The scientific school of physical-geographical and landscape-geoecological research of the world was formed under the leadership of Professor A.M. Ryabchikov, whose centenary is celebrated in 2018. The main areas of research are physical-geographical analysis of terrestrial natural landscapes; study and mapping of natural-anthropogenic (or present-day) landscapes; analysis of natural resources and agronatural land potential; study of natural-anthropogenic processes in the environment. These lines of research laid a foundation for landscape-geoecological studies, including the assessment and forecast of the state of the world’s landscapes under global change.

The results of studying 300 years of land use changes in the north-western part of the Privolzhskaya Upland are presented. A key plot with the area of 1950 km2 in the Kirsanov district of Tambov region in the northern forest-steppe zone was studied. Land cover map of the territory showing the locality types was compiled by automated and visual interpretation of Landsat 7 and 8 images and global DEM SRTM with account of field data, as well as the land use map showing settlements, arable lands, forests, meadows, bogs and erosion network.

Characteristic feature of the region is widespread hydromorphic territories within the interfluve undrained and interfluve slowly-drained locality types, limiting the agricultural development. Large-scale materials of the General Land Survey were used for land use structure reconstruction as of the end of the 18th century; they show specific features of half-century long regional economic development. Correlation of land cover map with the recent and reconstructed land use maps revealed that in the 18th century arable lands were much more determined by land cover than nowadays.

300 years ago arable lands were more common for interfluves and gentle slopes with slight hydromorphism; nowadays these restrictions are partially leveled by agrotechnical practices. The percentage of arable lands within the interfluve undrained locality type increased from 50 to 70% and from 62 to 90% in the intermittent slowly-drained type. At the end of the 18th century forests and virgin steppes accounted for larger areas (as compared with nowadays) within the interfluve undrained, floodplain and terrace locality types, which are marginally suitable for agriculture. 

An algorithm for calculating the amount of soil matter washed out from the arable lands as a result of accelerated soil erosion for the period of intensive land use (the last 300 years) and associated organic carbon accumulation in deposited matter, as well as the actual carbon dioxide flow from this carbon pool, was proposed. The calculations are based on the current intensity of soil erosion in the river basin and the content of organic matter in the soils, transformed to the period of intensive land use by time-dependent corrections to erosion factors, i. e. climate change, soil conditions and land use. The calculations show that over 300 years about 16,9 109 tons of soil was washed away from the arable lands in the Don River basin (425 000 km2) including 0,41 109 tons of organic carbon. 95% of this matter was accumulated in the bottoms of balkas and dry valleys on the area of 12 900 km2, forming a layer of deposited soils (stratozems) with an average thickness of 0,9–1,0 m. The lower part of the profile of these cumulic soils (below 0,25– 0,45 m) was classified as buried soils, since there is practically no renewal of organic carbon. The organic matter of the buried soils was mineralized and its content decreased in time. The modern uncompensated carbon emission (as CO2) in the Don River basin was calculated to be 1,6–2,1 t/km2 per year, amounting to about 0,5–0,75% of microbial respiration of modern soils in the steppe zone of Russia. Despite rather large amount of organic carbon buried in the cumulic soils, the modern emission of carbon dioxide from this carbon pool formed by the accelerated erosion and accumulation processes does not affect significantly the CO2 budget in the atmosphere. It is thus possible not to consider it in the scenarios of the anthropogenic climate change.

The palaeogeomorphological analysis lower of Volga, Don and Kuban rivers made it possible to reconstruct the mechanism of palaeo-deltas formation in valley bays and mouth lagoons. In the valley bays (Don and Volga rivers) stage-by-stage accumulation of alluvium, development of river arms network and formation of a deltaic flood-plain took place.

Transgression-regression character of the sea level fluctuation caused partial erosion and burial of deltaic sediments under liman-marine deposits during the rising sea level followed by the full-bay delta expansion in the period of sea level lowering.

In the mouth lagoon a few-arm full-lagoon delta was initially formed, and at the stage of the total fulfillment of mouth lagoon with river deposits a deltaic plain had formed, joining the marine bloc-shit. At the final stage of full-lagoon delta formation the arms went out to the open mouth offshore and protruding deltas were formed in their mouths. 

Application of the modern hydrometric and geodetic equipment during field works in small mesotidal estuaries of the Kyanda and Tamitsa rivers flowing into the Onega Bay of the White Sea made it possible to investigate specific features of tidal waves propagation and dynamics of reversing currents. Variations of hydraulic parameters during a tidal cycle were studied using one-dimensional flow scheme. A paradoxical hydrodynamic phenomenon of negative turbulent viscosity was recorded and its nature is investigated in context of the energy dissipation mechanism in turbulent flows under the cyclic water level fluctuations and reverse currents in tidal estuaries.

