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- 1 -
Mid-Congress Excursions
Information
Sponsored by
CONTENTS
Trip 1. Shallow geothermal system and UNESCO World Heritage .................................................. 3
Site 1. KIGAM Geothermal system ........................................................................................................................................................... 3
Site 2. Gongju and Buyeo UNESCO World Heritage ....................................................................................................................... 13
Trip 2. World’s longest 33.9 km sea dike and historic temple ....................................................... 17
Site 1. The Saemangeum reclaimed area ............................................................................................................................................... 17
Site 2. Naesosa temple ................................................................................................................................................................................... 22
Trip 3. National Groundwater Information System and Korean Traditional House Village ...... 24
Site 1. NGIC (National Groundwater Information Management and Service Center) ....................................................... 24
Site 2. Daecheong Multi-purpose Dam ................................................................................................................................................... 27
Site 3. Groundwater Monitoring Station (Cheongwon Gaduk) .................................................................................................... 31
Site 4. Jeonju Hanok Village ...................................................................................................................................................................... 33
Trip 4. KURT (KAERI’s Underground Research Tunnel) and UNESCO World Heritage .............. 34
Site 1. KURT (KAERI’s Underground Research Tunnel) .............................................................................................................. 34
Site 2. Gongju and Buyeo UNESCO World Heritage ....................................................................................................................... 39
Trip 5. Daesan riverbank filtration site and Upo Wetland ............................................................... 44
Site 1. Daesan riverbank filtration site ................................................................................................................................................... 44
Site 2. Changnyeong Upo wetland ............................................................................................................................................................ 48
Trip 6. Geologic Park and Cine Theme Park ....................................................................................... 49
Site 1. Jeokbyeokgang-peperites ............................................................................................................................................................... 49
Site 2. Chaeseokgang ..................................................................................................................................................................................... 52
Site 3. Buan Cine Theme Park ................................................................................................................................................................... 57
Trip 7. Gyeongju LILW disposal facility and UNESCO World Heritage .......................................... 60
Site 1. Gyeongju Donggung Palace and Wolji Pond .......................................................................................................................... 60
Site 2. Bulguksa temple ................................................................................................................................................................................ 61
Site 3. Gyeongju LILW disposal facility ................................................................................................................................................ 62
Trip 8. Maisan geologic park and Wine cave ..................................................................................... 70
Site 1. Muju Meoru wine cave ................................................................................................................................................................... 70
Site 2. Muju pumped Storage power plant (Jeoksangsan Mountain) ......................................................................................... 70
Site 3. Maisan Geopark ................................................................................................................................................................................ 71
Trip 9. Baengnyong Cave ........................................................................................................................ 82
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Trip 1. Shallow geothermal system and UNESCO World Heritage
Site 1. KIGAM Geothermal system
Geothermal energy, one of the new and renewable energy, has until recently had
little economic potential except in areas where high-enthalpy geothermal energy resources,
i.e. thermal water or steam, are found. This has lately changed with developments of
geothermal heat pump (GHP) systems, sometimes referred to as ground-source heat pump
(GSHP) systems, using low-enthalpy geothermal energy resources for heating and cooling
purposes. They use the almost constant temperature of the shallow ground as the exchange
medium instead of the outside air temperature. This allows that the electrical efficiency of the
GHP system is better than that of the air-source heat pump (ASHP) system because ground
temperature is higher than air temperature in the heating season and is lower than air
temperature in the cooling season.
(a) (b)
(c) (d)
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Figure 1. Types of the geothermal heat pump system: (a) vertical closed-loop, (b) horizontal
closed-loop, (c) standing column well, and (d) open-loop. Cold water from heat pumps is
injected into the ground and then warm water heated by ground is produced for heating
operation.
There are three basic types of GHP systems:
(1) closed-loop systems;
(2) open-loop systems;
(3) standing column well systems.
The closed-loop GHPs (Figure 2) circulate a mixture of water and antifreeze through a closed
loop that is buried underground. The loop tubing can be installed horizontally as a loop field
in trenches or vertically as a series of long U-shapes in boreholes. The open-loop GHP
system produces groundwater directly from wells. Once the produced groundwater has
circulated through the system, it returns back to the ground through injection wells or is
discharged into the surface. The standing column well (SCW) system is a specialized type of
open loop system. Groundwater is produced from the bottom of a deep well, passed through a
heat pump, and injected back to the top of the well, where flowing downwards it exchanges
heat with the geologic medium or groundwater. This figure shows schematic diagram of the
GHP system with three core components, boreholes and pipes, heat pump, and circulation
pump.
Figure 2. Schematic diagram of the vertical closed-loop GHP system with three core
components. Simulations of the vertical closed-loop GHP system that consists of multiple
BHEs can be feasible.
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The Korean government has adopted subsidy programs and Mandatory Acts for the
new and renewable energy. As a result of government funding and regulations, three GHP
systems were installed in recently constructed buildings in our Institute (Figure 3). The first
GHP system and its monitoring system were installed in the A2 building, and they have
operated and been monitored since 2006. This vertical closed-loop GHP system comprises 79
heat pumps, 4 fluid pumps, and 28 BHEs. There are 16, 31, and 32 heat pumps on the first,
second, and third floors of the A2 building, respectively. Three fluid pumps supply the
circulating fluid to the heat pumps on each floor and to the BHEs. The fourth fluid pump is
an auxiliary fluid pump. There are 8, 10, and 10 BHEs connected to the heat pumps on the
first, second, and third floors, respectively under the yard of the A2 building. The dimensions
of the BHE field are 35 m from east to west and 42 m from north to south. Each BHE
consists of a closed circuit with a double U-tube in a grouted borehole 200 m deep. To
measure the temperature and flow rate of the circulating fluid at the BHE inlet and outlet,
monitoring equipment has been installed for three BHEs. The second GHP system installed in
the A1 building have operated since 2015 and been monitored since 2017. This vertical
closed-loop GHP system comprises 10 heat pumps, 5 fluid pumps, and 50 BHEs. Each BHE
consists of a closed circuit with a single U-tube in a grouted borehole 200 m deep. The
monitoring system for the A1 building consists of thermometers and flowmeters to measure
temperatures and flow rates of the circulating fluids connected to each heat pump and
wattmeters to measure electric powers of each circulation pump and heat pump. The newest
GHP system installed in the KIGAM SPOREX building is currently under construction and
will be finished soon. This experimental hybrid open/closed-loop GHP system consists of
two heat pumps, one circulation pump for the closed-loop system, one well pump for the
open-loop system, and three boreholes without grout. A borehole named “Geothermal well”
is equipped with both the U-tube for the closed-loop system and well pump and pipes for the
open-loop system.
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Figure 3. Three buildings (A1, A2, and SPOREX) equipped with GHP systems for cooling
and heating purposes in KIGAM.
< GHP systems in the A1 building >
Figure 4. Layout of the BHE field of the A1 building.
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Figure 5. Layout of the GHP system and its monitoring system in the A1 building.
Figure 6. Screenshot of the main computer for data processing and storage.
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< GHP systems in the A2 building >
Figure 7. Layout of the GHP and its monitoring system in the A2 building.
Table 1. Characteristics of the BHE, heat pump, and rock in the BHE field of the A2 building.
Borehole heat
exchanger
Dimensions
Number of BHEs: 1F (8), 2F (10), 3F (10)
Depth: 200 m
Spacing between BHEs: 7 m
Borehole radius: 82.5 mm
U-tube radius (inner): 17 mm
U-tube radius (outer): 21 mm
Thermal
conductivity
(W/mK)
U-tube: 0.366 (Polyethylene pipe)
Grout: 0.800 (Sand–E-plug mixture)
Circulating fluid: 0.580 (Water)
Specific heat
(kJ/kgK)
U-tube: 2.09
Grout: 2.20
Circulating fluid: 4.20
Heat pump
Type FHP EM Series
(EM012, EM015, EM024, EM028, EM041)
Number of heat
pumps
1F: EM024 (9), EM028 (5), EM041 (2)
2F: EM012 (11), EM015 (16), EM024 (3), EM028 (1)
3F: EM012 (10), EM015 (17), EM024 (4), EM028 (1)
Rock
Flow properties Porosity: 0.014
Hydraulic conductivity: 1.0 10–4 to 1.0 10–8 m/s
Thermal
properties
Thermal conductivity: 2.98 W/mK (harmonic mean)
Specific heat: 0.82 kJ/kgK (harmonic mean)
Density: 2.67 g/cm3 (harmonic mean)
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(a)
(b)
Figure 8. Comparisons of simulated temperatures and monitored temperatures at the inlet
and outlet of the BHE during four weeks of operation of the GHP system in the A2 building:
(a) first floor and (b) second floor.
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Figure 9. A gradual increase (0.1℃/year) of the groundwater temperature measured at two
different depths in the 300-m-deep monitoring well for 10 years.
< GHP systems in the KIGAM SPOREX building >
Figure 10. Layout of three boreholes of the KIGAM SPOREX building.
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(a)
(b)
Figure 11. Layout of the geothermal well of the KIGAM SPOREX building: (a) side view, (b)
plan view.
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Figure 12. Layout of the GHP system and its monitoring system in the KIGAM SPOREX
building.
Figure 13. Three operation modes of the closed-loop GHP system in the KIGAM SPOREX
building.
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Site 2. Gongju and Buyeo UNESCO World Heritage
1) Gongsanseong Fortress
Gongsanseong Fortress was called Ungjinseong, serving the royal palace of the
Baekje Kingdom for the sixty-four years of the Ungjin Period (475-538 CE). This mountain
fortress occupied 20ha area cross administrative district of Geumseong-dong and Sanseong-
dong of Gongju. Gongsan Mountain is connected with downtown Gongju to the south and the
Geumgang River to the north. Outer side of Gongsan Mountains, except in the southeastern
part, form cliffs, providing optimal geographical conditions for natural fortification.
