Geography of Ecuador

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Ecuador is one of the smaller countries in South America. Located on the west coast and straddling the equator, Ecuador has a total area of about 280,000 square kilometers, which includes the Galápagos Islands. Roughly the size of the state of Colorado, Ecuador encompasses a wide range of natural formations and climates, from the desertlike southern coast to the snowcapped peaks of the Andes Mountains to the plains of the Amazon River Basin.

Ecuador is bounded on the west by the Pacific Ocean, on the north by Colombia, and on the east and south by Peru. Ecuador continues to contest the boundary with Peru, which was established by the Protocol of Peace, Friendship, and Boundaries (Rio Protocol) of 1942 and ceded to Peru a large portion of territory east of the Andes.

Natural Regions

Ecuador is divided into three continental regions--the Costa, Sierra, and Oriente--and one insular region--the Galápagos Islands. The continental regions extend the length of the country from north to south and are separated by the Andes Mountains. The Galápagos Islands, officially called the Archipiélago de Colón, are located 1,000 kilometers west of the Ecuadorian coast within 1 south of the equator.

The Costa, located between the Pacific Ocean and the Andes Mountains, consists of coastal lowlands, coastal mountains, and rolling hills that separate river valleys. The widest part of the region stretches 150 kilometers from Cabo San Lorenzo in Manabí Province to the foothills of the Andes Mountains. In the southern part of Guayas Province, east of the Gulf of Guayaquil, the narrow coastal plain is only fifteen to twenty kilometers wide. The lowlands of the Costa do not exceed 200 meters in elevation, whereas the coastal mountains extend no higher than 1,000 meters. The coastal mountain chain, known as the Cordillera Costañera, divides the region into the Costa Externa, next to the coast, and the Costa Internal, next to the Andes. The Cordillera Costañera reaches from Esmeraldas in the north to Guayaquil in the south. North of Portoviejo in Manabí Province, the Cordillera Costañera loses its character as a mountain chain and becomes a series of hills and small mountains.

The Sierra consists of two major chains of the Andes mountains, known as the Cordillera Occidental (Western Chain) and Cordillera Oriental (Eastern Chain), and the intermontane basin or plateau between the two chains. Several transversal mountain spurs, known as nudos, cut across the plateau. The Nudo del Azuay, at 4,500 meters the highest of these transversal spurs, divides the Sierra into two subregions--the area of modern volcanism to the north and the area of ancient volcanism to the south. The former area consists of newer, higher mountains than those in the ancient volcanism section, which with time have eroded to lower levels.

The Sierra has at least twenty-two peaks over 4,200 meters in height. Of the two cordilleras, the Cordillera Oriental is wider and generally higher, with peaks averaging over 4,000 meters. The Cordillera Occidental, however, contains the highest point in Ecuador, which is the Mount Chimborazo at 6,267 meters. The Sierra also contains the highest point on the equator, Mount Cayambe at 5,790 meters.

The Sierra has at least thirty peaks of volcanic origin, including six still active. These peaks, which vary in width from 80 to 130 kilometers, are located in the area of modern volcanism known as the Avenue of the Volcanos. The most active volcano is Mount Sangay, 5,230 meters high. Although its last major outpouring of lava occurred in 1946, specialists consider Mount Sangay to be in a constant state of eruption because of fires and bubbling lava at its crater. Mount Cotopaxi, at 5,897 meters the highest active volcano in the world, last erupted in 1877 and is now listed as "steaming." Its crater is 800 meters in diameter. In addition to the other damage caused by eruptions, volcanos in the Sierra have melted snowcaps, which in turn generate massive mudslides and avalanches. Earthquakes and tremors also are common in the region.

The intermontane plateau between the two cordilleras is divided by the nudos into roughly 10 basins, or hoyas, that range from 2,000 to 3,000 meters in altitude. The average altitude of the plateau is 2,650 meters.

The Oriente to the east of the Cordillera Oriental consists of two subregions: the Andean piedmont and the Eastern lowlands. The piedmont drops from a height of 3,353 meters to the featureless lowlands, which spread out at an altitude of 150 to 300 meters.