Changes of temperature and salinity for the Baltic Sea in general and for the Slupsk Trough and the Gdansk Depression in particular were described, according to the World Ocean Atlas (WOA 13) and Helcom data, and using the observation data. The main purpose is to study the inflows of the North Sea waters (or Major Baltic Inflows – MBI), influencing the deep water layer formation in the Baltic Sea. The conditions of the seasonal cold interlayer (CIL) waters formation were analyzed. The parameters of the layer and MBI waters were correlated with the North Atlantic Oscillation (NAO) Index.

Regularities of seasonal variability of water discharge and suspended sediment concentration interactions were studied for rivers in the Kamchatka Krai territory. The limited number of types of such interactions was established for the region. In most cases the increase of suspended sediment concentration usually coincides with increasing water discharge, and during the decrease of water discharge the reduction of suspended sediment concentration is observed. However, the maximum of suspended sediment concentration is in advance of the maximum water discharge. The volcanic activity appeared to be a significant factor impacting the disturbance of interaction between the variables. The analysis of data on measured water discharges and suspended sediment concentrations demonstrated that there are four types of S-Q relations for rivers in various hydrological regions of the Kamchatka Krai. They represent the most important factors influencing the formation of the seasonal suspended sediment yield. The largest part of suspended sediments (90% and more) is transported during the high water periods in rivers of the studied region. The ratio between relative suspended sediment concentration and water discharge depends on water amount in particular year.

The present-day interest to renewable energy is related to sustainable and safe energy supply rather than its environmental benefits. High growth rates of renewable energy sector in the almost stagnant energy market suggest that renewable energy with new technologies claims a serious role in the future world energy. An important indicator of this is the investment inflow. The post-crisis period demonstrates a geographical shift in the investments to the renewable energy sector: the developing countries approach the developed ones in terms of the absolute amount of investments. The per capita parameter is an objective criterion of the level of investment promotion. A map Geography of investment in the renewable energy sector of the world was compiled. Four types of countries in terms of investment per capita were identified and described.

The data on the execution of the budgets of million-plus cities in 2006-2016 are analyzed. Particular importance was attached to the assessment of the degree of city authorities’ independence in making decisions on budget spending. It is shown that the autonomy of city okrugs’ (municipalities) authorities is very low and tends to decrease; city okrugs’ authorities have lost influence on the development of health care, but came to spend relatively more money on the economy; the amount of funds administered by city districts authorities is several-fold less than in Moscow and St. Petersburg. It was concluded that the powers of city okrugs’ authorities should be expanded and the status of million-plus cities should be brought closer together basing on the analysis of direct expenditures of the regional budgets.

The latitudinal and longitudinal transportations of goods and passengers developed in the Russian Far East are revealed and evaluated. The latitudinal transportation is always predominant, in the past, present and future. The main factors are the well-developed inter-district ties, the access to the Pacific ports and the markets of the Asian-Pacific countries, and also the largest transportation ways of the region, such as the Trans-Siberian Railway, the BAM, the Khabarovsk-Chita-Moscow highway, river transport along the Amur River and the Northern Sea Route. In the long term various sea transport operations in combination with the land ones are considered to be the most perspective for Pacific Russia.

The basic centers of formation of the latitudinal ways are identified on the Pacific coast, and the basic centers of formation of the longitudinal ways on the Arctic coast, as well as different variants of the intermediate transport-economic centers and knots and their transport clusters. Transport knots formed on the crossings of latitudinal and longitudinal directions of the transportation network are regarded as basic ones. 

An empirical analysis of geographical features of the distribution of youth unemployment in Russia was performed. The economic, demographic and social determinants of interregional differences are described. The highest rate of youth unemployment is typical of agricultural and raw-material regions, while the lowest is recorded in the regions with developed services sector. The results of the evaluation of regression equations show that the creation of new high-tech jobs with decent working conditions and remuneration, and the diversification of employment structure contribute to reducing the rate of youth unemployment in the regions of Russia. At the same time, the increasing employment in the agricultural sector and the demographic pressure on the labor market increase the risks of its growth. The models constructed for a group of agricultural regions demonstrate positive correlation between the rate of youth unemployment and the share of people younger than the working age in the structure of population. The increasing share of people with secondary vocational education reduces the rate of youth unemployment in the rawmaterial regions. In the regions with a higher share of manufacturing industries, the increasing share of households having access to the Internet is another factor reducing the rate of youth unemployment. It is concluded that the geographical features of the distribution of youth unemployment are to a large extent determined by a set and combination of parameters characterizing the population of the region, the local labor market and the level of economic development. 

The possibilities of producing main agricultural products in the eastern regions of the Russian Federation are discussed. Areas with different levels of availability of these products are identified. The export of agricultural products by positions of the commodity nomenclature of external economic activity is analyzed. The prevailing role of raw export directions (fish, grain, oil seeds) is shown, but with a tendency to increase the share of products of processing industries. The results of the study allow identifying the main trading partners of Russia (agricultural segment) in the east of Asia and the structure of their imports. The regions were grouped according to the export potential of the agroindustrial complex.