1. GEOGRAPHY AND CLIMATE
(Welcomme, 1979a)
The Democratic Republic of Congo (with a surface area of 341 500 km2) can be divided into four topographical regions:
There is some dry savanna in the centre of the country but most of it is covered with dense rain forest.
There is one long rainy season which lasts for eight months of the year and peaks in April and November. The dry season lasts from June to September. Temperatures are even, but reach a minimum during the dry period.
Congo is primarily an agricultural country although it also has a considerable forestry industry.
2. HYDROGRAPHY (see Figure 1)
2.1 Lakes
There are several minor lakes associated with river floodplains (i.e., Lakes Tele, Cayo, Dinga, Nanga). Brazzaville is located on Pool Malebo (Stanley Pool), a lake-like enlargement of the Zaire/Congo River.
2.2 Rivers, Floodplains and Swamps
The Zaire/Congo River forms the frontier between Zaire and Congo for over 500 km of its lower course. The frontier continues for a further 500 km up the Ubangui. The hinterland of these rivers forms a vast marshland (the Cuvette Congolaise) with extensive seasonal savanna floodplains and permanently flooded gallery forests. The area which covers about 30–45 000 km2 is drained by the River Sangha, the Likouala and Likouala-aux-Herbes as well as by numerous smaller rivers. Of several smaller coastal rivers, the Kouilou is the largest.
2.3 Reservoirs
There is one impoundment on the Bouenza (tributary of Kouilou) at Moukoukoulou and a second is planned at Sounda on the Kouilou.
2.4 Coastal Lagoons
There are three small lagoons: Conkouati, Loubi and Malonda.
3. FISHERY PRODUCTION/POTENTIAL
3.1 Aquaculture
In 1986, 525 private fish farmers, exploiting 1 454 ponds for a total area of 4 479 ares and production of 45 t/yr, were counted by an FAO/UNDP project. Ten aquaculture centres are managed by the Government with FAO/UNDP assistance. An industrial fish farm is in operation in Brazzaville and produces 15 t Oreochromis niloticus per year (Deceuninck, 1988). In 1987, 115 t Oreochromis niloticus were produced in the whole country (Vincke, 1989, pers. comm.).
3.2 Fish production and per caput supply
Table 1. FISH PRODUCTION AND PER CAPUT SUPPLY - Congo, 1970–1987
Nominal Domestic Production (excluding exports) (t) 2 | Nominal Consumer Supply (excluding imports and exports) (kg/person) | ||||||||
Year | Population '000 1 | Inland capture | Aquaculture 3 | Marine capture | Total | Inland capture | Aquaculture 3 | Marine capture | Total |
1970 | 1 201 | 3 000 | - 4 | 9 700 | 12 700 | 2.5 | - | 8.0 | 10.5 |
1971 | 1 230 | 6 000 | - | 7 600 | 13 600 | 4.9 | - | 6.1 | 11.0 |
1972 | 1 259 | 7 000 | - | 14 000 | 21 000 | 5.5 | - | 11.1 | 16.6 |
1973 | 1 289 | 8 000 | - | 15 500 | 22 500 | 5.4 | - | 12.0 | 17.4 |
1974 | 1 320 | 8 000 | - | 14 794 | 22 794 | 6.0 | - | 11.2 | 17.2 |
1975 | 1 352 | 8 000 | - | 15 103 | 23 103 | 5.9 | - | 11.1 | 17.0 |
1976 | 1 385 | 8 000 | - | 17 869 | 25 869 | 5.7 | - | 12.9 | 18.6 |
1977 | 1 419 | 8 000 | - | 15 364 | 23 364 | 5.6 | - | 10.8 | 16.4 |
1978 | 1 454 | 8 000 | - | 16 297 | 24 297 | 5.5 | - | 11.2 | 16.7 |
1979 | 1 491 | 8 000 | - | 19 630 | 27 630 | 5.4 | - | 13.1 | 18.5 |
1980 | 1 529 | 8 000 | - | 20 965* | 28 965 | 5.2 | - | 13.7 | 18.9 |
1981 | 1 568 | 12 000 | - | 17 665* | 29 665 | 7.7 | - | 11.2 | 18.9 |
1982 | 1 609 | 11 956 | 44 5 | 18 835* | 30 835 | 7.4 | 0.03 | 11.7 | 19.1 |
1983 | 1 651 | 11 989 | 11 5 | 21 702* | 33 702 | 7.3 | 0.006 | 13.1 | 20.4 |
1984 | 1 695 | 11 971 | 29 5 | 19 297 | 31 297 | 7.1 | 0.02 | 11.4 | 18.5 |
1985 | 1 740 | 13 500 | 39 5 | 16 336 | 29 875 | 7.7 | 0.02 | 9.4 | 17.1 |
1986 | 1 788 | 11 918 | 82 5 | 17 994 | 29 994 | 6.7 | 0.04 | 10.0 | 16.7 |
1987 | 1 837 | 13 385 | 115 5 | 17 513 | 31 013 | 7.3 | 0.06 | 9.5 | 16.8 |
1 Source: FAO
2 Source: FAO Fisheries Department, FISHDAB
3 included in “Inland capture” if not specified
4 - = data not available
5 Vincke, 1989 (pers.comm.)
* Marine exports were: 1980: 850t; 1981: 60 t; 1982: 730 t; 1983: 500 t
3.3 Inland catch range and potential yield
See Table 2.
Table 2. INLAND CATCH RANGE AND POTENTIAL YIELD
Water body | Period | Annual catch range (t) | Potential annual yield (t) * |
Lake Louandjili | - | - | 3 |
Pool Malebo | - | 1 000 | - |
Lake Ndembo | - | - | 3 |
Cuvette Congolaise Floodplain and Likouala, Likouala-aux-Herbes and Sangha Rivers | - | 10 000–15 000 | 60 000–100 000** |
Other water bodies | - | - | 10 000–15 000*** |
No specific data available for: | |||
Lakes Cayo, Dinga, Loufoualeba, Nanga, Tchipounga, Tele, and Youbi; | |||
Rivers Congo, Kouilou, Ogooue and Ubangi; | |||
Lagoons Conkouati and Malonda. |
* when not specified, included in “other water bodies”
** based on 15–25 kg/ha/yr; see text
*** rough estimate.
Total annual yield: | 11 000–16 000 t |
12 000 (Deceuninck, 1988) | |
Potential annual yield: | 70 000–115 000 t |
100 000 (Corsi et al., 1980) |
4. STATE OF THE FISHERY (mainly after Welcomme, 1979a)
4.1 Yield
There is little doubt that the present catch from Congo is very low, relative to the potential.
4.2 Factors influencing yield
The main fishery is at present concentrated on the extensive floodplains of the Congo Basin (centered around Mossaka, Loukolela and Djoundou), but are fished at a low level because of their inaccessibility and low population densities. Some small coastal lacustrine bodies are in need of environmental rehabilitation.
