The natural environment of Buan-gun, Jeollabuk-do, such as the location, mountains, rivers, and climate.
Location and Area
Buan-gun is located between 35°33' to 35°48' north latitude and 126°05' to 126°27' east longitude. Wido-myeon (island) is located about 15 km west off the coast [35°36' north latitude, 126°17' east longitude]. To the east is a hilly mountainous area, bordering Jeongeup City, and to the north is a plain area of the Gyehwado reclaimed land, bordering the coast and the Saemangeum reclamation district. Buan-gun faces Gomso Bay to the south while its central and western areas form a mountainous area extending to the west coast. Buan-gun has thirty-five islands [7 inhabited islands, 28 uninhabited islands] off the west coast boasting the total length of coastline of 173.3 km. The total area of Buan-gun is 493.35 km2. Byeonsan-myeon [86.03㎢, 17%] is the largest administrative unit and Wido-myeon [14.32㎢, 3%] is the smallest one. Byeonsanbando National Park is created over a vast area of 153.934㎢ or 31.4% of the total land surface of the county.
Classification by Terrain Conditions
In terms of terrain conditions, Buan-gun can be classified into four areas: (1) the plain area in the northeast (Gyehwa-myeon, Haengan-myeon, Dongjin-myeon, Baeksan-myeon), (2) the hilly area in the eastern part (Buan-eup, Jusan-myeon, Sangseo-myeon, Haseo-myeon, Boan-myeon, Julpo-myeon), (3) the mountainous area of the western Byeonsan Peninsula (Byeonsan-myeon, Jinseo-myeon), and (4) the island region (Wido-myeon, etc.). In the northern part of Buan-gun is an artificial flat land created by the reclamation of Gyehwa Island. As river deposition areas centered on the Gobucheon and Dongjin River estuaries, Dongjin-myeon and Baeksan-myeon in the northeast are part of the Honam Plain. The eastern hilly region consists of multiple hills running from north to south such as Yeomchangsan (52.0m), Goseongsan (68.3m), Sangsosan (114.9m), Sieosan (aka Haengansan, 102.9m), Seungamsan (84.3m), Nuongmae (105.4m), Jusan ( 231.1m) and Jangjisan (134.0m). The Byeonsan Peninsula in the southwestern part of the mountainous region consists of Naebyeonsan in the inland and Oebyeonsan in the coastal side. Off the shoreline are a total of thirty-five islands such as Sangwangdeungdo and Hawangdeungdo in addition to Wido.
Byeonsan Peninsula
Administratively, the Byeonsan Peninsula includes Byeonsan-myeon, Jinseo-myeon, Boan-myeon, Sangseo-myeon, and Haseo-myeon in Buan-gun. The peninsula has Naebyeonsan, a mountainous region, and Oebyeonsan, a coastal region. Naebyeonsan includes Junggye-ri in Byeonsan-myeon and Cheongnim-ri in Sangseo-myeon while Oebyeonsan mainly refers to the western coastal area of >Byeonsan-myeon. Most mountainous areas in the southwestern peninsula are now part of Byeonsanbando National Park. Byeonsanbando National Park is located at 126°37' 40" to 126°44' 20" east longitude and 34°21' 40" to 34°47' 20" north latitude over an area of 153.934 km2. Designated as a provincial park in 1971, the area became a national park in June 1988. The Naebyeonsan region of the Byeonsan Peninsula is surrounded by numerous peaks including Uisangbong (508.6m), the highest in the area, and Bukoknyeobong (354.7m) to the north; Ugeumsan (329m) and Sangyeobong (395m] to the east; Namoknyeobong (434.4m), Sebong (433m), Gwaneumbong (424.5m) and Sinseonbong (488.2m) to the south; and Mangpodae (494.1m), Nakjodae (447.0m), and Ssangseonbong (460.7m) to the west. Geologically, the peninsula is composed of volcanic rocks such as rhyolite and tuff caused by volcanic activity during the Cretaceous period. The fault line appears in the north-south direction in two places around Maljae (86m) and Badjae (180m). The mountainous area of the peninsula surrounds the Baekcheon Basin, which flows from east to west. In the north are Uisangbong, the highest on the peninsula, Sweppul Rock, and Bukoknyeobong while Ugeumsan and Sangnyeobong stand between Wooseuljae (120m) and Badjae (180m) in the east. The southern part of the mountain ranges