Читать книгу Congo Basin Hydrology, Climate, and Biogeochemistry - Группа авторов - Страница 94

The interannual evolution of the water flow from the Ubangi at Mobaye is similar to that of the Ubangi at Bangui (Figure 6.6), with a very marked hydrological break in 1971 and a semblance of resumption of flows from 2013 onwards (Nguimalet & Orange, 2019). The flow deficit on the Ubangi at Bangui is slightly more marked than at Mobaye, with an average value of the hydrological index around –1 for Bangui and –0.8 for Mobaye. Thus the hydrological deficit of the Ubangi at Bangui is –27% between the wet period 1960–1970 (4,877 m³/s) and the first dry period of 1971–1982 (3,577 m³/s), while the deficit is slightly lower at Mobaye, –24% between the wet period of 1957–1968 (3919 m³/s) and the dry period of 1969–1980 (2,986 m³/s). The beginning of the resumption of flows recorded in 2013 comes, as on the Ubangi River at Bangui, a few years after the rainfall recovery of 2008 (Figure 6.3), but a year ahead of schedule (Nguimalet & Orange, 2019). This one‐year delay indicates a difference in the upstream–downstream hydrological behavior of the Ubangi: the hydrological support of flows is better ensured in the upstream basin.

Figure 6.6 Comparative interannual evolution of the runoff (LE) of the Ubangi basin at Mobaye and Bangui (from 1938 to 2015). The periods 1950, 1958–1969, 1971, and 1975–2014 have been reconstructed from the Ubangi discharges at Bangui.