Among the participating countries of the ENI Program, cross-border cooperation Hungary - Slovakia - Romania - Ukraine 2014-2020 are among the main regions (among others) Košice Region in Slovakia and Transcarpathian Region in Ukraine. Through the activities prepared within the project, we point out the state of the environment with attention to the watercourses of the border area. Several watercourses are typical for the Zemplín region in the Košice region and the Transcarpathian region. Biomonitoring sites and planned activities are connected to the Laborec and Uh rivers.
Zemplín is a region in the east of Slovakia whose dominant and symbol is the river Laborec. In terms of hydrogeographical characteristics, the territory of the Zemplín region belongs to the Black Sea basin, a collecting area of the Tisza River with the Bodrog basin. From a hydrological point of view, it represents a complex river system, which consists of four main rivers - Latorica, Laborec, Uh and Ondava, meeting each other in a small area. The threat of floods in some places required the regulation of watercourses.
The Laborec River springs in the Laborecká vrchovina highlands above Čertižný, at an altitude of 710 m. n. m. and is 132.5 km long. The river bypasses the Vihorlat Mountains and flows into the East Slovakian lowlands, where it merges with the large left-hand tributary of the Uh, most of which is located in Transcarpathian Ukraine (1,613 km2, which is 61%).
Due to the activities planned in the project, the location of which is in the town of Strážske, we will focus on the tributaries of the Laborec, which flow through the city and are easily accessible for biomonitoring.
The Duša (Soul) stream springs southwest of Strážske town towards the former farm Pláne. It forms a right-hand tributary of the Laborec river with a length of 41.1 km. The investigated locality on the Duša stream is a place near its source, where a massive oak tree grows, which could be the subject of protection in the future.
The Strážsky brook, which flows through the cadastral territory of the town, springs on the slopes of Čubok, not far from Hudcovce village. It flows through the chemical company Chemko Strážske and then bypasses the city along the railway. In front of the village Voľa it flows into Laborec. On most of its course, the Strážsky brook is modified and performs the function of draining water from the surface runoff and from the municipal sewage treatment plant. Surface water from the Chemko complex is discharged in a regulated manner through the emergency accumulation tank and discharged through pipes into the Strážsky brook. If necessary, the water from the emergency accumulation tank is cleaned in a sewage treatment plant.
The Uzh river flows from the southern slopes of the Verkhovyna Watershed from a spring near the Uzhotskyi Pass. On the territory of Slovakia it flows into the Laborec river that is the right tributary of the Latorica. The length of the Uzh river is 128 km, the catchment area is 2750 km2. Main tributaries are: right – Ug, Ulychka, Ublia; left – Luta, Turia. The upper part of the basin is located on the slopes of the Watershed and Polonynskyi ridge, the lower part is on the Transcarpathian Lowland. The width of the river in the upper reaches is about 1 m, downstream it increases to 15-30 m, near Uzhhorod it reaches 135 m; depth is 0.1-0.6 m, the largest – 2.6 m. The valley is winding, the relief of the Uzh valley in the upper part of the basin is medium- and low-mountainous, in the middle part is hilly, in the lower part is plain. In the mountainous part of the basin is composed of Carpathian flysch, in places in the riverbed and along the coast there are almost continuous steep outcrops of flysch, which can stretch up to several hundred meters.
There are up to several dozen non-permanent islands on the river, located every 5-10 km.
In the lower reaches, the natural regime of the river is distorted by the regulatory influence of the dam built near the Kamianytsia village.
The following locations were selected to carry out the planned project activities:
Skalka. Uzh river on the eastern outskirts of the Kamianytsia village. The width of the riverbed is 50-60 m, the flow is calm, slow, the bottom is muddy. It’s a checkpoint for the “Kamianytsia-dam” site, which is located 2.5 km downstream. For comparison of the changes in water quality and biota composition.
Kamianytsia-dam. A small artificial water reservoir on the Uzh river in front of the dam, which serves to drain water into the Nevytske-Uzhhorod derivation canal. The width of the riverbed is 90-100 m, the flow is almost absent, bottom is muddy. The dam was built to fill the canal from which water is taken to supply water to the left bank of Uzhhorod town. Disruption of the flow of a mountain river changes the composition of the biota and prevents the migration of aquatic biota, in particular, fish upstream.
Kamianytsia-bridge is a checkpoint with the site "Kamianytsia-dam", located 0.5 km upstream. The width of the riverbed is 30-40 m, the flow is calm, not fast, the bottom is rocky. It will serve for comparison of the changes in water quality and biota composition below the water reservoir. Uzhhorod-Bozdosh is a place of confluence of communal sewage from sewage treatment plants into the Uzh river in the western part of Uzhhorod town. The river acquires the character of a plain river. The width of the riverbed is 50-60 m, the flow is calm, slow, the bottom is muddy. Sewage needs to be cleaned in municipal treatment plants. However, the quality of water discharged into the river can be unsatisfactory, especially during rainy periods when urban sewers are congested.
Uzh river near the Ukrainian-Slovak border in the north-eastern part of Storozhnytsia village. The width of the riverbed is 40-50 m, the flow is not fast, the bottom is rocky and muddy. It’s a checkpoint for comparison with the site "Uzhhorod-Bozdosh", which is upstream of about 3.5 km. It will be interesting to investigate the ecological condition of the Uzh river on the Ukrainian-Slovak cross-border, in particular, for comparison of changes in the composition of biota and water quality, as the influence of urban sewage is no longer visually noticeable.
