Seoul Topography

[Pompeo Mixon]

TheKorean Peninsula extends southward from the northeast part of the Asian continental landmass. The Japanese islands of Honshū and Kyūshū are located some 200 km (124 mi) to the southeast across the Korea Strait; the Shandong Peninsula of China lies 190 kilometers to the west. The west coast of the peninsula is bordered by the Korea Bay to the north and the Yellow Sea and Korea Strait to the south; the east coast is bordered by the Sea of Japan. The 8,640-kilometer coastline is highly indented. Some 3,579 islands lie adjacent to the peninsula. Most of them are found along the south and west coasts.

After World War II and before June 25, 1950, the line between the two Korean states was the thirty-eighth parallel of latitude. After the Korean War, the Korean Demilitarized Zone (DMZ) formed the boundary between the two. The DMZ is a heavily guarded, 4,000-meter-wide strip of land that runs along the demarcation line established by the Korean Armistice Agreement from the east to the west coasts for a distance of 241 kilometers (238 kilometers of that line from the land boundary with North Korea).

The total land area of the peninsula, including the islands, is 223,170 square kilometers. Some 44.8 percent (100 210 square kilometers) of this total, excluding the area within the DMZ, constitutes the territory of the Republic of Korea. The combined territories of North Korea and South Korea are about the same size as the United Kingdom. South Korea alone is about the size of Portugal or Hungary, or the U.S. state of Indiana.[2]

The largest island, Jeju Province, lies off the southwest corner of the peninsula and has a land area of 1,825 square kilometers. Other important islands include Ulleung and Liancourt Rocks in the Sea of Japan and Ganghwa Island at the mouth of the Han River. Although the eastern coastline of South Korea is generally unindented, the southern and western coasts are jagged and irregular. The difference is caused by the fact that the eastern coast is gradually rising, while the southern and western coasts are subsiding.

South Korea is largely mountainous, with 3/4 of its landmass consisting of mountains.[1] Early European visitors to Korea remarked that the land resembled "a sea in a heavy gale" because of the large number of successive mountain ranges.[citation needed] Many tall mountains exceeding 1,000 m (3,281 ft), which are concentrated in the north and the east, form the "topological backbone" of the country.[1] There are two major mountain ranges within South Korea: the Taebaek Mountains, and the Sobaek Mountains. The highest mountain peak in South Korea is Hallasan (1,950 m (6,398 ft)), which is the cone of a volcanic formation constituting Jeju Island. Geologically, Precambrian rocks such as granite make up the landmass.[3]

Approximately 30 percent of the area of South Korea consists of lowlands, with the rest consisting of uplands and mountains. The great majority of the lowland area lies along the coasts, particularly the west coast, and along the major rivers. The most important lowlands are the Han River plain around Seoul, the Pyeongtaek coastal plain southwest of Seoul, the Geum River basin, the Nakdong River basin, and the Yeongsan River and the Honam plains in the southwest. A narrow littoral plain extends along the east coast. A recent global remote sensing analysis suggested that there were 1,833 km2 of tidal flats in South Korea, making it the 17th ranking country in terms of how much tidal flat occurs there.[4]

The Nakdong is South Korea's longest river (521 km (324 mi)). The Han River, which flows through Seoul, is 514 km (319 mi) long, and the Geum River is 401 km (249 mi) long. These three rivers have their sources in the Taebaek Mountains.[3] Other major rivers include the Imjin, which flows through both North Korea and South Korea and forms an estuary with the Han River; the Bukhan, a tributary of the Han that also flows out of North Korea; and the Somjin. The major rivers flow north to south or east to west and empty into the Yellow Sea or the Korea Strait. They tend to be broad and shallow and to have wide seasonal variations in water flow.

In the early part of the 20th century and especially the period during and after World War II and the Korean War, much of the existing Korean forests were cut down, which led to problems with flooding and soil erosion. Combination of reforestation efforts (e.g. Arbor Day was celebrated as a national holiday starting in 1949) and policies designed to reduce the use of firewood as a source of energy (e.g. restriction of inflow of firewood into Seoul and other major cities starting in 1958) helped to spark a recovery in the 1950s.[5] Comprehensive reforestation programs starting in the 1970s and continuing into the late 1990s aided in an acceleration of forest volume increase,[6] and the forest cover reached a peak of 65% of national land area in 1980 as opposed to a low of 35% in 1955.[5]

News that North Korea was constructing a huge multipurpose dam at the base of Geumgangsan (1,638 m (5,374 ft)) north of the DMZ caused considerable consternation in South Korea during the mid-1980s. During 1987 the Geumgangsan Dam was a major issue that Seoul sought to raise in talks with Pyongyang. Though Seoul completed a "Peace Dam" on the Pukhan River to counteract the potential threat of Pyongyang's dam project before the 1988 Olympics, the North Korean project still was in its initial stages of construction in 1990.

