TRENDS IN POPULATION CHANGE AND THE SUSTAINABLE SOCIO-ECONOMIC DEVELOPMENT OF CITIES IN NORTH-WEST RUSSIA

The Northwestern Federal District is a Russian macro-region that is a unique example of a model region. It accounts for 10 % of the country’s total area and 9.5 % of its population. This article aims to trace the patterns of city distribution across the region, to assess the conditions of differently populated cities and towns, and to identify sustainability trends in their socio-economic development. Population change is a reliable indicator of the competitiveness of a city. As a rule, a growing city performs well economically and has a favourable investment climate and high-paid jobs. The analysis revealed that population change occurred at different rates across the federal district in 2002—2017. A result of uneven socio-economic development, this irregularity became more serious as globalisation and open market advanced. The study links the causes and features of growth-related differences to the administrative status, location, and economic specialisation of northwestern cities. The migration behaviour of the population and the geoeconomic position are shown to be the main indicators of the sustainable development of a city.


Introduction
When studying the urban population distribution and its dynamics over the past decades, it is necessary to take into account the territorial heterogeneity of the socioeconomic and demographic processes taking place in the Russian Fed eration. For analysis at the macroregional level, it is advisable to use a geodemo graphic typology and economic zoning schemes developed back in the Soviet period for the purposes of spatial planning [1, p. [5][6][7][8][9][10]. They investigated current trends in the urban population dynamics in Russian cities, including cities of the Leningrad region and coastal cities of the Baltic region, the polarization of the settlement system, and other aspects associated with the demographic processes occurring in the regions of the country.
Geodemographic development trends in the Baltic region at the national and regional levels were described in detail by T. Yu. Kuznetsova [11;12] who has identified and analyzed the components that determine population dynamics in various administrative-territorial units and factors that have a significant impact on demographic processes. The evolution of the system of urban settlements and the dynamics of natural and socioeconomic processes in the Russian Arctic are considered in the study by V.L. Baburin and S.P. Zemtsov [13].
The UN report on the world urbanization prospects 2 indicates that although the problem of the outflow of population from large, medium and small cities and the growth of the largest cities are typical for most countries, they are espe cially relevant for countries of Eastern Europe and lowincome countries with significant differences in the conditions and standards of living of the popula tion. International researchers emphasize that the main path of development for cities and rural settlements is the compliance with the principles of sustainabil ity in the economic and social spheres as well as in environmental development [14; 15]. The development of indicators for assessing the sustainability of urban development has been the subject of a large number of international 3 and Rus sian studies [16].
At present, in many cities across the world, "sustainability is the dominant paradigm of urban development and is a factor in the growth of competitiveness," while in Russia "there is a transition from a stochastic to strategic implementation of the sustainable development approach while preserving formal imitation moments" [17, p. 95].
Swedish researchers have studied in detail the feasibility of implementing the UNHabitat Agenda in terms of developing and applying sustainability indicators in cities of different sizes in Sweden and Russia, taking into account citizens' interest and actual participation in urban development [18].
The studies of Chinese scientists on the increase in the population of the largest cities in China and the opportunities for their sustainable development are of particular interest. The rapid growth and globalization of the domestic economy have dramatically accelerated urbanization in the country leading to significant environmental consequences and challenging its sustainable development. Using a multistage model that takes into account the age, gender, education and migration distribution in rural and urban areas, the paper assesses the development of the urbanization process in China until 2030 and addresses the main issues of urban sustainability. The results show that, according to some assumptions, the urban population of China will almost double from 2000 to 2030; labour force will make up a larger share of the total population in urban areas than in rural areas due to internal migration of young workers, especially in Beijing and Shanghai, which may put pressure on China's industrial structural transition from an agricultural to a servicebased economy [19].
In the Baltic region, there is an increase observed in the number of large cities and a decrease in small cities. The growth of large cities in the Baltic States is analyzed mainly in the context of urban development in the post Soviet space in Central and Eastern Europe. Recently, local researchers, mainly urban geographers and urban planners, have also shown interest in this topic [20; 21]. Generally, the emphasis of the studies is on capital cities and metropolitan regions undergoing major transformations: Vilnius, Riga and Tallinn. Research on modern urban development in the Baltic States allows for further discussions on the growth of large cities to identify the specific causes and consequences of this phenomenon from the standpoint of urban sustainability.
Despite a large number of studies conducted, the identification of negative factors affecting the geodemographic dynamics in Russia's subjects, and ongoing state federal and regional programs, the situation does not change in many cities and regions as they continue to lose population. This indicates the need for further research on the dynamics of the population of Russian cities, factors in their development and key areas for increasing sustainability.
