The Present Day Drainage Patterns of the Congo River System and their Neogene Evolution - Geology and Resource Potential of the Congo Basin - page 307

Fig. 15.2 A north-east facing terrain view of central Africa,
highlighting major features of the CB. The limit of the hydrographic
CB basin is shown ( heavy black line ). Notable rivers are— Ar Aruwimi,
Cu Cuanza, Ka Kasai, Kw Kwango, Lu Lukemie, Ma Malagarasi, Og
Ogou´, Ou Oubangui, Sa Sangha, Ts Tshuapa and Za Zambezi. Major

landforms labelled include—CC Congo Canyon, CH Cameroon
Highlands, KU Kundelungu Plateau, LU Luangwa Valley, LV Lake
Victoria, RW Rwenzori Mountains, UP Upemba trough, BP Bat´k´
Plateau (generated from: ETOPO1 (Amante and Eakins 2009 ) and
SRTM DEM V4 250 m (Reuter et al. 2007 ; Jarvis et al. 2011 )

Equatorial forest, not only the CR and its large tributaries
(e.g. Tshuapa) reveal insights into the development of these
central basin landscapes. Understanding the interplay
between tectonically induced topography and geomorphic
responses of fluvial networks can reveal where and when
important events occurred in fluvial evolution (Karner and
Driscoll 1999 ; Burbank and Anderson 2001 ).
Recent advances in remote sensing and availability of
digital geospatial datasets makes it feasible to study the
CRS in greater detail. In particular the digital surface
model (DSM) derived from the Shuttle Radar Topography
Mission (SRTM) (Kobrick 2006 ; Reuter et al. 2007 ) has
enabled the characterisation of the large scale geomorphol-
ogy of the CB (Figs. 15.2 and 15.3 ). Utilising this dataset in
conjunction with biological evidence (phylogeographic
data), we have analysed aspects of the Neogene evolution
of the CRS.

present day climate of the CB is dominantly tropical (hot
and humid) around the equatorial region. As the basin
straddles the north-south global climatic zone, the seasonal
movement of the Inter-Tropical Convergence Zone (ITCZ)
is the dominant controlling factor of rainfall in the basin
(Fig. 15.1b ). The basin thus experiences the northern hemi-
sphere wet season from April to September that maintains
the outflow of the southerly flowing tributaries (e.g. the
Oubangui River), with northerly flowing tributaries of the
southern catchment having high flows during the southern
wet season, from October to May. The equatorial basin
interior receives 1,600-2,400 mm of rainfall per a year
(Nicholson 2000 ; Runge 2007 ). A large portion of the north-
ern central and eastern CB north Equator has no dry season,
while the rest of the basin experiences two wet and dry
season; maximum rainfall occurs over November—Decem-
ber with the rainy season being 7-12 months long
(Nicholson 2000 ). This results in the CR having a double
discharge peak flow regime, although there is a limited water
level fluctuation in Malebo Pool (Runge 2007 ). The larger
peak occurs during November-January, and a smaller, sec-
ond peak occurs during April-June (Laraque et al. 2009 ).
The southern highlands (ranging from ca . 850 to a maximum
of ca . 1,400 m.a.s.l) are cooler and drier compared to the
central basin, with the highlands ( ca . 900 m to maximum of
ca . 3,000 m.a.s.l) in the east being cool and wet. Since the

15.2 The Congo Basin

15.2.1 Overview

The crescent shaped CR is the only large river in the world to
cross the Equator twice (Fig. 15.1 ), ensuring that some
sector of the river always experiences a wet season. The