Wouri estuary

The Wouri estuary, or Cameroon estuary is a large tidal estuary in Cameroon where several rivers come together, emptying into the Bight of Biafra. Douala, the largest city in Cameroon, is at the mouth of the Wouri River where it enters the estuary. The estuary contains extensive mangrove forests, which are being damaged by pollution and population pressures.

The estuary lies to the east of Mount Cameroon and empties into the Bight of Biafra. It is fed by the Mungo, Wouri and Dibamba rivers. The estuary lies in the Douala Basin, a low-lying depression about 30 metres (98 ft) on average about sea level, with many creeks, sand bars and lagoons. The Wouri alluvial aquifer, a multi-layer system with alternating sequences of marine sands and estuarine mud and silt lies below the estuary and surrounding region and is an important source of well water. The upper aquifer in this system is an unconfined sandy horizon that is hydraulically connected to the brackish waters of the estuary and to the coastal wetlands.

The spring tides at the mouth of the estuary are 2.8 metres (9.2 ft). Rainfall is from 4,000 millimetres (160 in) to 5,000 millimetres (200 in) annually. Salinity is very low, particularly during the rainy season. Surface salinity of 0.4% is common around Douala throughout the year. The Mungo river splits into numerous small channels that empty into the estuary complex. The tidal bore in the bay travels as far as 40 kilometres (25 mi) up the Mungo. In this section of the river, large flats and sand banks are exposed at low tide. The Wouri is affected by the tides for 45 kilometres (28 mi) above Douala, with blocks of tidal forest along its shores throughout this stretch.

To the west of the estuary, the slopes of Mount Cameroon are covered with banana plantations. To the northeast, the mangroves are backed by freshwater tidal swamps 5 kilometres (3.1 mi) wide. One block of freshwater swamp between Muyuka and Dibombari covers 7,500 hectares (19,000 acres). There are still some patches of permanent swamp forest on the Dibamba river, but many others have been cleared and drained for oil palm plantation. The river's fauna are not well protected; particularly endangered is the African Manatee (Trichechus senegalensis).

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