Detecting long term and abrupt changes of river overflows in Slovakia

Abstract

Abstract In hydrometeorological processes, it is crucial to detect changes, since it can help prevent or at least prepare for extreme events like floods and drought. In this article, long term and abrupt changes in the development of average monthly overflow of main rivers of Slovakia are detected. Since the data follow non-normal distribution, results are obtained by means of nonparametric methods. Significant trends in the series were detected by applying the Mann–Kendall test, the Spearman’s rho test and the Cox–Stuart test. Change-points were detected by using the Pettitt’s test and the Buishand test. Since an abrupt change in the series could cause a misleading outcome of the trend analysis, first we applied change-point detection. If at least one significant change appeared in the series, trend analysis is applied on each segment bounded by the change-points. Otherwise a trend analysis is applied to the whole series.