The Galápagos Islands consist of a chain of large, medium, and small islands that have a combined area of roughly 8,000 square kilometers. The largest island is Isabela Island, also known as Albemarle Island, which is 120 kilometers long with an area of 4,275 square kilometers. All of the islands are of volcanic origin, and some have active cones. Santo Tomás, located on Isabela Island, is the highest peak of the Galápagos at 1,490 meters. Its crater is ten kilometers in diameter.


Almost all of the rivers in Ecuador rise in the Sierra region and flow east toward the Amazon River or west toward the Pacific Ocean. The rivers rise from snowmelt at the edges of the snowcapped peaks or from the abundant precipitation that falls at higher elevations. In the Sierra region, the streams and rivers are narrow and flow rapidly over precipitous slopes. Rivers may slow and widen as they cross the hoyas yet become rapid again as they flow from the heights of the Andes to the lower elevations of the other regions. The highland rivers broaden as they enter the more level areas of the Costa and the Oriente.

In the Costa region, the Costa Externa has mostly intermittent rivers that are fed by constant rains from December through May and become empty riverbeds during the dry season. The few exceptions are the longer, perennial rivers that flow throughout the Costa Externa from the Costa Internal and the Sierra on their way to the Pacific Ocean. The Costa Internal, by contrast, is crossed by perennial rivers that may flood during the rainy season, sometimes forming swamps.

The Guayas River system, which flows southward to the Gulf of Guayaquil, constitutes the most important of the drainage systems in the Costa Internal. The Guayas River Basin, including land drained by its tributaries, is 40,000 square kilometers in area. The sixty-kilometer-long Guayas River forms just north of Guayaquil out of the confluence of the Babahoyo and Daule rivers. Briefly constricted at Guayaquil by hills, the Guayas widens south of the city and flows through a deltaic network of small islands and channels. At its mouth, the river forms a broad estuary with two channels around Puná Island, the deeper of which is used for navigation.

The second major Costa river system--the Esmeraldas--rises in the Hoya de Quito in the Sierra as the Guayllabamba River and flows westward to empty into the Pacific Ocean near the city of Esmeraldas. The Esmeraldas River is 320 kilometers long and has a 20,000-square-kilometer drainage basin.

Major rivers in the Oriente include the Pastaza, Napo, and Putumayo. The Pastaza is formed by the confluence of the Chambo and the Patate rivers, both of which rise in the Sierra. The Pastaza includes the Agoyan waterfall, which at sixty-one meters is the highest waterfall in Ecuador. The Napo rises near Mount Cotopaxi and is the major river used for transport in the Eastern lowlands. The Napo ranges in width from 500 to 1,800 meters. In its upper reaches, the Napo flows rapidly until the confluence with one of its major tributaries, the Coca River, where it slows and levels off. The Putumayo forms part of the border with Colombia. All of these rivers flow into the Amazon River. The Galápagos Islands have no significant rivers. Several of the larger islands, however, have freshwater springs.


Each region has different factors that affect its climate. The Costa is influenced primarily by proximity to warm or cool ocean currents. By contrast, climate in the Sierra varies more as a function of altitude. The Oriente has a fairly uniform climate that varies only slightly between the two subregions. Climate in the Galápagos Islands is both moderated by the ocean currents and affected by altitude. Throughout Ecuador variation in rainfall primarily determines seasons. Temperature is determined by altitude. With each ascent of 200 meters in altitude, temperature drops 1° C. This phenomenon is particularly significant in the Sierra.

The Costa has a tropical climate. Temperatures for the region as a whole remain fairly constant, ranging from 23° C in the south to 26° C in the north. Although seasonal changes in temperature are not pronounced, the hottest period occurs during the rainy season, especially from February to April. Near Guayaquil, the coolest months are August and September. Rainfall in the Costa decreases from north to south, with vegetation changing from tropical rainforest in the north to tropical savannah to desert in the south.

Differences in temperature and rainfall in the Costa are caused by the Peruvian Current and periodic appearances of El Niño. The Peruvian Current, also formerly known as the Humboldt, is a cold ocean current that flows north along the coasts of Chile and Peru. At Cabo Blanco, where the Gulf of Guayaquil begins, the main current veers to the west; a branch continues northward to Cabo Pasado, in Manabí Province, where it also turns westward to merge with the main current near the Galápagos Islands. The cold water and air temperatures associated with the Peruvian Current inhibit rainfall along the coast, creating dry to arid conditions. This effect is greatest along the southern coast of Ecuador.

