E3S Web Conf.
Volume 17, 20179th Conference on Interdisciplinary Problems in Environmental Protection and Engineering EKO-DOK 2017
|Number of page(s)||8|
|Published online||24 May 2017|
Stationarity of maximum low-flow periods duration in the right-bank area of the Upper Vistula catchment – Mann-Kendall versus Spearman test
Cracow University of Technology, Institute of Water Engineering and Water Management, ul. Warszawska 24, 31-155 Kraków, Poland
* Corresponding author: Katarzyna.Baran-Gurgul@iigw.pk.edu.pl
This study compares two methods of analyzing the stationarity of time series – the Spearman test and the Mann-Kendall test, with the formula adjusted by Hamed and Rao. Daily discharge series collected at 78 gauging stations were compared for a period of 30 years. The study area consisted of the right-bank area of the Upper Vistula River catchment. Low-flow periods were identified via the pit under threshold method (PUT). Threshold discharge values in the study were represented by Q70%, Q80%, and Q90%. Maximum annual durations TmaxR,i, (i = 1, 2, ..., 30 low-flow periods) were identified for assumed threshold discharge values based on low-flow period duration series for selected gauging stations. Research on the stationarity of TmaxR series for most of the studied water gauging stations has shown an absence of a basis for the rejection of the hypothesis of a lack of a trend for peak low-flow period duration relative to time, independently of assumed threshold discharge. Most of the detected trends are decreasing trends. The lower the threshold discharge value, the larger the number of TmaxR series being non-stationary. The Spearman test detected more non-stationary series than the Mann-Kendall test for the studied gauging stations, independently of assumed threshold discharge values.
© The Authors, published by EDP Sciences, 2017
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