4.3 Future development possibilities
The potential for increasing catches is very great. The floodplain complex of the Sangha/Likouala/Likouala-aux-Herbes (Cuvette Congolaise) Rivers is one of the most important undeveloped inland fisheries in Africa. The 30–40 000 km2 of floodplains are partly savanna and although the gallery forests and flooded rain forests are covered with blackwaters, the savanna plains are flooded by white-waters. Even a conservative estimate of sustainable potential (15–25 kg/ha) gives a yearly catch range of 60–100 000 t. Because of its inaccessibility and the difficulties of operating there, the development of the area may take some time. However, current activities for the creation of pre-cooperative groups and the introduction of new fishing methods promise a rapid development of the sector in the near future.
Fig. 1. HYDROLOGICAL NETWORK OF REPUBLIC OF CONGO
(Stauch, 1963)
5. KEY BIBLIOGRAPHY
Corsi et al., 1980
6. WATER BODIES DIRECTORY
Lakes | ||
Cayo | Pool Malebo (= Stanley Pool) | Tchipounga |
Dinga | Nanga | Tele |
Louandjili | Ndembo | Youbi |
Loufoualeba | ||
Rivers | ||
Congo/Zaire | Ogooue | |
Kouilou | Sangha (and Floodplain) | |
Likouala (and Floodplain) | Ubangi/Oubangui | |
Likouala-aux-Herbes (and Floodplain) | ||
Lagoons | ||
Conkouati | ||
Loubi (=Djeno) | ||
Malonda |
LAKE CAYO
Geographical data | |
Location: | Congo coastal plain - 4° 55'S; 12° 0'E |
Surface area: | 16.5 km2 |
Depth: | 4.5 m (max.); 4.2 m (mean, at max. volume) |
Volume: | 30–70 × 106 m3 (varies seasonally) |
Max. length: | 7.5 km |
Max. width: | 5.0 km |
Annual fluctuation in level: 1.8 m | |
Major inflowing river: | Loèmè (from Lake Loufoualeba) |
Outflowing river: | Loèmè (to Malonda Lagoon) |
Special features: | Heavily infested with papyrus |
Physical and chemical data | |
Surface temperature: | 26–35.5° C |
Oxygen: | low (0–4.5 mg/l) oxygen levels due to decomposition of dead plant material |
Fisheries data | |
No. of fish species: | only Protopterus dolloi present in lake. |
LAKE DINGA
Geographical data | |
Location: | Congo, coastal plain - 4° 11'S; 11° 53'E |
Altitude: | circa 400 m asl |
Surface area: | 4.7 km2 |
Max. length: | 4.5 km |
Max. width: | 1.5 km |
Major inflowing river: | lateral spillage from Kouilou River |
LAKE LOUANDJILI
Geographical data | |
Location: | Congo, coastal plain - 4° 21'S; 11° 37'E |
Depth: | 9.0 m (max.) |
Surface area: | about 2 km2 |
Physical and chemical data | |
pH: | 5.40–6.1 |
Temperature: | 30.0–31.9° C |
Fisheries data | |
Potential annual yield: | 3 t (15 kg/ha, acid water: Welcomme, 1989, pers.comm.) |
LAKE LOUFOUALEBA
Geographical data | |
Location: | Congo coastal plain - 4° 53'S; 11° 57'E |
Surface area: | 5.7 km2 |
Depth: | 4.5 m (max.); 3.0 m (mean, at max. volume) |
Volume: | 8–17 × 106 m3 |
Max. length: | 5 km |
Max. width: | 2 km |
Annual fluctuation in level: 1.3 km | |
Major inflowing rivers: | Loèmè, Koulombo |
Outflowing river: | Loèmè (to Lake Cayo) |
Special features: | Heavily infested with papyrus |
Physical and chemical data | |
Temperature: | 25.5–32° C |
Oxygen: | low (<4 mg/l) oxygen levels, due to decomposition of dead plant material |
Fisheries data | |
No. of fish species: | only Protopterus dolloi present in lake. |
POOL MALEBO (= STANLEY POOL)
(International water)
Geographical data | |
Location: | Congo, Zaire - 4° 15'S; 15° 28'E |
Surface area: | 550 km2 (330 km2 in Congo; 220 km2 in Zaire) |
Depth: | 20 m (max.); 3 m (mean) |
Max. length: | 40 km |
Max. width: | 20 km |
Shoreline: | 95 km |
Major inflowing river: | Congo/Zaire |
Special features: | Pool Malebo is a riverine lake, with a large central island (Ile Mbamou) and several smaller sandbanks which are subject to inundation. |
Fisheries data | |
Total annual catch: | circa 1 000 t from Congo waters |
LAKE NANGA
Geographical data | |
Location: | Congo, coastal plain - 4° 13'S; 11° 48'E |
Altitude: | circa 300 m asl |
Surface area: | circa 15 km2 |
Depth: | 2 m (max.); 1.5–2.0 m (mean, varies seasonally) |
Max. length: | 8 km |
Max. width: | 2 km |
Major inflowing river: | Louandjili |
Outflowing river: | Louandjili (tributary of Kouilou) |
Physical and chemical data | |
pH: | 6.35–7.20 |
Temperature: | 27–34° C |
LAKE NDEMBO
Geographical data | |
Location: | Congo, coastal plain - 4° 21'S; 11° 39'E |
Depth: | 6.5 m (max.) |
Surface area: | circa 2 km2 |
Physical and chemical data | |
pH: | 5.21–5.82 |
Temperature: | 30.8–32.5° C |
Fisheries data: | |
Potential annual yield: | 3 t (15 kg/ha, acid water: Welcomme, 1989, pers.comm.) |
LAKE TCHIPOUNGA
Geographical data | |
Location: | Congo coastal plain - 4° 43'S; 11° 54'E |
Surface area: | 0.08 km2 |
LAKE TELE
Geographical data | |
Location: | Congo, Cuvette Congolaise (Central Basin) - 1° 20'N; 17° 9'E |
Surface area: | 20 km2 |
Max. length: | 6.5 km |
Max. width: | 4.5 km |
Main inflowing river: | lateral flood spillage from Bali River (tributary of Likouala-aux-Herbes River) |
LAKE YOUBI
Geographical data | |
Location: | Congo, coastal plain - 4° 11'S; 11° 40'E |
Surface area: | 3.5 km2 |
Max. length: | 2.5 km |
Max. width: | 2.0 km |
CONGO/ZAIRE RIVER
(International water)
See also “ZAIRE RIVER” under “ZAIRE” (country) for more detailed data.
