Ogooué River

The Ogooué (or Ogowe), also known as the Nazareth River, some 1,200 km (750 mi) long, is the principal river of Gabon in west-central Africa and the fourth largest river in Africa by volume of discharge, trailing only the Congo, Kasai and Niger. Its watershed drains nearly the entire country of Gabon, with some tributaries reaching into the Republic of the Congo, Cameroon, and Equatorial Guinea.^[5]

Ogooué
The Ogooué watershed
Location
Country	Gabon, Republic of the Congo
Physical characteristics
Source
• location	Kengue, Republic of the Congo
• elevation	840 m (2,760 ft)
Mouth	Atlantic Ocean
• location	Port Gentil, Gabon
• coordinates	1.0272°S 8.8848°E / -1.0272; 8.8848
• elevation	0 m (0 ft)
Length	1,200 km (750 mi)[1]
Basin size	225,217.5 km2 (86,957.0 sq mi)[2]
Discharge
• location	Ogooué Delta
• average	(Period: 1971–2000)5,148.05 m3/s (181,802 cu ft/s)[2]
• minimum	1,950 m3/s (69,000 cu ft/s)[3]
• maximum	7,340 m3/s (259,000 cu ft/s) (13,500 m3/s (480,000 cu ft/s)[3]
Discharge
• location	Lambaréné
• average	(Period: 1971–2000)4,485.4 m3/s (158,400 cu ft/s)[2]
• minimum	1,610 m3/s (57,000 cu ft/s)[4]
• maximum	9,440 m3/s (333,000 cu ft/s)[4]
Discharge
• location	Ndjolé
• average	(Period: 1971–2000)3,194.8 m3/s (112,820 cu ft/s)[2]
• minimum	1,200 m3/s (42,000 cu ft/s)[4]
• maximum	6,600 m3/s (230,000 cu ft/s)[4]
Discharge
• location	Lastoursville
• average	(Period: 1971–2000)1,305 m3/s (46,100 cu ft/s)[2]
• minimum	650 m3/s (23,000 cu ft/s)[4]
• maximum	2,800 m3/s (99,000 cu ft/s)[4]
Discharge
• location	Franceville
• average	(Period: 1953–1981)253 m3/s (8,900 cu ft/s)[4]
• minimum	122 m3/s (4,300 cu ft/s)[4]
• maximum	520 m3/s (18,000 cu ft/s)[4]
Basin features
Progression	Atlantic Ocean
River system	Ogooué River
Tributaries
• left	Letili, Lebombi, Lekedi, Leyou, Lolo, Offoue, Ngounié
• right	Mpassa, Léconi, Sebe, Lassio, Dilo, Ivindo, Nké, Okano, Abanga

Geography

Course

The source of the Ogooué River was discovered in 1894 by Mary Kingsley, an English explorer who travelled up the banks by steamboat and canoe.^{[citation needed]} The river rises in the northwest of the Bateke Plateaux near Kengue, Republic of Congo.^[5] It runs northwest, and enters Gabon near Boumango. Poubara Falls are near Maulongo. From Lastoursville up to Ndjole, the Ogooué is non-navigable due to rapids. From the latter city, it runs west, and enters the Gulf of Guinea near Ozouri, south of Port Gentil. The Ogowe Delta is quite large, about 100 km long and 100 km wide.

Delta

A 30,000 ha site in the delta of the Ogooué River, including much of Mandji Island, has been designated an Important Bird Area (IBA) by BirdLife International because it supports significant populations of many bird species.^[6]

Basin

The Ogooué Basin is 223,000 km² (86,000 sq mi), of which 189,500 km² (73,200 sq mi) or 85 percent lies within Gabon.^[7]

Ogooué River Basin area by country:^[7]

Country	Area		%
	km2	mi2
Cameroon	5,200	2,000	2.34
Equatorial Guinea	2,000	770	0.89
Gabon	189,500	73,200	84.98
Republic of the Congo	26,300	10,200	11.79
Ogooué basin total	223,000	86,000	100.00

Distance from river mouth:^[8]

Station	River kilometer (rkm)	Altitude (m)
Lambaréné	183	12
Ngounié*	196	13
Abanga*	242	20
Ndjolé	280	25
Okano*	314	40
N'golo*	359	72
Offoué*	424	142
Booué	451	161
Ivindo *	481	180
Dilo*	503	182
Lolo*	512	186
Lassio*	535	200
Lastoursville	616	226
Sébé*	685	242
Leyou*	696	243
Léconi*	714	248
Lékabi*	725	249
Lébombi*	774	270
Mpassa*	802	280
Baniaka*	871	426

