Development of a water-vegetable frame of an urban area (Isilkul city, Omsk region)

The formation of a comfortable urban environment is inextricably linked with the planning of an anthropogenic landscape that performs environmental, reclamation and recreational functions.

"Ecological frame of the city", "landscape-ecological frame", "water-green city frame", "landscape-recreational frame of the city" - these are essentially synonymous phrases that are used in scientific and special literature depending on the scale and detail of the study. and urban landscape planning [Targaeva, 2022]. The term "ecological frame" was introduced into the everyday life of researchers by V.V. Vladimirov (1980, 1986). Later, the terminology of urban landscape ecology was developed in [Runova, 1993; Kuleshova, 1999; Georgita, 2011; Tukmanov, 2012]. Among the scientific works of contemporaries devoted to the history and development of the theory of urban landscape planning, the works of E.Yu. Kolbovsky et al. [2008, 2018]. In foreign literature, the ecological structure of cities has been defined as ecological network (ecological network) or green infrastructure (green infrastructure) [Green infrastructure..., 2013; Podoinitsyna, 2016; Klimanov, 2018]. According to its functional purpose, green infrastructure corresponds to the domestic green frame of the city [Baro et all., 2014].

This paper discusses the issues of landscape planning of the city of Isilkul, the center of the district of the same name in the Omsk region. Given the size and specialization, the current geo-ecological problems of the settlement and the natural and climatic conditions of the forest-steppe, the term water-plant urban frame is used. The water-vegetation urban frame is a structured set of adjacent territories with vegetation cover and water bodies within the city limits and its immediate environs, which performs environment-forming, reclamation and recreational functions.

Currently, the western regions of the Omsk region are characterized by the processes of rising groundwater levels, which caused flooding in 24 zones, with a total area of about 60 thousand hectares. Within one of these zones is the city of Isilkul. An unfavorable geo-ecological situation has developed in the city and in the adjacent territories, associated with swamping, and in some cases, salinization of soils.

The purpose of this article is to substantiate measures for the creation of a water-vegetation frame of Isilkul, located on the southern outskirts of Western Siberia within the Ishim Plain. Among the objectives of the research: the study of the infrastructure of the city; reconstruction of natural landscapes; determining the causes of flooding of the territory, designing the water-vegetation frame of the urban area.

Objects and methods of investigation

The territory of the study object is located in the central part of the eastern half of the Ishim Plain and forms an ellipse in plan, elongated from north to south (Fig. 1). Within the boundaries of the object of study are located Isilkul with its suburbs, partly the land of rural settlements of the Isilkul administrative district - Solntsevo, Boevoye, Lesnoye. In the north, the study area includes a fragment of the territory of the Kamyshlov log tract, in the south - the basin of the lake. Settlement.

The choice of research methods was determined by the specifics of the tasks being solved and the landscape features of the study area. First of all, this concerns a significant transformation of natural landscapes in the vicinity of the city and the need to reconstruct ecosystems in the built-up area. Another important methodological task was the development of recommendations for the localization of processes that cause flooding of the urban landscape. The use of traditional landscape methods and techniques for solving the set tasks turned out to be ineffective. This required a combination of field and office methods of landscape ecology and environmental protection, which included.

In total, 30 observation points were described during the research. Two landscape profiles of 12 km (along the line Kamyshlov Log - Lake Gorodishche) and 2 km (from west to east through Isilkul) were broken up and examined. Natural, introduced and ruderal vegetation has been studied. Surveyed urban engineering networks, ways of surface water runoff. As part of office work, reports and cartographic materials of the State Historical Archive of the Omsk Region were analyzed; landscape map of the Omsk region.