Gongsanseong Fortress was built for a royal palace and a defensive facility in utilizing the
natural topography and mountain peaks connected to each other across valleys. Important
facilities, including the royal palace, were built within the fortress.
From 1980, archaeological excavations were conducted, revealing the construction
styles of the fortress rampart, the royal palace site, and the ancillary structures of the royal
palace.
Gongsanseong Fortress consists of both earthen wall sections and stone wall sections,
although most parts are stone walls. The total length of the fortress amounts for 2,660m
(stone walls: 1,925m; earthen walls: 735m). Earthen ramparts are found in outer and inner
walls to the east section, and the outer wall area has kept its original appearance of the Baekje
Period. Most of the stone walls were built during the Joseon (1392-1910), the lower parts of
the stone walls were partially constructed during the Baekje Period. The current state of the
fortress shows both the earthen ramparts built during the Baekje Period and stone ramparts
partially reconstructed afterward. After the downfall of Baekje, the fortress ramparts of
Gongsanseong Fortress were reconstructed and rebuilt as stone walls.
Two mountain peaks (110m high) are located within Gongsanseong Fortress, with
the royal palace placed in a wide area (7,000m2) on the summit of the western peak. The
western peak commands a fine view of downtown Gongju, the Geumgang River, and the
Royal Tombs in Songsan-ri. An excavation conducted in 1985 had discovered archaeological
remains, most of which were building sites and ancillary facility sites dating to Ungjin Period.
Among the major archaeological remains are a number of sites once occupied by a large
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building with stud walls (35m east to west, 10m south to north), several buildings
with columns implanted in the ground, and a pond for the local water supply.
Diverse archaeological findings, including roof tiles, bronze mirrors, and
earthenware items, have also been discovered at this site.
2) Royal Tomb of King Muryeong
The Songsan-ri Tombs and Royal Tomb of King Muryeong (reign 462-523) contains
representative relics of the Baekje period (234~678). The Songsan-ri Tombs contain the
graves of kings from the period when Baekje's capital was Gongju, and it is believed to
contain 10 such graves. Only seven graves have been discovered so far.
The main attraction of Songsan-ri Tombs is the wall painting drawn on the number
six tomb – it is the only art of its kind in the world, created from the way the bricks were laid
to create the wall. The tomb is shaped like a long tunnel, the top rounded like a dome. There
are pictures of fire-breathing dragons on the tomb. Only the parts of the wall where the
pictures were to be drawn had earth coated on, and on that earth was drawn Sasindo, the Four
Symbols – blue dragon, white tiger, red peacock, and black turtle.
The popular Tomb of King Muryeong is the 7th tomb, and it is the resting place for
Baekje's 25th King Mu-Ryeong and his queen. This tomb was discovered accidentally when
installing pipes to prevent tombs number 5 and 6 from being flooded. Tomb of King
Muryeong was found to be unusual in the way it was built and what it contained. It was built
with bricks like the 6th Tomb, and many national treasures were found inside, supplying
scholars studying Baekje culture with precious research material. There were 108 kinds of
artifacts found inside, totaling 2,906 items altogether. Twelve of these artifacts were
designated National Treasures. They are all on display at Gongju National Museum. Some of
the representative treasures are the crowns worn by the king and the queen, gold decorations
for the crowns, gold earrings, necklaces, bronze mirrors, pillows, and foot rests. Recently the
tomb was permanently sealed off to protect the treasures. However, you can look at the
miniature of the tomb, an exact duplicate of the original, in the basement of the Gobungun
Building.
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3) Jeongnimsaji Temple Site
The Jeongnimsaji Temple Site, located in the heart of Buyeo, is one of the most well-
known temple sites dating from the Baekje period. It is surrounded by mountains, which
Geumseongsan located on its east and Busosan on its north. Jeongnisamji, which was situated
at the center of the capital during the Sabi period, contains a stone pagoda, with an inscription
describing the story of how the Tang dynasty caused the fall of Baekje. This implies that
Jeongnimsa was a symbolic place that shared the same fate as the Baekje Kingdom.
Jeongnimsaji has the typical layout of temples dating from the Baekje period. The middle
gate, stone pagoda, Geumdang (Golden Hall), and auditorium were built in a straight line in
the north-south direction, and they were surrounded by the living quarters of the monks and
passageways. While there are no evidentiary records on the exact time period during which
Jeongnimsa Temple existed, it is assumed that it must have been destroyed with the fall of
Baekje. This is based on the reddish earth layer, which had been burned, that was discovered
at the Geumdang during an excavation survey.
At present, the Jeongnimsaji Temple Site contains a five-story stone pagoda,
designated as National Treasure No. 9, and a stone seated Buddha statue dating from the
Goryeo period, designated as Treasure No. 108, and the temple site itself has been designated
as Historic Site No. 301.
Jeongnimsa Temple, located in the heart of Sabi, was a very important Buddhist
temple at the time, and it provides evidence of the fact that the Buddhist culture introduced
from China was completed as the Buddhist culture of Baekje. Jeongnimsaji had been
established in the typical Baekje temple style, with one Geumdang (Golden Hall) and one
pagoda, along with an auditorium. This tradition of building an auditorium continued until
the Goryeo Dynasty. The five-story stone pagoda at Jeongnimsaji, which is the sole stone
pagoda remaining from the Baekje period, actually demonstrates the structural characteristics
of a wooden pagoda. An interesting matter to note is that the stone pagoda construction
techniques of Baekje had been passed on to Silla, and set the stage for Korea to emerge as a
country with exquisite stone pagodas.
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4) Gungnamji Pond
Gungnamji Pond (Historic Site No.135), located in Seodong Park, is Korea’s first
artificial pond and was created by King Mu (from the Baekje Dynasty) who was in love with
and eventually married Princess Seonhwa. ‘Gungnamji’ (literally means ‘a pond in the south
of the royal palace’ in Korean) was named according to the Samguksagi record.
Seodong Park is a sculpture park displaying 68 sculptures created by famous Korean
sculptors. Mahan Hall showcases the lifestyle and culture of Mahan, a tribal confederation
during the Samhan period. The park also features various facilities such as an observatory,
fishing spot and a promenade.
According to a record in the Samguksagi, the History of the Three Kingdoms, King Mu dug
this lake south of his palace in the 35th year of his reign (634) and connected it by a 7800-
meter long waterway to the water source. The king then had willow trees planted around the
bank and had an artificial mound constructed in the middle of the lake.
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Trip 2. World’s longest 33.9 km sea dike and historic temple
Site 1. The Saemangeum reclaimed area
The Saemangeum reclaimed area is located offshore of an estuary with two rivers,
Mangyeong and Dongjin, on the mid west coast of Korea. The inland administrative districts
are the Gunsan, Gimje, and Buan counties (Fig. 1). The Saemangeum reclamation project,
which began in 1991, was designed to convert approximately 401 km2 of tidal flat into a
reclaimed land (283 km2) and a reservoir (118 km2) by building the world's longest 33.9 km
sea dike off the coast (Fig. 2). The sea dike construction was completed by connecting
isolated islands in 2006 and encompassing an estuary fed by two rivers (Fig. 3). The
reclaimed land is currently under construction for an eco-friendly multifunctional complex
that involves agriculture, business, eco-tourism, and renewable energy industry slated for
completion by 2020.
The inland bedrock consists of mainly middle Jurassic granite, which is overlain by
the last Quaternary alluvial deposit, and Cretaceous acidic volcanic rock that intrudes upon
these rocks. The small mountain’s bedrock in Buan county is exposed and weathered. From
the vertical geologic sections drawn from 116 borehole logging data of the tidal flat inside the
sea dike, the seabed is covered largely by sand (62%) up to 50 m of depth, including mud
(13%), silt (9%), pebble (9%), weathered rock (4%), and fresh granite (3%). The suspended
sediments from the two rivers have been known to feed a large mud deposit on a strip in the
inner shelf. However, the riverine mud rapidly accumulates on local tidal flats adjacent to the
river mouth inside the dike with a suspended sediment concentration up to 10 g L-1 during
fair weather. The reclaimed area is generally characterized by semidiurnal tide with a macro-
tidal range (~2 m).
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Figure 1. Location and area of the Saemangeum.
Figure 2. Location and area of the Saemangeum reclaimed land.
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Figure 3. Schematic view of the Saemangeum sea dike.
The Saemangeum sea dike has emerged as an economic hub of Northeast Asia. The
reclaimed lands are being turned into an eco-friendly complex with a declaration of low carbon
green growth center creating future industry environment (Fig. 4).
Firstly, the reclaimed land would be made as an export base for agricultural products and
processed foods. Agricultural lands would be located near vicinities of Mangyeong and Dongjin
rivers, which area accounts for 85.7 km2 (30.3% of the reclaimed land) (Fig. 5). Eco-friendly, high
quality agro-industry such as pilot complex for high-tech agriculture, green growth pilot farm,
and organic circulated farm would be founded in the designated zone. Advanced base for
agricultural export such as agricultural large scale companies, integrated horticultures and
flowers cultivation with high value would be promoted. In addition, infrastructures of green
growth, eco-tourism such as pilot complex, agricultural theme parks, rural villages, nursery
tree fields, and arboretums would be constructed.
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Figure 4. Development strategies for the Saemangeum reclaimed land.