from Badjae to Maljae and Gapnamsan (413.4m) with Namoknyeobong, Yonggakbong (370m), Sebong, Gwaneumbong, Sinseonbong, and Galmabong (486.4m) standing in-between. The western part includes Mangpodae, Bunchodae (422m), Nakjodae, and Ssangseonbong. The highest peak in the Byeonsan Peninsula is Uisangbong in the northern part. Peaks more than four hundred meters in the peninsula include Mangpodae, Sinseonbong, Galmabong, Ssangseonbong, Nakjodae, Namoknyeobong, Sebong, Gwaneumbong, Bunchodae, and Gapnamsan. The peaks within the Baekcheon Basin include Samyebong (355m), Deokseongbong (332m), Cheonjongsan (266.4m), Gungwanbong (294m) and Seoninbong (264m), which combine to form the Hoeyang Valley, Bongrae Valley, and Junggye Valley, displaying a variety of river topography. The Baekcheon Basin has little flat land except for a small flat land in an upstream area along the Baekcheon Stream in Cheongnim-ri, Sangseo-myeon. Currently, Junggye Valley is under the water by the Buan Dam (1996). The multiple passes that lead to the Baekcheon Basin include (starting from the east) Wooseuljae, Hakchi (140m), Sachangjae (220m), Badjae, Jaebaegi (160m), Maljae, Namnyeochi (100m), and Junggye Tunnel (120m). The Oebyeonsan region facing the sea consists of three areas: the northwestern coast, the western coast, and the southern coast. The northwestern part has sedimentary shores and sand beaches such as Byeonsan Beach and Gosapo Beach, with Haseom Island located within a stone’s throw. The western coast has Gyeokpo Beach, but it is composed of rocky areas such as Jeokbyeokgang, Chaeseokgang, and Yonggul (Danggul), which are active in erosion. The southern coast is a mixture of sedimentary topography including Sangnok Beach and Mohang Beach as well as tidal flats and erosion topography represented by Solseom Island, although this coastal area is not part of Byeonsanbando National Park. Natural monuments in the county include Population of Horned Hollies in Docheong-ri (Natural Monument No. 122), Population of Machilus in Gyeokpo-r (Natural Monument No. 123) and Population of Box-leaved Hollies in Junggye-ri (Natural Monument No. 124). The coastal area typically has rocky shores or sand beaches according to the constituent materials. In Oebyeonsan, an eroded coast composed of rocks including Chaeseokgang and Jeokbyeokgang appears on the part protruding to the west while the northwestern coastal area has sand beaches such as Byeonsan Beach and Gosapo Beach between rocky areas. Among the twelve geological attractions of the Jeollabuk-do West Coast National Geopark, Buan-gun is home to six attractions including five situated along the coast such as Jeokbyeokgang, Chaeseokgang, Solseom, Mohang, and Wido, and one located inland – Jigso Falls in Mt. Naebyeonsan. Three of them (Jeokbyeokgang, Chaeseokgang, and Jigso Falls) are located within Byeonsanbando National Park.
Geology and Soil
The Byeonsan Peninsula in Buan-gun consists of Cretaceous volcanic rocks (aka Buan Volcanic Rocks) that form a circular, independent mountainous topography in the area along the left-handed strike movement fault in the northeast-southwest strike direction. Volcanic rocks are composed of intrusive rocks, lava flows, volcanic clasts, and sedimentary rocks of acidic to neutral magma composition. The fact that the area has remnants of acidic volcanic rocks created by the subduction of the oceanic plate during the Cretaceous period indicates that the area was a volcanic zone with active volcanic activity during the period. The plains in the northeast and the gentle hills in the east consist of Paleozoic gneiss and Jurassic granite, which are vulnerable to weathering and erosion, whereas the high mountainous region (the Byeonsan Peninsula) is composed of Cretaceous volcanic rocks that are resistant to weathering. As such, the mountainous Byeonsan Peninsula area mostly consists of rocks or rock strata, with weathered layers distributed in the hilly areas of the eastern part, and alluvial layers spread in the plain area of the northeast.
