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Introduction. The increasing shortage of water resources in the Republic of Crimea, due to water supplies from the external water source being shut off, emphasized the need to rationally use the existing water resource potential, which in turn requires a balance between the water users’ interests and maintaining a favorable environmental situation in the peninsula’s watercourses. Although in Russian and global practice there is a whole range of approaches to assessing the impact of natural and anthropogenic factors on the state of river geosystems, not all of them are applicable to solving the indicated problem. Methods. By testing integrated techniques, methods and models for assessing the impact of human activity on the stability of river natural and engineering systems (using the Zuya River as an example), we selected the most appropriate approach to develop viable solutions in water management. Results. By comparing the possibilities of using the scoring index method to assess the stability and vulnerability of watercourses to changes in physical and geographical as well as hydrological parameters and water quality, and methodology for the integrated assessment of the geoecological state of water resources of small rivers and the system model “Minor River Basin”, we revealed that only with the use of the latter it is possible not only to assess the real situation but also identify the reasons that impede the rational use of the peninsula’s watercourses. Conclusion. When developing decisions related to water management in the Republic of Crimea, the use of a suitable methodological approach to assessing the impact of natural and anthropogenic factors on the stability of river geosystems will make it possible to avoid mistakes when choosing measures and prioritizing actions aimed at the rational use of the existing water resource potential.

Introduction. The problem of restoring and preserving the environmental state of watercourses with an increase in anthropogenic load has recently become more urgent, but the use of only one method or approach does not allow us to judge the current state of a river, so there is a need to combine various methods aimed at obtaining integrated information. The purpose of this study was to analyze the environmental state of the water bodies in the Beshterek River Basin (Republic of Crimea). Methods. The studies were carried out during 2018–2019 and included: visual observations of the watercourse state, water-protection zone, channel ponds; water flow measurement; sampling for the study of water chemistry; calculation of the water pollution index (WPI) and the integrated indicator of ecological condition (IIEC); study of water toxicity by means of bio-assay techniques using wheat and cress seeds; development of environmental measures. Results. The studies have found that the main pollutants in river water are sulfates, phosphates as well as heavy metals: Cd, Pb, Cu, Zn. The concentration of sulfates increased from 0.15–0.22 MAC (upper river) to 1.5–2.4 MAC (mouth of the river), which indicates the ingress of domestic wastewater into the watercourse. The content of phosphates in the middle reaches exceeded the standards by 1.9–11.1 times. The heavy metal content exceeding the MAC was recorded at all river stations: zinc (station No. 1 — 2.1 MAC), cadmium (station No. 3 — 1.24 MAC), lead (station No. 4 — 1.23 MAC) and copper (station No. 4 — 1.5–10 MAC). The water quality in terms of the WPI was II and III (“clean” and “moderately polluted”) in the river and II, III and IV (“polluted”) in the channel ponds. The bio-assay testing showed no toxic effect on the test cultures. Conclusion. Among the priorities, the following can be distinguished: the need to establish a permanent monitoring network for the observation of the qualitative and quantitative characteristics of the river flow, and develop a program for sewage handling in villages located in the river valley.

The main objective of researches is the definition of the ecological status of water bodies of the Salgir River using bioassay technique. The main goal is to define the feasibility of using these waters for irrigation. For this purpose the base alignments were chosen on the river, exposed on different intensity of anthropogenic loads, and also the treated wastewater from sewerage facilities of Simferopol. The bioassay technique presented growing seeds of test plants in the studied waters and following comparison of the length of their root system with the same seedlings grown in the distilled water. Garden radish and garden cress seeds were chosen as test plants seeds. The phytotoxicity of the tested waters was shown in inhibition of the root system development of test plants. The root system in contact with the studied waters has been developing more slowly, what proves the presence of harmful substances in testing waters, and shows their toxic effect on the plants developing. The biggest sensitivity to pollutants showed the garden cress, which had the maximal inhibiting effect of roots development of 41.8%, in comparison to the monitoring in distilled water. The experiment showed the prospects of use of test plants, with their short-term exposure with the studied waters, as a reflective criterion for bioassay testing of pollution of the natural and treated sewage waters.