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EL NIÑO AND LA NIÑA :
The Influence of El Niño and La Niña In
Panama
Panama’s
climate presents two distinct seasons, a rainy season (mid-April to
mid-December), and a dry season
(mid-December until mid –April).
The climatic events known as El Niño and La Niña have ample repercussion
in Panama. Both are characterized mainly by the alterations that they cause to
the regional precipitation patterns (Donoso and Bakkum, 1998)
El Niño is the
more studied of the two ENSO extremes, mainly because its effect on the country
is more widespread than that of its counterpart La Niña. Therefore, more information exists related
to El Niño than to La Niña. Depending on its intensity, El Niño usually causes
below normal precipitation in Panama, mainly on the Pacific side of Panama.
When a La Niña of considerable intensity occurs, precipitation in Panama tends
to be above normal. Floods tend to
accompany strong La Niña events. The intensity and duration of the deficit or
excess of rain in the country is highly correlated with the intensity of the
ENSO extreme event.
El Niño and La
Niña are responsible for causing major problems to the economy of the region,
and consequently to the economy of Panama. The appearance of these events
affects not only the economy of the country, but also the life of its
inhabitants (Comision Interinstitucional ENOS, 1997). Several socio-economic
sectors in the Republic of Panama are affected El Niño or La Niña. These
sectors include but are not limited to the following (CATHALAC, 1995):
·
The Water Resources and Energy Sector
·
The Natural Resources Sector
·
The Farming Sector
·
The Fisheries Sector
·
The Human Health Sector
According to
data released by government agencies and private companies, the productive
sectors experienced losses of over $50 million during the warm event of 1997-98
(Bouche, 1998).
Water Resources and Energy Sector
The energy generated in Panama is mainly
dependent on water resources availability; consequently, it depends on precipitation.
Therefore, energy generation is affected by El Niño. In years of extreme droughts, the country has been subjected to
blackout periods of more than five hours each day for several weeks (D. Farmun,
pers. Comm., 1999). During the 1997-98
El Niño, various cities of Panama experienced blackout periods ranging from two
to four hours (Cajar, 1998[a]). In addition to the irregularities in the
delivery of electric power supply, the population also suffers from shortages
in water supply for human consumption, mainly in urban areas. Equally, the transit of ships through the Panama
Canal has been affected by El Niño (Vargas, 1997). The most critical operating conditions due to drought observed since its construction were
registered during the events of 1982-83 and 1997-98. During the 1997-98 El Niño, the lakes of the Canal watershed
reached their lowest levels ever recorded in history. The Panama Canal
Commission, the organization in charge of the operation of the Canal at the
time, was forced to apply draft restrictions to ships in transit (M. Morris,
pers. comm., 2000).
Conversely, La Niña favors greater generation of hydroelectric power, because
of the considerable increase in the amount of rain. However, extreme events
have also caused problems. For one, the
intense and continuous rains can jeopardize the dams that form part of the
Canal system. Also, the necessity to
spill the excess waters can put in danger areas vulnerable to floods. Most
critical are areas populated by communities which tend to expand in the
direction of the rivers, and can thus be exposed to suffer great losses.
Natural Resources Sector
During the dry
season our country is periodically affected by forest fires. These fires not only harm the forests, but
also destroy the biological diversity of the region. This situation becomes
more critical in the presence of El
Niño (Diaz, 1998). Over most of the
last century, the Panama Canal watershed was considered part of the “Canal
Zone”, and was maintained under strict military surveillance. Very few trespassed beyond the barb-wired
fences that bordered “La Zona” (term used by the Panamanian to refer to the
Canal Zone). Forest fires in this area were totally due to
natural causes, lighting mostly.
Upon returning
the Canal Zone territory to the Republic of Panama (December 31, 1999), the
Authority of the Panama Canal was given the task to protect the watershed. This institution does not have the
capability of the US Armed forces to control trespassers. Therefore, the possibility of having big
forest fires during the next El Niño drought has increased exponentially. Already
during the 1997-98 warm event, several fires were reported in the Panama
Canal watershed. These were put
out rapidly, mostly by the US military,
and never progressed into major forest fires.