Rivers and Streams
Gobucheon starting from the Dongrim Reservoir in Seongnae-myeon, Gochang-gun flows north into the Dongjin River in Baeksan-myeon, Buan-gun whereas Baekcheon beginning at a watershed in Sangseo-myeon flows west and north to join the waters from the Hoeyang and Bongrae valleys and flow into the Saemangeum area in Haechang after going through the Buan Dam. Jusangcheon starts at Sasan Reservoir in Sangseo-myeon and flows into the western part of Saemangeum through Cheongho Reservoir. The Naebyeonsan area along the Baekcheon Stream flowing from east to west has the Buan Dam built downstream. The Baekcheon starts at Gaegol Reservoir on the west side of Wooseuljae and flows southwest to join the Geoseokcheon (Geoseokje, Cheongrimje) Stream flowing from the south in Cheongrim-ri, Sangseo-myeon. It flows further west and joins the Gamasocheon Stream (Hoeyang Valley), which also flows from the south near Junggye Bridge while joining the Jiksocheon stream flowing from Bongrae Gugok in the south at the western part of Junggye Bridge. In the north, the Baekcheon Stream joins waters from Gusigol Valley between Uisangbong Peak and Sweppul Rock. After embracing all the tributaries, the Baekcheon Stream flows west to stop at Buan Dam and then continue its journey into the Saemangeum Embankment on the west coast at Byeonsan Bridge in Haechang Bay. Waters flowing into the Baekcheon Stream from the south have created Bongrae Valley in Jiksocheon, Hoeyang Valley in Gamasocheon, and Junggye Valley in Baekcheon, the mainstream. The Baekcheon Stream has peaks that are over four hundred meters high to the north and south while flowing north to Haechang Bay through Wooseuljae in the east and Buan Dam in the west.
Inside the Saemangeum Embankment
Through the inside of Naebyeonsan flows the single water system of Baekcheon, but multiple water systems flow through its outside starting from the peak toward four directions: In the north, waters flow through Baekryeon-ri (Munsuje, Geumgwangje) and Seoksang-ri in Haseo-myeon and Tongjeong-ri in Haseo-myeon. In the east, waters flow north in Gaori and Gamgyo-ri (Gaeamje, Sasan Reservoir), Sangseo-myeon while waters flow south in Nampo-ri, Boan-myeon to Sinchangcheon (Yeongjeon Reservoir), with Hobeolchi serving as the watershed between Sangseo-myeon and Boan-myeon. In the south, waters flow south through Udong-ri (Udongje) in Boan-myeon, Jinseo-ri (Yeondongje) in Jinseo-myeon, Seokpo-ri (Seokpocheon, Seokpoje) and Unho-ri (Unho Reservoir, Maljae) in Jinseo-myeon. In the west, waters come through Byeonsan-myeon including Daehang-ri, Jongam Embankment in Gyeokpo-ri, Yuyuje in Mapo-ri, and Unsanje in Unsan-ri It is the Baekcheon Basin in the Naebyeonsan area that boasts the most diversely developed river topography with the largest amount of water in the Byeonsan Peninsula. The Baekcheon that originates from Wooseuljae in the northeast of the Byeonsan Peninsula runs northwest toward Byeonsangyo Bridge to flow into the West Seas through the Saemangeum District (the mainstream of about 18km long). The Baekcheon Basin included in the Naebyeonsan area boasts such attractions as Junggye Valley, Bongrae Valley, and Hoeyang Valley. All tributaries of the Baekcheon flow from south to north except for Gusicheon (Gusi-gol), which flows south from Uisangbong Peak and Sweppul Rock in the north: The Geoseokcheon Stream, which starts at Badjae and Hakchi in the south, flows in the northwest direction through the artificial reservoirs of Geoseokje and Cheongnimje, and joins with the Baekcheon at Geoseokgyo Bridge in Cheongnim-ri, Sangseo-myeon. Around the Geoseokcheon Stream is flat land formed with river sediment with villages and farmland created. A county-built road connects Cheongnim-ri in Sangseo-myeon and Udong-ri in Boan-myeon through Badjae. As the area is flat, the development of the river topography is insignificant. In Hoeyang Valley, waters flow west between Yonggakbong Peak and Namoknyeobong Peak to Gamaso in Gamaso Valley whose waters originate from Sebong, and then the waters combine to flow north between Gungwanbong Peak and Mt. Cheonjongsan into the Baekcheon Stream. The valley highlights various shapes of river topography such as waterfalls and ponds including Waryongso and Gamaso. The Jiksocheon Stream in Bongrae Valley starts at Mangpodae and Sinseonbong Peak and flows to the east before turning north. It merges with the Baekcheon Stream near Junggye Bridge after creating nine waterfalls and ponds. Bongrae Valley, aka Bongrae Gugok (nine valleys), boasts various attractions including Daeso Falls, Jigso Falls, Bunokdam, Seonnyeotang, Bongrae Valley, Yeongji, Geumgangso, Baekcheon, and Amji. Among the tributaries of Baekcheon, Bongrae Valley has the largest amount of water and the most diverse river topography due to its highest difference in elevation.