Geographical data | ||
Source: | The longest continuous stream is: Chambezi River, Lake Bangweulu, Luapula River, Lake Mweru, Luvua River, Lualaba River. The Lualaba River changes its name to Congo/Zaire at Kisangani, 2 000 km from the mouth. In the Congo it is navigable from Brazzaville to the Oubangui mouth. | |
Altitude: | The highest source is that of the Lualaba - 1 535 m asl. | |
Total length: | 4 700 km | |
Drainage area: | 4 014 500 km2 | |
Area of water: | (including Ubangui basin) | |
Congo/Zaire | 17 000 km2 | |
Tributaries of Congo/Zaire | 4 100 km2 | |
Ubangi and tributaries | 1 300 km2 | |
Other rivers | 8 500 km2 | |
Kasai and tributaries | 3 100 km2 | |
Countries traversed: | The basin covers parts of Angola, Burundi, Cameroon, Central African Republic, Congo, Rwanda, Tanzania, Zaire, Zambia. | |
Major tributaries: | Alima, Aruwimi, Elila, Itimbiri, Kwa, Lomami, Lowa, Lufira, Lukuga, Lulonga, Luvua, Mongala, Sangha, Ruki, Ubangi | |
Discharges to: | South Atlantic - 6° S; 12° E | |
Volume of discharge at mouth: 22–67 000 (mean 39 160) m3/sec | ||
Suspended silt load: | 50 500 000 t/yr | |
Flood regime: | Bimodal floods with peaks in May and December | |
Special features: | Lakes Kiyu, Tanganyika, Bangweulu, Mweru, Maji Ndombe, Pool Malebo, Upemba, Tumba. Waterfalls: Portes d'Enfer, Wagenia, numerous cataracts; dams on nearly all tributaries. |
Physical and chemical data | |||
pH: | Both pH and conductivity vary considerably in the different water courses of the system. pH may be as low as 4.4 in flooded forests; 5.5 in upper course; 6.5 in middle course; 4.00–6.5 in Tshwapa River; 7.05–7.8 at Yangambi. * | ||
(* Data provided by Gosse (1963) for the Zaire River at Yangambi, and by Matthes (1964) for the Tshwapa River.) | |||
Ionic composition: | (Meybeck, 1978) | ||
mg/l | |||
Ca | 2.40 | ||
Mg | 1.25 | ||
Na | 1.70 | ||
K | 1.10 | ||
HCO3 | 11.20 | ||
Cl | 2.85 | ||
SO4 | 2.95 | ||
SiO2 | 9.80 |
KOUILOU RIVER
Geographical data | |
Source: | Congo (Zala Mountains) |
Altitude: | 880 m asl |
Total length: | 605 km |
Drainage area: | 60 000 km2 |
Countries traversed: | Congo |
Major tributaries: | Louessè, Niari, Bouenza |
Discharges to: | Atlantic Ocean. 4° 28'S; 11° 42'E, Coastal plain |
Volume of discharge at mouth: 700 m3/sec mean (300–1 000 m3/sec) | |
Flood regime: | two peaks: April-May and November-December |
Special features: | Lateral floodplains in lower section with Lakes Dinga and Nanga. There is an impoundment at Moukoukoulou on the Bouenza, and a second is planned at Sounda on the Kouilou. |
LIKOUALA RIVER AND FLOODPLAIN
Geographical data (see Fig. 2) | ||
Source: | northwestern Congo | |
Altitude: | 780 m asl | |
Total length: | 480 km | |
Countries traversed: | Congo | |
Major tributaries: | Kouyou, Mambili, Lengouè | |
Discharges to: | Congo/Zaire River (1° 11'S; 16° 49'E) | |
Special features: | Extensive lateral floodplain (Cuvette Congolaise) along lower course. The combined area inundated twice yearly along the lower reaches of the Sangha, Likouala-aux-Herbes and Likouala Rivers is 30–40 000 km2. | |
Physical and chemical data (Stauch, 1963; Corsi, et al., 1980) | ||
pH: | Likouala-Mossaka: | 4.9–5.6 |
Temperature: | Likouala-Mossaka: | 25.5–27.5° C |
Conductivity: | Likouala-Mossaka: | 8.8 μ S/cm |
Fisheries data | ||
No. of fishermen: | 7–10 000 for combined floodplain | |
Total annual catch: | 10–15 000 t from combined floodplain | |
Potential annual yield for 40 000 km2 combined floodplain: | ||
60 000 t (15 kg/ha - Welcomme, 1989, pers.comm.) to | ||
100 000 t (20–25 kg/ha - Corsi, et al., 1980, for acid, brown and poor-in-minerals water). |
LIKOUALA-AUX-HERBES RIVER AND FLOODPLAIN
Geographical data | |
Source: | northeast Congo (see Fig. 2) |
Altitude: | 470 m asl |
Total length: | 475 km |
Countries traversed: | Congo |
Major tributaries: | Tanga, Moudongoumo, Bali |
Discharges to: | Sangha River (0° 50'S; 17° 12'E) |
Special features: | Lake Tele on Bali tributary. Extensive lateral floodplain (Cuvette Congolaise) along lower course. The combined area inundated twice yearly along the lower reaches of the Sangha, Likouala-aux-Herbes and Likouala Rivers is 30–40 000 km2. |
Physical and chemical data (Stauch, 1963; Corsi et al., 1980) | |
pH: | 5–6.4 |
Conductivity: | 25.3 μ S/cm |
Fisheries data | |
No. of fishermen: | 7–10 000 for combined floodplain |
Total annual catch: | 10–15 000 t from combined floodplain |
Potential annual yield for: 40 000 km2 combined floodplain: | |
60 000 t (15 kg/ha - Welcomme, 1989, pers.comm.) to | |
100 000 t (20–25 kg/ha - Corsi et al., 1980, for acid, brown and poor-in-minerals water). |
Fig. 2. HYDROLOGICAL NETWORK OF CENTRAL BASIN (CUVETTE CONGOLAISE)
(Stauch, 1963)
OGOOUE RIVER
(International water)
Geographical data | |
Source: | Congo (Leketi, Zala and Massa Mountains) |
Altitude: | 880 m asl |
Total length: | 920 km (100 km in Congo) |
Drainage area: | 205 000 km2 (at Lambarene) |
Countries traversed: | Gabon, Congo |
Major tributaries: | Ivindo, Ngouniè, Ofoouè |
Discharges to: | Atlantic Ocean - 1° 2'S; 8° 53'E |
Volume of discharge at mouth: | |
13 500 m3/sec (max.); | |
1 950–7 340 m3/sec (mean monthly); | |
Flood regime: | Bimodal flood with peaks in April-May and November-December |
Special features: | Large floodplain in lower reach with several associated lakes (Anengue, Avanga, Onangue, Gomè, Nkonie, Azingo and Nguene). Other swampy/floodplain depressions associated with Ngouniè and Ivindo tributaries (the latter mostly in Congo). |
SANGHA RIVER AND FLOODPLAIN
(International water)
Geographical data | |
Source: | Karre Mountains, western Central African Republic (see Fig. 2) |
Total length: | 1 000 km |
Countries traversed: | Cameroon, Congo, Central African Republic |
Major tributaries: | Likuala, Ekela and Dja Rivers |
