Changes in the discharge regimes

During the period of observations, a wide variety of influences may cause the discharge time series either inconsistent or non-homogeneous. Inconsistency is characterised by a change in the amount of systematic error associated with the recording of the data, while non-homogeneity results from natural or man-made changes to the environment ( Shaw, 1991 ). This chapter aims to examine the temporal changes in the discharge regimes of the Meuse river and the selected tributaries based on their available longest records. Both mean flows ( section 3.2 ) and extremes including floods ( sections 3.3 to 3.4 ) and low flows ( section 3.5 ) in the rivers are examined, with more attention paid to the floods. In addition, maximum moving-average streamflows and timing of occurrence of flood peaks are also included ( section 3.3 ). The identification of abrupt changes or shifts (regarding the mean values) in the observation series is emphasised in the statistical analyses, since it is very useful when searching for possible reasons behind the changing hydrological behaviour of the river system. Comparatively, the commonly performed detection of linear trends receives less attention.