IMPACT OF CLIMATE CHANGE ON THE MELT WATER RUNOFF IN THE SOUTH OF RUSSIA

Purpose: generalization and analysis of long-term observations for climatic indicators changes and the surface melt water runoff value and study of their effect on soil erosion using the example of Rostov region. Research objectives: to analyze global and regional climate changes in Rostov region from 1936 to 2019, to determine the patterns of the climate change impact on surface runoff and soil erosion (based on long-term field observations from 1970 to 2020). Methods: observations for surface runoff were carried out at runoff sites according to generally accepted methods; the methods of mathematical analysis and statistics were used to summarize and analyze the data obtained. Results. The analysis showed that for the period from 1936 to 2019, the average annual temperature in Rostov region increased by an average of 1.9 °С, the amount of precipitation increased by an average of 148 mm, but the unevenness of their precipitation by months increased, and only in August there is a regular decrease in precipitation at all observation points. This was reflected in the depth of soil freezing, which averaged 47.5 cm from 1970 to 1990, and from 2010 to 2020 decreased to 19 cm, i. e., almost 2.5 times. From 1970 to 1990, the water reserve in the snow before snowmelt was 53.6 mm, from 1991 to 2009 – 43.4 mm, from 2010 to 2020 – 33.5 mm, i. e., there was a decrease in comparison with the first period by 1.6 times. Conclusions. Observation for the melt water runoff for the above period showed that the runoff layer decreased from 19.0 to 4.2 mm, and the probability of its formation is 1 time in 3 years on loose arable land, and 2 times in 3 years on compacted land. In accordance with this, the value of soil washout in the period 1970–1990 amounted to 8.9 t/ha, and in the last decade, 2 times less – 4.2 t/ha. All these data should be taken into account when planning the system of soil protection measures.