The El Niño occurs periodically every six or seven years. Starting in late December, a change in atmospheric pressure shifts ocean currents so that warm waters come closer to shore and displace the cold waters. During this time, air and water temperatures, tides, sea levels and wave heights, and relative humidity all are higher than usual. These conditions produce heavy rainfall that generally lasts until May in an area that normally experiences nothing more than a drizzle. The resulting flooding and landslides can be devastating.

When the Peruvian Current is dominant, the amount of precipitation along the coast varies from north to south, with levels ranging from 300 centimeters to 30 centimeters, respectively. Two rainy seasons in the northernmost part of the coast become a single season (December through June) not far south. Near Esmeraldas, average annual rainfall is 250 centimeters. The rainy season shortens farther south, lasting only from January to May at Guayaquil. Very little rainfall occurs on the end of the Santa Elena Peninsula west of Guayaquil. Arid conditions prevail on the border with Peru south of the Gulf of Guayaquil.

Separated from the effects of ocean currents by the Cordillera Costañera, the Costa Internal has a hot and humid climate. Temperatures can surpass 26° C, and the vegetation and cloud cover tend to retain and augment the heat. Rain is constant during the winter months of December through May, with the heaviest rainfall occurring in February and March.

Temperatures in the Sierra do not vary greatly on a seasonal basis; the hottest month averages 16° C and the coolest month, 13° C in the upper elevations. Diurnal temperatures, however, vary dramatically, from cold mornings to hot afternoons. The almost vertical sun and the rarified air in the higher Sierra region allow the land to warm quickly during the day and lose heat quickly at night. Mornings typically are bright and sunny, whereas afternoons often are cloudy and rainy. In general, rainfall amounts are highest on exposed locations at lower altitudes. Rain also can vary on a local basis. Sheltered valleys normally receive 50 centimeters per year, whereas annual rainfall is 150 centimeters in Quito and can reach 250 centimeters on exposed slopes that catch rain-bearing winds. On a seasonal basis, the driest months are June through September.

Climate in the Sierra is divided into levels based on altitude. The tropical level--400 to 1,800 meters--has temperatures ranging from 20° C to 25° C and heavy precipitation. The subtropical level-- 1,800 to 2,500 meters--has temperatures from 15° C to 20° C and moderate precipitation. The temperate level--2,500 to 3,200 meters- -has a year-round temperature in the range of 10° C to 15° C and an annual rainfall of 100 centimeters. The temperate level experiences rainstorms, hailstorms, and fog. Winter, or the rainy season, lasts from January through June, and the dry season or summer from July through December. Most rain falls in April. There also is a short rainy period in early October caused by moisture penetrating the Sierra from the Oriente. Quito and most other populated areas in the Sierra are located at this temperate level. The cold level extends from the temperate zone to 4,650 meters. Here, average temperatures are 3° C to 9° C, and the precipitation often appears in the form of rain, hail, and thick fog. Above 4,650 meters is the frozen level, where peaks are constantly capped with snow and ice, and temperatures range from below zero to 3° C. Precipitation frequently is in the form of snow, fog, and rain.

The Eastern lowlands in the Oriente experience an equatorial climate. Rainfall is abundant, especially in the Andean piedmont, sometimes exceeding 500 centimeters per year. Temperatures average 25° C in the western parts of this region. The jungle-covered plains of the Eastern lowlands register high levels of rainfall and temperatures surpassing 28° C.

Being located on the equator, the Galápagos Islands would have an equatorial climate were it not for the modifying effects of the Peruvian Current. Instead, climate on the islands follows a pattern more like that of the Sierra than the Costa. At sea level, the land is desertlike with temperatures of 21° C. The eight summer months experience no precipitation, whereas the winter months of January through April have some fog and drizzle. Above sea level to an altitude of 450 meters, the islands have a mixture of tropical, subtropical, and temperate climates. In general, temperatures are around 17° C. There is constant fog and drizzle in the summer and rain in the winter. The cold level above 450 meters has temperatures below 14° C.

SOURCE: Library of Congress Country Studies/Area Handbook

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