Maximum river runoff regime in The North Caucasus under the influence of recent climate change

Difficult climatic conditions characterized The North Caucasus and high flood hazard in this region. Over the past decades, significant climate changes have occurred, which has influenced the flow of mountain rivers, including the maximum flow. Since the end of the last century, there has been an increase in the number of dangerous floods in the basins of North Caucasus rivers, which led to significant material damage and deaths. In the flood zone were several tens of thousands of houses. In addition, infrastructure facilities were destroyed and hydraulic structures damaged. In this regard, there is an urgent task of analyzing the spatio-temporal changes in the characteristics of the maximum runoff and the factors that determine them.

In the course of the study, methods of statistical analysis, geoinformation methods, graphoanalytic, and the method of geographical generalization were used. Calculation of statistical parameters and visualization were carried out using the programming languages R and FORTRAN.

The spatial variability of the maximum runoff of the rivers of the North Caucasus over the past 70-80 years was analyzed. The results indicate a predominantly negative trend of maximum water discharge in the highlands of the North Caucasus and a positive in the middle reaches of the Kuban. This is consistent with data on the absence of a positive trend in average annual temperatures in the highlands due to lower temperatures in the winter, as well as with an increase in the number of days with heavy rainfall. The latter factor determined the almost universal increase in interannual variability of maximum expenditures, which indicates an increase in flood hazard throughout the region.

An analysis of the characteristics of the flood flow showed that the dependence of floods on precipitation in the mountains manifests itself at extreme values, while for all the main factor is air temperature. The maximum discharge of rain floods tends to increase in foothill areas, while no changes have been detected in the mountains.

The results can give a clearer view of the processes of changing the maximum flow, and become the basis for the development of measures to minimize the damage from such natural disasters.

This work was financial supported by RFBR (Project 20-35-70024)