Cambongo Dam / Sassa

The same applies to other rivers and their most important tributaries, as is the case with the two between which the Cambongo-Negunza basin is located, the Cuvo-Queve to the north and the Cubal-Quicombo to the south. the enormous complexity of the river routes, whether in the coastal sector, closer to the Ocean, where elements of the Cambongo-Negunza basin cross a strip of about 28km wide of Mesozoic and later materials from the Sedimentary Rim, or in the interior, much more vast, of precambrian, metamorphic and eruptive rocks of the Ancient Massif.
From its sources in massifs of the Marginal Mountain (altitudes of more than 2000m), the river descends through the flattening staircase to the sea, arriving through a section of valley embedded in sedimentary rocks.
In the various sectors, it also reveals the majority of its tributaries, traces imposed by tectonic structures, fractures and faults, generally in orthogonal networks.
Long, almost straight sections of the Cambongo-Negunza River are other testimonies of these influences (Quaternary Cretaceous).
The coastal flattening surface, including the raised beaches (altitudes of around 40 to 100m), flattening the land of the Sedimentary Rim and the Ancient Massif, rises towards the east, gradually, until a well-marked topographic limit, that of the base (altitudes of around 280 to 300m) from the western foothills of a NNE-SSW quartzite ridge with a dissymmetrical transversal profile – the Engelo mountain range, with altitudes between 1,400 and 1,700m –, which also has faults, highlighted by thermal water springs.
From that coastal surface, in the band of crystalline rocks, some residual reliefs emerge with characteristics of inselberge or island mountains, which raise several problems, such as the extension, towards the west, of quartzite formations and their dismantling, the behavior of the same materials in the processes complexes of the genesis and evolution of the extensive regional line of N-S scarps against which the flattened surfaces of the coastal edge end.
In the limestones close to the coast, the Cambongo-Negunza river has an underground route, through galleries and large caves, emerging shortly before the small terminal plain.
Not far from its valley, sinkholes of various sizes and carved surfaces can be observed.
The climatic conditions reveal semi-aridity: annual precipitation is less than 700mm, evaporation is high, vegetation cover is that of a mosaic of savannas, steppes and xerophytic balcedos, with scattered trees or without them.