Secondary, a clean city where humans and nature co-exist, a pleasant and beautiful
waterfront tourism city, and an eco-friendly green transport city (hereafter, U-complex) would be
realized. U-complex would be located in southern part of the reclaimed land, which area accounts for
67.3 km2 (23.8%). U-complex is heading to international waterfront city, global city, green
growth pilot city, human-centered city, and cultural city with Korean traditions. Various lands
would be arranged by the balanced city development plan including industrial lands,
international affairs lands, tourism and leisure lands, and ecological and environmental lands.
Thirdly, an industrial land would be developed with a vision for a eco-friendly industrial
complex on the basis of low carbon and green growth, which would be located in northern part
of the reclaimed land (18.7 km2, 6.6%). Science and research lands (23.0 km2, 8.1 %) would be
located near the industrial land, which would build up college-centered research clusters
developing into a global cluster and research foundation with government-funded research
institute. In the science and research lands, connectivity with surrounding areas such as
industrial lands, international affairs lands, and new and renewable energy lands by offering
idealistic environment, such as high technologies, excellent human resources, and residential
conditions, to organizations and companies would be realized.
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Fourthly, a new and renewable energy lands would build up global new and recycling
energy industry hub with a foothold for exportation through inducing green growth industry
and strengthening global competitive power. This land would be located between Mangyeong
and Dongjin rivers and its area accounts for 20.3 km2 (7.2%). In this land, the value chain of the
core technology related to global export of new and renewable energy would be built up. In
addition, competition power through integrating industries, constructing pilot complexes, and
R&D foundations would be enhanced.
Fifthly, urban lands (14.6 km2, 7.2%) and Ecological environmental lands (59.5 km2,
21.0%) would be constructed in the reclaimed land. These two lands would provide living spaces,
harmonious life among cities-nature-human, and comfortable residential cultural spaces with
ecological area to balance nature and human.
Lastly, one mega leisure complex would be constructed at the center of the sea dike
(1.95 km2, 0.7%). A unique sea dike leisure area would be constructed with a space for ecology, rest,
and recreation facility. Hotel for landmark, commercial facilities, convention centers, marina,
medical centers, and water parks would be placed.
Figure 5. Comprehensive development plan of the Saemangeum.
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Site 2. Naesosa temple
Naesosa Temple was built by Buddhist Monk Hye-Gu in 633 AD during the Baekje
Dynasty and was rebuilt by Monk Cheong-Min in 1633 AD during the Joseon Dynasty. The
Daeungbojeon (the main hall) in the temple was built at the same period. In 1986 AD, the
temple area (radius of 500m) was designated to be a culturally protected area by the Korean
government.
Large fir trees are located along both sides of the main gate (600m across). As
tourists walk down the walkway, they will come across a row of cherry trees. Just before the
temple itself, are four gods called Sacheonwangsang that “guard” the temple. Upon reaching
the temple itself (just past the guards) the first thing tourists will notice is the 1000-year-old
Dangsan tree. Long times ago, people played in front of the base of the tree.
A bronze bell, which is found in many Buddhist Temples, is housed in Beomjonggak.
This bell was made during the Goryeo Era and is particularly engraved with three images of
Buddha, called “Samjonsang”. The center building of the temple, called “Daeungbojeon” is
also an artistic masterpiece, decorated with splendid colors and designs. The flower Salmun
doors featuring lotus and Chrysanthemum flowers add another element of traditional beauty
to the building.
Of all the temple treasures, Haewuso (meaning “a place that gets rid of worrries”) is
not to be missed. True to its name, the most tourists will find themselves forgetting all their
worries with listening to the soft swaying of the surrounding bamboo grove.
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Figure 6. Naesosa temple
Figure 7. Naesosa temple
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Trip 3. National Groundwater Information System and Korean
Traditional House Village
Site 1. NGIC (National Groundwater Information Management and Service Center)
[Main Roles]
Establishment and operation of groundwater information for efficient utilization such
as observation data of groundwater, new technology and research data
Supporting the establishment of groundwater policy by collecting, managing, and
analyzing groundwater information
Standardization groundwater data, the real time-linkage and cooperation of
groundwater information
[Construction of Groundwater database]
Groundwater facilities information (165 million hole)
Monitoring data (5,427 locations)
- MOLIT: National monitoring network (428)
- ME: Water quality/Local water quality measurement network (262/2,021)
- MAFRA: Agricultural/Seawater permeation monitoring network (268/172)
- Local Gov.: Supplementary groundwater observation network (2,276)
Groundwater survey information
Groundwater policy data
[Providing Information Service to the Nation]
Groundwater facility information, hydrogeological maps, observation data,
groundwater survey information, policies/guidelines etc.
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Establishing policies by providing groundwater information and promoting efficient
groundwater management
[Establishment of groundwater GIS-based system & Providing Information]
Groundwater facility, Basic survey result, Provide GIS Based MAP Service for
Survey Report D / B
-Groundwater Development Facility, Groundwater Information Map, Groundwater
Statistical Map
Groundwater status
Water quality/ Source of pollution
Observation/ survey data
Analysis & statistics
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[National Groundwater Monitoring Network System]
National Groundwater Monitoring Network 428
stations
- Monitoring Items: Water level, EC, Temperature,
Water quality
-Monitoring Periods: Water level, EC, Temperature
(every 1hour), Water Quality (twice a year)
-Monitoring Methods: Automatic
☞ Measurement Data transferred Groundwater
management system and show on GIMS homepage
[Providing Groundwater Information to the Public through the Website]
Groundwater technology / Low Q&A News, Information request etc.
-Mobile Service Delivery to Improve Public Comfort (Review Possibility of groundwater
development, Development procedure, Contact information)
[Publication of National Statistical Data]
(Survey) National Groundwater Utilization Status ＆ Publication of the
groundwater survey annual analysis of the water quality test result (’95 year~)
(Observation) National groundwater observation data (Water level, Water temperature, EC) ＆
Water quality inspection groundwater Observation yearbook (’97 year~)
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Site 2. Daecheong Multi-purpose Dam
The Daecheong Multi-purpose Dam is a concrete and rockfill combined type dam
that is 72 m in height, 495 m in length and 1,234 million m3 and a regulation dam. In the
region of the main dam, there are three saddle dams that prevent the overflow of water from
the reservoir. Upon the completion of Daecheong Dam, the damage caused by flood and salty
water on the crops in the downstream area has been significantly reduced.
Figure 1. Daecheong Multi-purpose Dam.
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[Facilities]
Main Dam
- Type: Combined concrete gravity and rock-fill dam
- Height: 72 m
- Length: 495 m
- Catchment Area: 3204 km2
- Gross Storage: 1,490 million m3
- Flood Water Level: 80.0 (EL.M)
- Normal High Water Level: 76.5 (EL.M)
Elecric Power facility Generation
- Type Vertical: Francis turbine
- Installed capacity: 90,000 kW (45,000 kW*2)
- Electrical generation capacity: 240 million kWh/year
Minimizing flood damages
- Flood Control Storage: 250 million m3
(Control flood damage to downstream areas of the river by storing rainy season water)
Provied water stability
- Water Supply Capacity: 1,649 million m3/year
• Domestic and industrial use: 1,300 million m3/year
• Agricultural use: 349 million m3/year
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[Functions and roles]
By testing water regularily, Daecheong Dam
provides safe water to communities.
-Contribute to people’s health by providing
high quality water
Keep the lake clean and clear using
submersible aerators and by expanding
cultivation of water hyacinths, a kind of
hydrophyte
-Make the lake cleaner by installing
submersible aerators that circulate the water
of the lake to prevent algae formation and
by cultivating water hyacinths that clean
water
Actively listen in order to improve the lake
-The operation and research committee
consists of environmental and civic groups,
academic groups, and local governments to
discuss various interests for enhancing the
water quality of Lake Daecheong,
preserving the lake, and solving community
environmental problems together.
Endeavor to be an eco-friendly business
-Around the dam, built and observation
platform, greenways, wild flowers gardens
and in-line skating facility in an eco-friendly
way and installed more leisure facilities,
such as benches.
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Provide areas to relax
-Provide rest areas by developing tourism
and leisure spaces in accordance with
nature, such as green ways, tourist
complexes, recreation facilities, etc. around
the lake.
Provide educational and cultural spaces
-Use the dam as a classroom, providing
environmental education by developing
comprehensive educational theme studies
connected to the water cultural spaces and
galleries.
-Help schoolchildren learn how to love
water so as to attract active participation in
conserving water and improve public
relations through various field trips.
Contribute to the development of
community culture
-Participate in the community’s cultural
events such as the Daecheong Marathon, the
International Environmental Drawing
contest, etc. which serve to stimulate the
community’s culture
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Site 3. Groundwater Monitoring Station (Cheongwon Gaduk)
[Purpose]
Continuously monitor and observe groundwater level fluctuations
Prevent groundwater source depletion, subsidence, water pollution in advance
Provide basic data for establishing national groundwater policy
[Installation Status]
Installation Principles : National equivalent (by watershed, by city, by hydrology)
Places of interest
-Representative area by major groundwater discharge, discharge area, hydrological
geology unit
-Areas with low water levels due to heavy groundwater use
Development, Development procedure, Contact information)
Before `09yr G/W monitoring station
Afrer `09yr G/W monitoring station
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[Cheongwon Gaduk GW Monitoring Well Information]
[Cheongwon Gaduk GW level]
Well Type Rock Alluviam
Well Elevation(m) 87.59m 87.617m
Installation Date 1995.12.27 1995.12.27
Well Depth(m) 65m 25m
Well aperture size Upper 350mm
Well aperture size
Strainer Installation
Section
Bottom 250mm 350mm
18.0~26.0m
36.0~42.0m
6.0~12.0m 250mm
Measuring Instrument Installation location 24m 19.8m
Measurement(auto) pH, EC,
Temperature
pH, EC,
Temperature
Rock
alluviam
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Site 4. Jeonju Hanok Village
Jeonju Hanok Village is located in the city of Jeonju and overlaps Pungnam-dong
and Gyo-dong. There are over 800 traditional Korean hanok houses. While the rest of city has
been industrialized, Hanok Village retains its historical charms and traditions.
