The effects of climate change on the essential characteristics of catchment runoff in the Uppest-Tisza Basin

Water is a key socio-economic factor (e.g. drinking water, sanitation, irrigation, energy) affecting the main challenges of this century. Therefore, it is important to analyse the projected regional hydrological changes related to climate change. The estimated trends may help to build and implement appropriate adaptation strategies in water-management (including flood defence and water storage) in order to mitigate the potential hazards.

In the present study, the estimated changes of water discharge are analysed at four cross-sections (i.e. Tiszabecs, Mizshirja, Uszti Csorna, Rahiv) in the Uppest-Tisza Basin, located in Eastern-Central Europe. For the investigation, the DIWA (Distributed Watershed) hydrological model is applied, while the necessary meteorological input data (daily minimum and mean temperature, precipitation) were provided by the CARPATCLIM database for the historical period (1972–2001) and by a regional climate model simulation for the future (2069–2098), taking into account two different RCP scenarios (RCP4.5 and RCP8.5). In order to eliminate the systematic errors of climate model simulations, a bias-correction is completed by adjusting the parameters of the distribution of temperature, dry and wet spells and precipitation amount. The correction factors are determined by the differences between the reference database and the historical climate model simulation. Furthermore, to take into account all the possible changes, the DIWA simulations are embedded in a Monte Carlo cycle, hence, several hundreds of possible realisations of water discharge values can be investigated.

According to our results, higher temperature values are likely to occur in the target area by the end of the 21^st century, and winter precipitation is projected to increase. The mean water discharge is projected to decrease from April to September in the case of RCP4.5, and from March to October in the case of RCP8.5, while in January and February an increase is likely to occur.

Acknowledgements: Research leading to this study has been supported by the Hungarian National Research, Development and Innovation Fund (under grants PD-138023 and K-129162), and the National Multidisciplinary Laboratory for Climate Change (RRF-2.3.1-21-2022-00014).