Discharges to: | Zaire/Congo River |
Volume of discharge at mouth: 700–4 300 m3/sec | |
Special features: | Extensive lateral floodplain (Cuvette Congolaise) along lower course in Congo. The combined area inundated twice yearly along the lower reaches of the Sangha, Likouala-aux-Herbes and Likouala Rivers is 30–40 000 km2. |
Physical and chemical data (Corsi, et al., 1980) | |
pH: | Sossolo: 6.2 |
Conductivity: | 43.7 μ S/cm |
Fisheries data | |
No. of fishermen: | 7–10 000 for combined floodplain |
Total annual catch: | 10–15 000 t from combined floodplain |
Potential annual yield: for 40 000 km2 combined floodplain: | |
60 000 t (15 kg/ha - Welcomme, 1989, pers.comm.) to | |
100 000 t (20–25 kg/ha - Corsi, et al., 1980, for acid, brown and poor-in-minerals water). |
UBANGI/OUBANGUI RIVER
(International water)
Geographical data | ||
Source: | The Ubangi is formed by the confluence of the Uèlè and Bomu Rivers at Yakoma. The Uèlè rises in the mountains near Lake Albert; the Bomu has its source on the frontier between Sudan, Central African Republic and Zaire. | |
Total length: | Mbomou/Bomu: | 710 km (Zaire, Central African Republic) |
Uèlè: | 1 210 km (Zaire) | |
Ubangi: | 1 060 km (Congo, Central African Republic, Zaire) | |
The longest continuous course is the Uèlè + the Ubangi (2 270 km) | ||
Drainage area: | 772 800 km2 | |
Countries traversed: | Congo, Central African Republic, Zaire | |
Major tributaries: | Kotto, Ouaka, Mbori, Chinko | |
Discharges to: | Congo/Zaire at Liranga | |
Flood regime: | August to December, max. in October (unimodal); low in March-April | |
Flow at Bangui: | 800 to 11 000 m3/sec; mean: 4 000 m3/sec | |
Level variation: | 5.5 m (mean); 9 m (max.) | |
Physical and chemical data - at Ndjoundou (Corsi, et al., 1980) | ||
pH: | 7.1 | |
Conductivity: | 55.5 μ S/cm | |
Oxygen: | mean at Bangui: 6 mg/l, 75% saturation (Micha, 1973) | |
Fisheries data | ||
No. of species: | 233 in 25 families (Gosse, 1968; Micha, 1973) |
CONKOUATI LAGOON
Geographical data | |
Location: | Congo, Coastal plain - 3°58'S; 11°20'E |
Surface area: | 24 km2 |
Depth: | 5 m (max.); 2.5 m (mean) |
Volume: | 60 × 106 m3 |
Annual fluctuation in level: 0.3 m | |
Max. length: | 17 km |
Max. width: | 4.5 km |
Major inflowing rivers: | Niambi, Ngongo, Louvandzi |
Outflow: | to Atlantic Ocean |
Physical and chemical data | |
Salinity: | 3.17–32.94‰ |
LOUBI (= DJENO) LAGOON
Geographical data | |
Location: | Congo, coastal plain - 4°54'S; 11°55'E |
Special features: | Highly polluted by petroleum wastes which have gravely affected the ichthyofauna. |
MALONDA LAGOON
Geographical data | |
Location: | Congo, coastal plain - 4°57'S; 11°57'E |
Surface area: | 0.05 km2 |
Depth: | 2.5 m (max.); 0.8 m (mean) |
Volume: | 40 000 m3 |
Annual fluctuation in level: 0.5 m | |
Major inflowing river: | Loèmè (from Lake Cayo) |
Outflow: | 50 m-long-canal to Atlantic Ocean |
Special features: | Low (<4.0 mg/l) oxygen levels due to high BOD input from Lakes Cayo and Loufoualeba, upstream. |
Physical and chemical data | |
Surface temperature: | 27.5–34°C |
Salinity: | <3 ‰ |
7. BIBLIOGRAPHY
Corsi, et al., 1980
Deceuninck, 1988
Gosse, 1963; 1968
Matthes, 1964
Meybeck, 1978
Micha, 1973
Stauch, 1963
1. GEOGRAPHY AND CLIMATE
The surface area of Kenya is 569 250 km2. The western and central parts of Kenya consist of highland plateaus which are divided from north to south by the Great Rift Valley. The plateaus are crowned by mountains, of which Mount Kenya (5 200 m) is the highest. The highlands slope downward to the east.
Kenya has a wide range of climates. The north and much of the east of the country are desertic with little rainfall and high temperatures. The highland plateaus have warm temperate climates with two well marked rainy season: February-May and October-December. The coast has a monsoon climate with a prolonged wet season peaking in May.
The highlands of Kenya are used for agriculture, whereas the lowland areas tend to be occupied by pastoral peoples. Large areas of the country have been reserved as game parks and much of the north is desertic and supports only very limited population.
2. HYDROGRAPHY (see Figure 1)
2.1 Lakes (Welcomme, 1979a) (see Table 1)
The major Kenyan lakes fall into two main groups: (a) Lake Victoria; and (b) the Rift Valley lakes. Kenya possesses 69% of Lake Victoria. A considerable portion of this is located in the shallow and productive Kavirondo Gulf. The larger Rift Valley lakes are Lakes Turkana, Baringo, Bogoria, Nakuru, Elementeita, Naivasha and Magadi. One small lake, Lake Jipe, lies between Kenya and Tanzania (about half in each country). Many other small lakes are dotted around the country, and there are several on the lower floodplains of the Tana and Sabaki Rivers.
2.2 Rivers, Floodplains and Swamps (Balarin, 1985a; Welcomme, 1979a)
The drainage system of Kenya is largely influenced by the Great Rift Valley and five drainage basins are evident (see Figure 1; Table 2):
Lake Victoria: the Lake Basin is a multi-river basin containing eight rivers of significant size. These rivers drain about 47% of the total of Kenya's runoff, carrying it westward into Lake Victoria. Their catchment comprises the whole of the area west of the Rift Valley, delineated by Mount Elgon in the North.
Rift Valley: an area with its own internal drainage, discharging northwards into Lake Turkana and southwards into Lake Natron, with several sub-drainage rivers and lakes. Although one of the larger catchments, its mean annual runoff is very low.
Athi River: the southern catchment east of the Rift Valley, draining from the central highlands to the Indian Ocean.
Tana River: drains eastward from Mount Kenya to the Indian Ocean; one of the largest rivers with the second highest MAR, 7% of rainfall.
