The aim of the paper is to determine the relationship between meteorological drought and hydrological drought in the agricultural basin of the River Osa (northern Poland) in the years 1966-2015. Meteorological droughts appear as a result of insufficient amount or lack of atmospheric precipitation. As a consequence of meteorological droughts occurrences, there appear hydrological droughts which are characterized by low discharges of a river. Standardized Precipitation Index (SPI) and Standardized Runoff Index (SRI) indicators were used for the identification of droughts at various accumulation periods, i.e. 1, 3, 6, 9 and 12 months. In the years 1966-2015, there were identified from 63 (SPI-1) up to 10 meteorological droughts (SPI-12), while hydrological droughts – from 22 (SPI-1) to 8 (SPI-6, 9 and 12). The strongest relationship between the two kinds of droughts occurred in the periods of accumulation from 9 to 12 months. The values of the correlation coefficient between the meteorological and hydrological droughts were above 0.5 in those cases. Those indicators can be used for a system of early drought warning, which is of particular importance for crop production in agricultural areas. Long-lasting meteorological droughts contribute to increase of water intake for irrigation purposes, thus deepening the hydrological drought. As a consequence of the prolonged and intense hydrological drought, further irrigation may be impossible due to too low river discharges.

The objective of the work, carried out as part of research programme on current change of the regional climate, was to confirm the hypothesis about the increasing frequency and intensity of droughts in May and June in the region of Kujawsko-Pomorskie (central Poland) in the years 1981 – 2010. Furthermore, the aim was to confirm a significant relationship between indicators characterizing meteorological and agricultural droughts. Material for the research was the data from five meteorological measuring points located in the region. Atmospheric precipitation and air temperature in the period of high water needs of cereals and rapeseed (May–June) were used. Statistical methods widespread in climatological studies were applied, particularly the method of trends. The average multiannual totals (1981–2010) of rainfall in May–June allow ranking the region of Kujawsko-Pomorskie into the area of the lowest rainfall in Poland. The frequency of meteorological drought in May and June is 23.3–30.0% in the region. In the analysed period there were no significant changes in the frequency and intensity of these droughts with the passage of years. Rainfall shortages in cereal crops and rapeseed production range on average from -19 to -35 mm, and extend to maximum of -93 to -117 mm. The values of shortages did not show any significant changes in the years of the study. The significant dependence between the indicators of meteorological and agricultural droughts allows for determination of the rainfall shortages in crop production on the basis of the SPI values.

The aim of the paper is to present the spatial diversity of water resources in the Kuyavian-Pomeranian Voivodship during the drought in 2015. The region’s area is characterized by the lowest average annual precipitation in Poland, the lowest water resources and high water demand associated with intensive plant production. Hydrological research was carried out in September 2015 in 145 measurement points on various rivers. Despite the low precipitation recorded in August 2015 at the majority of meteorological stations, the volume of the specific discharge from the Kuyavian-Pomeranian region was characterized by high variability. The largest specific discharges were recorded for rivers located in the northern part of the region whose sources are located in the Pomeranian Lake District, i.e. Brda and Wda (over 2 dm3 sE−1 kmE−2) and the Masurian Lake District (Drwęca over 1 dm3 sE−1 km E−2). The smallest specific discharges (less than 0.5 dm3 sE−1 kmE−2) were recorded in the catchments located in the Kuyavian region (Tążyna, Zgłowiączka and Noteć) in the southern part of the Kuyavian-Pomeranian Voivodship and from the Osa River catchment. These areas are intensively used for agricultural purposes. The use of surface water resources as a potential source of irrigation water for crops can only be taken into account in connection with groundwater resources.

The aim of the article was to develop formulas, which can be used to model forecasts of production and economic effects of irrigated faba bean (Vicia faba var. minor), depending on drought severity level in a growing season. For the analysis we used data of ten-year (2005 – 2014) production effects of irrigated faba bean and indices calculated on the basis of meteorological data from the measuring point set in the vicinity of the experimental site in region of Bydgoszcz city, central Poland. Based on them, the most relevant relationships between irrigation productivity and chosen drought indices, calculated for a period of high water needs of the plant, were searched. Presented results have demonstrated that the non-irrigated faba bean yields depended significantly on drought severity level and showed very high variability in time. Irrigation contributed to a significant 49% increase in yields and their stability in the years. Due to this treatment, the coefficient of variation of the yield decreased from 55.1 to 19.6%. The production effects of irrigation depended significantly on moisture conditions over the period of high water needs of faba bean. In wet seasons, the increases in yields due to irrigation were insignificant and about three-fold lower, while in the dry periods – more than a half higher (57%) than the average increases. The results presented in the work are of great importance because they can be used to model forecasts of production, as well as to plan the development of irrigation systems in the given area.