Changes in Runoff During the Growing Season in the Upper Reaches of the Naryn River in the Context of Global Climate Change

In this article, attention focused on the analysis of the tightness of relationships between the runoff during the growing season and the main climatic factors of the formation of river flow in the annual and growing season. Long-term fluctuations in runoff during the growing season determined by cold precipitation in the catchment areas and the temperature regime of the summer months.2000 to 2019 the amount of precipitation in the upper reaches of the Naryn River between October to April increased significantly. The sum of positive air temperatures has increased most significantly over the past twenty years in the alpine zone and over the past forty years—in the lower reaches of the catchment. The number of days with positive temperatures is also increasing. For example, in the high mountain zone over the past 20 years it has increased from 109 to 122 days, and in the middle mountain zone of the river—from 220 to 236 days over the past 40 years. As a result, the air temperature above 0 °C shifted from mid-May–June to April–May at the Tien-Shan meteorological station, from mid-March to the first half of March at the Naryn meteorological station. Therefore, the runoff of the upper reaches of the Naryn River during the growing season, according to the data from the Naryn gauging station, Naryn city, has been increasing the average growing water discharge since 1992.