Ewaso Ngiro: the largest but driest catchment in Kenya, it extends from north of Mount Kenya and the Aberdares to empty into the Iorian swamp. In exceptional floods, flows continue into Somalia.
DRAINAGE BASINS | NATURAL LAKES | MAIN RIVERS | |
1 Lake Victoria | L1 Victoria | L8 Hannington (Bogoria) | R1 Tana |
2 Rift Valley | L2 Turkana | L9 Nakuru* | R2 Ewaso Ngiro |
3 Athi-Sabaki River | L3 Baringo | L10 Elementaita | R3 Sabaki (Athi) |
4 Tana River | L4 Magadi | L11 Chala | R4 Turkwel |
5 Ewaso Ngiro | L5 Naivasha | L12 Logipi | R5 Migori |
L6 Amboseli* | * = seasonal | R6 Nzoia | |
L7 Jipe |
Fig. 1. MAJOR LAKES, RIVERS AND DRAINAGE BASINS IN KENYA
(adapted from: Survey of Kenya, 1970)
Table 1. MORPHOLOGICAL DATA AND USE OF MAJOR LAKES AND RESERVOIRS
(Balarin, 1985a, based on Govt. of Kenya, 1979a; Limiri, pers.comm)
Water body* | Drainage basin | Volume (106/m3) | Area (km2) | Fishery potential (t/yr) | Use a | Altitude ab. MSL m | |
Natural Lakes | |||||||
L.1 | Victoria | I | 3 785 | w,c,r,f | 1 134 | ||
L.2 | Turkana | II | 6 405 | f,w,r | 375 | ||
L.3 | Baringo | II | 130 | f,w,r,i | 975 | ||
L.4 | Magadi | II | 104 | c | 580 | ||
L.5 | Naivasha | II | 115–191 | f,w,r,(p) | 1 875 | ||
L.6 | Amboseli b | III | 0–115 | r | 1 190 | ||
L.7 | Jipe | III | 40 | 500 | f | 700 | |
L.8 | Hannington | II | 34 | r (p) | 960 | ||
L.9 | Nakuru b | II | 5–50 | r,f | 1 757 | ||
L.10 | Elementaita | II | 18–21 | r | 1 783 | ||
L.11 | Chala | 4 | 200 | f | |||
L.12 | Logipi | 34 | |||||
Reservoirs | |||||||
B.1 | Masinga | IV | 1 560 | 120.0 | 480 | p,f,i | |
B.2 | Kamburu | IV | 156 | 15.0 | p,f | ||
B.3 | Gitaru | IV | 20 | 3.1 | p,f | ||
B.4 | Kindaruma | IV | 16 | 2.4 | p,f | ||
B.5 | Sasumua | IV | |||||
B.6 | Munyu c | III | 499.0 | 175 | p,i,f | ||
B.7 | Kiambere c | IV | 25.0 | 40–60 | p,i,f | ||
Wanjii | IV | p | |||||
Grand Falls c | IV | 119 | p | ||||
Adamson's Falls c | IV | 102 | p | ||||
Koreh Falls c | IV | 190 | p |
* Numbers refer to Figure 1.
a i=irrigation; c=commercial/industrial; f=fishery; r=recreation; p=power generation; w=water supply
b seasonal
c proposed
The rivers of Kenya fall into two main groups:
coastal rivers - the Sabaki (Athi, Galana) River with a broad floodplain in its lower reaches, and the Tana River;
rivers flowing into Lake Victoria - of which the Nzoia, Yala and Sio Rivers are the most important.
Several seasonal rivers, such as the Turkwell, drain the western rift wall toward Lake Turkana. FAO/UNDP (1966) estimated a total of about 3 000 km of rivers in the country.
The rivers exhibit seasonal flow patterns characteristic of the peak wet seasons, generally flooding from March to May and from October to December.
Table 2. CATCHMENT AREA AND MEAN ANNUAL RUNOFF FOR MAJOR RIVERS AND DRAINAGE BASINS
(Balarin, 1985a, based on: Bhushan, 1982; Govt. of Kenya, 1970; Ongwenyi, 1979; Litterick, 1981; Coche & Balarin, 1982; Survey of Kenya, 1970)
DRAINAGE BASIN/River system | Major River Systems | Total catchment | Rainfall runoff | Runoff as % of rainfall | |||||
Length (km) | Catchment (km2) | MAR (million m3) | Mean rainfall (mm/yr) | Total MAR* | |||||
('000 km2) | % | 106 m3 | % of total | ||||||
I. LAKE VICTORIA | |||||||||
Nzoia | 258 | 12 696 | 1 777 | 45 | 8.4 | 1 245 | 6 706–7 290 | 46.9 | 12 |
Mara | 290 | (8 941) | 1 038 | ||||||
Gucha (Migori) | 6 368 | 952 | |||||||
Kibos | 4 992 | 68 | |||||||
Sondu | 110 | 3 489 | 845 | ||||||
Nyando | 3 450 | 247 | |||||||
Yala | 180 | 3 262 | 1 114 | ||||||
Sio (Malakisi) | 2 326 | 287 | |||||||
Kuja | 90 | ||||||||
II. RIFT VALLEY | |||||||||
Molo | 39 | ||||||||
Suam-Turkwel | 380 | 20 720 | 127 | 21.8 | 535 | 806–860 | 6.0 | 1 | |
Gilgil | 28 | ||||||||
Ewaso Ngiro (S) | 140 | ||||||||
Perkerra | 125 | ||||||||
Melawa | 110 | 184 | |||||||
Arror Kerio | 350 | ||||||||
III. ATHI RIVER | |||||||||
Athi-Galana-Sabaki | 547 | 44 029 | 750 | 70 | 12.0 | 585 | 1 294 | 9.0 | 3 |
Voi | 210 | ||||||||
Tsavo | 138 | ||||||||
Njoro-Lumi | 293 | ||||||||
IV. TANA RIVER | |||||||||
Tana | 708 | 62 160 | 4 700 | 132 | 22.7 | 535 | 4 700 | 32.9 | 7 |
V. EWASO NGIRO | |||||||||
Ewaso Ngiro (N) | 830 | 56 980 | 740 | 205 | 35.1 | 255 | 740 | 5.2 | 2 |
Total | (4 203+) | 579 | 14 299–14 830 | 100.0 | |||||
Mean | 631 | 5 |
There are extensive seasonal floodplains and swamps in Kenya which are water-filled during the rainy season for about 3–4 months of the year. The extent of these areas is not known. Similarly, there is a large number of pans and water holes, natural depressions which temporarily store rain runoff.
The groundwater reserves are extensive at an average depth of 78 m below surface. This implies a water table deeper than in most places in Africa. But a large number of shallow wells is also common. There is an extensive domestic water supply network throughout the densely populated areas.