Jeonju Hanok Village is especially beautiful for its unique roof edges, which are
slightly raised to the sky. Hanok houses are generally divided into two sections, Anchae and
Sarangchae. Sarangchae is where the men dwell, and is referred to as the Seonbi room.
Because men and women had to remain separate, Anchae is situated deep inside the house so
that it is secretive and quiet.
Another trait of Hanok is that all the houses are heated with ondol, a unique sub-floor
heating system. Since Koreans enjoy sitting, eating, and sleeping on the floor, it needs to
remain heated. A part of Hanok has been set aside so that tourists can experience traditional
Korean life, called Hanok Life Experience Hall. You can enter the rooms to experience the
warm floor first-hand. An advantage of this system is that it is warm in the winter and cool in
the summer.
The food provided is very traditional, which adds to the traditional ambience. At
Jeonju Hanok Village, visitors can enjoy traditional Korean life and traditional foods like
bibimbap, the most well known dish from the Jeonju region.
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Trip 4. KURT (KAERI’s Underground Research Tunnel) and
UNESCO World Heritage
Site 1. KURT (KAERI’s Underground Research Tunnel)
Since 1997, a long-term Research and Development (R&D) program to develop a
reference High-Level radioactive Waste (HLW) disposal system has been carried out in Korea
Atomic Energy Research Institute (KAERI), and a preliminary disposal concept was
suggested in 2002. To investigate the feasibility, stability and safety of the suggested disposal
concept, KAERI proposed a research program with an underground research facility to the
Korean Government, and the Planning Committee for the Korean Nuclear Energy R&D
Program decided to construct a small scale underground research laboratory at KAERI, which
is called KAERI’s Underground Research Tunnel (KURT) in 2003. After site characterization
and detailed design, KURT in phase I was constructed and completed in November 2006.
After completing several in-situ experiments, KURT was extended for the phase II project
especially to provide independent spaces where the in-situ tests do not affect each other (Fig.
1).
Figure 1. KURT in phase II [Modified from Lee et al., 2016]
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KURT is a generic underground research laboratory, and it intends to obtain
information on the geological environment, and the behavior and performance of engineered
barriers under repository conditions. KURT also plays a significant role in developing and
demonstrating the repository disposal concept and the technologies needed for the
construction and closure of a repository. In this paper, the in-situ tests for characterizing the
hydrogeological properties of fractured rock and their results were summarized, and the
significance of the results was discussed in terms of safety assessment of a subsurface
repository for radioactive waste.
The host rock of KURT is Jurassic granite. Several events of geological survey and
aging dating of the rocks were performed to delineate the geological history of the site, and
the results show that the Jurassic biotite granite intruded into the Paleoproterozoic biotite
gneiss or schist at 185-178 Ma in KURT site and then was deformed into foliated biotite
granite due to mylonitization [Oh et al., 2018]. After mylonitization, two mica and biotite
Jurassic granites intruded at 172-168 Ma. During the exhumation of the Jurassic granite,
extensional fractures formed due to decompression. After that Cretaceous granite of mafic
dyke intruded at 87-85 Ma, major fault system with the trend of N-S or NNE-SSW formed
due to local or regional tectonic stress. Fig. 2 shows the geological map of KURT site.
Figure 2. Geological map of KURT site
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Groundwater in fractured rock tends to flow through conductive fractures rather than
impermeable matrix, and thus groundwater flow in fractured rock is quite heterogeneous and
discontinuous contrary to that in a porous medium. The R&D works in KURT regarding
hydrogeology have focused on development of the techniques for hydrogeological
characterization of fractured rock and evaluation of their uncertainty. The objectives, methods
and results of several in-situ tests on the hydrogeological characterization and its uncertainty
were summarized as follows.
The hydrogeological model for a given site, which is one of the site descriptive
model, is essential for groundwater flow and solute transport modeling thus safety assessment
of a subsurface repository. To build the hydrogeological model, the geological model is
needed to be constructed before carrying out the hydrogeological investigation. KAERI has
been performed several geological investigations such as geophysical surveys and borehole
drillings to build the geological model since 1997 [e.g. Ji et al., 2014; Park et al., 2018].
Recently, two deep boreholes with 500 m and 1,000 m depth from surface, respectively, were
drilled to confirm and validate the geological model. Based on the geological model,
hydrogeological characterization works have been conducted. The hydrogeological
characterization includes evaluation of hydraulic properties for each hydrogeological domain
(e.g. weathering zone, fracture zones and rock mass) and understanding of the processes that
govern the natural groundwater flow system of the site [Park et al., 2018]. These results
finally are synthesized to construct the hydrogeological model.
Long-term monitoring is an important aspect of the development and operation of a
HLW repository starting from the initial site characterization and continuing through to
closure and sealing of the repository and possibly longer. Monitoring provides valuable data
that feed into safety assessment calculations, either as input data or as information that can be
used to confirm and refine predictions. Important lessons learned in the preliminary
monitoring during the Phase I KURT project were the needs to collect good baseline data and
to carry out geochemical analyses on groundwater as early as possible during site
characterization. These considerations have important implications for the groundwater
monitoring methods used in particular for deep borehole monitoring in KURT. A network of
boreholes and several deep boreholes equipped with long-term monitoring systems have been
established in KURT and water samples from water sources and groundwater have been
analyzed in specified time intervals. In KURT, continuous groundwater monitoring has been
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performed using multiple packer system with multiple test intervals a monitoring equipment
has been successfully tested in a large number of in-situ experiments in KURT [Ji et al.,
2016].
From the results of hydraulic tests conducted in KURT, we found the possibility that
a small change of water pressure during a hydraulic test may cause small aperture change and
affect the hydraulic test result. To verify this idea, we directly observed the change in fracture
aperture when we change the water pressure in an interval. The results indicate that a slight
change in fracture hydraulic head leads to a change in aperture, and this suggests the aperture
change should be considered when planning characterization hydraulic tests for a sparsely
fractured rock aquifer [Ji et al., 2013].
Figure 3. Observed hydraulic heads, flow rates and aperture changes during the water
injection tests [Modified from Ji et al., 2013]
When water flows through a geologic medium in the subsurface, an electric field is
generated in the flow field due to direct electrokinetic coupling attributed to existence of the
electric double layer (EDL) at the rock-water interface. The electric potentials, referred to as
streaming potentials (SP), associated with such an electric field can be measured and used to
characterize the groundwater flow-field. In KURT, nine vertical boreholes with 10 m length
were radially installed and several in-situ tests have been conducted to quantify the
correlation between SP and in situ groundwater flow in fractured rock [Ji et al., 2012].
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Figure 4. Borehole nest for the in-situ test to quantify the relation between SP and
groundwater flow during pumping in fractured rock [Ji et al., 2012].
From many laboratory experiments and numerical studies, it was reported that
nonlinear flow in a fracture could be arisen due to the various apertures and roughness and
affect the hydraulic property of a fracture. To evaluate the influence of nonlinear groundwater
flow during a hydraulic test in fractured rock, slug tests were conducted with various initial
head displacements in KURT. For each slug test, the nonlinear flow regime was identified by
calculating the representative Re at a fracture in the test zone using the geophysical logging
and slug test results. The results show that the degree of nonlinearity increased and the
estimated hydraulic conductivity from the test results decreased when the initial head
displacement increased. To estimate the hydraulic property in a linear flow regime, an
equation from the Forchheimer equation and cubic law was introduced. Comparison between
the observed properties in the linear flow regime and the estimated values from the
introduced equation shows a possibility that the suggested equation can be used to estimate
the hydraulic conductivity in a linear flow regime using data from the slug tests in a nonlinear
flow regime [Ji and Koh, 2015].
To evaluate the natural barrier system of a deep geologic disposal system, it is
necessary to characterize the current status of a geologic condition and to estimate its
evolution. For the phase I and II KURT projects, the methods to establish the hydrogeological
model of a disposal site including the hydrogeological characterization techniques and to
reduce uncertainty in the established model have been mainly studied. As future works,
evaluation of the evolution of hydrogeological properties of a disposal site during the life
cycle of a subsurface repository (i.e. construction, operation and closure) is planned to be
conducted based on in-situ experiments in KURT.
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Site 2. Gongju and Buyeo UNESCO World Heritage
1) Gongsanseong Fortress
Gongsanseong Fortress was called Ungjinseong, serving the royal palace of the
Baekje Kingdom for the sixty-four years of the Ungjin Period (475-538 CE). This mountain
fortress occupied 20ha area cross administrative district of Geumseong-dong and Sanseong-
dong of Gongju. Gongsan Mountain is connected with downtown Gongju to the south and the
Geumgang River to the north. Outer side of Gongsan Mountains, except in the southeastern
part, form cliffs, providing optimal geographical conditions for natural fortification.
Gongsanseong Fortress was built for a royal palace and a defensive facility in utilizing the
natural topography and mountain peaks connected to each other across valleys. Important
facilities, including the royal palace, were built within the fortress.
From 1980, archaeological excavations were conducted, revealing the construction
styles of the fortress rampart, the royal palace site, and the ancillary structures of the royal
palace.
