Recent trends in the low-flow variability in Romania

Abstract

In the context of climate changes, knowing the low-flow trends is very important for establishing appropriate measures for water resources management, in order to ensure their sustainability. This paper focuses on Romanian rivers and aims to identify the recent trends (during the period 1980-2013) in the low-flow variability. The analysis is based on discharges data series (daily and monthly) recorded at 54 gauging stations, with a quasi-natural flow regime. The significance of trends for annual, monthly and seasonal low-flow in the analyzed period has been established using the nonparametric Mann-Kendall test. The variability of the lowest annual values of the mean daily and monthly discharges showed positive trends at gauging stations located mainly in the Carpathian area, while negative trends were found in lowland regions (plains and tablelands). During the winter there were identified positive low-flow trends, while negative trends were found in summer and spring. Increases in the minimum monthly flow were particularly evident in February, March and December, and negative trends were identified especially in the summer (July, June and August) and the autumn months (September and October).

Keywords

• trend analysis
• low-flow
• natural regime
• Mann-Kendall test
• Romania