Precipitation regime and anthropogenic activities are the main factors that influence the river flow along the time. To assure the flow regulation and the flood mitigation some structural measures must be implemented. Building dams represents one of these measures. Their impact on the stream flow and climate change must be studied for avoiding negative effects on the environment. Therefore, our study focuses on the variability of the Buzau River (in Romania) water flow and its seasonal variation. The analysis is done for the period before and after the moment when the Siriu Dam (Romania) was built. The stationarity and the trend existence are analysed and the results are compared by statistical methods.

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The purpose of this article is analysing the variability of Buzau river monthly mean discharges, maximum and minimum over time and the impact of Siriu Dam on these discharges. Keeping a stable, moderate variability on the water flow has a significant importance, as this assures normality of life and functionality of the dams. On another hand, the dams are in-built with a range of parameters, decided according to this variability of the discharges. The used data has been collected from Nehoiu and Basca Roziliei hydrometric stations and spans on 55 years, from 1st January 1955 to 31st December 2010. Mid-period, on 30th September 1984, Siriu Dam started operating and the results reveal that its impact on the variability has been moderate on a large time scale. Important changes appear on smaller time scale, as months. The results are supported by graphs drawn in Excel and methods embedded by software.

It is widely recognized that temperature’s changes have an important impact on the environment, in particular on sea waters, plants, animals and human life. This article presents the results of the study of the temperature’s evolution trend in Constanta, the main city and harbour on the Romanian Black Sea shore. Have been used the maximum and minimum daily temperatures, collected from the European Climate Assessment & Dataset project website. The data span over 58 years, from 1961 to 2018, period long enough to consider the results significant. Change points detection is done for annual and seasonal data, followed by testing the trend existence for maximum and minimum annual and seasonal series. The results proved the existence of increasing trend for all the temperature series, fact that confirms the global warming effect in this part of the world.