The aim of this article is to identify patterns of distribution of urban settlements across the region and to detect trends in sustainability of their socioeconomic development, as well as to assess the condition of cities of different size.

Research Methods and Information Basis
To analyze the evolution of urban settlements in Northwest Russia, the re search uses the method of spatio-temporal analysis of urban system emergence and development, as well as the methods of comparative, statistical analysis and systematization. A study of the dynamics of urbanization made it possible to identify several stages and the most significant trends in the process that influenced the change in the spatial distribution of cities in Northwest Russia.
To determine the role of population migration in ensuring sustainable devel opment of the northwest regions, the Spearman's rank correlation coefficient was calculated.
The study uses the data of the Federal State Statistics Service, its territorial divisions in the Northwestern Federal District, as well as materials from the SGM rating agency, which calculates the sustainable development rating of cities of the Russian Federation 4 .
Statistical research materials for this study are presented mainly in absolute terms allowing to demonstrate the significance of population growth dynamics in St. Petersburg and the Leningrad Region, as well as to identify demographic prerequisites for sustainable urban development.

Urban population trends in the Northwestern Federal District
Currently (in 2019), there are officially 147 cities in the Northwestern Federal District, including: -1 city with a population of more than 1 million people; -6 major cities (250,000 to 500,000 inhabitants); -3 large cities (100,000 to 250,000 inhabitants); -13 medium cities (50,000 to 100,000 inhabitants); -124 small cities (less than 50,000 inhabitants). As follows from the data in Table 1, the Leningrad and Kaliningrad regions hold leading positions in the number of cities (32 and 22, respectively). This is due to historical and geographical reasons, their longstanding development, as well as the influence of St. Petersburg on the territorial development and growth of cities in the Leningrad region and the border position of the Kaliningrad re gion, an exclave of the Russian Federation. The specific features of the urban settlement structure of the Northwestern Federal District include the presence of a city of federal significance, Saint-Petersburg, which is a subject of the Russian Federation, and the fact that there is only one city in the Nenets Autonomous Okrug. The lowest share of the urban population in the total population is ob served in the Leningrad Region (64 %), which is explained by its proximity to St. Petersburg. 4    From 2002 to 2017, the population of the subjects of the RF in the NWFD, with the exception of the Nenets Autonomous Okrug, the Kaliningrad and Lenin grad regions as well as St. Petersburg, decreased. A similar trend was observed in the urban population dynamics (Fig. 1). The greatest loss of urban population was observed in the northern subjects of the RF (more than 10 % in 2002-2017), as well as in the Novgorod and Pskov regions.
The study includes the analysis and compilation of classification of the data on the urban population of the NWFD in 2017 presented in Table 2. The most numerous cities (those with a population of less than 50 thousand people) were examined in more detail. They were divided into three separate subgroups (mi nor, lesser and small). Major and large cities are represented by industrial and administrative centres of the subjects of the RF. They are the major nodes of the settlement system in the northwest. Source: compiled on the basis of Rosstat data (2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016)(2017)(2018).
The end of Table 2 The study of the evolution of urban settlements in Northwest Russia is based on the method of spatiotemporal analysis of emergence and development of the urban system. The analysis of the urbanization dynamics in Northwest Russia allowed distinguishing two stages. By the middle of the 19th century, a core net work of "historic cities" had emerged. These were the centres of settlement in the European part of Russia in the preindustrial period. Early Industrialization period saw the emergence of a new trend to develop new territories by founding mostly primary producing cities.
There are several urbanization trends having considerable influence on the spatial distribution of cities in Northwest Russia.
St. Petersburg as a city of federal significance and the centre of the macrore gion dominates in all socioeconomic spheres (industry and services, transport, innovation, financial and credit, and scientific and cultural ones).
The centres of republics and regions with a population of over 100,000 peo ple play an important role in the district settlement system. The largest regional centre is Kaliningrad with a population of 459,000 people, which is 50 % of the region's population. One of the largest and oldest major nodes in the North is the Arkhangelsk agglomeration accounting for 25 % of the total urban popu lation of the Russian Arctic. The second largest is Murmansk (14 %). Although during the period of booming economic activity it had bypassed Arkhangelsk, with the onset of the crisis of the 1990s, it turned out to be the leader in popu lation and production potential losses. Large cities of the Vologda region (two industrial centres of Vologda and Cherepovets) have a population of more than 300,000 people each. It is also necessary to highlight such cities as Petroza vodsk (277 thousand) and Syktyvkar (243 thousand), the centres of the Re public of Karelia and the Republic of Komi respectively, having great regional significance in the NWFD. The city of Severodvinsk, the expression of the third stage of development of the Russian Arctic, concentrates about 8 % of its urban population.
