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Figure 3. Topography and Drainage

Izalco Volcano, Sonsonate Department

Two parallel mountain ranges cross El Salvador east to west with a central plateau between them and a narrow coastal plain hugging the Pacific (see fig. 3). These physical features divide the country into two physiographic regions. The mountain ranges and central plateau covering 85 percent of the land comprise the interior highlands. The remaining coastal plains are referred to as the Pacific lowlands.

The northern range of mountains, the Sierra Madre, forms a continuous chain along the border with Honduras. Elevations in this region range from 1,600 to 2,200 meters. The area was once heavily forested, but overexploitation led to extensive erosion, and it has become semibarren. As a result, it is the country's most sparsely populated zone, with little farming or other development.

The southern range of mountains is actually a discontinuous chain of more than twenty volcanoes, clustered into five groups. The westernmost group, near the Guatemalan border, contains Izalco and Santa Ana, which at 2,365 meters is the highest point in El Salvador. Between the cones lie alluvial basins and rolling hills eroded from ash deposits. The volcanic soil is rich, and much of El Salvador's coffee is planted on these slopes.

The central plateau constitutes only 25 percent of the land area but contains the heaviest concentration of population and the country's largest cities. This plain is about 50 kilometers wide and has an average elevation of 600 meters. Terrain here is rolling, with occasional escarpments, lava fields, and geysers.

A narrow plain extends from the coastal volcanic range to the Pacific Ocean. This region has a width ranging from one to thirty-two kilometers with the widest section in the east, adjacent to the Golfo de Fonseca. Near La Libertad, however, the mountains pinch the lowlands out the slopes of adjacent volcanoes come down directly to the sea. Surfaces in the Pacific lowlands are generally flat or gently rolling and result from alluvial deposits from nearby slopes.

El Salvador has over 300 rivers, the most important of which is the Rio Lempa. Originating in Guatemala, the Rio Lempa cuts across the northern range of mountains, flows along much of the central plateau, and finally cuts through the southern volcanic range to empty into the Pacific. It is El Salvador's only navigable river, and it and its tributaries drain about half the country. Other rivers are generally short and drain the Pacific lowlands or flow from the central plateau through gaps in the southern mountain range to the Pacific.

Numerous lakes of volcanic origin are found in the interior highlands many of these lakes are surrounded by mountains and have high, steep banks. The largest lake, the Lago de Ilopango, lies just to the east of the capital. Other large lakes include the Lago de Coatepeque in th1e0 the west and the Lago de Güija on the Guatemalan border. The Cerron Grande Dam on the Rio Lempa has created a large reservoir, the Embalse Cerron Grande, in northern El Salvador.

Data as of November 1988