The Ngounié River, with a basin area of about 33,100 square kilometres (12,800 sq mi), is the second largest tributary of the Ogooué River.
It rises in the Chaillu Mountains.
For 60 kilometres (37 mi), the river has a south and then west flow, and forms a border with Congo.
At the Polo River confluence, it changes direction, heading northwest, before passing through three waterfalls.
It then establishes a floodplain within a 220 kilometres (140 mi) valley between the Moukande Mountains and the Massif due Chaillu.
After meandering for more than 400 kilometres (250 mi) on the valley floor, it joins the Ogooué prior to Lambaréné.
Development in the floodplain occurs mostly in the areas between Lebamba and Mouila, and again from the Fougamou area to the Ogooué at Lambarene.
Conservatively, the estimated valley flood land area is approximately 150,000 hectares (370,000 acres).
The left bank is characterized by sandy clay soils.

The Ngounié River Valley is formed between the forest-covered Du Chaillu Hills and the Ikoundou Mountains, and has grassy vegetation.
The region within this valley is also known as Ngounié.

Its tributaries include Louetsié, which passes through Lebamba and Mbigou; Ikoy, whose main tributary are the Ikobe River and the Oumba River; Dollé, which passes through Ndendé; as well as the Ogoulou, Ngongo and Ovigui rivers.
Imperatrice Falls (also known as Samba Falls, or Empress Eugénie Falls), are approximately 10 metres (33 ft) in height.
They are located in a river bend in the Ngounié Province, 5 kilometres (3.1 mi) from Fougamou.
Here, the Ngounié measures approximately 150 metres (490 ft) in width and contains small islands.
This is within the Peneplain Chaillu, which features granite gneiss and hills as well as rocky bays.
The Ngounié River, with a basin area of about 33,100 square kilometres (12,800 sq mi), is the second largest tributary of the Ogooué River. It rises in the Chaillu Mountains. For 60 kilometres (37 mi), the river has a south and then west flow, and forms a border with Congo. At the Polo River confluence, it changes direction, heading northwest, before passing through three waterfalls. It then establishes a floodplain within a 220 kilometres (140 mi) valley between the Moukande Mountains and the Massif due Chaillu. After meandering for more than 400 kilometres (250 mi) on the valley floor, it joins the Ogooué prior to Lambaréné. Development in the floodplain occurs mostly in the areas between Lebamba and Mouila, and again from the Fougamou area to the Ogooué at Lambarene. Conservatively, the estimated valley flood land area is approximately 150,000 hectares (370,000 acres). The left bank is characterized by sandy clay soils.
The Ngounié River Valley is formed between the forest-covered Du Chaillu Hills and the Ikoundou Mountains, and has grassy vegetation. The region within this valley is also known as Ngounié.
Its tributaries include Louetsié, which passes through Lebamba and Mbigou; Ikoy, whose main tributary are the Ikobe River and the Oumba River; Dollé, which passes through Ndendé; as well as the Ogoulou, Ngongo and Ovigui rivers. Imperatrice Falls (also known as Samba Falls, or Empress Eugénie Falls), are approximately 10 metres (33 ft) in height. They are located in a river bend in the Ngounié Province, 5 kilometres (3.1 mi) from Fougamou. Here, the Ngounié measures approximately 150 metres (490 ft) in width and contains small islands. This is within the Peneplain Chaillu, which features granite gneiss and hills as well as rocky bays.
Ngounié River