Cadastral and landscape modeling of lakes as a prerequisite for protected and recreational nature resource management

The cadastral information about the lakes of the nature reserve fund (NRF) should be based on landscape-geographic principles using modern geo-information systems.Within the research, based on the instrumental field research and the use of software packages ArcGIS Desktop and ReefMaster Software, a bathymetric map of Lake Serednie (Nobel National Natural Park, Ukraine) and other spatial models were developed. The main hydrological and morphometric parameters of the lake basin were calculated, a landscape map of the natural aquatic complex was created and its landscape metric analysis was carried out at the level of aquatic tracts and facies. The research revealed changes in the level regime and shoreline of the lake caused by the long dry periods of 2016-2021 and life activity of beavers. The created integrated cadastral landscape model of the lake with limnology parameters should serve as a basis for the recreational nature use, monitoring and geo-ecological certification of the reservoirs of the NRF.


Introduction
According to Article 56 of the Law of Ukraine "On the Nature Reserve Fund of Ukraine", the state cadastre of the territories and objects of the nature reserve fund (NRF) is a system of necessary and reliable information about the natural, scientific, legal and other characteristics of the territories of the objects included to the NRF [1].In Ukraine, the natural reserve fund is safeguarded as a national asset and subject to a distinct set of rules for its protection, reproduction, and usage.Furthermore, Ukraine regards this fund as a crucial component of the global network of special-protected natural territories and objects.The corresponding cadastral system should incorporate current geospatial data, metadata, and various online sources, including publications, that comply with the terms of the Spatial Data Infrastructure [2].In 2021, the Ministry of Environmental Protection and Natural Resources of Ukraine presented an electronic cadastre of territories and objects of the NRF.The information layer "Nature Reserve Fund" appeared on the Public Cadastral Map, which at that time contained information on 8,633 NRF objects, or 88 percent of the area of the NRF of Ukraine [3].
Lake reservoirs occupy a prominent place in the structure of the NRF objects of Ukraine.They are part of nature reserves, national nature parks, regional landscape parks, landscape reserves, hydrological natural monuments, protected tracts, etc.Unfortunately, there is rather limited information about lakes of the NRF and, it should be noted, such situation is not unique [4].On the Public Cadastral Map, lake objects of the NRF and other water bodies are shown as separate entities with provided information about the area, ownership, etc. Undoubtedly, information on some parameters of land use and landscape components can be added in other layers.
Today, one of the important tasks of protected nature resource management is the creation of an information database about local NRF objects, including lakes, which should later appear on the Internet portals of the institutions of the nature reserve fund.The cadastral information should serve as a basis for recreational nature use, monitoring observations, geo-ecological certification of water bodies [5].In 2015, Svidzynska et al updated the issue of developing an open cadastre of protected areas of Ukraine [6], which support geo-ecological approaches in the organization of nature reserves.
Among the other studies, which are similar in subject matter, it is worth highlighting the work on the anthropogenic loads on surface water status in Lithuania [7].A model of geographic management of a nature reserve [8] was developed within the framework of the "Electronic Turkey" project.Some studies were devoted to the validation of remote sensing indices for water monitoring using Sentinel-2 [9,10], which can be applied to the cadastre development of lake systems of protected areas.Although successfully tested the methods of capturing littoral zones (up to 1.6 m under clear water conditions) using a UAV complex with a LIDAR scanner on board [11].The use of the proposed technology greatly facilitates the collection of data for cadastral landscape modeling of lakes, since the shallow zone with higher aquatic vegetation is the most inconvenient for measurements.
For a long time, we have been conducting landscape and limnology studies within the boundaries of Polissia region of Ukraine with the aim of developing cadastral and landscape models of lakes [12,13], primarily in the territory of the NRF.