2.3 Reservoirs (see Table 1)
There are four important hydroelectric impoundments on the upper Tana River. Also listed in Table 1 are a number of the larger man-made reservoirs. Those considered are built mainly for hydroelectric power (HEP) schemes or irrigation projects, but there are numerous smaller water storage units dispersed throughout the country (Balarin, 1985a). Welcomme (1979a) suggests over 3 000 farm dams, as reported by Rhodes (FAO/UNDP, 1966).
2.4 Coastal Lagoons
There are several small seasonal lagoons in coastal areas at the mouths of the Tana and Galana Rivers. In addition, large coastal tracts of tidal mangrove swamps exist (combined area of over 12 960 km2 estimated by Bell and Canterbery, 1976).
3. FISHERY PRODUCTION/POTENTIAL
3.1 Aquaculture
FAO/UNDP (1966) indicates that in 1965 there were between 12 500 and 22 000 small rural ponds with a combined surface area of between 280 and 500 ha. Most of the ponds were small and many were abandoned. In 1975 official estimates suggest over 28 000 fish ponds ranging from 0.04 to 0.8 ha (Kagai, 1975).
The most recent official statistics (1986 Fisheries Statistical Bulletin, Govt. of Kenya) indicates that fish farming production reached 980 t. A recent FAO re-evaluation (Vincke, pers. comm., 1989) estimates the actual aquaculture production at a lower level: 224 t in 1986, 210 t in 1987. In 1987, 5 t of common carp (Cyprinus carpio), 121 t of tilapia (mainly Oreochromis niloticus), 80 t of trout (Salmo gairdneri) and 4 t of shrimps (Penaeus spp.) were produced.
3.2 Fish production and per caput supply
See Table 3.
Table 3. FISH PRODUCTION AND PER CAPUT SUPPLY - Kenya, 1970–1987
Nominal Domestic Production (excluding exports) (t) 2 | Nominal Consumer Supply (excluding imports and exports) (kg/person) | ||||||||
Year | Population '000 1 | Inland capture | Aquaculture 3 | Marine capture | Total | Inland capture | Aquaculture 3 | Marine capture | Total |
1970 | 11 290 | 25 800 | - 4 | 7 900 | 33 700 | 2.3 | - | 0.7 | 3.0 |
1971 | 11 736 | 21 300 | - | 6 900 | 28 200 | 2.8 | - | 0.6 | 2.4 |
1972 | 12 199 | 22 300 | - | 7 700 | 30 000 | 2.8 | - | 0.6 | 2.4 |
1973 | 12 681 | 25 000 | - | 4 000 | 29 000 | 2.0 | - | 0.3 | 2.3 |
1974 | 13 182 | 25 800 | - | 3 600 | 29 400 | 1.9 | - | 0.3 | 2.2 |
1975 | 13 703 | 22 810 | - | 4 531 | 27 341 | 1.7 | - | 0.3 | 2.0 |
1976 | 14 259 | 36 872 | - | 4 149 | 41 021 | 2.6 | - | 0.3 | 2.9 |
1977 | 14 844 | 38 443 | - | 4 339 | 42 779 | 2.6 | - | 0.3 | 2.9 |
1978 | 15 456 | 41 760 | - | 4 634 | 46 394 | 2.7 | - | 0.3 | 3.0 |
1979 | 16 096 | 47 688 | - | 4 055 | 51 743 | 3.0 | - | 0.2 | 3.2 |
1980 | 16 766 | 42 171 | - | 5 552 | 47 723 | 2.5 | - | 0.3 | 2.8 |
1981 | 17 465 | 51 385 | - | 6 316 | 57 701 | 2.9 | - | 0.4 | 3.3 |
1982 | 18 196 | 73 822 | 195 5 | 7 512 | 81 529 | 4.1 | 0.01 | 0.4 | 4.5 |
1983 | 18 960 | 90 867 | 201 5 | 7 070 | 98 138 | 4.8 | 0.01 | 0.4 | 2.5 |
1984 | 19 761 | 84 706 | 207 5 | 6 041 | 90 954 | 4.3 | 0.01 | 0.3 | 4.6 |
1985 | 20 600 | 99 551 | 213 5 | 6 196 | 105 960 | 4.8 | 0.01 | 0.3 | 5.1 |
1986 | 21 483 | 113 362 | 224 5 | 6 212 | 119 798 | 5.3 | 0.01 | 0.3 | 5.6 |
1987 | 22 405 | 124 096 | 210 5 | 6 875 | 131 181 | 5.5 | 0.01 | 0.3 | 5.8 |
1 Source: FAO
2 Source: FAO, based on: Statistical Bulletin, Fisheries Department, Ministry of Tourism and Wildlife, Govt. of Kenya.
Note: FAO Yearbook, Fishery Statistics, Vol. 62, 1986): Kenya. Landings recording system for Lake Victoria which accounts for 70% of the total catch, considered unreliable. Increased catch recorded in 1986 largely due to improved coverage.
3 included in “Inland capture” if not specified
4 - = data not available
5 Vincke, 1989, pers.comm.
3.3 Inland catch range and potential yield
Table 4. INLAND CATCH RANGE AND POTENTIAL YIELD
Water body | Period | Annual catch range (t) 1 | Potential annual yield (t) 1 |
Lake Baringo | 1985 | 317 | 900–3 500 |
1986 | 154 | ||
Lake Chala | 1982 | 90 | |
1983–86 | 10-1 | ||
Lake Jipe | 1983–86 | 463-128 | 100–300 |
Lake Naivasha | 1986 | 576 | 1 000–4 000 |
Lake Turkana | 1986 | 7 324 | 5 000–20 000 |
Lake Victoria | 1986 | 103 163 4 | 25 000–40 000 |
Ewaso Ngiro River and Ngare Ngiro Swamp | 1965 | 300 | - |
Sabaki River | 1960 | 300 | - |
Aruba Reservoir | 1965 | 20 | - |
Lessos Reservoir | 1965 | 50 | - |
Miscellaneous Lakes, Rivers, including Reservoirs | 1986 | 870 2 | 2 600–23 000 3 |
Aquaculture | 1987 | 210 | - |
No information available for: | |||
Lakes Kabongo, Kanyaboli, Kwenia, Logipi and Nakuru; | |||
Rivers Migori, Nzoia, Tana, Turkwel and Lorian Swamp; | |||
Reservoirs Gtaru, Kamburu, Kindaruma and Masinga. |
1 Source: see text “Water bodies directory”
2 Source: Statistical Bulletin, Fisheries Dept., Govt. of Kenya
3 Source: Balarin, 1985a
4 see Note 2, Table 3
Total annual yield: using most recent data: 113 094 t (see also Table 3)
Potential annual yield: 34 600–90 800 t
4. STATE OF THE FISHERY
(mainly adapted and updated from Balarin, 1985a)
4.1 Yield
In 1986, 94.5% of the total landings originated from freshwater sources and 5.5% from marine fisheries. Lake Victoria produced 86.1% of this catch and Lake Turkana 6.1%. Other lakes and rivers contributed 2.3% only (based on 1986 Fisheries Statistical Bulletin, Kenya).
