Stationarity analysis of runoff time series in Arctic basins

Abstract

In the world, climate change happened regionally and globally, rapidly and gradually. Also it has great impacts on atmosphere, hydrosphere and biosphere. From the inter-annual and long-term variation in hydrology, it reflects generally the influence of climate changes. The river runoff plays an important role in the hydrological cycle. Therefore, the study of longterm runoff time series is of great significance. In this thesis, runoff time series are analyzed. There are many characteristics in runoff time series, such as homogeneity, stationarity, trend, periodicity and persistence. The main purpose of this thesis is to analyze the stationarity of river runoff time series in basins. Four river basins around the Arctic ocean are collected for this thesis: the Mackenzie River, the Ob River, the Yenisei River and the Lena River. To study inter-annual and long-term changes of river runoff, the period from 1930 to 2000 is selected. In order to analyze clearly, the time series are investigated on four aspects: trend, amplification, break points and seasonal stationarity. In relation to the overall process of the analysis, we primarily analyzed the mean and maximal river runoff. Through analysis, it can be drawn a conclusion. The runoff of these four rivers is generally stable over the whole studied period. Moreover, for a given month, the change of river runoff is basically stable. There are many factors affecting the river runoff, such as precipitation, snow melting and human intervention, which have impacts on the results of this thesis. In order to study the stability of the time series of the river runoff, analysis of the influence factors is required.