Gongsanseong Fortress consists of both earthen wall sections and stone wall sections,
although most parts are stone walls. The total length of the fortress amounts for 2,660m
(stone walls: 1,925m; earthen walls: 735m). Earthen ramparts are found in outer and inner
walls to the east section, and the outer wall area has kept its original appearance of the Baekje
Period. Most of the stone walls were built during the Joseon (1392-1910), the lower parts of
the stone walls were partially constructed during the Baekje Period. The current state of the
fortress shows both the earthen ramparts built during the Baekje Period and stone ramparts
partially reconstructed afterward. After the downfall of Baekje, the fortress ramparts of
Gongsanseong Fortress were reconstructed and rebuilt as stone walls.
Two mountain peaks (110m high) are located within Gongsanseong Fortress, with
the royal palace placed in a wide area (7,000m2) on the summit of the western peak. The
western peak commands a fine view of downtown Gongju, the Geumgang River, and the
Royal Tombs in Songsan-ri. An excavation conducted in 1985 had discovered archaeological
remains, most of which were building sites and ancillary facility sites dating to Ungjin Period.
Among the major archaeological remains are a number of sites once occupied by a large
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building with stud walls (35m east to west, 10m south to north), several buildings with
columns implanted in the ground, and a pond for the local water supply.
Diverse archaeological findings, including roof tiles, bronze mirrors, and
earthenware items, have also been discovered at this site.
2) Royal Tomb of King Muryeong
The Songsan-ri Tombs and Royal Tomb of King Muryeong (reign 462-523) contains
representative relics of the Baekje period (234~678). The Songsan-ri Tombs contain the
graves of kings from the period when Baekje's capital was Gongju, and it is believed to
contain 10 such graves. Only seven graves have been discovered so far.
The main attraction of Songsan-ri Tombs is the wall painting drawn on the number
six tomb – it is the only art of its kind in the world, created from the way the bricks were laid
to create the wall. The tomb is shaped like a long tunnel, the top rounded like a dome. There
are pictures of fire-breathing dragons on the tomb. Only the parts of the wall where the
pictures were to be drawn had earth coated on, and on that earth was drawn Sasindo, the Four
Symbols – blue dragon, white tiger, red peacock, and black turtle.
The popular Tomb of King Muryeong is the 7th tomb, and it is the resting place for
Baekje's 25th King Mu-Ryeong and his queen. This tomb was discovered accidentally when
installing pipes to prevent tombs number 5 and 6 from being flooded. Tomb of King
Muryeong was found to be unusual in the way it was built and what it contained. It was built
with bricks like the 6th Tomb, and many national treasures were found inside, supplying
scholars studying Baekje culture with precious research material. There were 108 kinds of
artifacts found inside, totaling 2,906 items altogether. Twelve of these artifacts were
designated National Treasures. They are all on display at Gongju National Museum. Some of
the representative treasures are the crowns worn by the king and the queen, gold decorations
for the crowns, gold earrings, necklaces, bronze mirrors, pillows, and foot rests. Recently the
tomb was permanently sealed off to protect the treasures. However, you can look at the
miniature of the tomb, an exact duplicate of the original, in the basement of the Gobungun
Building.
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3) Jeongnimsaji Temple Site
The Jeongnimsaji Temple Site, located in the heart of Buyeo, is one of the most well-
known temple sites dating from the Baekje period. It is surrounded by mountains, which
Geumseongsan located on its east and Busosan on its north. Jeongnisamji, which was situated
at the center of the capital during the Sabi period, contains a stone pagoda, with an inscription
describing the story of how the Tang dynasty caused the fall of Baekje. This implies that
Jeongnimsa was a symbolic place that shared the same fate as the Baekje Kingdom.
Jeongnimsaji has the typical layout of temples dating from the Baekje period. The middle
gate, stone pagoda, Geumdang (Golden Hall), and auditorium were built in a straight line in
the north-south direction, and they were surrounded by the living quarters of the monks and
passageways. While there are no evidentiary records on the exact time period during which
Jeongnimsa Temple existed, it is assumed that it must have been destroyed with the fall of
Baekje. This is based on the reddish earth layer, which had been burned, that was discovered
at the Geumdang during an excavation survey.
At present, the Jeongnimsaji Temple Site contains a five-story stone pagoda,
designated as National Treasure No. 9, and a stone seated Buddha statue dating from the
Goryeo period, designated as Treasure No. 108, and the temple site itself has been designated
as Historic Site No. 301.
Jeongnimsa Temple, located in the heart of Sabi, was a very important Buddhist
temple at the time, and it provides evidence of the fact that the Buddhist culture introduced
from China was completed as the Buddhist culture of Baekje. Jeongnimsaji had been
established in the typical Baekje temple style, with one Geumdang (Golden Hall) and one
pagoda, along with an auditorium. This tradition of building an auditorium continued until
the Goryeo Dynasty. The five-story stone pagoda at Jeongnimsaji, which is the sole stone
pagoda remaining from the Baekje period, actually demonstrates the structural characteristics
of a wooden pagoda. An interesting matter to note is that the stone pagoda construction
techniques of Baekje had been passed on to Silla, and set the stage for Korea to emerge as a
country with exquisite stone pagodas.
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4) Gungnamji Pond
Gungnamji Pond (Historic Site No.135), located in Seodong Park, is Korea’s first
artificial pond and was created by King Mu (from the Baekje Dynasty) who was in love with
and eventually married Princess Seonhwa. ‘Gungnamji’ (literally means ‘a pond in the south
of the royal palace’ in Korean) was named according to the Samguksagi record.
Seodong Park is a sculpture park displaying 68 sculptures created by famous Korean
sculptors. Mahan Hall showcases the lifestyle and culture of Mahan, a tribal confederation
during the Samhan period. The park also features various facilities such as an observatory,
fishing spot and a promenade.
According to a record in the Samguksagi, the History of the Three Kingdoms, King Mu
dug this lake south of his palace in the 35th year of his reign (634) and connected it by a
7800-meter long waterway to the water source. The king then had willow trees planted
around the bank and had an artificial mound constructed in the middle of the lake.
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References
Ji, S.-H., D.H. Lee, I.W. Yeo, K.W. Park, and Y.K. Koh (2014), Derivative-assisted
classification of fractured zones crossing a deep borehole, Groundwater, 52(1), 145-
155.
Ji, S.-H., H.-B. Lee, B.-W. Kim, B. Malama, Y.-K. Koh, M.Y. Lee, J.-W. Choi (2012),
Streaming potential response during pumping in a fractured rock aquifer, American
Geophysical Union Fall Meeting, San Francisco.
Ji, S.-H., N.-Y. Ko, Y.-K. Koh, J.-S. Kwon, J.-H. Ryu, K.W. Park, C.-K. Park, S. Yoon, S.Y.
Lee, J.-K. Lee, J. Lee, C. Lee, and S. Jung (2016), A Safety Case of the Conceptual
Disposal System for Pyro-processing High-Level Waste Based on the KURT site
(AKRS-16): II. Site Description, KAERI/TR-6728/2016, KAERI, Daejeon.
Ji, S.-H., and Y.-K. Koh (2015), Nonlinear groundwater flow during a slug test in fractured
rock, Journal of Hydrology, 520, 30-36.
Ji, S.-H., Y.-K. Koh, K.L. Kuhlman, M.Y. Lee, and J.W. Choi (2013), Influence of pressure
change during hydraulic tests on fracture aperture, Groundwater, 51(2), 298-304.
Lee, J., I.-Y. Kim, D.-S. Bae, M. Lee, and H.-J. Choi (2016), A Safety Case of the Conceptual
Disposal System for Pyro-processing High-Level Waste Based on the KURT site
(AKRS-16): I. Design Base and Disposal Facility, KAERI/TR-6727/2016, KAERI,
Daejeon.
Oh, C.W., K.S. Yengkhom, S.H. Lee, and J.S. Kim (2018), The character and history of brittle
deformation in the Yuseong area, KAERI/CM-000/2017, KAERI, Daejeon.
Park, K.W., K.S. Kim, Y.K. Koh, and S.-H. Ji (2018), Hydrogeological model of KURT site,
Econ. Environ. Geol., 51(2), 121-130, in Korean (English abstract available).
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Trip 5. Daesan riverbank filtration site and Upo Wetland
Site 1. Daesan riverbank filtration site
Daesan waterworks operated by Changwon City is the first riverbank filtration site in
Korea for the public water supply of local government. Changwon city is located in
southeastern part of Korean Peninsular and the city is capitol of Gyoungsangnam-Do. Daesan
waterworks is nearby Nakdong-River which is longest river in South Korea (Figure 1).
Daesan waterworks comprise of intake facilities and water treatment plants. The
design intake capacity is currently known to about 130,000 m3/day and the capacity has been
developed in three stages over 10 years (Table 1). However, the third stage facilities are not
fully developed and operational yet. The wells are installed in alluvial deposit of which
thickness is about 40 to 50m (Figure 2) and the basement is believed to Cretaceous volcanic
rocks (Figure 3). The sandy gravel over the weathered basement rock plays a role as main
aquifer system in the site. The transmissivities of the aquifer from pumping tests show wide
range of 10-4 to 10-1 m2/sec with the average of about 3.0*10-2 m2/sec.
The statistics report of water supply shows that Daesan waterworks supplied 26
million m3 in 2016 and the daily maximum intake from riverbank filtration wells was about
76,000 m3/day which is 58% of design intake capacity. According to recent local news, some
radical collector wells are said to be in preparation for full supplying of intake capacity.
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Figure 1. The location map of Daesan riverbank filtration site in Changwon City.
Figure 2. The simplified geological section of alluvium system
in Daesan riverbank filtration site.
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Figure 3. The geological map of Daesan riverbank filtration site
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Table 1.Riverbank filtration system in Daesan Waterworks.
