The Prut River under Climate Change and Hydropower Impact

Abstract

Climate change and intensive hydropower development pose serious challenges to the sustainable water supply of natural and social systems. This study’s purpose is to statistically estimate the complex influence of these factors on the Prut River flow. Its methodical approach is based on a comparative analysis of the flow in 1961–1990 and 1991–2018, reflecting the regional climate before and after an intensive global warming onset, and in 1950–1975 and 1980–2017, before and after the construction of the Stanca-Costesti hydropower plant (HPP) on the Prut’s riverbed. The compared statistics include annual, seasonal and monthly averages and trends of climatic and hydrological parameters for each period. Since the 1990s a statistically significant increase has been demonstrated in the basin-wide annual mean, maximum and minimum temperatures, of 1.04, 1.11 and 1.21 °C, respectively. Negative trends of annual precipitation were negligibly small and statistically insignificant in both periods (−2.1 mm and −0.6 mm/year, respectively), with annual totals differing by 1.4 mm. The seasonal transformation and changes of the Prut river flow, showing a small annual increase in the period 1961–1990 and a 1.8% decrease over next decades, are in good agreement with variability patterns of temperature (positive tendencies) and precipitation (negative tendencies). The operation of mean-capacity HPP has no significant impact on the total water discharge downstream, but modifies the seasonal distribution of the river’s streamflow.

Assessing the impact of hydropower constructions on functioning of Dniester and Prut rivers ecosystems within the Hydroeconex project

“…On the Prut river, the comparative analysis of the flow on the Prut's riverbed in 1961-1990 and 1991-2018 -before and after global warming, and in 1950-1975 and 1980-2017, before and after the construction of the Costesti -Stanca hydropower plant (HPP) demonstrated no significant impact on the total water discharge downstream, but only the seasonal distribution of the river's streamflow [1]. Hydropower constructions on Dniester river have caused dramatic deteriorations at ecosystem level, Such changes are for example fragmentation of river continuity, deterioration of the self-purification capacity of the river [2][3], loss of ecosystem services [4], big fluctuation of the water flows and levels [5], alteration of temperature and oxygen regimes [6], bedrock structural changes and annual stock of suspended particles [7], the rate of mineralization and dynamics of the main ions [8], penetration and distribution of alien and parasitic species [9][10].…”

“…The proposed methodology developed by International Association of River Keepers "Eco-Tiras" can be used at different scales -the catchment (basin) scale allow quantifying processes related to water cycle and for the implementation of monitoring plans, at the water body scale -specific functions of ecosystems, supporting certain services are analyzed. The methodological guide developed provide a theoretical description of the approach complemented by examples of evaluating the impact of hydropower and climate change in the context of Dniester River environment [1]. These estimations were based on the results of physical and biochemical parameters, identified in the framework of HydroEcoNex project.…”