The next group is urban settlements with a population of 50,000 to 100,000 people. The largest cities are also located in the north. They are characterized by the most considerable decline in population in the postSoviet period. These are primarily singleindustry towns with prevailing mining and metallurgical special ization (Vorkuta -coal, Ukhta -oil and gas production, Apatity -apatites and nepheline ore) [22].
The most numerous group of urban settlements is cities with a population of 10,000-20,000 people. This group includes historic settlements in the North of Russia, for example, Kem, Anadyr, Kola, Belomorsk, as well as industrial settlements (Polyarnye Zori -nuclear power plants, Kovdor -iron ore pro duction, Urengoy -natural gas production). In the Murmansk region, most of them are closed administrativeterritorial entities (ZATOs). These are the entities with local governments as well as military and other facilities located on their territory. They have a special regime established for the secure functioning and protection of state secrets, including special living conditions for citizens. The Ministry of Defense's ZATOs include naval submarine bases in the Murmansk region: Zaozersk (10 thousand), ZATO Aleksandrovsk, consisting of three cities: the city of Gadzhievo (12.9 thousand), the city of Polarnyi (17.5 thousand), the city of Snezhnogorsk (12.7 thousand). The largest ZATO in the Murmansk region is Severomorsk (51.2 thousand), where the base of surface ships of the Northern Fleet is located. The smallest is the city of Ostrovnoy (1,876 people) rapidly losing its population over the past decade. It has decreased eightfold since 1996. This is the location of the Gremikha Naval base of the Northern Fleet, and one of the smallest cities in Russia.
Ostrovnoy is a part of the group of urban settlements with the smallest popu lation. Formally, these are cities, although they have more than halved in size to have less than 10,000 inhabitants. The bulk is singlecompany settlements and regional centres with difficult accessibility. This is the largest group in North west Russia, the majority of these cities are in the Kaliningrad (10), Vologda (8) and Pskov (8) regions. These are majorly the most vulnerable cities in terms of socioeconomic sustainability. However, there are also dynamically developing cities with large port complexes, for example, Primorsk and Vysotsk in the Len ingrad region.
The studies of the factors and conditions of economic differentiation of urban settlements and the research on their correlation with the distribution of produc tive forces allowed to develop a structuralfunctional typology of urban and rural settlements of the Northwestern Economic Region [23]. This work analyses ur ban settlements of the Leningrad, Novgorod and Pskov regions.
The spatial heterogeneity of the regions of Northwest Russia is the result of the formation of a vast peripheral area with stable stagnation of its population and production. The city of St. Petersburg acts as an external factor in this case. Being the largest socio-economic as well as scientific and technical centre in the northwest, it has a steady impact on the development of cities in the suburban areas of the Leningrad region forming the modern boundaries of the St. Peters burg metropolitan area. Moreover, the city indirectly affects the manufacturing industry in the urban settlements of the Novgorod and Pskov regions, as it is the largest sales market in the northwest.
Internal factors enhancing the polarized development of the regions of the NWFD include weakly diversified economies of the Novgorod and Pskov re gions, heavy concentration of industrial production in the regional centres, lawquality basic, core, research and technological infrastructure, as well as insufficiently developed engineering, social and transport infrastructure in pe ripheral areas, concentration of skilled labour in large cities and a decrease in the share of economically active population in peripheral territories, the sin gleindustry structure of the economy and weak organizational and economic relations of most of the regional centres of the Novgorod and Pskov regions.
In order to study the factors and conditions of economic differentiation of urban settlements and to determine their correlation with the distribution of pro ductive forces, the authors developed a structural and functional typology of urban settlements of the Leningrad, Kaliningrad, Novgorod, Pskov regions, as well as regional and republican centres of the NWFD. It is presented in Table 3 along In the Novgorod region, the territorial differentiation of economic devel opment seems more dispersed. The key territories with sufficient potential for economic growth and balanced development of the region as a whole include the regional centre Veliky Novgorod, as well as industrial hubs with advanced engineering (Staraya Russa), woodworking industry (Chudovo, Malaya Vish era) and the production of refractories and building materials (Borovichi). In the Pskov region, prosperous areas include Pskov, Velikiye Luki, Ostrov and other centres of diversified economic activities, specializing in the manufacturing of engineering products. In the Kaliningrad region, cities with a population of less than 50,000 include administrative centres specializing in mechanical engineering, fish processing and food industry, ship repair and those performing port functions (Baltiysk, Svetly). In addition to industrial functions, a number of cities perform recreation al functions. These are resort cities (Svetlogorsk, Zelenogradsk).
