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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.
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.
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.