The research conducted by experts of the “Eco-Tiras” International Environmental Association of River Keepers highlighted a significant increasing trend in stream bank erosion in the Bălțata basin. Very few sectors, accounting for just 0.3% of the main streams length, represented a decrease in bank erosion in the analyzed period. The results also show that croplands might have the strongest impact on stream bank erosion over time, while relatively large water-covered areas are much more important for erosion increasing than any other land use type. Innovative technologies were applied in the assessment of soil erosion and sediments in Moldova to reach such conclusions.
In a news conference hosted by IPN, “Eco-Tiras” Association executive director Ilya Trombitski, doctor of biological sciences, said that two hydrological models - SWAT (Soil and Water Assessment Tool) and WEPP (Water Erosion Prediction Project) - were used in the project. The SWAT modeling of the Bălțata potential annual runoff in the current climate (1981-2020) can reach 0.048 cubic kilometers. Although, given an undoubted bias in these estimates due to an anthropogenic load on the watershed, these results should be considered with some caution. They provided a basis for assessing the expected climate change impacts.
SWAT modeling showed that depending on a time horizon and radiative load, the Bălțata flow can change from increase by 7-8% in the first half of 21th century to a decrease from about 8% to more 25% in 2071-2100. On average, an increase in runoff can reach about 2% in 2021-2050, and a decrease - up to 17% in 2071-2100. Moreover, SWAT has simulated the water accumulation in three reservoirs in its riverbed. This annual water accumulation can amount to 65% of the watershed total runoff.
The WEPP modeling stimulated soil loss and sediment yield in the Bălțata basin, caused by sheet and rill erosions occurring in channels due to hydraulic shear. In most of the watershed, the annual sediments per hectare are less than 1/4 t, followed by areas with sediments from 1/4 to 1/2 t, and only in the riverbed’ lower they reach 1-2 tons. The total value of soil loss, estimated through onsite approach amounted ~21542 ton/yr). Moreover, this method has provided a high degree of soil loss detail across the basin.
There were used remote sensing techniques to identify the erosion-prone areas, using the Earth's surface historical satellite monitoring. Analysis of the research outputs has shown that just 8.37% of the Bălțata basin’s area is affected by erosion or exposed to it. The dominant erosion forms are landslides, which cover two times larger areas than gullies, occupying 40% of the erosion-prone area where moderate exposure is observed on 32%, low exposure - on 23%, and high exposure - on slightly above 4% of this area. The analysis included also the distribution of erosion depending on slopes, soils and land use.
Olga Crivova, expert of the project, said that said that the RUSLE – Revised Universal Soil Loss Equation – was another applied method. The resulting RUSLE model for the project area allows to estimate stream banks susceptibility to erosion. The right bank of the Baltata River has the largest share of steep slopes in the entire river basin. However, due to the fact that the same area accounts for most of the extended areas with forests, as well as half of the orchards and vineyards of the basin, the annual loss of soil under these plantations is quite small. At the same time, where the protective effect of the vegetation cover is absent, we observed the most prone to erosion zone - to the south of the village of Baltata.
The collector for capturing floating waste was another element of the project research. As a tool to prevent river pollution, it was installed on the Răut River. The installation allows the collection of plastic waste and other floating physical pollutants from the surface of a portion of the river. The catchment collector was designed, built and installed by the NGO “Renașterea Rurală”, the subcontractor of the project (Chisinau). The catchment collector collects approximately one ton of waste per month, preventing it from reaching the Dniester River and then the Black Sea. All collected waste is sorted and the plastic is transported to the recycling plant.
The activities and research were carried out in the framework of the project “Protecting streams for a clean Black Sea by reducing sediment and litter pollution with joint innovative monitoring and control tools and nature-based practices BSB963)” which was implemented during July 2020 – July 2023. The project is financed as part of the EU INTERREG IV “Joint Operational Program Black Sea Basin 2014-2020”. The total budget for the five countries involved in the project is over €907,000, with over €834,000 being the European Union’s contribution.
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