Assessment of water resources of the Ukrainian rivers according to the average statistical models of climate change trajectories RCP4.5 and RCP8.5 over the period of 2021 to 2050

Abstract

The relevance of the presented work is due to the necessity of assessment of a possible state of Ukrainian water resources in the 21st century according to climate change scenarios in order to justify the strategy of economic development.
 The research object is presented by water resources of the Ukrainian rivers.
 The research focuses on the effects of global warming on Ukrainian water resources in 2021-2050.
 The work aims at assessing a possible impact of climate change on Ukrainian water resources in the 21st century, using the data from the climate change trajectories RCP4.5 and RCP8.5 over the period of 2021 to 2050.
 Calculations of water resources over the period of 2021 to 2050 are performed according to the average statistical model from the ensemble consisting of 14 climatic models of the CORDEX experiment for the RCP4.5 and RCP8.5 trajectories. Water resources are assessed based on the Climate-runoff model developed by OSENU. The result of such calculations is the evaluation of moisture and heat resources, as well as water resources in the natural conditions of their formation. Natural (undisturbed by water management) average long-term annual runoff determined by the meteorological data is usually called "a climatic runoff". The accuracy of climatic runoff calculations using the map of isolines is ±10%. The calculations are performed in the grid nodes. The geographical location of the selected nodes corresponds to the location of meteorological stations the total number of which is 115.
 Evaluation of heat, moisture and water resources changes was performed by comparing the calculated values and the basic ones. The climatic runoff for the period of observations before 1989 is thought to be basic.
 According to the average statistical model of the RCP4.5 trajectory over the period of 2021 to 2050, the expansion of the semi-arid zone and insufficient humidification zone to the north is to be expected (when compared to the basic period). The insufficient humidification zone will expand to the northwest displacing the sufficient humidification zone. The reduction of water resources will reach to minus 40-50% in the south of the country and to 0% - minus 10% in the north. The area of water resources growth will be preserved in the Ukrainian Carpathians.
 Comparing to the RCP4.5 the RCP8.5 trajectory is considered to be more “rigid” in relation to the state of Ukrainian water resources. The reduction of water resources will occur on the nearly entire territory, except Bukovyna, due to the increase of arid climate. Water resources will decrease to minus 50-60% in the south and to minus 30% in the north.
 Both RCP4.5 and RCP8.5 trajectories offer a forecast of water resources that is unfavourable for the development of Ukrainian economy, as it will cause expansion of both semi-arid and insufficient humidification zones. This will increase the water resources shortage in Ukraine.