Summary:

The aim of the study was to attempt to estimate the demand for water for upward irrigation of urban green areas in parks of four selected cities in the Kuyavian-Pomeranian Voivodeship (Bydgoszcz, Grudziądz, Toruń, Włocławek) depending on expected climate changes. The study takes into account two scenarios: the RCP 4.5 scenario assuming an increase in CO2 concentration to the level of 540 ppm in 2100 and achieving radiative forcing of 4.5 W/m2, and the RCP 8.5 scenario assuming an increase in CO2 concentration to 940 ppm in 2100 and achieving radiative forcing of level 8.5 W/m2. Three selected decades (decades) of the 21st century are included: 2021-2030, 2051-2060 and 2091-2100. Based on the adopted assumptions and calculations, it was found that the largest amounts of water for irrigation will be needed in the last decade of the 21st century. The greatest demand for water will occur in July, and then in August. Higher water needs of urban green areas - compared to the RCP 4.5 scenario - (except for Grudziądz) were found in the RCP 8.5 scenario. Among the four examined cities in the Kuyavian-Pomeranian Voivodeship, the lowest demand for water occurred in Grudziądz, higher in Bydgoszcz, even higher in Toruń, and the highest - in Włocławek. In the decade 2091-2100, expressed as a unit inflow, the demand for water for irrigation of urban green areas using a upward system with variable damming in July - for the RCP 4.5 and RCP 8.5 scenarios in very dry years (p=10%), respectively, will amount to 1 .19 and 1.19 dm3·s-1·ha-1 in Grudziądz, 1.18 and 1.21 dm3·s-1·ha-1 in Bydgoszcz, 1.23 and 1.25 dm3·s-1· ha-1 in Toruń and 1.26 and 1.29 dm3·s-1·ha-1 in Włocławek.