Mountains and Hills
Between the Korean peninsula and Manchuria
flow, in opposite directions, the two largest rivers of the region,
the Amnokgang (Yalu) and Dumangang (Tumen), both originating at Mt.
Baekdusan (2,744m), the highest mountain in the region. The peninsula
is surrounded by the Yellow Sea, the East Sea, and the South Sea. |
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Mt. Seoraksan National Park |
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Nearly 70 percent of the Korean Peninsula is covered by mountains and hills.
Low hills in the southern and the western regions give way gradually to increasingly
higher mountains toward the eastern and the northern areas. On the whole, the
western and southern slopes of the peninsula are wide with some plains and basins
along rivers, while the eastern slope is very steep as high mountains precipitate
into the East Sea.
Most of the high mountains are located along the Taebaek mountain range which
runs parallel to the east coast, roughly north-to-south. West of this range
are the drainage basins of the Hangang and Geumgang rivers. This range extends
to the Nangnim range in North Korea, forming the geological and geomorphological
backbone of the peninsula and constituting the watershed between the western
and eastern slopes of the peninsula. Mt. Nangnimsan (2,014m), Mt. Geumgangsan
(1,638m), Mt. Seoraksan (1,708m), and Mt. Taebaeksan (1,567m) are some of the
highest peaks along these ranges. Just southwest from the Taebaeksan range is the Sobaeksan range, which culminates in the massive Mt. Jirisan (1,915m). This range
was historically a great barrier between the central and southern parts of the
peninsula, and also between the eastern and western regions in the south. The
Nakdong river basin is thus segregated in southeastern Korea. The Gaemagowon
Plateau, the so-called "Roof of Korea," located in the northwestern corner of
the peninsula, has an average elevation of about 1,500 meters above sea level.
The landmass of the peninsula is rather stable geologically in spite of its
proximity to Japan; it has neither active volcanoes nor strong earthquakes.
There are, however, a few dead volcanoes that were formed during the Pleistocene
era. Mt. Baekdusan is famous for a large caldera lake, "Cheonji," meaning heavenly
tarn. Mt. Hallasan in Jejudo island, the highest mountain in South Korea, was
recorded to have had minor volcanic activity in the early 11th century. It has
a small crater lake, "Baengnokdam," and there are about 400 parasitic cones
in its piedmont.
About two-thirds of the Korean Peninsula is composed of pre-Cambrian metamorphic
and granitic rock. Although the distribution of sedimentary rock is very limited,
limestone is quite abundant in some regions and a number of limestone caves
can be found, some of which are tourist attractions. Among the most famous caves
are Gossigul, Gosugul and Seongnyugul, all of which are adorned with stalagmites
and stalactites.
Rivers and Plains
Most of major rivers flow into the Yellow
Sea and a few into the South Sea, draining the western and southern
slopes of the peninsula. Considering its size, Korea has a relatively
large number of long rivers, six of them exceeding 400 kilometers. The
discharge of rivers fluctuates very much due to the summer monsoon.
In the summertime, rivers swell with heavy rainfall, flooding valley
plains every once in a while. In drier seasons, the water level drops
and often much of the river bed is exposed. Typhoons, which hit the
southern part of the peninsula once every two or three years, also bring
heavy rainfall in late summer and early autumn. |
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The Han-gang River |
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In the past, rivers were important for transportation. Historical capitals such
as Pyeongyang and Buyeo are located adjacent to major rivers, as is Seoul. After
the introduction of railroads and automobiles, however, the importance of rivers
for transportation has decreased sharply, and rivers are now used mainly for
the irrigation of rice fields and power generation. During the last two decades
a number of huge dams have been constructed for flood control, electricity,
and irrigation. But these dams have gradually begun to play a major role as
reservoirs for piped water supply to large cities and industrial plants as a
result of rapid urbanization and industrialization nationwide.
Most farming fields are narrow floodplains developed along rivers, especially
in their lower reaches. These plains serve as the major rice-producing lands.
Large tidal differences at the mouths of major rivers flowing into the Yellow
Sea inhibited the development of deltaic plains, although rivers transport large
amounts of sediment during floods. Only the Nakdonggang flowing into the
South Sea has a small delta at its mouth. Erosional basins along rivers in areas
of granitic rocks have also served as agricultural regions since ancient times.
Many large cities such as Chuncheon, Cheongju, and Wonju are located in such
basins.
Coasts
Korea has a long coastline divided into
the east, west and south coasts. The east coast has small tidal differences,
a third of one meter at the most, and a relatively smooth shoreline
with few islands offshore. The Taebaek range runs closely along the
East Sea. Where mountains protrude from the Taebaeksan range, coasts are
rocky in general, but some beaches are found in places into which small
streams carry sediment from the high mountains. In many instances, the
beaches take the form of sand spits and bars enclosing lagoons, which
are notable features of the east coast. Along the coast between Wonsan
and Gangneung are located a series of lagoons, including Gyeongpo and
Hwajinpo, two famous resorts. The highway connecting Gangneung and
Seoul has been expanded recently, reducing the travel time between the
central region and the east coast. |
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The Dadohae National Park at the
tip of the Korean Peninsula |
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The shorelines of the south and west coasts are very irregular with innumerable
small peninsulas and bays as well as a large number of islands. The west coast
facing the Yellow Sea, which is very shallow, has large tidal ranges, which
rise above 10 meters in places. Harbors have been difficult to develop while
tidal flats are common coastal features especially in bays into which rivers
discharge sediment during floods. Tidal flats have been reclaimed from ancient
times mainly for rice fields, but since the 1970s, the reclamation grew in terms
of magnitude. The Saemangeum Project, the largest such project ever undertaken,
seeks to reclaim a total of 40,100 hectares of the flats through the construction
of huge dikes, but it faces strong opposition from environmental groups.
The south coast shows a typical ria shoreline, a coastal zone which has been
submerged. The length of coastline is nearly eight times longer than its straight-line
distance, and its indentation is far greater than that of the west coast. The
tidal ranges are relatively small at two to five meters, and tidal flats are
not as wide as along the west coast. Although mountains face the sea, there
are few beaches and sea cliffs along the mainland coast, as innumerable islands
prevent the penetration of waves from offshore. Narrow straits between the mainland
and islands are associated with extremely rapid tidal currents. At Uldolmok
toward the western end of the south coast, the tidal current reaches up to 13
knots.