The main indicator of urban sustainability in the NWFD is the migration be haviour of the population and geoeconomic development. Tracing the general results of population migration by the subjects of the district in 2016 and 2017 (Table 4.), one can note the significant migration increase in the Kaliningrad re gion (9.9 thousand and 9.8 thousand, respectively), the Leningrad Region (21.6 and 30.8 thousand) and St. Petersburg (44.7 and 64.5 thousand) 6 . Table 4 General population migration by subjects of the NWFD for 2016-2017  These regions leading in terms of inward internal migration show positive dy namics, while in the other regions internal migration results in population losses. In 2016, the Novgorod and Pskov regions showed insignificant positive dynamics stemming from considerable migrant quotas for the citizens of other countries, including refugees from Ukraine who, after receiving a residence permit and cit izenship of the Russian Federation, move to St. Petersburg. In 2017, there was an internal outflow resulting in negative migration balance in both regions. The other regions of the NWFD saw a significant internal outflow by far exceeding the size of positive international migration both in 2016 and 2017. Such dynamics is the reason behind the change in the urban population in the NWFD cities at the regional level.

Sustainability of socio-economic development of the cities of the Northwestern Federal District
The sustainability of the socioeconomic development of a modern city is a current challenge that requires the engagement of all its residents and manage ment in order to ensure a high quality of the urban environment, life, as well as the balance between urban and natural environment. Sustainable development of the city should satisfy the needs of its residents [24]. It was at the end of the 20th century that the cities of the world started moving towards sustainability. The UN has created certain institutions to assist this process (HABITAT -UN Centre for Urban Settlements, UEF -Urban Environment Forum, UNEP -UN Environ ment Program, etc.) [25].
With the development and adoption of sustainable urban development pro grams, there are hopes for achieving longterm sustainable development of ur ban settlements. Their difference from any known programs is that they are built around the central idea of ensuring sustainability. This allows for the compre hensive understanding of sustainable development and for prompt counteraction against any negative trends in the evolution of the city.
Urban sustainability requires minimizing the consumption of space and re sources, optimizing the urban form to facilitate urban flows, protect both the eco system and human health, ensure equal access to resources and services, and maintain the cultural and social diversity and integrity of the urban environment. "The most remarkable thing about cities is that, even with urban sprawl, they take up merely 3 % of the earth's land surface, but accommodate more than half the world's population. Cities have lower per capita costs of providing clean water, sanitation, electricity, waste collection, and telecommunications, and offer better access to education, jobs, health care, and social services." [26, p. 2].
As a rule, socioeconomic programs for urban development consider social, economic, industrial, energy, agricultural, tax, transport and other problems sepa rately and in isolation from environmental factors. The current international trend is the increase in strategies and programs for sustainable development, approved and recommended by the UN Rio92 Conference for governments and peoples of all countries. In 1995, the Russian Federation also approved the Concept of Russia's Transition to Sustainable Development. Such sustainability strategies and programs are the most advanced documents in which for the first time all policies in social, economic, environmental and other spheres are put together. It is the task of any government to facilitate the drafting of sustainable development legislation based on sound economic, social and environmental principles.
In 1994, the participants of the European Conference on Sustainable Cities and Towns (Aalborg, Denmark) adopted the Charter of European Cities & Towns Towards Sustainability. It set forth the following aspects of sustainable socioeco nomic development of cities: -Sustainable development as a creative, local, balanceseeking process at the city level; -Urban economy towards sustainability; -Social equality for urban sustainability; -Sustainable landuse planning; -Sustainable urban mobility patterns; -Involvement of local government as a necessary precondition for the tran sition to sustainability, etc.
In 2015, the UN Member States adopted the 2030 Agenda for Sustainable De velopment outlining 17 goals and 169 targets for sustainable development. Goal No. 11 is ensuring the inclusiveness, security, resilience and environmental sus tainability of cities and settlements. One of its targets is "by 2020, substantially increase the number of cities and human settlements adopting and implementing integrated policies and plans towards inclusion, resource efficiency." 7 Many European Commission legal documents and reports, as well as UN in ternational programs, speak of the need for sustainable urban development and the formation of a "sustainable urbanization policy." 8 Urban sustainability re quires an active, focused local strategy that must be both realistic and effective 9 . According to Russian researchers, "the main obstacles to the implementation of the principles of sustainable development in Russian cities include the diffi culty in perceiving the topic of sustainable development, lack of experience and expertise, and low qualifications of personnel in municipalities, as well as shortterm planning horizons" [28, p. 80].
