RESEARCH OF THE PIVDENNY BUH RIVER BASIN
HYDROMETEOROLOGICAL CHARACTERISTICS TIME TRENDS IN
THE CONDITIONS OF MODERN CLIMATE CHANGE

The climate change observed in recent decades affects all phases of river water availability, so it is an actual task to study the time series trends of the Pivdenny Buh River basin average annual hydrometeorological characteristics in the context of modern climate change.

Each year, research on climate change in Ukraine becomes increasingly relevant and in demand. This is due to the long-term trend in air temperature throughout the country, which indicates an increase in air temperature. There is an increase in the frequency of meteorological hazards in different regions of Ukraine. Climatologists detect climate records accompanied by abnormally warm winters and a shift in seasons. There is a redistribution of precipitation in time and space.

In recent decades, due to an increase in air temperature, there has been a tendency to increase absolute air humidity and, consequently, decrease relative air humidity, which affects the amount of evaporation from the surface of catchment areas and water bodies.

In order to research the influence of climate change on the annual distribution of the Pivdenny Buh River basin water balance components, a retrospective (as of 2020) analysis of time series of hydrometeorological factors and characteristics of the annual runoff of the rivers of the Pivdenny Buh River basin was conducted.

The constructed time series graphs of the Pivdenny Buh River basin air temperature in indicate the presence of a pronounced general trend towards an increase in air temperature, which certainly affects the amount of evaporation in the basin, which is included in the water balance equation as an indicator of losses in river catchments.

The time series graphs of the Pivdenny Buh River basin absolute air humidity according to the data of separate meteorological stations of the Pivdenny Buh River basin indicate a general tendency to increase values over a multi-year period. The difference integral curves of average annual values of absolute air humidity of the Pivdenny Buh River basin are cyclical in nature with a tendency to decrease from the beginning of the study period until 1998. Since 1998, there has been an upward trend in absolute air humidity.

The total annual precipitation, which is the incoming part of the water balance of rivers, tends to decrease. Total annual precipitation has been cyclical, with a downward trend since 1980, an upward trend since 1995, and a downward trend again until 2020.

The time series graphs of annual water layers (averaged over the period from 1980 to 2020) of the rivers of the Pivdenny Buh River basin show that there is a tendency to decrease values over a multi-year period, and the difference integral curves indicate the presence of cyclical variability in the annual runoff of the study area rivers – an increase in runoff until the late 90s of the last century, a decrease until 1995, then an increase until the early 2000s and then a decrease again (except separate gauging stations).

The time series graphs and difference integral curves of the annual water layers of the Pivdenny Buh River basin rivers are mostly synchronous, i.e., the same course of water content is observed throughout the entire time interval.

Keywords: water balance, climate change, the Pivdenny Buh River, hydrometeorological characteristics.