Buan Dam reshaping the basin using topographic conditions
In Gunmak-dong, Junggye-ri, Byeonsan-myeon at the Baekcheon Exit stands Buan Dam with the height of 47m, the length of 330m, the basin area of 58km2, and the storage capacity of 42 million cubic meters. Completed on November 6, 1996, with a total project cost of KRW 26 billion, the dam supplies 3,600㎥ of water to households in Buan-gun and Gochang-gun in addition to the Hanbit Nuclear Power Plant in Yeonggwang-gun. Before the dam completion, Jigsobo in Bongrae Valley served as a source of drinking water for the region. More than 80% of the water in the Byeonsan Peninsula gathers in the Baekcheon Basin after flowing alongside Mt. Naebyeon, an area which has hardly any noticeably large farmland or villages. In contrast, the outside area of the Baekcheon Basin is full of farmland and villages, requiring a significant amount of agricultural water while the development of rivers and streams in the area is insignificant. That’s why the county built so many small-scale reservoirs to store and use scarce water, including Munsuje and Geumgwangje to the north; Gaeamje, Sasan Reservoir, and Yeongjeon Reservoir to the east; Udongje, Yeondongje, Seokpoje, and Unho Reservoir to the south; and Jongam Embankment, Yuyuje (Mapo Reservoir), and Unsanje to the west. However, there are only three in the Baekcheon Basin such as Gaegol Reservoir, Geoseokje, and Cheongrimje. In order to resolve this imbalance in water supply and demand and use extra water in the inner Baekcheon Basin (Naebyeonsan) in other areas, the Seonggye District Agricultural Water Supply Project was launched to build Cheongrimje (at 100 meters above sea level) in Geoseokcheon Stream and make water in the reservoir flow into Udongje (at 40 meters above sea level, completed in 1957) for agricultural land in the southern region. The water supply project completed in 2008 sends water from a dam (at 100m above sea level) inside the Baekcheon Basic built to Udongje (at 40m above sea level) in the south through two underground aqueducts (1,000m and 600m long, respectively). The project utilizes the topographical conditions of the area by using the difference in elevation to draw water from an abundant water source in the Baekcheon Basin to the agricultural areas in the south that require a huge amount of water.
Climate
Based on the climatic conditions of Buan-gun with average values of meteorological data for 30 years (1981 to 2010), the average annual temperature is 12.6℃ (the highest 18.0℃, the lowest 8.0℃), the average humidity is 76.0%, the annual average precipitation is 1,250.4mm, and the average wind speed is 1.6 m/s. The inland side of the east demonstrates a continental climate while the Naebyeonsan region shows characteristics of a mountainous climate, and the west side of the Oebyeonsan region facing the West Sea indicates a maritime climate. Precipitation falls intensively between June and September, with more than 66% (about 823mm) of the annual precipitation (1,250.4mm) recorded during the period while the amount of precipitation in winter is 110.4mm, a sharp difference from that in the summer. Heavy snowfall occurs once or twice a year when the cold continental high pressure in the northwest expands into the region playing a vital role in the observation of snow cover on the west coast. The average annual wind speed is 1.6m/s, which is lower than that of other coastal areas. Yet, Gyeokpo Port in southwestern Buan sometimes records stronger winds than in the sea off the coast due to the topographical factors of the area. In 2018, Buan-gun had 90 sunny days, 88 cloudy days, 103 rainy days, 55 frosty days, 21 foggy days, and 25 snow days, 13 thunderstorm days and 5 yellow dust days, with an average annual temperature of 13.3°C and an average annual precipitation of 1,359mm. In 2018, precipitation was the highest in July (299.5mm) and August (258.2mm) followed by October (161.5mm), April (124.6mm), May (112.5mm), and June (105mm], with a total of six months recording precipitation in excess of 100mm. Of the 6 months with an average monthly precipitation of 100mm, December (26.4 mm) recorded the least. The average relative humidity was 71% and the number of hours of sunshine was 2,348.2 hours. The average wind speed was 1.7m/s, and the instantaneous maximum wind speed was 12.3m/s.