1st
Stage
Water supply
Start date 2001. December
Intake
facilities 7 vertical wells
Water
treatments
Aeration by falling tower - Rapid sand filtration -Granular
activated carbon filtration – Disinfection (chlorine)
2nd
Stage
Water supply
Start date 2006. September
Intake
facilities
36 vertical wells and
1 radical collector well
Water
treatments
Aeration by falling tower - Rapid sand filtration -
Granular activated carbon filtration – Disinfection
(chlorine)
3rd
Stage
Water supply
Start date
2013. March (Preliminary supplying.
Not fully operational yet)
Intake
facilities 5 radical collector wells
Water
treatments
Aeration by falling tower - Rapid sand filtration -
Granular activated carbon filtration – Disinfection
(chlorine)
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Site 2. Changnyeong Upo wetland
Upo Wetland located in Changnyeong-gun County, Gyeongsangnam-do Province, is
the largest riverine wetland in the Republic of Korea with a well preserved natural
environment. The area of Upo Wetland spans about 2.3km2 and many smaller wetlands are
scattered around. In recognition of its values as a migratory bird habitat, the wetland has been
inscribed on the Ramsar List of Wetlands of International Importance in 1998, and during the
10th Meeting of the Conference of the Contracting Parties (COP10) held in 2008, many
experts visited the wetland.
The creation of Upo Wetland dates back to when the Korean peninsula was formed.
It has provided people with a means of livelihood, while retaining its well-preserved
primitive ecosystem. In addition, the wetland plays an important role as a habitat for more
than 10 endangered species, a fact that draws global attention. The beautiful landscape
surrounding the wetland area increases the invaluable aspect of the wetland as a rich
repository of the primitive ecosystem.
Recent archaeological discoveries such as an old wooden boat found in Bibongri
Shell Mound Site confirm that in the past the inland area of Changnyeong region was
affected by the intrusion of sea water that flowed along the Nakdong River. The small
riverine marshes surrounding Upo were also created in this process. The shell mounds are
very important evidence in understanding the creation of Upo and its adjacent wetlands. The
wooden boat found in the shell mound is estimated to be 7500 years old, which places it
amongst the world's oldest boats such as those found in Kuwait and China (8000~7000 years).
The shell mounds, a pit for storing acorns and fishery tools, are believed to have been used by
people in communities who lived along the seashore, being evidence of prehistoric lifestyles
in this area. Besides, other archeological discoveries including stone pestles, grinding stones,
wooden goods, pottery shards and a mesh bag significantly enhances the site's archeological
value.
These archeological relics prove the previous interaction with sea water in this area
which is now regarded as a freshwater zone, and also provides a glimpse of lifestyles of the
Neolithic era. It also reveals how the relationship between the wetland and human beings has
changed with the flow of time.
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Trip 6. Geologic Park and Cine Theme Park
Site 1. Jeokbyeokgang-peperites
We visit this site to see the peperites developed at interface between rhyolite and
lacustrine sediments. The peperites have been studied by Gihm and Kwon (2017), and
description and interpretation for the peperites are based on their work with slight
modifications.
1) Geological setting
Well-developed Cretaceous volcano-sedimentary successions outcrop in the
southern part of the Korean Peninsula along NE–SW trending strike-slip fault systems (the
Gongju, Hamyeol, and Gwangju fault systems), and are thought to have formed due to a
combination of continental arc-volcanism and crustal deformation induced by oblique
subduction of the Izanagi plate (proto-Pacific plate) beneath the Eurasian plate (Fig. 1, Sohn
and Chough, 2010). One of these successions – the elliptical-shaped Buan Volcanics – occurs
at the southwestern termination of the Hamyeol Fault (Figs 1 and 2; Koh et al., 2013) and is
composed mostly of rhyolitic tuff and rhyolite. Nine lithostratigraphic units (formations) have
been identified within it on the basis of rock type (epiclastic or volcanic/volcaniclastic),
eruption style (explosive or effusive), grain size, and the composition of constituent minerals
and lithic clasts. From oldest to youngest, these units comprise the Cheonmasan Tuff, the
Yeondong Tuff, the Udongje Tuff, the Seokpo Tuff, the Gyeokpori Formation, the Gomso
Rhyolite, the Yujeongje Tuff, the Byeonsan Tuff, and the Samyebong Rhyolite (Koh et al.,
2013). A Sensitive High Resolution Ion Microprobe (SHRIMP) age for the Seokpo Tuff of 89
± 2.0 Ma (Koh et al., 2013)\
2) Peperites
The peperites investigated herein occur along the coastline in the western part of the
Buan Volcanics (Fig. 2b) where the Gyeokpori Formation is conformably overlain by an
isolated body of rhyolite (the Gomso Rhyolite; Fig 2). In this area, the Gyeokpori Formation
consists mostly of laterally continuous, laminated to bedded couplets of dark-gray mudstones
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and sandstones. At the contact with the Gomso Rhyolite, the host sediment’s laminae and
bedding are either distorted or completely absent (Fig. 3), and the host sediment is also
strongly indurated (hornfelsed). The deformed host sediment and overlying Gomso Rhyolite
share an undulatory contact due to the development of a series of load and flame structures,
which range in wavelength from ~1 m to greater than 10 m and have an amplitude of 0.1–1 m.
The overlying Gomso Rhyolite is more than 30 m thick and is interpreted to have been
emplaced as a lava flow (Choi et al., 2001). Peperites occur either as laterally continuous
layers or isolated patches that are generally thinner (<0.5 m) in load zones and thicker (≤3 m)
in flame zones. According largely to position of peperites on the load and flame structures,
juvenile clasts of the peperites have distinctive morphology and show vertical and lateral
textural variations. Therefore, we classified the peperites into two species (Type-1 peperites
and Type-2 peperites). Type-1 peperites are common in the load zones, whereas Type-2
peperites only occur above the flame zones of the load and flame structures.
Polyhedral juvenile clasts that commonly exhibit jigsaw-crack textures in Type-1
peperites (see Fig. 3 for description) indicate that the blocky juvenile clasts were produced by
in situ quenching-related fragmentation caused by thermal contraction of rhyolite (Fig. 8a;
Kokelaar, 1986). These thermal contractions would have opened fractures and caused a
localized drop in pressure, which resulted in injection of the underlying, fluidized host
sediment, thus forming mudstone infill in the cracks (Hanson and Wilson, 1993). The fine-
grained juvenile clasts surrounding the coarse-grained ones near the lava-flow base also
indicate upward injections of the fluidized host sediment. The juvenile clasts set in the
underlying host sediment would have formed by detachment of juvenile clasts from base of
lava flow due to instability of fluidized substrate (host sediment). The rounded juvenile clasts
formed by abrasion of initially angular juvenile clasts after brittle fragmentation occurred, as
evidenced by the abundance of platy to angular, fine-grained juvenile clasts near to the lava–
sediment contact that are likely initial angular margins of precursors of the rounded juvenile
clasts (Fig. 5a). Shearing caused by continued motion of the overlying lava flow has been
responsible for this abrasion (Fig. 5a).
The platy, angular to polyhedral juvenile clasts present in Type-2 peperites indicate
that they also formed by brittle fragmentation (see Fig. 4 for description). The lateral tapering
of Type-2 peperites and a decrease in abundance of fine-grained juvenile clasts away from the
flame zones suggest that the efficient of responsible fragmentation processes propagated from
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flame zones towards the interior of the featureless rhyolite (Fig. 4). In addition, abundant
fine-grained juvenile clasts with jagged margins in the proximal zone and the lateral
disappearance of the reticular fracture networks in the distal zone indicate that Type-2
peperites formed by internal steam explosions (Hanson and Hargrove, 1999, Fig 5b). Poorly
sorted mixtures of fine- and coarse-grained juvenile clasts, alongside vertical connections
with the underlying host sediment indicate that the proximal zone can be regarded as
explosion sites (e.g., Lorenz and Kurszlaukis, 2007).
The internal steam explosions are thought to have produced large amounts of fine-
grained juvenile clasts with ragged margins, and the clasts intermingled with fluidized host
sediment injected from the flame zones, forming poorly sorted proximal zone (White, 1996).
However, the rare occurrence of a jigsaw-crack texture in proximal zone implies that the
fragmentation processes induced by the internal steam explosions were not fully efficient and,
heat exchange between the fragmented coarse-grained juvenile clasts containing remnant heat
and injected host sediment caused the coarse-grained juvenile clasts to be fragmented by in
situ thermal contraction (White, 1996). In contrast to the proximal zone, the common
occurrence of jigsaw-crack textures in the middle and distal zones indicates that the juvenile
clasts formed by in situ quenching fragmentation, rather than the internal steam explosions,
resulted from rapid heat transfer from hot, brecciated rhyolite (precursor of juvenile clasts) to
water-saturated host sediment. Opening and lateral propagations of the fractures during the
internal steam explosions resulted in a rapid drop in pressure within the interior of the lava
flows. As a result, the fluidized host sediment has been sucked from the proximal zone
through the fractures, as indicated by the preferential orientations of long axes in fine-grained
juvenile clasts in the distal zone (Fig. 4e). A lateral decrease in abundance of the fine-grained
juvenile clasts is interpreted to result from blocking by coarse-grained juvenile clasts in the
middle zone that prevented lateral migration of the fine-grained juvenile clasts with the host
sediment, which also suggests transportation of the host sediment from the proximal zone
towards the distal zone (Fig. 4c). The lateral tapering, merging, and disappearance of the
reticular fracture networks in the distal zone likely corresponded to the limit of the region
affected by brecciation during the internal steam explosions (Fig. 4d).