The increase in recent years in fishery landings are evident from Table 3. Until 1975, total catch remained below 30 000 t/yr but by 1981 the catch had doubled. It has increased even more dramatically in recent years. The upward trend represents a 28% per year increase in output but this has been primarily in the freshwater catch. Marine landings have remained static: between 4 000 and 7 000 t/yr.
The fisheries status has been reviewed on numerous occasions, notably by FAO/UNDP (1966), Fisheries Department (1977), FAO (1980a), KMFRI (1981) and more recently by Coche and Balarin (1982) and Balarin (1985a).
4.2 Factors influencing yield
The Lake Victoria fishery has been the subject of a detailed study by Coche and Balarin (1982), Zonneveld (1983) and Reynolds and Greboval (1988). Results indicate conflicting statistics.
It would appear that the recent increase in Lates niloticus stocks have defied all forms of yield evaluations, as reflected by the 1982 catch of 61 000 t. Of interest is the fact that smaller species (such as Haplochromis), liable to be consumed as prey, have almost disappeared from the landings (Coche and Balarin, 1982; see Tables 5 and 6 under “Lake Victoria” entry). It is suspected that stocks are being overfished. Concern over this has led the Fisheries Department to initiate a restocking programme; tilapias have been chosen as the most favoured candidate.
Lake Turkana, also reviewed in Coche and Balarin (1982), was the subject of a NORAD symposium (1983). Concern has been expressed over the downward trend in this fishery: down 57% in 1986 from a peak catch in 1976. Overfishing due to the limited mobility of fishermen, fishing of breeding grounds, climatic influences, and a change in fishermen structure have been implicated as reasons for drop in catches. A research programme to study the change, to restock the lake, and to initiate a deep-water fishery are to be assisted by NORAD. The originally estimated yields of 50 000–160 000 t/yr are now considered excessive; 20 000 t/yr is likely to be a more acceptable level.
The other lakes in Kenya are minor. Development of hydroelectric and irrigation schemes, especially along the Tana River, is likely to raise the fishery resources - but not to any significant level. Likely potentials are indicated in Table 1.
4.3 Future development possibilities
The estimates of maximum sustainable yields of Kenya's 10 000 km2 of inland waters and 6 500 km2 of fishable offshore waters generally lie between 81 000 and 305 000 t/yr, although estimates as low as 45 000 t/yr have also been advanced. The generally accepted estimate lies between 140 000 and 150 000 t/yr, split almost equally between freshwater and marine resources (Coche and Balarin, 1982). More recent estimates, however, suggest that marine reserves are considerably lower and the total likely yield may well be below 100 000 t/yr. If this should be the case, freshwater resources are fully exploited and there is small scope for expansion in the marine sector.
5. KEY BIBLIOGRAPHY
General: Balarin, 1985a
Lake Victoria: Reynolds & Greboval, 1988
Rift Valley Lakes: Burgis & Mavuti, 1987
6. WATER BODIES DIRECTORY
Lakes | ||
Amboseli | Kabongo | Nakuru |
Baringo | Kanyaboli | Natron |
Bogoria (= Hannington) | Kwenia | 01 Bolossat |
Chala | Logipi (Namakat) | Turkana (Rudolf) |
Elementeita | Magadi | Victoria |
Jipe | Naivasha | |
Rivers and swamps | ||
Ewaso Ngiro | Nzoia | Turkwel |
Ganale Dorya/Juba | Sabaki (Galana, Athi) | Lorian Swamp |
Migori | Tana | |
Reservoirs | ||
Aruba | Kindaruma | Sasumua |
Gtaru | Lessos | Wanjii |
Kamburu | Masinga |
LAKE AMBOSELI
(International water)
Geographical data | |
Location: | Kenya, Tanzania - 2°32'–43'S; 37° 1'–14'E |
Altitude: | 1 140 m |
Surface area: | 189 km2 (max); (Kenya: 177 km2; Tanzania: 12 km2) |
Max. length: | 30 km |
Max. width: | 9 km |
Major inflowing river: | Namanga |
Special features: | Lake Amboseli is a seasonal water body. |
LAKE BARINGO
Geographical data | ||||
Location: | Kenya - 0° 40'N; 36° 05'E | |||
Altitude: | 965 m | |||
Surface area: | 130 km2 | |||
Depth: | 5.6 m (mean); 7.5 (max.) | |||
Volume: | 0.7 km3 | |||
Max. length: | 21 km | |||
Max. width: | 11 km | |||
Major inflowing rivers: | Molo, Tangulbei | |||
Physical and chemical data | ||||
pH: | 8.7–8.9 | |||
Conductivity: | K20 416 μ S/cm (Talling & Talling, 1965) | |||
Ionic composition: | ||||
(Beadle, 1932) | (Talling & Talling, 1965) | |||
mg/l | mg/l | |||
Na | 126.0 | 95 | ||
K | 15.0 | 13 | ||
Ca | 22.0 | 11.5 | ||
Mg | 2.0 | 3.15 | ||
HCO3+CO3 | 341.6 | 347.7 | ||
SO4 | 40.0 | 19.0 | ||
SiO2 | - | 23.5 | ||
PO4-P | 545 μ g/l | - | ||
Fisheries data | ||||
Fish species: main catches: | (Lincer, et al., 1981) Oreochromis niloticus Barbus gregori Clarias mossambicus Labeo cylindricus |
Total annual catch and effort:
(Source: Statistical Bulletin, Fisheries Dept, Govt. of Kenya)
Year | Total catch (t) | No.of fishermen | No.of boats |
1964 | 600 | - | - |
1965* | 600 | - | - |
1967 | 518 | - | - |
1968 | 554 | 100 | 10 |
1969 | 503 | 120 | 33 |
1975 | 240 | - | - |
1976 | 257 | - | - |
1977 | 246 | - | - |
1978 | 315 | - | - |
1979 | 326 | - | - |
1980 | 411 | - | - |
1981 | 467 | - | - |
1982 | 401 | 102 | 12 |
