THE PANAMA CANAL :

 

History

 

The Panama Canal, described as one as most important works of engineering in the world, was inaugurated on August 15, 1914. This complex structural system allows the passage of ships between the Atlantic and the Pacific oceans, considerably reducing shipping distances between nations around the globe.   Before the construction of the Panama Canal, the Straits of Magellan around the southern tip of South America was the route used to go from one ocean to the other.  This sea route not only took much more time, but in addition it was a very dangerous journey. 

 

Many powers were interested in the construction of a route through some narrow portion of the American continent that would expedite communication between countries bordering either ocean. This idea goes back to the time of the conquest of the continent by the Spaniards in the 1500s.  It was not until 1878, however, that a formal agreement was reached in Paris, between France and Colombia, to carry out the construction of an inter-oceanic sea level Canal that would cross the Central American Isthmus (Castillero, 1962).  The task of directing such enterprise was given to Fernando de Lesseps, the man who had been in charge of constructing of the Suez Canal. 

 

However, difficulties in the administration and company organization as well as health problems forced the interruption of the Canal’s construction in 1890.  The construction company was cited to appear before the French courts, and eventually had to declare bankruptcy. Four years later, a new European company resumed the work, but they too could not advance much, and ended up transferring its rights to the United States of North America in 1899 (Castillero,1962).

The building of the Canal by the United States  did not start without major changes in the regional political arena.  At the time, the Isthmus of Panama was but an administrative department of Colombia.  To make official the construction of the Canal by the US, the Herrán-Hay treaty was put forward on January 22, 1903.  However, the Colombian Senate did not agree with the wording of the document, and rejected the treaty on the basis that it was harmful to the sovereignty of Great Colombia (Castillero, 1933).  This situation motivated the United States to promote and support the separation of Panama from Colombia.  On November 3, 1903, the Isthmus of Panama declared its independence. Fifteen days later, the government of the newly established Republic of Panama and the United States signed the Hay-Bunau Varilla treaty which was based on the same conditions that had the previously rejected by Colombia Herrán-Hay treaty.

 

Analyzing the various problems that faced the companies that had previously tried to carry out the construction of the Canal, the United States decided to build a waterway with locks. In addition, they were well organized, administratively and technically.  But most important, the US had the means to mitigate the existing sanitary problems in the region, such as yellow fever, that had caused the loss of several thousands of human lives during previous construction attempts. Having overcome all of the difficulties that a work of this magnitude presented, the Panama Canal was finally inaugurated by the government of the United States in mid-August 1914.

 

The administration and operation of the Panama Canal was carried out jointly by a complex US civilian and military apparatus. To guarantee the security of the Canal, the United States received the concession of a strip of land eight kilometers wide on each side of the Canal and of the small portion of the Chagres watershed delimiting Madden Lake.  This strip of land was to be known as the Panama Canal Zone.

 

As time passed, and Panama began to grow as a nation, a new sense of nationalism developed.  The Panamanians felt the need to re-negotiate the American presence in the Canal Zone.  This motivated the formulation of new agreements between both nations.  After almost seventy-five years of symbiosis, interrupted frequently by periods of great tension between the “zoneans” and the Panamanians and the consequent cycles of unstable diplomatic relations, in 1977 the Torrijos-Carter treaty was signed.  Under this treaty, the United States was committed to return to the Government of the Republic of Panama the complete control of the Canal on the December 31, 1999. 

 

The repatriation of the Canal Zone to Panama has just taken place. At present, the Panama Canal is administered by the Panamanians and it is incumbent on the Authority of the Panama Canal (in Spanish, Autoridad del Canal de Panamá, ACP) to effectively continue to comply with the tasks for which it was built.

 

 

The Panama Canal Hydrographic Watershed

 

The Canal watershed (see Figure 1)

 

 

is defined as the geographic area, the surface and underground waters which flow toward the Canal and/or are spilled into it or into its tributary lakes.  The borders of the watershed are defined by an imaginary line that joins the highest points of the mountains that surround the hydrologic system of the Canal.  Until 1999, the watershed was said to cover 1,289  square miles. With the approval of the new  Law 44 of  August  31, 1999,  the legal territory of the hydrographic watershed was extended to included three other river basins, namely Rio Indio, Caño Sucio and Coclé del Norte, all three located to the west of Gatun lake in the Atlantic region (Donoso and Adames, 2000).

