Assessment of the Kolyma Runoff under Current Climate Changes

Abstract

The Kolyma is the largest river, the basin of which lies entirely in the zone of continuous permafrost and is subject to considerable climate changes, which affects its hydrological regime. The current dynamics of water flow and runoff-formation factors over 1979–2020 are analyzed, and the sensitivity of water regime characteristics of the Kolyma River to changes in climate parameters is studied. The comparison of the mean values of meteorological characteristics in the Kolyma basin over 2000–2020 with the mean values over 1979–1999 showed an increase in the normal annual air temperature by 1.3°C, the total annual precipitation increased by 8.3% with the most abrupt increase in September and March. According to observation data, the annual river runoff at the Kolymskoe gage (283 km from the Kolyma mouth), increased by 5.2%. Physical-mathematical models of river runoff formation have gained in popularity as a tool for studying the features of the water regime and its dynamics. In this study, the ECOMAG model is applied to the Kolyma R. basin, where its calibration and verification for two gages showed a good reproducibility of the actual water discharges. To better understand the mechanisms of the response of Kolyma water regime to changes in the climate characteristics based on ECOMAG model, the sensitivity of runoff characteristics to air temperature and precipitation was analyzed.