Results of research

Prior to the start of construction, the territory of Isilkul was a flattened isometric upland typical of the Ishim steppe with a relative excess of height above the surrounding area of 1-5 m. The gentle slopes of the upland were occupied by grass-forb steppe meadows on carbonate chernozems and solods. Locally, in the hollows of the flat top and in moist relief depressions along its periphery, spiked aspen-birch forests grew in a mosaic pattern, which alternated with small lakes. The shores of reservoirs were occupied by reed and reed-sedge bogs. Increased mineralization was characteristic of the waters of endorheic lakes and soils along their banks.

There is no centralized rain sewerage system in the city. Rain, melt, groundwater is collected in ditches and flows down them into natural and artificial reservoirs (pits), as well as into natural relief depressions in the city. In the off-season, excess surface water is partially transferred using mobile pumps from the center of the northern part of the city to the southern part, and then, through a dug channel, is diverted to Lake Gorodishche. Partially, surface runoff is discharged naturally and by force through ditches outside the central part and accumulates in depressions and ditches of the city's bypass roads. The total length of ditches in Isilkul is about 300 km, however, about 90 km require repair and deep cleaning, and about 24 km need to be re-laid. Also, in many places there are no roads or bypass pipes in a non-working condition.

The reason for the periodic flooding of the city, along with the increased amount of precipitation, is the deterioration of the filtration properties of soils and soils, insufficient capacity and violation of the operating conditions of the drainage system. The predisposition of forest-steppe landscapes to secondary salinization, together with increased fluctuations in the level of groundwater, and their pollution with unorganized runoff, have caused excessive mineralization of urban soils.

The discussion of the results

Reconstruction of sewerage networks should become the top-priority measure to create a water-vegetable frame of the city.

Expected result of the reconstruction of the drainage system: lowering the level of groundwater and reducing the risk of flooding of the territory; increased soil drainage and reduced concentration of soluble salts; improvement of the sanitary and epidemiological situation in the city.

The reconstruction of the landscapes of the territory, the analysis of the transport infrastructure made it possible to propose a sectoral structure of forest plantations for Isilkul, in which the inner boundaries of the sections are forest protection belts of roads and railways. Forest parks in the form of strips and semicircles 300-600 m wide are planned to be laid in relief depressions at a distance of 1-2 km from the boundaries of the existing development (Fig. 4).

A latitudinal strip of green zone will pass through the territory of the city. It will connect the existing squares and green sports grounds with the green recreational areas of the city center. Thus, a latitudinal vegetation corridor is formed, connecting the water-vegetation frame through the central territory of the city.

Favorable places for planting in the modern landscape are marked by residual birch-aspen forests, lakes or swamps. Most often, these are waste lands that do not belong to agricultural land. In essence, it is proposed to carry out reforestation and form insular small-leaved forests of a given configuration, typical for the natural zone. At the same time, road belts, in addition to protecting soils from wind erosion, should strengthen the ecological unity of island forest ecosystems. The surveyed large forest areas in the west and north-west of the region are distinguished by the preservation of the indigenous flora and can be used to collect seeds of wild plants and select seedlings. The results of the study of natural and introduced flora made it possible to differentiate the species composition of future plantings according to optimal growing conditions and expand the list of species proposed for landscaping (Table 1-3).

The water-vegetation urban framework will include lakes, natural and artificial runoff troughs, drainage ditches, suffusion depressions, as well as all areas occupied by vegetation (Fig. 3-4).

The implementation of the program to create a water-green frame of the city will have a positive impact on the environment and comfort:

- will lower the level of groundwater;

- dry the territory of the city of Isilkul and the surrounding environs;

- eliminates the flow of sewage into the lakes Gryaznovskoye, Gorodishche;

- will significantly increase the comfort of living for city residents, which will contribute to the influx of people into the city of Isilkul and the Isilkul region as a whole.

The supply of purified water to the lakes Kamyshlovo, Salt, Krivoe will increase the area of the water surface of these reservoirs, which will increase the production of fish products. Lowering the groundwater level, as well as abandoning the cesspool sewerage system, will make it possible to save money allocated for the removal of sewage by sewage trucks, annual flood control, and annual repair of flooded buildings and structures.