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Site 2. Chaeseokgang
The Gyeokpori Formation is composed mainly of dark-gray mudstones intercalated
with sandstones and conglomerates. Detailed sedimentological studies have interpreted that it
was deposited in a lacustrine fan-delta system, with eight individual depositional
environments having been identified based on constituent sedimentary facies and stacking
patterns: (1) a subaqueous talus; (2) a delta plain; (3) a steep-gradient large-scale delta slope;
(4) the base of a delta slope to a prodelta setting; (5) a small-scale nested Gilbert-type delta;
(6) a small-scale delta-lobe system; (7) a subaqueous fan, and (8) a basin plain (Kim, 2000;
Kim et al., 2003). Following descriptions and interpretations are on the basis of Kim et al.
2003.
At the Cheseokgang site, we can see a small-scale delta-lobe system composed of
mound-shaped or lobate bodies of sandy conglomerate deposits. Each body is a few metres
high (up to 9 m) and a few tens of metres wide (up to 30 m). They are conformably underlain
and overlain by sandy black shale deposits, forming an isolated or coalesced package. Flame
structures are common along the planar bases of the mound-shaped bodies. Coarsening-
upward trends are prominent. Individual beds dip outward towards both lateral margins,
abruptly downlapping onto the underlying strata (Fig. 6). Each unit is irregularly bedded and
commonly dissected by syndepositional normal faults. Conglomeratic units are mostly
inversely graded and contain outsized floating or protruding clasts. Each bed either thickens
down-dip, forming a blunt terminus, or thins down-dip, being transitional to concentrated
gravel clasts at the terminus. Sandy units are mostly normally graded with a stratified or
laminated upper part and include rip-up mudstone chips.
The mound-shaped external form and the coarsening- upward stacking pattern
suggest progradational delta lobes. Development of inverse grading, incorporation of large
outsized clasts and downdip coarsening with clast-concentrated termini in the conglomeratic
units suggest cohesionless debris flows or modified grain flows (Lowe, 1982; Nemec & Steel,
1984; Surlyk, 1984). On the other hand, the normally graded sandy units indicate sandy
turbidity currents (Lowe, 1982; Surlyk, 1984). Poor development of prodelta or bottomset
deposits can be accounted for by the predominance of laminar, high-strength, non-cohesive
mass flows over the turbulent expansive flows. High sedimentation rates are inferred for the
prograding slopes from the ubiquitous syndepositional faults and upward injection of soft
substrate (flame structures) at the base.
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Figure 1. Simplified geological map showing the Cretaceous volcanic-sedimentary successions
of the Korean Peninsula. Volcanic-sedimentary successions are mainly distributed along sinistral
strike-slip fault systems (the Gwangju and Gonju Fault Systems) and are composed of
sedimentary rocks (SR), volcanic rocks (VR), and intrusive bodies (IR, typically Granite). The
inset map shows the regional tectonic regime. MTL (in the inset map) = Median Tectonic Line.
Figure modified after Ko et al. (2015).
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Figure 2. Geological map of the Buan Volcanics.
The Buan Volcanics consists of rhyolitic (lapilli) tuff, rhyolite and sedimentary rocks
(Gyeokpori Formation), which are categorized into nine stratigraphic units (or formations).
Figure modified from Koh et al. (2013).
Figure 3. Photographs of Type-1 peperites.
(a) Rounded juvenile clasts with gently curved margins (arrows and inset).
The rounded juvenile clasts occur near to the boundary.
(b) Upward decrease in abundance of fine-grained juvenile clasts
(c) Jigsaw-crack texture.
(d) Dispersed juvenile clasts within the host sediment.
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Figure 4. Panorama view of Type-2 peperites (upper) and photographs of Type-2 peperites
(lower). Type-2 peperites only occur above the flame zones and laterally penetrate into the
interior of the featureless rhyolite. A decrease in thickness and textural variations of the
juvenile clasts allows proximal, middle, and distal zones away from the flame zone to be
identified.
(a) The proximal zone of Type-2 peperites.
(b) Close-up view of the proximal zone, which is composed of poorly sorted mixtures of
fine-grained (ash- to medium lapilli-sized) and coarse-grained (coarse lapilli- to block-sized)
juvenile clasts. Jigsaw-crack textures (indicated by an arrow) rarely occur.
(c) Photographs of the middle zone, which consists mostly of tetragonal to polyhedral,
coarse-grained juvenile clasts that commonly contain jigsaw-crack textures. Note a lateral
decrease in the amount of fine-grained juvenile clasts with distance away from the flame
zone.
(d) Interconnected, reticular, and mud-filled fractures, and tabular to wedge-shaped, coarse-
grained juvenile clasts in the distal zone. (e) Detailed view of the interconnected, reticular,
and mud-filled fractures in the distal zone. The long axes of angular to platy, fine-grained
juvenile clasts are typically aligned parallel to the directions of the fractures.
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Figure 5. Schematic models for the formation processes of Type-1 and Type-2 peperites (not
to scale). See section 5.2 in the main text for detailed interpretation (Abbreviations: P=
proximal zone, M= middle zone, D= distal zone).
Figure 6. Lobate and mounded-shaped sand and conglomerates.
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Site 3. Buan Cine Theme Park
Buan Cine Theme Park is a large film production complex in Gyeokpo-ri, Byeonsan-
myeon, Buan-gun measuring a total of 148,400 square meters in area. The park is comprised
of a two main sections: a folk village (89,696 m²) and an indoor studio called Sunset Village
(58,704m²). Inside the folk village, Korea’s representative royal palace (Gyeongbokgung
Palace) has been recreated along with traditional houses of the noble class, village schools,
traditional streets, a pond, a fortress, and more. The park became famous after serving as the
main filming location for popular Korean movies “The King and The Clown” (2005),
“Hwang Jin-yi” (2007), and “The Sword With No Name” (2009).
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References
Choi, S. W., Lee, Y. E., Park, K. H., Lee, C. H., 2001. Occurrence and formation model of
peperite in the Jugmagri area, Byeonsan Peninsula, Korea. J. Geol. Soc. Korea 37, 197-308
(in Korean with English abstract).
Chough, S.K., Sohn, Y.K., 2010. Tectonic and sedimentary evolution of a Cretaceous
continental arc-backarc system in the Korean peninsula: new view. Earth Sci. Rev. 101, 225-
249.
Gihm, Y.S., Kwon, C.W., 2017. Textural variations and fragmentation processes in peperites
formed between felsic lava flow and wet substrate: An example from the Cretaceous Buan
Volcanics, southwest Korea. J. Volcanol. Geotherm. Res. 331, 92–101.
Hanson, R.E., Hargrove, U.S., 1999. Processes of magma/wet sediment interaction in a large-
scale Jurassic andesitic peperite complex, northern Sierra Nevada, California. Bull. Volcanol.
60, 610-626.
Hanson, R.E., Wilson, T.J., 1993. Large-scale rhyolitic peperites (Jurassic, southern Chile). J.
Volcanol. Geotherm. Res. 54, 247-264.
Ko, K., Park, S., Kwon, C.W., 2015, Soft-sediment deformation structures in the Cretaceous
Gyeokpori Formation of the Buan area, Korea: Structural characteristics, reconstruction of
paleoslope and triggering mechanism of slump. J. Geol. Soc. Korea 51, 545-560.
Koh, H.J., Kwon, C.W., Park, S.I., Park, J.U., Kee, W.S., 2013. Geological report of the Julpo,
Wido, and Hawangdeungdo sheet, institute. Korea Institute of Geoscience and Mineralogy
Resources, Daejeon, Korea.
Kokelaar, B.P., 1986. Magma water interactions in subaqueous and emergent basaltic
volcanism. Bull. Volc. 48, 275-289.
Kim, S.B., 2000. Sedimentary processes and environments of the Kyokpori Formation
(Cretaceous), SW Korea. PhD Thesis, Seoul National University, Seoul, Korea.
Kim, S.B., Chough, S.K., Chun, S.S., 2003. Tectonic controls on spatio-temporal
development of depositional systems and generation of fining-upward basin fills in a strike-
slip setting: Kyokpori Formation (Cretaceous), south-west Korea. Sedimentology 50, 639-
665.
Lorenz, V., Kurszlaukis, S., 2007. Root zone processes in the phreatomagmatic pipe
emplacement model and consequences for the evolution of maar-diatreme volcanoes. J.
Volcanol. Geotherm. Res. 159, 4-32.
Lowe, D.R., 1982. Sediment gravity flows. II. Depositional models with special reference to
the deposits of high-density turbidity currents. J. Sed. Petrol., 52, 279–297.
Nemec, W., Steel, R.J., 1984. Alluvial and coastal conglomerates: their significant features
and some comments on gravelly mass-flow deposits. In: Sedimentology of Gravels and
Conglomerates (Eds E.H. Koster and R.J. Steel), Can. Soc. Petrol. Geol. Mem. 10, 1–31.
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Surlyk, F. (1984) Fan-delta to submarine fan conglomerates of the Volgian–Valanginian
Wollaston Forland Group, East Greenland. In: Sedimentology of Gravels and Conglomerates
(Eds E.H. Koster and R.J. Steel), Can. Soc. Petrol. Geol. Mem., 10, 359–382.
White, J.D.L., 1996. Impure coolants and interaction dynamics of phreatomagmatic
eruptions . J. Volcanol. Geotherm. Res. 74, 155-170.
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Trip 7. Gyeongju LILW disposal facility and UNESCO World
Heritage
Site 1. Gyeongju Donggung Palace and Wolji Pond
Donggung Palace and Wolji Pond in Gyeongju is an artificial pond in Gyeongju
National Park, South Korea. It was part of the palace complex of ancient Silla. It was
constructed by order of King Munmu in 674 CE. The pond is situated at the northeast edge of
the Banwolseong palace site, in central Gyeongju. It is an oval shape; 200m from east to west
and 180m from north to south. It contains three small islands.
