GEOGRAPHY AND POPULATION
The Libyan Arab Jamahiriya has a total area of about 1.76 million km². It is bordered in the east by Egypt and Sudan, on the south by Chad and Niger, in the west by Algeria and Tunisia, and in the north by the Mediterranean Sea. Four physiographic regions can be distinguished:
About 95 % of the country is desert. The cultivable area was estimated at 3.80 million ha, which is only slightly over 2 % of the total area. In 1987, the total cultivated area was estimated at 2.28 million ha, or 60 % of the cultivable area, of which 1.93 million ha consisted of annual crops and 0.35 million ha consisted of permanent crops.
TABLE 1 - Basic statistics and population
|Area of the country||1995||175 954 000||ha|
|Cultivable area||1992||3 800 000||ha|
|Cultivated area||1987||2 278 648||ha|
|- annual crops||1987||1 933 648||ha|
|- permanent crops||1987||345 000||ha|
|Total population||1995||5 407 000||inhabitants|
|Population density||1995||-||3 inhab./km²|
|Water supply coverage:|
The total population is about 5.4 million (1995) of which 14 % is rural. The annual demographic growth rate was 4. 1% between 1980-91. The average population density is 3 inhabitants/km², but varies between 50 inhabitants/km³ in the northern regions of Tripolitania and Cyrenaica to less than 1 inhabitant/km³ elsewhere. Agriculture contributes less than 5% to GDP, although it provides employment for approximately 13 % of the active population.
CLIMATE AND WATER RESOURCES
The climatic conditions are influenced by the Mediterranean sea to the north and the Sahara desert to the south, resulting in an abrupt transition from one kind of weather to another. The following broad climatic divisions can be made:
TABLE 2 - Water: sources and use
|Renewable water resources:|
|internal renewable water resources||0.6||km³/yr|
|Total (actual) renewable water resources||1995||0.6||km³/yr|
|Total (actual} renewable water resources per inhabitant||1995||111||m³/yr|
|Total dam capacity||1992||387||106 m³|
|- agricultural||1994||4 000||106 m³/yr|
|- domestic||1994||500||106 m³/yr|
|- industrial||1994||100||106 m³/yr|
|Total water withdrawal||4 600||106 m³/yr|
|as % of total (actual) renewable water resources||767||%|
|Other water withdrawal||-||106 m³/yr|
|Average groundwater depletion||-||106 m³/yr|
|Wastewater - Non-conventional water sources:|
|- produced wastewater||-||106 m³/yr|
|- treated wastewater||-||106 m³/yr|
|- reused treated wastewater||1990||100||106 m³/yr|
|Desalinated water||1988||70||106 m³/yr|
The average annual rainfall is 26 mm, with more than 100 mm/year over only 7% of the land surface. The highest rainfall occurs in the northern Tripoli region (Jabal Nafusah and Jifarah Plain) and in the northern Benghazi region (Jabal al Akhdar) - these two areas being the only ones where the average annual rainfall exceeds the minimum value (250-300 mm) considered necessary to sustain rainfed agriculture. Rainfall occurs during the winter months, but great variability is observed over space and time (year to year).
The total mean annual runoff calculated or measured at the entrance of the wadis in the plains is estimated at 200 million m³/year, but part of it either evaporates or contributes to the recharge of the aquifers. Therefore the surface water resources are roughly estimated at 100 million m³/year. Sixteen dams, with a total storage capacity of 387 million m³ and with an expected average annual volume of water controlled in the order of 60 million m³, had been constructed by 1991. Additional dams are planned, to achieve a total storage capacity of 686 million m³. This difference between the average annual runoff and the storage capacity of the dams is so that the runoff water of exceptionally wet years can be stored.
Currently, aquifers are only recharged only in the northern regions, namely in the northwestern zone, Jabal Nafusah and Jifarah Plain, and in the north-eastern zone, Jabal al Akhdar. Renewable groundwater resources are estimated at 800 to 1 000 million m³/year, but part (perhaps 50%) now flows out either to the sea or to evaporative areas (sabkhas). Not all the renewable groundwater can be abstracted without affecting the environment, because of the deterioration of water quality by saline water encroachment. For this reason, the safe yield has been estimated at 500 million m³/year. South of the 29th parallel, an important development of Palaeozoic and Mesozoic continental sandstone enabled water to be stored safely during the long period of the late Quaternary, before the climate turned extremely arid. Most water used in Libya comes from these huge fossil reserves.
