Читать книгу Congo Basin Hydrology, Climate, and Biogeochemistry - Группа авторов - Страница 90

The break tests on the rainfall P and hydrometric Q series were performed with the Khronostat 1.01 software (IRD, 1998) to characterize the stability periods of these two long time sequences, establishing if possible homogeneous flow subsequences, or hydroclimatic periods. Pettitt, Lee and Heghinian rank tests, and Hubert’s segmentation were applied (Hubert & Carbonnel, 1987). The combination of these various methods is justified by the fact that the first two methods (Pettitt’s and Lee and Heghinian’s) are tests of homogeneity whose null hypothesis indicates that a time series is homogeneous between two given dates and according to two laws of different distributions. On the one hand, these tests are known for their robustness but do not allow the detection of more than one break in a time series. On the other hand, Hubert’s test gives the year of the different breaks observed in the series with the means and standard deviations of the different segments. This method has been the subject of numerous publications in different regions of Africa (Ardoin et al., 2003; Bodian et al., 2011; Servat et al., 1999) and in Central Africa (Nguimamet & Orange, 2020). These tests have not been applied to the Uele time series, which are series inferred from the surrounding basins.