On the way to sustainable development, a city must make the following stra tegic choice: 1) Avoid industrial production and develop creative technologies; 2) Diversify the existing industrial cluster; 3) Create a new industrial cluster that meets the current needs of the economy [29, p. 298].
These strategies are not in opposition, but it is important to choose the key strategy based on the city's competitive advantages. In 2018, the Ministry of Economic Development of the Russian Federation developed a new system for assessing Russian cities, the urban development index. It was to become a unified tool for identifying problems and priorities in the development of all types of cities. The index is needed for a spatial development strategy, in which the largest cities are considered as centres of social and economic growth [30; 31].
The choice of sustainability indicators is also of great importance, as they can be included in strategies and state programs for the development of the subjects of the RF, as well as municipal strategies and programs.
Given the vast territory of the NWFD and the low population density in com parison with Western Europe, as well as the imperfect transport routes, cities have always been key elements linking agricultural zones and industrial centres, ensuring the development of the regional economy and the preservation of cul tural and historical heritage. To maintain this role in an open market economy and ongoing globalization processes, each city regardless of its category needs to create a comfortable and attractive living environment. The main indicator of the attractiveness of the city is the migration behaviour of the population. The simplest calculation done using the Spearman's rank correlation coefficient (r s ) on the data on the regional centre's sustainability (according to the annual sus tainability rating of cities of the Russian Federation 10 ) and the migration growth rate per 1,000 people in the subject of the RF 11 indicates a fairly high degree of correlation (r s = 0.6) ( Table 5). However, in the rating of sustainable urban development compiled by the rat ing agency SGM, the data were analyzed only for the cities with a population of more than 100,000 people. As follows from the data given in Table 3, the situation in this category of cities in the NWFD is the most favourable. The main outflow of the population is observed in medium and small cities, which are the biggest contributors to the negative values of the migration growth coefficient of most subjects of the NWFD of Russia.

Conclusion
The Northwestern Federal District is one of the highly urbanized regions of Russia. The reason behind it is the longstanding development of the area and the emergence of cities, primarily St. Petersburg that has evolved into a large ag glomeration and exerts a versatile influence on the socio-economic development of not only the suburban areas but also more remote territories. The trend towards an increase in the urbanization of the region remains at present, although the share of the urban population in the total population is growing insignificantly. At the same time, differences in the dynamics of the population of regions and re publics, as well as urban settlements, are likely to intensify. The northern regions (with the exception of the Nenets Autonomous Region) and the old industrial regions (Novgorod and Pskov) lose their populations. This decrease is a result of natural decline. The factor is especially pronounced in the southern regions with the large share of the older population and growing outward domestic migration of workingage population. The population in the Kaliningrad and Leningrad re gions is increasing. At the same time, a peculiar situation has developed in the Leningrad Region where, unlike in other northwest regions, in 2002-2017, the share of the urban population has decreased from 66.4 % to 64 %. The reason for this phenomenon is that not only urban settlements, but also rural settlements in the suburbanized zone of St. Petersburg are attractive to migrants. A similar situ ation, although in a milder form, has developed in the Kaliningrad region.
Of particular note is St. Petersburg, as in 2002-2017 its population increased by 613,000 people. After the decline of the 1990s, the city managed not only to restore the previous population but also to increase it. It is important to note the intensification of the agglomeration ties of the city.
As for the centres of the regions, the subjects of the RF, only Arkhangelsk and Murmansk, both located in the Arctic zone, saw a decline in population. A unique situation for this group developed in NaryanMar, where the population increased by 32.5 %, which in absolute terms is an increase of 6,000 people.
Significant differences in population dynamics are demonstrated by cities that have a lower administrative status or do not have one. The highest dynamics were shown by Vsevolozhsk, Sertolovo, Kommunar, Nikolskoye, Otradnoye and Shlisselburg. All of them are part of the St. Petersburg agglomeration. Their growth rates range from 17 % to 55 %. The similar dynamics is shown by the cit ies of the Kaliningrad region: Guryevsk, Zelenogradsk and Svetlogorsk. The rest of the cities, as follows from the above study, demonstrate either small population growth or negative dynamics. The latter clearly prevails.
Data on the dynamics of the urban population allow us to draw the following conclusions: polarization is increasing in the southnorth direction, the Arctic ter ritories are losing their population, and however, there is further concentration within the agglomeration of St. Petersburg and in the exclave of the Kaliningrad region. The population dynamics clearly captures the nature of sustainable devel opment of the cities of the Northwest Federal District.