*River in confluence

Gauging stations along the Ogooué River:^[2]

Station	River kilometer (rkm)	Elevation (m)	Drainage basin (km2)	Average discharge (m3/s) *
Ogooué Delta	0	0	225,217.5	5,148.05
Lambaréné	183	12	205,228.5	4,485.4
Ndjolé	280	25	160,106.9	3,191.5
Booué	451	161	130,931.4	2,746.9
Lastoursville	616	226	45,767.1	1,305
Franceville	802	280	8,570.2	233.4
* Period: 1971–2000

Discharge

Ogooué River multiannual average discharge at gauging stations. Period from 1971 to 2000.^[2]

Period	Average discharge (m3/s)
Ogooué Delta	5,148
Lambaréné	4,485
Ndjolé	3,192
Booué	2,747
Lastoursville	1,305
Franceville	233

Month	Average monthly flow (m³/s) at delta[9][10]
	Dry years	Normal	Wet years
DEC–FEB	3,744.5	4,285	4,826.5
MAR–MAY	4,883	6,336	7,789
JUN–AUG	1,625.3	1,997	2,188.7
SEP–NOV	6,935	8,041	9,147
Average	4,296.7	5,142.25	5,987.8

Ogooué River discharge (m³/s) at Lambaréné gauging station (period from 1929–2017):

Water year	Min	Mean	Max		Water year	Min	Mean	Max
1929/30	1,250	3,569	5,030		1969/70	2,193	5,386	9,533
1930/31	1,390	4,238	6,980		1970/71	1,649	4,214	8,220
1931/32	1,590	4,259	7,580		1971/72	1,739	3,826	6,871
1932/33	1,380	4,126	6,630		1972/73	1,720	4,199	7,100
1933/34	2,390	5,449	10,800		1973/74	1,570	4,252	8,260
1934/35	1,850	4,888	6,690		1974/75	1,670	4,642	8,940
1935/36	1,690	4,612	7,850		1975/76–1979/80: No data
1936/37	1,930	4,835	8,210		1980/81	1,550	4,290	7,820
1937/38	1,780	4,791	7,180		1981/82	1,740	4,100	6,900
1938/39	2,170	5,905	11,300		1982/83	1,140	3,520	8,550
1939/40	1,950	4,762	6,930		1983/84	902	4,230	6,530
1940/41	1,740	3,936	6,460		1984/85	2,200	4,670	7,610
1941/42	1,430	3,707	5,720		1985/86	1,610	4,060	6,800
1942/43	1,370	4,292	6,880		1986/87	1,580	3,690	7,160
1943/44	2,330	5,874	9,450		1987/88	1,970	4,940	8,880
1944/45	2,140	5,273	7,980		1988/89	1,780	4,700	9,810
1945/46	1,690	4,600	8,490		1989/90	2,060	5,030	10,800
1946/47	2,340	5,861	9,310		1990/91–1994/95: No data
1947/48	2,120	5,545	9,780		1995/96	1,300	4,450	8,310
1948/49	2,640	5,912	10,600		1996/97	1,320	4,216	6,510
1949/50	1,950	5,300	9,600		1997/98	1,110	3,661	6,300
1950/51	1,640	5,280	9,470		1998/99	1,290	3,595	7,940
1951/52	2,350	5,660	9,080		1999/00	1,280	4,798	8,350
1952/53	2,050	4,770	7,200		2000/01	1,290	3,971	7,770
1953/54	1,300	3,597	5,690		2001/02	1,200	4,629	8,260
1954/55	1,900	4,383	7,530		2002/03	1,570	4,722	8,030
1955/56	1,400	4,278	8,100		2003/04	1,900	3,703	5,590
1956/57	1,660	4,252	7,420		2004/05	1,350	3,717	6,020
1957/58	979	3,093	5,110		2005/06	1,500	4,695	8,640
1958/59	1,580	4,179	8,250		2006/07	1,740	4,883	8,720
1959/60	2,160	5,073	9,350		2007/08	1,640	5,112	11,170
1960/61	2,190	5,970	11,000		2008/09	2,520	5,850	9,180
1961/62	1,910	5,227	8,210		2009/10	1,480	3,985	7,260
1962/63	2,170	4,799	6,830		2010/11	1,510	3,690	5,790
1963/64	1,810	4,647	8,500		2011/12	2,190	4,038	9,420
1964/65	2,100	5,074	7,510		2012/13	960	3,931	7,270
1965/66	2,150	5,500	9,470		2013/14	1,420	4,588	8,370
1966/67	1,600	4,482	10,100		2014/15	1,090	3,890	6,930
1967/68	1,823	4,451	7,557		2015/16	980	3,794	8,090
1968/69	2,093	5,020	7,607		2016/17	1,510	3,846	6,490
Source:[11][12][13][14][15][1]

