Change Point Detection and Trend Assessment of Suspended Sediment Transport in the Upper Danube River

The Danube river basin is the world`s most international river basin, as it extends into the territories of 19 countries and comprises a total area of 801,463 km². Strong alterations of the Danube River have led to significant changes in the sediment load. This imbalance contributes to flood risks, reduces navigation possibilities and hydropower production and leads to the loss of biodiversity within the Danube basin. Analysis of erosion processes and sediment delivery patterns in basins is a key factor for many applications such as land-use management, hazard assessment and infrastructure design. Considering the importance of sediment transport to river management, an assessment to detect changes and trends has been performed on monthly and annual historical suspended sediment concentration data from the upper Danube located in Germany, for the period of 1986 to 2016.

The non-parametric methods under statistical approach are used to detect if data of a given set either follows a distribution or has a trend of a fixed level of significance. In a given time series, there may be changes in the form of an increasing or decreasing trend. Homogeneity tests are capable of determining if a series may be considered as homogeneous over time, or if there is a time, at which a change occurs. Homogeneity test involves a large number of different tests. In this paper, we employed Pettitt’s test, von Neumann ratio test, Buishand’s range test and standard normal homogeneity test to identify the turning point or the monotonic change of the suspended sediment concentration pattern in the upper Danube. Furthermore, the non-parametric tests including Mann-Kendall and Sen’s slope tests were applied for trend analysis. The monthly and annual maximum, mean and minimum of suspended sediment concentration for the period of 30 years in the analysis were used for these tests. Change points with statistically significant decreasing trends of annual sediment load were detected by the Mann-Kendall test and Sen’s slope test for mean suspended sediment concentrations at Bad Held and Kachlet stations, and for min suspended sediment concentrations at Vilshofen and Ingolstadt stations.