Farming Sector
During intense
El Niño events, the farming sector is one of the most affected. Severe droughts
cause poor crops production (rice, corn,
and beans, mainly). In May 10, 1998, under a photograph of a desert-like
countryside, the Panama America daily newspaper wrote “ El Niño phenomenon has
harmed farmers and Indian communities that live out of the products of the
land, and have not been able to harvest a thing since last year” (El Panama
America, 10 May, 1998). Some 3,861 Ha
insured under ISA (Instituto de Seguro Agropecuario) were affected by El
Niño. The most impacted crop was the
tomato. Around 48% of the losses
experienced in the agriculture sector were attributed to tomato plantations
(Rosales, 1998). Another important crop
affected was rice. In the provinces of
Herrera, Coclé and Veraguas, the Ministry of Agriculture Development granted
US$247,000.00 indemnification to over 233 rice-farmers (Muñoz, 1998).
Droughts reduce
the quality and quantity of pasture available for cattle, and therefore affects
the meat and milk production. In
addition, considerable amount of cattle die due to illnesses originated by the
shortage of water. The losses are considered in the tens of millions of
dollars. Only ISA itself paid 1.47
millions of US dollars compensation to 596 farmers and cattle raisers.
But not all
crops suffer because of El Niño. In the
provinces of Chiriqui and Bocas del Toro,
coffee growers reported a production increase of ten thousand sacs in comparison to last year’s yield (Bocharel,
1998).
In aquaculture,
a decrease in shrimp production is detected, due to low survival rates and poor
growth. Shrimp farming is very sensitive
to changes in precipitation and in air temperature.
During extreme
cold events or La Niña, many crops are also affected. This can occur because the planting season is delayed, or simply
because the rain is so abundant that it “drowns” the plants.
Fisheries Sector
The effects of
El Niño and La Niña in the Fisheries sector are not yet well understood.
However, some observations show a tendency toward a decrease in the number of
landings, during warm events. The cause
of this trend is attributed to the anomalous increase of the sea surface
temperatures (SST). Some local species
such as pargo and cherna
migrate to deeper waters when the SST increase. This migration makes it difficult for local fisherman to reach the schools of
fish in their indigenous weak fishing boats.
By mid-August 1997, the decrease in fish catchments had affected 95% of
the Pedesi district fishing industry
(Cortes, 1997; El Panamá América, 1997).
In addition,
the salinity of water in shallow inshore coastal areas is also altered during
ENSO events. A substantial decrease in precipitation or the abnormal extension
of the dry season can cause considerable increase of the salinity of shallow
near-shore coastal waters, such as delta areas. These changes in the properties
of sea water contributes to the migration of numerous species, and consequently
to the alteration of their biological
(reproductive) cycles.
Human Health Sector
The impacts of ENSO warm events on the
country’s economy is most significantly experienced by the poorest sectors of
the population, mainly farmers and natives.
Drinking water in rural areas becomes scarce, which brings as a
consequence an increase in the incidence of water-related diseases. As stated by Arturo Sanchez, member of the
Climate Change working group for Central America, the presence of EL Niño
conditions result in “an increase in insect and vector transmitted diseases,
such as dengue and malaria” (La Prensa, April 1, 1998). In many cases, the deterioration of the
quality of subsurface waters caused by infiltration from domestic and
industrial sources can aggravate the health scenario. Studies carried out by
researchers within the framework of the Trade Convergence Climate Complex (TC3)
research initiative also showed during El Niño 1997-98 an increases in the
number of people affected by respiratory, dermatological, and vector
transmitted diseases such as hepatitis, diarrhea, and dermatitis, among other
(Castro, 2000). According to government
health agencies, 53,683 families were treated for different illnesses related
to the 1997-98 El Niño (Castillo, 1999).
Not much
research has been done on the impacts of La Niña events on the general health
conditions of the population. However,
excessive rains and consequent floods are deemed to affect the incidence of
certain health problem, such as leishmaniasis, mainly in places susceptible to floods or water
stagnation.
Level of Scientific Investigation on El
Niño in Panama
The Department
of Meteorology and Hydrography of the Panama Canal Authority is mainly
responsible for the management of water resources in the Canal watershed. This institution has an operational mandate,
and has not carried out specifically scientific investigations on El Niño (M.
Morris, pers. comm., 2000). Nevertheless, making use of the records of physical
data registered over the years since 1903, they have produced time series that
after being processed and analyzed can be used to infer the effects of El Niño
in the Panama Canal watershed.