Materials and methodology
The model protected nature area of this research is Nobel National Natural Park (NNP) in Ukraine, which is located within the physiographic region of Volyn Polissia.The landscapes of the park are characterized by an extensive hydrographic network, swampy wetland complexes, sand dunes and green massifs of forests with areas of cranberries, blueberries, lingonberries, etc.The park includes 12 lakes (Nobel, Omyt, Nihovyshche, Zasvitske, Postvitske, Zadovzhe, Ostrivske, Velyke, Serednie, Khoromne, Lypenske, Liubynske).
The lakes play a significant role in the hydrological functioning of the landscape, the accumulation of fresh water and organic-mineral resources represented by sapropel.Among the most important functions -serving as habitats for waterfowl and numerous migratory bird species.The lakes of Nobel NNP have significant recreational and tourist potential.Among the lakes of the park, a group of Ostrivski lakes stands out.This group includes a picturesque Lake Serednie, which was formed in the Nyzhnostyrskyi physical-geographical district of Volyn Polissia (figure 1).
The development of the cadastral landscape model of Lake Serednie (North 51.72392176915384, East 25.834182861365576) included field instrumental research, in particular, high-precision echo sounding of the reservoir, research into the composition and thickness of lake sediments, the study of the species diversity of above-water and underwater plant communities, and determination of the temperature regime in the summer.The hydrometric work was carried out in May 2021 using a Humminbird 597ci HD sounder mounted on the transom of a rubber boat.The water level during the measurements was recorded using a Leica GNSS/RTK receiver.SRTM v.3 radar survey data were processed in the ArcGIS Desktop software complex to set the boundaries and configuration of the catchment area.Probing of the bottom sediments of the lake was carried out from the ice in winter with a spoon-type geological drill.
The next stage was the processing of field materials, development of a bathymetric map and landscape mapping of Lake Serednie.The cartographic models were developed using ArcGIS Desktop and ReefMaster Software.From the landscape point of view, we consider the lake to be a natural aquatic complex (NAC) of the rank of a complex tract.The landscape map of the NAC of the lake was developed based on the materials of the bathymetric survey, taking into account the micro-relief of the lake basin, the composition and thickness of sapropel deposits, the species diversity of the plant communities of the reservoir and thermal features.
The research methodology was based on the studies on the field geographical research [14], underwater landscape science [15], limnology [16], bathymetry and GIS mapping [17,18], as well as many years of experience in constructive landscape modeling of lake-basin systems in Polissia region of Ukraine.
The purpose of the research is to develop a cadastral landscape model of Lake Serednie (Nobel NNP) for the needs of protected and recreational nature resource management.

Results and discussion
The basin of Lake Serednie was formed in the following landscape areas: 1) high areas between rivers on water-glacial sands with close deposits of chalk marls; 2) inter-fluvial marshy plains on fluvial-glacial and ancient alluvial deposits.The Pleistocene glaciation, as well as postglacial processes, had a significant impact on the formation and development of the landscapes of the basin system of Lake Serednie and Nobel NNP as a whole.The activity of water flows, aeolian processes and excessive moistening subsequently affected the morphological structure of the landscapes of Nobel NNP and lake-basin systems (LBS).

4
The field research in the lake basin and its adjacent territories revealed dominant morphological units of the landscape of a lower rank, in particular, tracts (or geotopes): 1) Hills and dunes with gentle (6-10°) slopes, covered with lichen-shrub pine forests on hidden podzolic, sometimes crushed stone, sandy soils.2) Elevated areas between rivers, complicated by karst funnels, covered with lichen-bilberrygreen moss pine and birch-pine forests on slightly podzolic, sometimes clayey, sandy soils.3) Undulating areas between rivers covered with sedge-bilberry-green moss and various grassgreen moss oak-pine and birch-oak-pine forests on sod-weak podzolic clayey sandy and loamy soils, sometimes meliorated.4) Local closed mounded depressions covered with various grass-cereal-green moss and sedgejuncus -green moss alder-birch-pine sparse forests on sod gumbo sandy and sandy loamy soils.5) The lakeside narrow depressions, which are filled with water during floods, covered with reed-sedge-herbaceous and shrubby-sedge-reed alder and willow small forests on meadow layered gumbo sandy and sandy loamy soils.6) Lake depressions of irregular shape formed on sapropel deposits.
The catchment area of Lake Serednie is not big and makes 54.3 hectares.It is elongated in a sub-latitudinal plan from the northwest to the southeast in accordance with the configuration of the lake.
Based on the results of echo sounding data processing, we built a bathymetric map of Lake Serednie (figure 2).Isobaths are drawn at intervals of 0.25 m.Up to 2.0 m, the depth increases gradually, and from 2.0 m, the isobaths have some differences.In the northwestern part, a funnel-shaped depression with a maximum depth of 5.67 m was found from 4.0 m and deeper.The central part of the bed of the lake basin has a depression of elongated shape of more than 3.0 m.The average depth of the reservoir is 2.4 m.The area of the lake is 0.19 km 2 .The length of the reservoir is 1.002 km, the maximum width is 0.262 km, and the average is 0.190 km.The coastline has a length of 2.257 km.The northwestern part of the coastline and lakeside terrace is undergoing transformations due to the life activity of beavers (numerous burrows leading from the shore into the lake, fallen trees).The volume of the lake water is 435.2 thousand m 3 .Other morphometric and hydrological parameters of the lake are given in table 1.
The developed three-dimensional model of Lake Serednie is an additional element of the visualization of the lake basin micro-relief (figure 3a).
It clearly shows a depression in the cone-shaped northwestern part of the basin bed.The aforementioned funnel-shaped depression is very well shown on the longitudinal profile of the underwater topography of the lake (figure 3b).The slopes of the lake basin from the water surface are steep (10-15 • ) up to 2.0 m, very steep (15-20 • ) up to 3.0 m, and steep (more than 20 • ) from 3.0 m and deeper.The differentiation of the relief of the basin by the steepness of the slopes is important in the further development of the legend of the landscape map, in particular, the determination of the processes of accumulation or transit of mineral particles and dead remains of aquatic organisms.
The relief of the lake basin affects the distribution of areas and volumes of water masses of the lake (figure 4).
The area of the littoral zone of the reservoir with a depth of up to 3.0 m is the largest and is 15.35 hectares (78.8 %), it accumulates 413.3 thousand m 3 of water masses (94.95 %).21.20 % of the area of the lake with 20.9 thousand m 3 of water is at a depth of more than 3.0 m.
Based on the results of bathymetric surveying, landscape field research and computer processing of materials, a digital landscape map of Lake Serednie was developed (figure 5).
Typical landscape elements shown in figure 5: I. Littoral aqua subtract on sandy-muddy, peat-swamp sediments and sapropel underlain by alluvial sands with species diversity of surface and underwater plant communities.Aquafacies: 1.1.Littoral, accumulative peat-swamp and sandy-muddy of low-thickness (up to 0.5 m) Carex-Typha-Phragmites associations, with a homogeneous temperature regime in summer.1.2.Littoral, accumulative swamps and peat-swamps of low-thickness (up to 1.5 m) sparse     Two types of aquafacies were identified in the sublittoral-profundal aqua subtract with depths of more than 3.0 m.In total, there are 13 landscape contours in the NAC; the average area of a landscape contour is 1.5 hectares.Other landscape metric characteristics of Lake Serednie NAC are given in table 2. The research identified two aqua subtracts and seven types of aquafacies in the lake NAC.The littoral aqua subtract with depths mainly up to 3.0 m occupies more than 78.0 % of the NAC area and includes five types of aquafacies.The differentiation of aquafacies was carried out taking into account the micro-relief of the lake, the composition and thickness of bottom sediments, the characteristics of aquatic plant communities and the temperature regime in the summer season.

