorology and Water Management forecasts, the number of days with precipitation in October 2020 (the last month of the hydrological year) in most of the country should be in the "below normal" class, and the highest probability of the "below normal" class should apply to the Olsztyn-Bydgoszcz-Toruń-Poznań-Wrocław-Opole belt, as well as in the Warsaw-Lublin-Rzeszów-Kraków-Zakopane strip. These forecasts are unfavorable in the context of recovery of water resources (both surface and groundwater) after a longlasting drought. The forecast of the state of groundwater resources until the end of September assumes that under unfavorable meteorological conditions (low rainfall), the occurrence of a hydrogeological low flow in the following provinces: Lubuskie, Wielkopolskie, Kujawsko-Pomorskie and Śląskie.

Source: IUNG, stop.suszy.pl