The Department of
Hydrometeorology of the Institute of Hydraulic Resources and Electrification
(IRHE, in Spanish), recently privatized under the name Electric Transmission
Company (ETESA, in Spanish], was responsible for monitoring the behavior of
meteorological parameters in time and space. Until the early 1990s, this was
the sole government institution to carry out sporadic studies of El Niño. These
studies were centered mainly on the variations of the precipitation in Panama
during warm events. In 1995, a study was carried out aiming to establish the
effects of El Niño in Panama, and its impact on the generation of electric
energy (CATHALAC, 1995).
Another
government institution, the Department of Agricultural Meteorology of the
National Authority for the Environment (ANAM) carried out a study on the
precipitation regime in Panama. This
study was of much value in dealing with the 1997-98 El Niño event although it
was not its main goal. This institution also started to work on an evaluation
of the impacts of the El Niño on the natural resources sector (C. Castillo,
pers. comm.,1999).
At some universities of the country,
evaluations have been made on the influence of the El Niño phenomenon
in several production sectors.
Studies on the influence of climate variability on certain crops have
been carried out by the Institute of Agricultural Research (IDIAP) of the
Ministry of Agriculture Development.
The interest in
Panama on the El Niño phenomenon begins to arise after the warm event of
1982-83, but very timidly, with few works of investigation as it were already
indicated. It is not but until the middle of the decade of the 90, when a
global scientific interest for this influential phenomenon is spread throughout
the continent, that Panama begins to involve itself intensively in ENSO
oriented research. An important role in
promoting and carrying out research on El Niño in Panama is being played by the
Trade Convergence Climate Complex Network (TC3). This group of researchers from the physical and social sciences
begin to organize different activities aimed to evaluate the impacts of El Niño
on crucial socio-economic sectors.
These activities bring together scientists and decision-makers. In the
mid 90's, Panama starts to take important steps to combine efforts between
different national institutions and regional organizations to exchange
experiences and knowledge and thus to increase the understanding of El Niño and
its effects and consequences in Panama. One of these first initiatives was the
organization by the TC3 Network, under the coordination of the Water Center for
the Humid Tropics of Latin America and the Caribbean (CATHALAC), of the First
National Forum " The El Niño Phenomenon and its Impact in Panama "
which took place in November 1995. Many national organizations participated in
the Forum, including personal of the Meteorology and Hydrography Branch of the
Panama Canal Commission, as well some international institutions.
In 1996, the
TC3 Network join forces with the Inter-American Institute on Climate Change
Research (IAI) to further strengthen research efforts on El Niño. In August 1996, the forum “El Niño
Phenomenon and its impact in the Socio-Economics Activities in the Central
Provinces of the Republic of Panama " was carried out under the partnership
of IAI, TC3 and CATHALAC (CATHALAC, 1996[a]). Other activities followed, such
as the forum “El Niño phenomenon and its impact in the Socio-Economics
Activities of Chiriqui and Bocas del Toro”
in October of 1996 (CATHALAC, 1996[b), and the workshop “The Impact of
the Phenomenon of El Niño on the Biological Systems of Central America "
in December of 1997 (CIFLORPAN, SENACYT, OEA, CATHALAC, CIUDAD DEL SABER,
1997).
At present,
research on the impacts of climate variability in Panama by the TC3 Network of
scientists continues in collaboration with the IAI and other regional
organizations.
El Niño and Its Impact on the Gatun
Lake Level
Historical
studies and meteorological records give support to the effects of El Niño on
the precipitation patterns of the country.
Early studies made by Estoque et
al. (1985) indicate that El Niño is associated with below normal
precipitation values. The annual mean deviation of the anomaly of the
precipitation during the years of the warm events is 8 percents below normal in
the region of the Canal watershed. Table 1 presents the anomalies in percentage
of precipitation for El Niño years according to Estoque et al. (1985). It can be observed that in 11 of the 12 years of
warm events, the precipitation anomaly is negative. It can also be observed
(Figure 3) that there is a reduction in the net river discharge contributing to
the Gatun Lake during El Niño years, which implies a decrease of the lake
level. The run-off is expressed in millions of cubic feet (MCF).
Figure 4 presents the registered levels of Gatun Lake during three of the most
severe recent events, 1976-77, 1982-83 and 1997-98.
It is possible
to see the clear decrease of the level of the lake. One can also observe how the level gets to be below critical
during extended periods. This fact
forced navigational draft restrictions in the Canal. After the deepening of the
navigable channel by 3 feet in 1983, the critical level was established at 81.5
feet (Panama Canal Spillway, 1996).
These records
are clear evidences of the existing relation between precipitation over the
Canal watershed and deficit in the Gatun Lake levels during El Niño years.