Seasonal and Annual Probabilistic Forecasting of Water Levels in Large Lakes (Case Study of the Ladoga Lake)

The production functions of water-dependent sectors of the economy can include the water level in the lake as a natural resource. This characteristic must be able to reliably predict for the effective functioning of sectors of the economy. In the article the main attention is paid to the methods of forecasting based on the extrapolation of natural variations of the large lakes water level. As an example, is considered. In this paper, it is assumed that the level varies accordingly to a stochastic multi-cycle process with principal energy-containing zones in frequency bands associated with seasonal and multi-annual variations. Hence, the multi-year monthly and yearly averaged time series are represented by the ARIMA (auto-regression integrated moving average) processes. Forecasts are generated by using of the seasonal ARIMA-models, which take into account not only the seasonal but also the evolution non-stationarity. To compare the forecasts and the actual values, the relative errors are computed. It is shown that implementation of the models mainly allows receiving good and excellent forecasts. Subject Classification Numbers: UDC 556.555.2.06(4)

INVASION OF ZEBRA MUSSEL DREISSENAPOLYMORPHA (PALLAS, 1771) IN THE BASIN OF LADOGA LAKE AND THE BIOCHEMICAL ROLE OF THE INVADER

In June 2017 in one of the career in the basin of Lake Ladoga (Kakolowski career, Kirovskiy district, Leningrad oblast), a stable population of Dreissena polymorpha was found. The biological observation and study of microelement composition of the shells of Dreissena p . were conducted. It was revealed that the population referred to young one with high potential for further development under favorable environmental conditions. The latter is expressed by the relatively high mineralization of the water reservoir, which provides the optimal level of necessary elements for the construction of the calcareous skeleton of a large number of individuals. The main chorological types formed here were dreissen-brushes and druses, allowing the fullest use of resources in a limited space. The participation of shells in the accumulation and bio-burial of a number of trace elements is shown.

Sediment Runoff and Water Turbidity of the Main Tributaries of the Lake Ladoga

The vast catchment area of the Lake Ladoga is characterized by variety of underlying surface types and a complex hydrographic network. The processes of eutrophication of the southern littoral areas of the Lake Ladoga determine the relevance of assessing the removal of solid matter from the river flow to the estuaries of the tributaries of the Ladoga. Observations of sediment runoff of the main tributaries the Lake Ladoga were not carried out. In this regard, for each tributary were selected rivers-analogues the main criteria in the selection was the slope, the grain size of sediments and the catchment area (water availability). The modeling of annual solid runoff and turbidity of the Ladoga tributaries is based on an analytical formula for sediment flow by M.V. Shmakova and a stochastic model of annual solid runoff (M.V. Shmakova). According to the calculations, the annual flow of sediment entering the Ladoga water area is about 432 thousand t/year. The main sources of sediment are three major tributaries of the Lake Ladoga – the Svir, Volkhov and Vuoksa rivers, which account for 253 thousand t/year or 59 % of the total amount of sediment received in the lake. However, these watercourses have the smallest annual module solid flow, due to retention of sediment of backwater areas before hydroelectric dams on these rivers and as a consequence, a decrease in the overall sediment discharge. At the same time, the average annual solid runoff modulus for the Ladoga lake catchment area is 1.53 t/(km2·year), which corresponds well to the previous estimate of this value for the territory under consideration. The analysis of the annual module of solid runoff showed a good correspondence between the obtained values of this value and the conditions for the formation of solid runoff in the catchment, the characteristics of its soils.

The specificities of coastal territories of Ladoga Lake and their impact upon formation of recreational system of the coastline

The object of this research is the coastal territories of Ladoga Lake, their structure substantiated by the natural-geographical peculiarities, and specificities conditioned by anthropogenic development. The coastline of Ladoga Lake is capable of ecological stabilization of a significant territory, ensure the population of Leningrad Oblast and the Republic of Karelia with a wide variety of recreational functions, and forms of tourism. The dynamic processes of its economic development require the elaboration of new principles and grounds of landscape-recreational organization of coastal areas, creation of typical models for Northwestern Russia. Analysis is conducted on the natural-climatic, historical-cultural and other specific characteristics of the coastal areas of Ladoga Lake, as well as determines their impact upon landscape-recreational organization of coastline. The author also examines the cartographic data and statistical reports, carries out a comparative analysis of environmental indexes in retrospective, as well as systematized data on the spatial-planning system of coastline based on the land use documents. Climatic specificities determine the focus of attention not on the beach recreation, but other types based on the uniqueness and diversity of natural components of the coastline of Ladoga Lake. Integrating into the system of environmental framework, the infrastructure of recreational areas, their transport and pedestrian support alongside specially protected zones, performs an environmental protection function. In order to prevent future destruction of landscape complexes on the coastline of Ladoga Lake, it is essential to establish universal rules and regulation for natural and water resource management. Due to natural and climatic factors, landscape peculiarities and historical-cultural value of Ladoga Lake coastline, one of the fundamental vectors in arrangement of its recreational zones is ecotourism.