Congo Basin Hydrology, Climate, and Biogeochemistry. Группа авторов

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Название Congo Basin Hydrology, Climate, and Biogeochemistry
Автор произведения Группа авторов
Жанр География
Серия
Издательство География
Год выпуска 0
isbn 9781119656999



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have been a rainfall recovery since the early 1990s, perhaps more marked on the Uele basin.

Streams Interannual average (m3/s) Pettitt Lee and Heghinian Segmentation of Hubert (m3/s) Standard Deviation Hydroclimatic trends Q divided by interannual average (%)
Ubangi at Mobaye (403,800 km2) 3,059 1970 1970 1948–1953: 2,925 1954–1967: 3,804 1968–1968: 5,524 1969–1980: 2,986 1981–1994: 2,208 232 513 0 414 288 Dry Wet Hyper Wet Dry Hyper Dry –4 +24 +81 –2 –28
Mbomu at Bangassou (115,000 km2) 782 1975 1951–1960: 731 1961–1969: 1,051 1970–1993: 706 129 187 185 Dry Hyper Wet Sèche –7 +34 –10
Mbomu at Zemio (29,300 km2) 171 1981 1981 1951–1961: 165 1962–1968: 249 1969–1980: 180 1981–1993: 128 22 49 37 35 Dry Hyper Wet Wet Hyper Dry –4 +46 +5 –25
Kotto at Kembe (77,500 km2) 360 1970 1948–1965: 401 1965–1969: 651 1970–1984: 345 1985–1993: 169 67 38 43 27 Wet Hyper Wet Dry Hyper Dry +11 +81 –4 –53
Kotto at Bria (61,500 km2) 244 1985 1948–1984: 268 1985–1993: 134 40 22 Wet Hyper Dry +10 –45
Schematic illustration of rainfall index of upstream basins of the Ubangi at Mobaye, from 1951 to 1995.

      Statistical tests show rainfall breaks only on the two basins of the Kotto; Hubert’s segmentation showed three homogeneous rainfall periods at different dates, only the recent period 1992–1993 is noted as wet. However, the 1970 rainfall break characteristic of the Central African continent (Laraque et al., 2001) is not confirmed. It can only be found in the analysis of the rainfall time series from the Kotto at Bria, for which the dry period is marked over a period of nearly 25 years (from 1967 to 1991) with a significant rainfall deterioration of –12%. The Kotto at Bria is the northernmost of the six basins studied.

      It is remarkable that only the Pettitt test detects a rainfall break in 1970 on the Mbomu basin at both Bangassou and Zemio. This absence of a break in the Mbomu sub‐basins is thought to be due to the impact of the forest cover that regulates rainfall systems, as also observed in the Tomi basin at Sibut in north‐central CAR (Nguimalet & Orange, 2020).

Schematic illustration of hydrologic index from 1948 to 1995 for the hydrological basins of the Ubangi at Mobaye, the Kotto at Kembe and Bria, and from 1951 to 1995 for the hydrological basins of the Mbomu at Bangassou and at Zemio, estimated hydrologic index of the hydrological system Uele + Bili at the confluence with the Mbomu.

      6.5.1. Comparative Interannual Evolution of the Ubangi at Mobaye with the Ubangi River at Bangui

Schematic illustration of comparative interannual evolution of the runoff (LE) of the Ubangi basin at Mobaye and Bangui.