1983 | 352 | - | - |
1984 | 297 | - | - |
1985 | 317 | 40 | 9 |
1986 | 152 | 68 | 23 |
Potential annual yield:
2 500–3 500 t (FAO/UNDP, 1966)
1 500 t (Govt. of Kenya, 1979b)
900 t (Welcomme, 1979a)
LAKE BOGORIA (= HANNINGTON)
Geographic data | ||
Location: | Kenya, 0°15'N; 36°06'E | |
Altitude: | 975 m | |
Surface area: | 34 km2 | |
Max. length: | 17 km | |
Max. width: | 4 km | |
Max. depth: | 8.5 m (Tuite, 1981) | |
Special features: | High alkalinity, closed basin. Hot springs, geysers and fumaroles along lakeshore. | |
Physical and chemical data | ||
Temperature: | 24° C | |
pH: | 9.8–10.3 (Tuite, 1981) | |
Conductivity: | 72 000 μ S/cm (Melack, 1976) | |
35 700 – 80 000 μ S/cm (Tuite, 1981) | ||
Ionic composition: | (Beadle, 1932) | |
mg/l | ||
Na | 14 360 | |
K | 304 | |
Ca | 26 | |
SO4 | 204 | |
Cl | 3 450 | |
Alkalinity (HCO3) | 35 300 | |
Fisheries data: | There are no fish in Lake Bogoria (Burgis & Mavuti, 1987). |
LAKE CHALA
(International water)
Geographical data | |||||
Location: | Kenya, Tanzania - 3°19' S; 37°42'E | ||||
Surface area: | 5.2 km2 (Kenya: 2.6 km2; Tanzania: 2.6 km2) | ||||
Max. length: | 4 km | ||||
Max. width: | 3 km | ||||
Fisheries data | |||||
Total annual catch and effort: | |||||
(Source: Statistical Bulletin, Fisheries Dept., Govt. of Kenya) | |||||
Year | Total catch (t) | No.of fishermen | No.of boats | ||
1982 | 90 | - | - | ||
1983 | 10 | - | - | ||
1984 | 2 | - | - | ||
1985 | 2 | 50* | 10* | ||
1986 | 1 | 50* | 10* |
LAKE ELEMENTEITA
Geographical data | |||
Location: | Kenya - 0°26'S; 36°05'E | ||
Altitude: | 1 829 m | ||
Surface area: | 20.7 km2 | ||
Max. length: | 8 km | ||
Max. width: | 4 km | ||
Max. depth: | 1.9 m | ||
Special features: | High alkalinity; no outflow (closed basin). | ||
Physical and chemical data | |||
pH: | 9.4 (Melack & Kilham, 1974) | ||
Alkalinity: | 1982 mg/l (Melack & Kilham, 1974) | ||
Conductivity: | 43 800 μ s/cm (Talling & Talling, 1965) | ||
15 000–40 200 μ s/cm (Melack, 1976) | |||
Ionic composition: | (Melack & Kilham, 1974) | ||
mg/l | |||
Na | 3 795 | ||
K | 274 | ||
Mg | 0 | ||
Si | 0 | ||
SO4 | 177 | ||
Cl | 38 | ||
Fisheries data: | There are no fish in the lake (Burgis & Mavuti, 1987). |
LAKE JIPE
(International water)
Geographical data | |||
Location: | Kenya, Tanzania - 3°35'S; 37°85'E | ||
Altitude: | 700 m | ||
Surface area: | 39 km2 (19.5 km2 in Tanzania; 19.5 km2 in Kenya) | ||
Max. length: | 12 km | ||
Max. width: | 3 km | ||
Major inflowing river: | Lumi | ||
Physical and chemical data (Kilham, 1971) | |||
Total alkalinity: | CaCO3 437 mg/l | ||
Conductivity: | K25 618 μ S/cm | ||
Ionic composition: | mg/l | ||
Na | 170.0 | ||
K | 11.0 | ||
Ca | 7.6 | ||
Mg | 20.2 | ||
Cl | 94.0 | ||
SO4 | 8.0 | ||
SiO2 | 46.0 |
Fisheries data
Total annual catch and effort (in Kenya)
Year | Total catch (t) | No.of fishermen | No.of boats | Source |
1965 | 150 | 514 | - | (a) |
1982 | 409 | - | - | (b) |
1983 | 463 | - | - | (b) |
1984 | 396 | - | - | (b) |
1985 | 94 | 50* | 10* | (b) |
1986 | 128 | 50* | 10* | (b) |
* including Lake Chala
(a) Source: FAO/UNDP, 1966
(b) Source: Statistical Bulletin, Fisheries Dept., Govt. of Kenya
Potential annual yield:
100 t (Welcomme, 1979a)
300 t (FAO/UNDP, 1966)
LAKE KABONGO
Geographical data | |
Location: | Kenya - 2°7'S; 36°25'E |
Altitude: | 1 066 m |
Surface area: | 3.2 km2 |
Max. length: | 4.5 km |
Max. width: | 1 km |
LAKE KANYABOLI
Geographical data | |
Location: | Kenya - 0°4'N; 34°10'E |
Altitude: | 1 189 m |
Surface area: | 10.5 km2 |
Max. length: | 5 km |
Max. width: | 3 km |
Inflowing river: | Yala |
LAKE KWENIA
Geographical data | |
Location: | Kenya - 1°47'S; 36°30'E |
Altitude: | 1 140 m |
Surface area: | 7 km2 |
Max. length: | 5 km |
Max. width: | 2 km |
LAKE LOGIPI (NAMAKAT)
Geographical data | |
Location: | Kenya - 2° 14'N; 36° 33'E |
Surface area: | 22.8 km2 |
Max. length: | 6.5 km |
Max. width: | 5 km |
LAKE MAGADI
Geographical data | ||||
Location: | Kenya - 1° 43'– 2° 00'S; 36° 13'–36° 18'E | |||
Altitude: | The lake area is divided in two by a ridge to give a large southern element (Amagad) which lies at 660 m, and a smaller element (Little Magadi) which lies at 683 m. | |||
Surface area: | 108 km2 | |||
Depth: | 0.6 m (max) (Tuite, 1981) | |||
Special features: | (Burgis & Mavuti, 1987) Lake Magadi only contains water after heavy rain and its alkaline sediments are commercially exploited for soda ash. It is the second largest expanse of solid trona (sodium carbonates and derivatives) in the world. It has almost no input of freshwater and is fed primarily by “boiling hot soda springs”. It has no outlet. | |||
Physical and chemical data | ||||
Conductivity: | K20 160 000 μ S/cm (Talling & Talling, 1965) | |||
Surface temperature: 28–43°C | ||||
pH: | <10.5 (Coe, 1966) | |||
Ionic composition: | (Talling & Talling, 1965) | |||
mg/l | ||||
Na | 38 000 | |||
K | 537 | |||
Ca | <10 | |||
Mg | <30 | |||
HCO3+CO3 | 7 980 | |||
Cl | 22 600 | |||
CO4 | 900 | |||
SiO2 | 250 | |||
Total P | 11 000 | μ g/l | ||
Fisheries data: | The endemic cichlid Oreochromis alcalicus grahami (Coe, 1966) is confined to hot springs at the lake margins where they tolerate temperatures up to 40°C, salinities around 30‰ and pH of 10.5. |