 

The Madden dam divides the Canal watershed into 2 different regions: 1) the upper basin  to the east of the navigation channel, which includes Madden Lake and its tributaries - the Chagres, Pequení and Boquerón rivers; and 2) the lower basin, which consist of main Gatun Lake and its tributaries, the Gatun rivers, Ciri Grande and Trinidad. The upper basin is a region of mountain land and dense forests. The lower basin region is conformed of small hills and smooth slopes.

 

The Canal not being at sea level (lake Gatun is  85 feet above sea level), the ships are elevated by a system of three sets of locks. Going from the Atlantic Ocean towards the Pacific, a ship passes the locks of Gatun, Pedro Miguel and Miraflores,  (see Figure 2).

 

 

The locks are fed by water displaced only by the effects of gravity; water in not pumped into the locks. The water elevates or descends the ships in the locks. During each transit, approximately 52 million gallons of water are used. The total water storage capacity of the Canal is of approximately 1,660 billions of gallons. However, the net capacity is of approximately 365 billions of gallons. The Gatun Lake provides 203 billions of gallons, and the Madden Lake 162 billions of gallons.

 

According to Article 84 of the Law of July 1, 1998,  "the administration, use, maintenance and conservation of the water resources of the hydrographic watershed of the Panama Canal, will be the responsibility of the Panama Canal Authority, in coordination with the National Authority for the Environment (ANAM, in Spanish), and having as a basis the strategies, policies and programs related to the sustainable management of the natural resources in these river basins ".

The Authority of the Panama Canal  uses the water of the canal  watershed according to the following distribution:  58 percent  for the operation of the locks, 36 percent  for the generation  of hydroelectric power, and  6 percent for municipal consumption (C. Vargas, pers. comm., 1999).

 
General Overview of the Hydrologic Cycle in the Panama Canal Watershed

 

The climate of the region is characterized as tropical.  Both, temperature and humidity are relatively high throughout the year, and precipitation is abundant. There is a clear seasonal variation in the time distribution of precipitation.  The dry season normally begins around December and lasts approximately 4 months, whereas the rainy season covers the rest of the year (approximately 8 months).

The annual mean precipitation for the stations in the Canal watershed vary between a maximum of more than 3,300 mm (130 inches), on the Atlantic coast, to a minimum of approximately 1,500 mm (60 inches), in the Pacific coast. In general, for the entire watershed, the annual mean precipitation from climatology for a period of 10 years (1985-1994) is 2.596 mm (102 inches). The stations located in the Madden Lake report an annual mean precipitation generally higher than that reported by the stations located in the area downstream of the Madden dam.

 

High winds usually occur during the floods season, and tend to extend from September to the beginning of January. Maximum winds are predominantly from the northwest with an average speed of approximately 12.9 Km/h (8 mph). The maximum gusts are generally smaller than 48 km/h (30 mph), and are usually associated with thunderstorms.

 

The run-off distribution in the Panama Canal watershed is seasonal, extremely variable, and follows the same pattern as the precipitation. Beginning around May, the run-off begins to increase until October and November (normally the months of maximum run-off), and diminishes gradually during the dry season, from December through April.  The Madden Lake sub-basin is a more productive region in terms of water resources availability than the sub-basin downstream of the Madden dam. Although the area of the sub-basin of Madden only represents approximately 31 percent of the total area of the Hydrographic Canal watershed, the water contributed by this region adds to 45 percent of the total run-off of the basin.

 

As was indicated earlier, the annual mean precipitation from climatology at the Panama Canal watershed is 2.596 mm (102 inches). The water losses in the watershed due to infiltration, evapotranspiration processes in plants, and other external factors, are considered to be around 41 percent, that is to say, 1,061 mm (42 inches). Therefore, the gross amount of water that manages to store itself in the lakes is only 59 percent of the total annual rainfall that is approximately 1.535 mm (60 inches). Of this accumulated gross amount of water stored in the lakes, approximately 11 percent, equivalent to 174 mm (7 inches), is lost by the effects of direct evaporation from the surface of the Gatun and Madden lakes. The remainder 89 percent, 1361 mm (53 inches), constitutes the net run-off.