Introduction: the article discusses the modes of gas-liquid flow in relation to the operating conditions of flooding gas wells at the late stage of field development by example of the Cenomanian deposit of the largest deposits in Western Siberia and the Far North. Materials and methods of the research: a method for nodal analysis for studying laws of gas-liquid low behavior in gas wells vertical lift pipes is described, based on the ratios used in calculating the pressure loss in a two-phase flow (in the "reservoir-well" system). The results of the study and their discussion: the results of experiments and studies on the construction of approximation dependencies of the obtained data are presented, and approximation formulas for calculating the reduced pressure gradient are proposed. Test examples are presented for comparing numerical modeling of the dependence of the critical low rate on the bottomhole pressure and the diameter of the lift pipes according to the developed algorithm. Conclusions: on the basis of experimental studies in the conditions of operation of water wells in Cenomanian gas deposits, a mathematical model of the movement of gas-liquid lows in vertical lift columns and a corresponding computational algorithm have been developed.

Introduction: there are several geomorphological zones in the Stavropol Krai. One of them is the Stavropol Upland, located between the Kuma and Kuban Rivers and Kumo-Manych Depression. Due to the peculiarities of the hydrogeological and geomorphological structure the landslide processes are typically for this territory. They pose a threat to settlements and economic facilities. The purpose of the paper was to study the scale of landslide distribution and the activity of their manifestations in the landslide zones of the Stavropol Upland. Materials and methods of the research: main research method was the analysis of various sources containing information on the distribution and activity of landslides in Stavropol Upland. Cartographic method was also used to visualize the landslide zones distribution in the study area. The results of the study and their discussion: conditions for the activation and spread of landslide processes in the Stavropol Upland were analyzed. It was found out that the main factors of landslide activation are: atmospheric precipitation, erosion, groundwater level changes and technogenic impact. In addition, 4 main types of landslides were identified. Major landslides and potential landslide areas are confined to the western part of the Stavropol Upland and are combined into 16 landslide zones, which are characterized by different activity and landslide hazard. Unfortunately, now it’s impossible to present a complete picture of landslide development in the territory under study, as there are no large-scale landslide survey materials and no maps of the exact location of the main landslide massifs within the Stavropol Upland. Conclusions: systematization and analysis made it possible to assess the conditions and causes of landslides formation, the scale of their development and their mode in the Stavropol Upland during 2005-2019. In this 15-year period, natural factors had the greatest impact on the landslide activity. The degree of landslide activity in different landslide zones of the Stavropol Upland was determined. This process was mainly developed in the Tatarskaya and Prikalausskaya zones. The most significant landslide movements were observed in 2005, 2006, 2017-2019. According to the survey results, the settlements most exposed to landslide processes were identified, and information on the scale of deformation of residential houses and economic facilities was provided.

Introduction: the aim of the study is to analyze the recreational needs of the population of the South of Russia, to study the geography of tourist flows in the macroregion, the ranking of preferences for tourist destinations, and motives for tourist trips. The importance of studying the recreational needs of the population as the main factor generating the demand for tourism services is substantiated. Materials and methods of the research: the study is based on a generalization of the results of a sociological survey of the population of seven subjects of Southern Russia. The survey was implemented using the Google Forms online service. The data obtained in the course of a sociological survey supplement statistical information and allow comprehensive study of various aspects of tourism in the macro-region. The results of the study and their discussion: as a result, the main directions of tourist lows in the South of Russia were identified, the most popular tourist centers were revealed, the most preferred types of transport and types of accommodation establishments were determined. The analysis of the main factors restraining the development of tourism in the South of Russia is presented. Conclusions: an analysis of the data of a sociological survey allows to identify: the neighboring position and transport accessibility as a key factor in choosing a destination for recreation; traditional high demand for resorts on the Black Sea coast of the Krasnodar Territory and the emerging demand for mountain climatic resorts, especially in the summer; insignificant interest of potential tourists in the excursion centers of the plain part of the South of Russia.

Introduction: cross-border cooperation, which due to the absence of significant barriers and the high «transparency» of the border, its contact function is actively developing in the field of tourism, especially interesting prospects are emerging in the tourism sector in the border regions of Russia and Belarus. The Russian-Belarusian border area has a diverse cultural, historical and natural potential, which is poorly used in the tourism sphere of the two countries. It is suggested that it is the border regions of Russia and Belarus (Smolensk, Vitebsk and Mogilev regions) that, due to the low barrier function of the border, are currently experiencing a greater interstellar effect that affects the development of their tourist and recreational activities. Materials and methods of research: theoretical statements are supported by up-to-date statistical data and illustrated by examples from domestic and foreign practice at the national, regional and local levels. The article presents the results of expert interviews conducted both in Russia and in Belarus. The results of the study and their discussion: the study focuses on the identiication of a new tourist role of the Russian-Belarusian border area in the system of relations between the two countries. It is stated that the current state of tourism and recreation activities in the Russian-Belarusian border area is largely the result of the impact on it of the largest megacities of the two countries. Conclusions: the effect of the interstellar zone has an ambiguous effect on the development of tourist and recreational activities in the regions of the Russian-Belarusian border area. On the one hand, the opportunities that allow the border region to attract and increase resources for the development of the tourism industry are increasing, and on the other hand, the potential of the tourism industry in the border region is noticeably lagging, which increases the infrastructure problems of tourism development and delays tourist flows to the capital regions.

