The article presents the course of meteorological droughts in Vistula subcatchments in years 1981–2010 and their influence on the occurrence of hydrological droughts. Using the Standardized Precipitation Index (SPI) as an indicator of meteorological drought on the one hand and the Standardized Water-level Index (SWI) and Standardized Runoff Index (SRI) as indicators of hydrological drought on the other, the mutual relationships between precipitation conditions and hydrological conditions were evaluated, as well as the relationships between the two drought types. Studies were conducted for three cumulative periods of these indices, of 12, 24, and 48 months. It was determined that meteorological droughts occurred earliest in the north-western and central part of the basin, and latest in areas lying above 300 m a.s.l. and in the south of Poland. Total duration, depending on the cumulative period, for SPI comprised from 38 to 41% of the analyzed period and for SWI (35–47%) and SRI (24–51%). The strongest relationships were identified in the central part of the Vistula (0.8 < r < 0.85), while the weakest relationships were recorded in the foothill region (r < 0.5). There were also indicated non-climate-related factors influencing those relationships (underground reservoirs, diverse Vistula water resource usage for municipal and industrial intake).

The study aims to estimate the amount of available renewable water resources in Poland in the years 1999–2018 and the extent of their use by various sectors of the national economy at the national and regional levels. In the study period, the selected meteorological elements were found to have changed, resulting in a decrease in the flows of the two largest rivers in Poland: the Vistula and the Oder. The outflow of the Vistula and Odra basins determines the size of Poland’s water resources. Poland is classified as a country of low water resources, as evidenced by the per capita amount of surface water, which in the years 1999–2018 was 1566 m³/capita. Water consumption to meet the needs of the economy and the population was stable, and averaged 283 m³/capita in this period. The analysis of water consumption by region showed that the areas with the lowest annual precipitation consume significant amounts of water for economic purposes, which may limit or destabilise socio-economic development in the region in future. Based on the difference between the amount of precipitation and water losses in the form of evaporation and water abstraction for economic purposes, maps were drawn up showing the deficit of surface water in a dry year. During periods of surface water scarcity, groundwater uptake increases. An area particularly exposed to water scarcity is central Poland.

On 11 March 2020, the World Health Organization declared the new COVID-19 disease a pandemic. Most countries responded with a lockdown to reduce its effects, which brought beneficial consequences to the environment in many regions, but the pandemic also raised a series of challenges. This review proposes an assessment of the COVID-19 pandemic positive and negative impacts on water bodies on different continents. By applying a search protocol on the Web of Science platform, a scientific bank of 35 compatible studies was obtained out of the 62 open-access articles that were initially accessible. Regarding the positive impacts, the SARS-CoV-2 monitoring in sewage waters is a useful mechanism in the promptly exposure of community infections and, during the pandemic, many water bodies all over the world had lower pollution levels. The negative impacts are as follows: SARS-CoV-2 presence in untreated sewage water amplifies the risk to human health; there is a lack of adequate elimination processes of plastics, drugs, and biological pollution in wastewater treatment plants; the amount of municipal and medical waste that pollutes water bodies increased; and waste recycling decreased. Urgent preventive measures need to be taken to implement effective solutions for water protection.

This study examines trends in temperature, precipitation and discharge rates over a 65-year observation period (1951–2015) and compares the two sub-periods 1951–1980 and 1981–2015. The research was carried out on annual and monthly values. The research area is the basin of the Vistula, the largest river in Poland. The main aim of the study was to assess how changes in air temperature and precipitation in the Vistula basin have translated into river hydrology. In the 65-year study period, a lack of statistically significant trends in outflow prevailed. Compared to the full period 1951–2015, the sub-period 1951–1980 stood out for its statistically significant increase in annual average outflows. In the years 1981–2015 a slight falling trend in outflow of the Vistula was noted, though the values were not statistically significant. This was caused by significant warming during this period (an increase in air temperature of between 0.27 and 0.45 °C per decade, depending on location) and a slight increase in precipitation. Seasonal changes in outflows were more volatile. The results indicate that the Vistula’s water resources have fallen slightly as a result of changes in air temperature and precipitation and due to the river’s significant hydrological inertia, which in turn results from the catchment being very large and physiographically diverse.

The paper presents impact of meteorological drought on hydrological drought on the Vistula River in Toruń in the period of 1971-2015. It uses index method for the assessment of hydrological drought threat degree as a result of multi-month lasting meteorological drought. Based on the values of the SPI-24 (24-month standardized precipitation index) it was determined that meteorological drought in Toruń appeared six times and the total time of the phenomenon was 33% of the studied interval. Periods of hydrological drought on the Vistula River in Toruń have been determined based on the values of the SWI-24 (24-month standardized water level index). It has been found out that hydrological drought appeared four times and its total time was 10% longer that the meteorological drought. Based on the values of both indices (SPI-24 and SWI-24) correlation coefficient for months, seasons and years, it was found that the relation between both kind of droughts is weak (r < 0.5). That result is also confirmed in the distribution of both kinds of drought. Only in 32 months (8% of the total time) the intensity of the two simultaneously occurring drought was at least moderate. The achieved results revealed that the hydrological drought was occurring periodically, independent on meteorological drought. Hydrological drought was also influenced by the external factors (hydropower plant in Włocławek, Major Groundwater Basin - GZWP) and climate factors appearing in the upper and middle part of the river basin.

The study aims to identify long-term trends in the changes of drought occurrences using the Mann-Kendall (MK) test and the Theil-Sen estimator. Trend research was carried out on the example of the catchment area of the Upper Noteć River, which covers an agricultural area of Poland with some of the lowest water reserves. The meteorological droughts were identified based on the Standardized Precipitation Index (SPI), while the hydrological droughts were determined on the basis of the Standardized Runoff Index (SRI) in various time scales (1, 3, 6, 9 and 12 months) in the period of 1981–2016. The relationship between SPI and SRI was determined on the basis of the Pearson correlation analysis. The results showed that statistically significant trends (at the significance level of 0.05) were identified at 3 out of 8 meteorological stations (downward trend at Kłodawa station and upward trend for drought at Sompolno and Kołuda Wielka stations). Statistically significant hydrological droughts showed an increase in occurrences at the Łysek station, while a downward trend was noted at the Noć Kalina station. No trend was found at the Pakość station. The analysis of the correlation between meteorological and hydrological droughts showed a strong relationship in dry years. The maximum correlation coefficient was identified in longer accumulation periods i.e., 6 and 9 months. The example of the catchment of the Upper Noteć River points to the necessity of using several indicators in order to assess the actual condition of the water reserves.