Data on annual runoff at 15 gages, reflecting the relatively natural conditions of runoff formation were used to reveal the present-day features of its space and time variations. Out of these, data ...from nine gages now in operation were used to carry out full statistical analysis of long-term observation series. In some rivers, the annual runoff was found to have been increasing since 1991. The dependences of the mean long-term water discharges in rivers under natural conditions on their orders determined by A. Scheidegger method were evaluated. By the character of this dependence, Crimean rivers were found to follow the general regularities in such relationships derived for other Russian rivers. In particular, the mean long-term water discharges in Crimean rivers are higher than those calculated by the bottom envelope curve for the relationship between mean long-term water discharges and the orders of different Russian rivers; this allowed it to be used to calculate the least possible value of the mean long-term volumes of annual river runoff in Crimea and, accordingly, the volume of renewable water resources, equal to 371 million m
3
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Lake Mogilnoe (Kildin Island, the Barents Sea) is a meromictic lake located in the high latitudes of the Arctic. It was formed by separation from the Barents Sea and retained an underground ...connection with it through a rocky barrier. The first researchers of the lake mentioned the upper fresh-water layer, the middle salty layer, lower anaerobic layer containing hydrogen sulfide, and noted the existence of a layer with rose water in the redoxcline. Observations carried out during the 20th century pointed to a gradual change in the vertical structure of the lake: mineralization increase of the surface layer and the rise of the hydrogen sulfide distribution boundary. In the past 10 years, there have been signals about acceleration of these changes. This is a big concern about an isolated population of Kildin cod (G. morhua kildinensis) listed in the Red Book of the Russian Federation, an endemic to this lake subspecies of Atlantic cod. In July, August and October 2018, three expeditions were organized to Lake Mogilnoe to study the current hydrological state of the lake, seasonal variability of hydrological characteristics, and outline possible causes of the registered changes and the threat to the Kildin cod population.
The paper presents the results and a brief analysis of in-situ measurements of thickness and other characteristics of the ice cover of the Rybinsky reservoir, which took place during two expeditions ...in February and April 2022. In expeditions, 49 ice cores were taken, which provide enough information to evaluate the heterogeneity of the ice cover. The most accurate data were obtained for two profiles, which cross the reservoir from the north to the south and from the southwest to the northeast and coincide with two tracks of the satellite altimeter Jason-3. In 2022 ice cover of the Rybinsky reservoir was heterogeneous and made up several different ice layers. Combination and thickness of these layers were distributed unevenly over the surface of the reservoir and were changing over time. The most uneven distribution was observed in the winter: near the shore and in the southwest part of the reservoir ice cover consisted of black ice, central part of the reservoir was made of black ice and frazil ice and east part of the reservoir was made up black ice and white ice. In the spring, ice cover became much more homogeneous and consisted of thick layers of white ice and black ice.
The space and time variations of winter low-water runoff and its major characteristics are considered. The study area includes the basins of major rivers in European Russia: the Northern Dvina, the ...Onega, the Mezen, the Volga, and Don, etc. Variations of the minimal, mean, and maximal runoff values in winter low-water season are evaluated against the background of climate changes in recent decades. The extent of such changes over period 1978–2010 is given and compared with period 1946–1977.
The formation conditions of subsurface and surface water runoff and their resources have been analyzed. It has been shown that changes in recent years were accompanied by a considerable decrease in ...the unevenness of within-year distribution, an increase in the subsurface and a decrease in the surface components of river runoff. The natural regulation of runoff in many Russian rivers has been found to increase, a factor that can improve the reliability of water use, especially, during dry seasons. Analysis of the current formation conditions of runoff and water resources of watersheds and regions in European Russia will ensure better forecasts of groundwater resources for the nearest and distant perspective, taking into account different variants of changes in the major resource-forming climate characteristics in accordance with the existing scenarios of global and regional climate models.
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