Assessment of the water balance of the Morozova Creek watershed based on new geocryological data

The Morozova Creek watershed is a typical hydrological object in the rocky talus landscape, a widespread feature in the mountain permafrost zone of the Northeast. The absence of vegetation and high rock permeability create specific geocryological conditions that influence the formation of streamflow. The watershed is unique due to the long-term observations carried out over a historical period by the Kolyma Water Balance Station (KWBS). In recent decades, no studies of hydrological processes in rocky talus landscapes have been conducted. The authors team resumed comprehensive observations in the Morozova Creek watershed in 2020. The aim of this study is to investigate the geocryological and hydrological processes in the rocky talus in the current climate based on historical and modern data and mathematical modeling. The hydrological model Hydrograph was used. It describes heat transfer processes within the ground profile and allows for the calculation of hydrological and geocryological characteristics. Runoff formation processes were modeled using historical and modern data obtained by KWBS in 1968-1996 and by the authors in 2020-2025. The scientific novelty lies in the use of data from a temperature borehole installed at the watershed in 2022 to parameterize the model. Satisfactory results were obtained for modeling ground temperature, with Nash-Sutcliffe criteria at depths of 1, 1.5, and 2 m averaging over 0.93. The runoff modeling was verified using historical streamflow data (1968-1996) and for the 2025 summer season. The use of new data improved the quality of runoff modeling: the average Nash-Sutcliffe criteria increased from 0.52 in earlier studies to 0.68. For the first time, the water balance of the Morozova Creek watershed has been calculated for the modern period 1997–2025. The results are applicable for water resource assessment, analysis of hydrological regime changes under climate change, and hydrological forecasts and calculations in the mountain permafrost zone.