Tributaries

Ogooué River

Fan women and child, banks of the Ogoway. From The earth and its inhabitants, Africa (published 1890-1893 [v.1, 1892] )

The Ogowe River receives water of numerous tributaries including:

• Abanga, which rises in the Cristal Mountains, near Medouneu
• Baniaka
• Dilo
• Iyinda, the most important tributary
• Letili
• Lassio
• Lebombi
• Lekabi
• Lekedi
• Lekoni, which flows across Akieni and Leconi
• Letili
• Leyou
• Lolo
• Mbine
• Ngolo
• Ngounie
• Nke
• Offoue
• Okano, whose main tributary is the Lara River
• Mpassa, which flows across Franceville
• Sebe, which flows past Okondja
• Wagny

The main river and tributaries are (sorted in order from the mouth heading upstream):

Left tributary	Right tributary	Length (km)	Basin size (km²)	Average discharge (m3/s)
Ogooué		1,200	225,217.5	5,148.05
Ogooué Delta
Kolo			496.8	13.33
Nkomi		170	5,816.6	194.01
	Akiri	20	248.1	8.91
Lower Ogooué
Olimbé			1,352.9	43.41
	Lac Ompindi		325.8	12.28
	Alooué		552	21.45
	Mangoué		992.5	41.97
	Oronga		1,248.6	44.86
Nkovié			521.8	17.6
Agouma			1,983.3	70.11
Lac Zilé			322.4	9.15
Ngounié		680	32,636.7	1,002.4
	Biné		752.6	21.03
M'boumi		109	1,606.4	35.38
	Abanga	226	8,204.4	190.31
	Missanga	32	476.5	9.88
Middle Ogooué
Lébé			376.5	7.01
	Okano	280	11,257.2	192.91
Machoka			559.8	9.78
	Ngolo		1,023.1	14.62
Mingoué		113	1,178.9	21.17
Leledi			2,038.5	33.23
Lope			378.9	5.07
Offoué		235	7,673.9	166.63
	Nké		1,883.8	26.04
	Ivindo	686	63,201.4	1,112.4
	Dilo	190	3,166	54.3
Lolo		240	11,212.7	278.17
	Lassio	160	5,413.3	114.44
Upper Ogooué
Lehibou			410.4	9.81
	Momba		643.1	15.34
	Ouolo		640.7	16.08
	Sébé	292	10,069.7	236.97
Leyou		134	1,771	69.82
	Lékoni	252	7,592.8	344.36
	Lékabi		1,542.3	46.67
Lekedi		48	1,244.5	34.63
Lébombi		91	3,769.4	106.89
	Mpassa	163	6,339.6	312
Baniaka			749.9	21.38
Letili			1,682.1	43.46
	Loua		361.6	11.03
Djoulou			509.3	12.71
Loungou			481.4	11.42
Léfou			382.7	8.88
	Djouéli		377.8	12.19
Léouké			1,006.9	23.32
	Nsiele		364.7	14.06
Source:[2][8]

Ecology

It mostly consists of undisturbed rainforest with some savanna grassland where the mid-year dry season is longest. It is home to a high biodiversity. All three species of African crocodile, for instance, occur in the river: the Nile crocodile, the dwarf crocodile, and the slender-snouted crocodile. It is also the type locality for the catfish Synodontis acanthoperca.^[16]

Economy

The Ogooué is navigable from Ndjole to the sea. It is used to bring wood to the Port Gentil Harbour.

The Ogowe Basin includes several major conservation reserves, including Lope National Park.

The catchment area has an average population density of 4 people per km². Towns along the river include Ayem, Adané, Loanda, Lambaréné, Ndjole, Booué, Kankan, Maulongo, Mboungou-Mbadouma, Ndoro, Lastoursville, Moanda, and Franceville near the Congo border.

Towns in Congo include Zanaga.

The first European explorer to trace the river to its source was Pierre Savorgnan de Brazza, who traveled in the area in the 1870s.^[5]