Conclusion
The research established that during the summer seasons of 2016-2021, the water level in the lake changed a lot.The retreat of the water cut from the shoreline of the lake was 5.0-6.5 m in the southeastern part of the reservoir.The shoreline of the lake undergoes noticeable changes due to the life activity of beavers, especially the littoral aquafacies with index 1.3.In our opinion, the activity of beavers affected the impoverished state of surface and underwater plant communities.The railway embankment is a limiting factor in the inflow of surface water from the catchment area in the northwestern sector.
The developed series of cartographic models: 1. Reflects the current geoecological state of Lake Serednie and is important in evaluating the geoecological parameters of the whole lake landscape system and its individual elements, and in revealing its functional features.2. Acts as an information and analytical basis for planning measures to optimize nature use and protect water resources from pollution and quality impairment.The spatial models and typological structure of the land areas within the lake basin and the aquatic complex are especially important in this respect.
The bathymetric maps, the calculated main hydrological parameters of the lake, and the developed aquatic complex model should become the basis of the landscape and cadastral passport of Lake Serednie for the needs of protected and recreational nature resource management.
The benchmark landscape and limnology characteristics of the entire lake basin should become the starting point of further monitoring observations.
In the conditions of climate change and its regional components, the demand for such research will only grow.

Figure 3 .
Figure 3. Three-dimensional visualization (a) and long axis profile A-B (b) of the Lake Serednie.

Figure 4 .
Figure 4. Morphometric curves of areas and volumes of water of the Lake Serednie.

Figure 5 .
Figure 5. Landscape structure of the natural-aqual complex of Lake Serednie.

Table 1 .
Morphometric and hydrological characteristics of the Lake Serednie * .Table notation: F -area; H abs. -absolute height of the water level; h max.-maximum depth; h mid.-average depth; L -Length; W max. -maximum width; l -length of the shoreline; C t.coefficient of shoreline unevenness ; C len. -coefficient of the lake lengthening ; C cap. -coefficient of capacity; C op. -coefficient of openness; C dep. -coefficient of depth; V lake -lake volume; Aarea index; ∆S -specific catchment; W inf lux -volume of inflow water from the catchment; a wat.-conditional water exchange; ∆a wat.-specific water exchange; A layer -water storage level on the catchment surface.

Table 2 .
The complexity of the natural-aqual complex territorial structure of the Lake Serednie.