TABLE 3 - Irrigation and drainage
|Irrigation potential||1992||750 000||ha|
|1. Full or partial control irrigation: equipped area||1990||470 000||ha|
|- surface irrigation||-||ha|
|- sprinkler irrigation||-||ha|
|% of area irrigated from groundwater||-||%|
|% of area irrigated from surface water||-||%|
|% of area irrigated from non-conventional sources||-||%|
|% of equipped area actually irrigated||1990||51||%|
|2. Spate irrigation area||-||ha|
|3. Equipped wetland and inland valley bottoms (i.v.b.)||-||ha|
|Total irrigation 11+2+3)||1990||470 000||ha|
|- as % of cultivated area||21||%|
|4. Flood recession cropping area||-||ha|
|Total water managed area (1+2+3+4)||1990||470 000||ha|
|- as % of cultivated area||21||%|
|- increase over last 10 years||-||%|
|- power irrigated area as % of water managed area||-||%|
|Full or partial control irrigation schemes: Criteria|
|Large-scale schemes > - ha||-||ha|
|Small-scale schemes < - ha||-||ha|
|Total number of households in irrigation|
|Total irrigated grain production||-||tons|
|as % of total grain production||-||%|
|Harvested crops under irrigation (full or partial control)||-||ha|
|- permanent crops: total||-||ha|
|- annual crops: total||-||ha|
|. other annual crops||-||ha|
|Drainage - Environment:|
|as % of cultivated area||-||%|
|- drained areas in full or partial control irrigated areas||-||ha|
|- drained areas in equipped wetland and i.v.b||-||ha|
|- other drained areas||-||ha|
|- total drained area with subsurface drains||-||ha|
|- total drained area with surface drains||-||ha|
|Area salinized by irrigation||-||ha|
|Population affected by water-borne diseases||-||inhabitants|
Through the Great Manmade River Project about 2 km³/year of fossil water is expected to be transported from the desert to the coastal areas, mainly for irrigation but part will be used for the water supply of the major cities.
Desalinated water and treated wastewater
There have been several attempts during the last 20 years to introduce and expand sea water desalination plants and wastewater treatment facilities. However, so far restrictions have been imposed by the high cost of energy and spare parts. A number of desalination plants of different sizes have been built near large municipal centres and industrial complexes. The total capacity of installed plants is approximately 140 million m³/year, but sections of them are either not in use or only partly operational. It is estimated that only 70 million m³ of water is desalinated each year. The present level of wastewater treatment is estimated at about 100 million m³/year.
Total water withdrawal for agricultural, domestic and industrial purposes was estimated at 4.6 km³ in 1994, which is almost eight times the annual renewable water resources. About 87 % of total water withdrawal is used for agricultural purposes (Figure 1). All desalinated water is currently used for domestic and industrial purposes and all treated wastewater for agricultural purposes.
Figure 1 - Water withdrawal (total: 4.6 km³ in 1994)
IRRIGATION AND DRAINAGE DEVELOPMENT
Irrigation potential has been estimated at 750 000 ha. However, the development of this potential would have to rely mainly on the use of fossil water. Considering renewable water resources, it is estimated that a maximum of 40 000 ha could be irrigated in the coastal areas.
The total water managed area is approximately 470 000 ha, all equipped for full or partial control irrigation. Sprinkler irrigation is practiced on almost the entire area, because of the sandy soils prevailing in most areas of Libya. Of the total area of 470 000 ha, only 240 000 ha was actually irrigated according to figures from several years ago, distributed as listed in the table below.
Regional distribution of irrigation
|Zone||Geographic region||Area actually irrigated (ha)||Estimated water use (106m³/yr)*||Year (approx.)|
|Murzuq Basin||South-west||50 000||551||1985|
|Jifarah Plain||North-west||100 000||500||1985|
|Jabal Nafusah; Suf al Jin; Western||North-west|
|Sirte; Hammada el Hamra||and North||25 000||241||1985|
|Al Jabal al Akhdar||North-east||40 000||150||1985|
|Al Kufrah-As Sarir||South-east||25 000||423||1990|
|Total||240 000||1 865|
* Figures probably under-estimated.
There are three different categories of farming in the irrigation subsector:
At present, no water fees are imposed on water users.
Responsibility for all water resources assessment and monitoring rests with the General Water Authority, while the Secretariat of Agriculture and Animal Wealth is responsible for the development of irrigated agriculture and the implementation of major projects. A special Authority The Great Manmade River Water Utilization Authority - is responsible for the use for agricultural purposes of the water transported from the desert to the coast. The Secretariat of Municipalities takes care of the water supply to urban settlements.
TRENDS IN WATER RESOURCES MANAGEMENT
Over-extraction of groundwater in the coastal regions has led to a continuing decline in the groundwater level and sea water intrusion is estimated to be advancing at a rate of 100 to 250 m/year. If this over-extraction is not stopped or reversed, it is expected that these intrusions will lead to the contamination and pollution of all productive aquifers by the year 2000.
Irrigation development in Libya is linked to the implementation of the project to transport fossil water from the aquifer below the desert. Through the Great Manmade River Project, consisting of five phases, the total volume of water to be transferred and redistributed within the country will amount to about 2 km³/year for a period of at least 50 years (Figure 2):
Figure 2 - Planned water transfer through the Great Manmade River Project
Part of the water transported will be used for the water supply of the major cities on the coast: Tripoli, Benghazi, Sirt and Misratah.
In addition to the development of both groundwater and surface water, a further increase in water supplies could be achieved through expanding the reuse of treated wastewater and/or adopting desalination technology.
MAIN SOURCES OF INFORMATION
Pallas, P. 1980. Water resources of the Socialist People's Libyan Arab Jamahiriya. In: The Geology of Libya. Proceedings of the Second Symposium on the Geology of Libya. Academic Press, London.
Saad A. Alghariani. 1993. Satisfying future water demands of northern Libya.
Salem, O.M. 1992. The Great Manmade River project. In: Water Resources Development, 8(4).