The question of ecological safety level decreasing within the West Polesie protected territories that concern changes in hydrological conditions driven by intensification of the influence of climate changes and anthropogenic loads, has been considered in the paper. Statistical analysis and field instrumental measurements were used for estimation the influence of regional climate on hydrological conditions within the territory. According to bathymetry surveys and geoinformation analysis results, the siltation degree of the deepest hollows of Svitiaz Lake was estimated. Hypotheses concerning the ways of underground water supply as well as the reasons for water level decreasing in the Lake were formulated, taking into account climatic conditions within the West Polesie territory: the lake is filled by infiltration of water from aquifers through permeable rocks; water infiltration occurs not only within the fault of Lake Svityaz, but also in its flatter part; significant intensity of trajectories (water streams) within the fault allows us to conclude that the main filling of the lake occurs within this part due to the opening of permeable rocks, which contributes to a more intensive release of groundwater.

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Modern technologies give an opportunity to create a large number of bathymetric maps, but less of them have been focused on processing the water depth data in order to study and estimate the subterranean sources of water object supply. This study aims to create a mechanism for estimating the productivity of subterranean sources of lakes water supply, based on bathymetric survey data. Lake Svitiaz was chosen as the study site as the deepest closed lake of natural origin in Ukraine with an area of 2500 ha and a maximum depth of 58.4 m. To get depth data, ground-based measurements were conducted using an echosounder Lowrance LMS-527cDF. The Lake morphometric changes were investigated, using bathymetric data and Sentinel A, and B data in the digital elevation model (15×15 m). Bathygrahic analysis was performed, allowing selecting areas for further echo-sounding, taking into account complex relief and specific basin forms of the Lake. To develop an appropriate technique for estimating the productivity of subterranean water supply sources, GIS and image (echogram) processing techniques were applied. The research tasks are completed as a technique for detecting ‘tracks’ and a mechanism that is quite effective, particularly for early evaluation of subterranean sources of water supply productivity that can be repeated on any similar water objects.