The country generally has sufficient rainfall to sustain its agriculture. Rarely does less than 750 millimeters (29.5 in) of rainfall fall in any given year; for the most part, rainfall is over 1,000 millimeters (39.4 in). Amounts of precipitation, however, can vary from year to year. Serious droughts occur about once every eight years, especially in the rice-producing southwestern part of the country. About two-thirds of the annual precipitation occurs between June and September.

South Korea is less vulnerable to typhoons than Japan, Taiwan, the east coast of China, or the Philippines. From one to three typhoons can be expected per year. Typhoons usually pass over South Korea in late summer, especially in August, and bring torrential rains. Flooding occasionally causes considerable damage, as do landslides, given the country's generally mountainous terrain.

In September 1984, record floods caused the deaths of 190 people and left 200,000 homeless. This disaster prompted the North Korean government to make an unprecedented offer of humanitarian aid in the form of rice, medicine, clothes, and building materials. South Korea accepted these items and distributed them to flood victims.[7]

The rainy season of South Korea refers to a phenomenon in which it rains continuously for several days in summer or rainy season, or the weather, or the rain itself. On average, the rainy season is 30 to 35 days, but it does not continue to rain during this period. In fact, it rains for about 15 to 20 days, and among them, it falls only for about 12 to 16 days due to the stagnant front. However, the rainy season varies greatly from year to year. The rainy season is a representative summer weather in East Asian countries, including the Republic of Korea, and accounts for more than 30% of the precipitation on the Korean Peninsula. For this reason, some call the rainy season the "fifth season."[9][10] It is usually a form of torrential rain that pours suddenly and then stops. In particular, the recent rainy season is referred to as a "nocturnal rainy season," and it is often in the form of a lull during the day, and local heavy rain pouring down at night. In the case of cloudy days, the upper layer may be heated rather than the ground during the day, and at night, the clouds trap the heat of the lower layer while the upper layer cools, so convection develops. In fact, considering that showers come during the day, nights account for a high percentage of 55%.[11] A distinct congestion front is created between the cold and humid Okhotsk Sea air mass located on the northern Russian coast and the hot and humid North Pacific air mass near the Ogasawara Islands, resulting in a rainy season. However, in the case of the Korean Peninsula, not only the Okhotsk Sea air mass but also the cold and dry Siberian air mass contributes to the rainy season. Another cause of the rainy season is said to be the Bering Sea and the Tibetan Plateau. To be exact, the speed of high pressure formation varies depending on the amount of ice in the Bering Sea and the amount of snow accumulated in the Tibetan Plateau, as the rainy season begins with the speed at which each high pressure in the north and south of the Korean Peninsula moves. For this reason, rainy seasons are regarded as a kind of East Asian seasonal wind climate abroad.[10] The rainy season ends when the North Pacific high pressure expands and the Okhotsk Sea fleet retreats. Since then, as the North Pacific high pressure began to dominate the Korean Peninsula, the heat wave began in earnest and entered the middle of summer. However, during the period from summer to autumn, as the North Pacific high pressure contracts and cold air expands in the north, the stagnant front moves south again and settles near the Korean Peninsula, which is called the "Autumn rainy season" or "second rainy season." The autumn rainy season generally occurs between late August and early September, and although it is usually shorter than the early summer rainy season, it sometimes pours more rain than the summer rainy season.[12]

Due to severe climate change caused by global warming in India, daytime temperatures have risen to 32 degrees Celsius since mid-April and 39 degrees in late April, resulting in a strong heat wave in mid-summer, which also hit Korea in early June this year.[13]

The head of the Korea Meteorological Administration pointed out in 2022 that it was impossible to predict the recent heavy rain, and that the traditional expression of "rainy season" now seems to have expired.[14]

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