Introduction: a general description of the water cycle in nature or the hydrological cycle, consisting of evaporation, condensation and precipitation, is too simple to explain the high degree of complexity of the phenomena involved. Several physical processes contribute significantly to determining the final balance (or local imbalance), for example, water vapor transport, sublimation, surface runoff, soil moisture, infiltration, percolation, plant absorption, and groundwater flow. Clouds and precipitation, along with the massive exchange of water vapor, play a significant role in climate variability, both globally and regionally. They affect not only the climate, but also the weather of all scales and determine the availability of water. Materials and methods of the research: the water cycle in nature is the most important physical mechanism that ensures the existence of life on Earth. Its components cover the atmosphere, land and oceans. The cycle consists of evaporation, sublimation, water vapor transfer, condensation, precipitation, runoff, iniltration and seepage, groundwater flow and absorption of plants. For the correct balance of the global water cycle, observations are necessary for all these processes from a global point of view. In particular, precipitation requires constant monitoring, as it is the most important component of the cycle, especially in conditions of changing climatic characteristics. Passive and active sensors aboard meteorological and environmental satellites now provide sufficiently comprehensive data that allows better measurements of precipitation from space to improve our understanding of cycle acceleration / deceleration in current and predicted climatic conditions. The results of the study and their discussion: the purpose of this article is to create a modern picture of the current state of observations of precipitation from space with the prospect for the near future of a satellite constellation, applications for modeling and water resources management. In particular, at present the problem of flood forecasting is an urgent problem, both from a scientific and from a practical point of view. Although the overall picture of the formation of loods is clear and understandable that they are mainly determined by the intensity and duration of precipitation over the river basin, there is still no mathematical approach in which it was possible to predict the time of the onset of floods with a sufficient lead time. This is due to the presence of many interdependent factors affecting the accumulation of moisture in the river basin. Therefore, any automated flood forecasting system should rely on Earth remote sensing data from space. Conclusions: a new mathematical model of floods with distributed parameters is obtained. It is shown that the proposed mathematical model describes an aggravated regime. This means that over a inite time, the amount of moisture in the soil tends to ininity.

Introduction: The 2019 Climate Report on the Territory of the Russian Federation states that warming continues in Russia, the rate of which is much higher than the global average for the globe. In recent years, the world has witnessed the largest natural disasters in modern human history, one of the reasons for which are abnormally high temperatures. Materials and methods of the research: Based on the meteorological data for the period 1961-2018 provided by the North Caucasus Department of Hydrometeorology and Environmental Monitoring, an analysis and forecast of the series of summer temperatures in the south of the European territory of Russia (ETR) was made. The analysis and forecast of time series are based on the method of singular-spectral analysis, implemented in the program «Caterpillar»-SSA. The method makes it possible to single out various regularities in the behavior of time series, which are often not a priori obvious. Forecast of average summer temperatures in the south of the ETR for the period 2019-2023 using the program «Caterpillar»-SSA was carried out. The results of the study and their discussion: For the possibility of using the method of singular-spectral analysis, the average summer temperatures were selected according to the results of prediction criteria that determine the stability of the trend: the maximum value of the Hurst exponent on trend stability (H > 0,80); the maximum value of the determination coefficient to determine the statistical significance of the trend (R² > 0,20). According to the results of a fractal analysis of the trend persistence of average summer temperatures, the maximum value of the Hurst exponent equal to H = 0,80 was obtained. To highlight the trend and periodic component, one (MC1) and three (MC3) main components were used. Using of the first twenty main components (MC20) made it possible to study and restore the internal structure of the entire time series as accurately as possible for a subsequent forecast for 5 years. The restoration, approximation and forecasting of the series was carried out by the obtained linear-recurrence formula. The forecast quality was determined by the following criteria: the standard deviation of the forecast series, the maximum deviation of the forecast values from the real ones, the relative forecast error and the results of the f-test conducted for the initial and forecast series for 1998-2018 at 5% error rate. Conclusions: According to the forecast for the period 2019-2023 average summer tem- perature tends to further increase. In 2022, one should expect an increase in average summer temperature to 22,0°C, which is close to the extremely high average summer temperature of 22,2°C in the south of the ETR in 2010.