302
J.E. Conde . G. Rodriguez
mographic boom was the unveiling of huge oil reserves, which triggered intense migratory influxes towards the State of Zulia. In 1941 more than 20% of the population in
the area had arrived from other regions (Vila 1952). Other densely populated areas are
the Colombian city of Cucuta and several towns located on the Norte de Santander
Departament, where 922700 persons have taken up residence.
In turn, this spectacular population growth has translated into two important impacts: (a) Land reclamation for urban and agricultural purposes; and (b) alteration of
baseline conditions in the basins. At the same time, intervention of basins has bring
about changes in the hydrological regime of the tributaries to the lake, due to deforestation, water course diversions for irrigation, and industrial and domestic uses; nutrient enrichment due to fertilizers employed in agriculture and cattle fodder, and because of the increase in domestic discharges carrying human excreta and phosphorous-rich detergents. Presently, the basins with the highest deforestation rates are those
in the Serrania de Perija, where furtive Colombian poppy growers have settled and
entrepreneurs are illegally extracting timber.
16.4
Water Diversion and Impoundment
The population boom has also caused an additional demand for water. Diking, damming, river bed diversion, and electric power generation, usually have huge ecological
impacts on ecosystems and communities. Another effect of the alterations to uplands
hydrology and changes to river's beds and flows due to agriculture, livestock raising
and urban development, is the erosion and transportation of particulate material and
its ensuing deposition in the coastal hinterlands an into the lake. Although the sedimentation of larger grains is considered a minor hazard to Lake Maracaibo, since they
are deposited in the flooded plains, muds and clays do silt in the lake and its impact
should be evaluated.
In 1996 there were four reservoirs in the Lake Maracaibo basin. Currently, water for
human and industrial consumption for EI Tablazo area and the city of Maracaibo comes
from the Tule Reservoir, which receives the Cachiri river water and the input of the
Socuy river through the Manuelote river. Both reservoirs supply 6 000 I of water per
second. On the western shore, the Viejo River Reservoir drains the Grande and Chiquito
rivers. Other reservoirs are on the Motatan river and on Onia river, a tributary of the
Escalante river. Besides, marginal dikes for flooding control and land reclamation have
been built in the Catatumbo, Chama and Escalante rivers.
Electric power generation also taxes heavily on the basin's water budget. For instance,
the Central Termoelectrica Tachira in the basin of the Tachira river, a tributary of the
Escalante river, has an output of 25 megawatts, while using 3 million m 3 of water yearly.
On the lake's shore, next to the city of Maracaibo, the Central Termoelectrica de Arriaga
utilizes 264 million m 3 of water annually to generate 220 MW. The Central Pueblo Viejo,
produces 40 MW and uses 48 million m 3 a-I. By consuming 24 million m 3 of water, the
Central San Lorenzo, yields 20 MW (COPLANARH 1972).
Cane sugar mills also are large water consumers. The Central Azucarero Merida,
located in the basin of the Chama river, uses 4000 m 3 of irrigation water to treat cane
that is cultivated over 500 ha. The Central Urena, in the Tachira river watershed, processes 2000 ha of cane using 6000 m 3 of irrigation water. The Central Bobures, at the
J.E. Conde . G. Rodriguez
mographic boom was the unveiling of huge oil reserves, which triggered intense migratory influxes towards the State of Zulia. In 1941 more than 20% of the population in
the area had arrived from other regions (Vila 1952). Other densely populated areas are
the Colombian city of Cucuta and several towns located on the Norte de Santander
Departament, where 922700 persons have taken up residence.
In turn, this spectacular population growth has translated into two important impacts: (a) Land reclamation for urban and agricultural purposes; and (b) alteration of
baseline conditions in the basins. At the same time, intervention of basins has bring
about changes in the hydrological regime of the tributaries to the lake, due to deforestation, water course diversions for irrigation, and industrial and domestic uses; nutrient enrichment due to fertilizers employed in agriculture and cattle fodder, and because of the increase in domestic discharges carrying human excreta and phosphorous-rich detergents. Presently, the basins with the highest deforestation rates are those
in the Serrania de Perija, where furtive Colombian poppy growers have settled and
entrepreneurs are illegally extracting timber.
16.4
Water Diversion and Impoundment
The population boom has also caused an additional demand for water. Diking, damming, river bed diversion, and electric power generation, usually have huge ecological
impacts on ecosystems and communities. Another effect of the alterations to uplands
hydrology and changes to river's beds and flows due to agriculture, livestock raising
and urban development, is the erosion and transportation of particulate material and
its ensuing deposition in the coastal hinterlands an into the lake. Although the sedimentation of larger grains is considered a minor hazard to Lake Maracaibo, since they
are deposited in the flooded plains, muds and clays do silt in the lake and its impact
should be evaluated.
In 1996 there were four reservoirs in the Lake Maracaibo basin. Currently, water for
human and industrial consumption for EI Tablazo area and the city of Maracaibo comes
from the Tule Reservoir, which receives the Cachiri river water and the input of the
Socuy river through the Manuelote river. Both reservoirs supply 6 000 I of water per
second. On the western shore, the Viejo River Reservoir drains the Grande and Chiquito
rivers. Other reservoirs are on the Motatan river and on Onia river, a tributary of the
Escalante river. Besides, marginal dikes for flooding control and land reclamation have
been built in the Catatumbo, Chama and Escalante rivers.
Electric power generation also taxes heavily on the basin's water budget. For instance,
the Central Termoelectrica Tachira in the basin of the Tachira river, a tributary of the
Escalante river, has an output of 25 megawatts, while using 3 million m 3 of water yearly.
On the lake's shore, next to the city of Maracaibo, the Central Termoelectrica de Arriaga
utilizes 264 million m 3 of water annually to generate 220 MW. The Central Pueblo Viejo,
produces 40 MW and uses 48 million m 3 a-I. By consuming 24 million m 3 of water, the
Central San Lorenzo, yields 20 MW (COPLANARH 1972).
Cane sugar mills also are large water consumers. The Central Azucarero Merida,
located in the basin of the Chama river, uses 4000 m 3 of irrigation water to treat cane
that is cultivated over 500 ha. The Central Urena, in the Tachira river watershed, processes 2000 ha of cane using 6000 m 3 of irrigation water. The Central Bobures, at the