Those were the secondary palace site which was used for the palace of the Crown
Prince along with other subsidiary buildings and it also was the banquet site for important
national event and important visitors. After the fall of Silla, the site was abandoned and
forgotton. The pond was referred to as "Anapji" instead during the time of Goryeo and Joseon
period. In the 1980s, pottery fragment with letters “Wolji” (a pond that reflects the moon)
carved onto it was found, revealing the true name of the pond. After the discovery, the site
has been renamed to the current Donggung Palace and Wolji Pond.
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Site 2. Bulguksa temple
Bulguksa Temple is the representative relic of Gyeongju and was designated as a
World Cultural Asset by UNESCO in 1995. The beauty of the temple itself and the artistic
touch of the stone relics are known throughout the world.
Bulguksa Temple was built in 528 during the Silla Kingdom, in the 15th year of King
Beop-Heung's reign (514-540). The temple was originally called ‘Hwaeom Bulguksa Temple’
or ‘Beopryusa Temple’ and was rebuilt by Kim Dae-Seong (700-774), who started rebuilding
the temple in 751 during the reign of King Gyeong-Deok (r. 742-765) and completed it in
774 during the reign of King Hye-Gong (r. 765-780). Upon completion, the temple’s name
was changed to Bulguksa.
Bulguksa Temple underwent numerous renovations from the Goryeo Dynasty (918-
1392) to the Joseon Dynasty (1392-1910), but was burned down during the Imjin War
(Japanese Invasions, 1592-1598).
Reconstruction started again in 1604 during the 37th year of King Seon-jo’s reign
(Joseon Dynasty) and was renovated about 40 times until 1805 (during the reign of King Sun-
Jo, 1790-1834). After this time, the temple suffered serious damage and was often the target
of robbers.
In 1969, the Bulguksa Temple Restoration Committee was formed and in 1973,
Mulseoljeon, Gwaneumjeon, Birojeon, Gyeongru, and Hoerang (all of which had previously
been demolished) were rebuilt. Other old or broken sites (such as Daeungjeon, Geungnakjeon,
Beomyeongnu and Jahamun) were repaired.
Even today, Bulguksa Temple is home to many important cultural relics such as
Dabotap Pagoda (National Treasure No. 20), Seokgatap Pagoda (National Treasure No. 21),
Yeonhwa-gyo & Chilbo-gyo Bridges (National Treasure No. 22), Cheongun-gyo & Baegun-
gyo Bridges (National Treasure No. 23), Seokguram Grotto (National Treasure No. 24), the
Golden Seated Vairocana Buddhist Figure (National Treasure No. 26), the Golden Seated
Amita Figure (National Treasure No. 27), and Saritap Pagoda (Treasure No. 61).
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Site 3. Gyeongju LILW disposal facility
1) Introduction
The safe management of radioactive waste is a national task required for sustainable
generation of nuclear power, and for energy self-reliance, in Korea. Since the initial
introduction of nuclear power in Korea in 1978, rapid growth in nuclear power has been
achieved. Since the closure of the oldest nuclear reactor (Kori 1) in June 2017, South Korea
has been operating 24 nuclear reators with a total capacity of 22.5 GW. In addition, as of May
2017, South Korea had five reactors under construction, of which three near completion, and
the other two about 30% complete (Shin Kori 5 and 6). In addition, six reactors were at a
planning stage. During his presidential campaign, Moon Jae-In promised to cancel
construction plans for eight new nuclear plants (the six planned reactors and the two
uncomplete reactors).
Amid growing public concerns over nuclear safety, the Moon administration
established and independent ad hoc committee on managing public debate and launched a
deliberative opinion poll on whether to permanently abandon Shin Kori 5 and 6 projects. In
October 2017, the public consultation showed support for both restarting construction of the
two reactors and scaling down of nuclear power generation. The government therefore
announced the immediate resumption of construction work on the two reactors.
Simultaneously, they announced its nuclear phase-out roadmap, which includes: 1. The
cancellation of plans to build the six planned nuclear reactors; 2. no extension of the lifespan
of 14 aging nuclear power reactors, totaling 12.5 GW of capacity; and 3. The closure of
Wolsong 1 (which is now the oldest reactor) earlier than scheduled.
South Korea will gradually reduce the number of nuclear reactors from 24 in 2017 to
18 in 2030 (after an initial rise to 27 reactors in 2022). Nuclear power capacity will first
increase to 27.5 GW by 2022, and then will gradually decline to 20.4 GW by 2030. This large
nuclear power generation program has produced a significant amount of radioactive waste,
and the amount of waste is steadily growing. Moreover, due to wide application of
radioisotopes, the annual generation rate of related radioactive waste from industry, hospitals,
and research institutions is also increasing.
In accordance with the fundamental principle of radioactive waste management
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recommended by the International Atomic Energy Agency (IAEA), the objective of
radioactive waste management is ‘protecting human health and environment now and in the
future, without imposing undue burden on future generations’. The radioactive waste
management facilities have been in operation so that the current generation, the beneficiary of
nuclear energy, is responsible for the safe management of radioactive waste. In Korea, ‘the
radioactive waste management measure’ was approved by the Atomic Energy Commission in
September 1998. In this measure is a declaration of the basic principles that radioactive waste
management should be under government responsibility, with a top priority on safety; that
radioactive waste generation should be minimized, and the site selection process should be
transparent; and finally, that the principle ‘polluters pay’ should be adopted. Then, in order to
meet the international standard and practice of radioactive waste management, a new law on
radioactive waste management was promulgated in March 2008 that laid the foundation for
the Radioactive Waste Management Fund, and for a new organization named the Korea
Radioactive Waste Agency(KORAD) [1].
Radioactive waste is defined in the Nuclear Safety Act as radioactive materials
(including spent nuclear fuel), or substances contaminated by them, that are subject to
disposal [2]. In Korea, radioactive wastes are classified into two categories; low- and
intermediate-level waste (LILW); and high-level waste (HLW), according to their specific
activity and degree of heat generation. Currently, there is no plan to reprocessing, therefore,
only spent nuclear fuel (SNF) comes under HLW. The radioactive wastes generated to date
are being stored at reactor sites, and LILW is to be disposed of in the Wolsong LILW
Disposal Center (WLDC), which is now under construction in Gyeongju City. Concerns,
however, are mounting as the national policy for SNF management has not been decided yet.
Since the capacity for wet storage at reactor sites is gradually saturated, it is time to establish
the long-term national policy for SNF management, as well as short-term, on-site
management options (e.g., re-racking and transshipment).
2) The current status and prospect of LILW management
- LILW generation
Since Kori-1 started operation in 1978, the amount of LILW has consistently
increased. Additionally, the more radioactive isotopes are used in industries, hospitals and
institutes; the more radioactive waste from those sources is produced. The total accumulation
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of LILW to date is about 120,000 drums (200ℓ equivalent) as of the end of December 2012. It
is assumed that Kori-1 has a 10-year life extension, the other reactors are to be operated
during its design life and a total of 34 reactors are to be constructed by 2024. It is also
assumed that 1-year of preparation will be carried out before decommissioning. Each plant
will take ten years to decommissioning at the end of their functional life-span.
- The status of the 1st stage construction of the LILW disposal facility
Gyeongju City in Gyeongsang Buk Do (Gyeongsang-North Province) was
designated as a LILW disposal site as a result of local referendum in November 2005, and
Wolsong, the rural area of Gyeongju City, was selected as the final candidate in January 2006.
KORAD has responsibility for construction and operation of the WLDC, which has a final
waste disposal capacity of 800,000 drums within the area of about 2,100,000 m2. As the first
stage of the disposal center construction (Figure 1), six silos are under construction to
accommodate 100,000 drums (35,200 m3). They are expected to be completed by June 2014.
The surface facilities, such as a waste inspection and storage building, a radioactive waste
treatment building, the main control center, and the equipment maintenance shop, are all
completed. The underground facility is divided into an operation tunnel, a construction tunnel,
an entrance shaft for workers, and six silos. Waste packages are disposed of in separate
vertical silos using concrete disposal containers. The 1st stage construction is about 95%
complete as of the end of June 2013.
In addition, in order to enhance the safety and reliability of the WLDC, an in-situ
demonstration test facility was constructed in part of the construction tunnel. Experiments
and research evaluating long-term degradation of the engineered barriers, and gas emissions
of the dry active waste have been undertaken, and a 10-year monitoring program will be
conducted to verify the safety measures.
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Figure 1. Layout of the 1st stage Wolsong LILW Disposal Center.
- New classification and management strategy of LILW
In 2009, a new classification of radioactive waste was created by which radioactive
waste is now sorted into six categories (i.e., high level, intermediate level, low level, very low
level, very short lived and exempt waste). This classification was recommended by the IAEA,
taking account of disposal options by half life, radioactivity and various types of radioactive
waste [3].
The result of an estimate of the expected accumulation of LILW, based on the new
classification, along with plans for additional NPP construction, shows that it would exceed
800,000 drums, the total capacity of WLDC. This is why it is necessary that the facilities for
volume-reduction be operated, that radioactive waste be sorted according to a more detailed
classification, and that new strategies of treatment and disposal are developed considering the
characteristics and activity of the wastes. In other words, it is essential to secure technologies
and to improve the system so that comprehensive management of the WLDC might be
realized. Most of decommissioning waste is metal or concrete, and under the new
classification about 67.1% of decommissioning waste is VLLW (4.2% ILW and 28.7% LLW),
it is desirable to dispose of them separately, according to a proper method, from among
geological disposal; engineered vault-type disposal; and trench-type disposal, by considering
waste characteristics.
In view of this point, KORAD has been preparing for construction of the engineered
Entrance Tunnel
6 silos
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vault facility as the 2nd stage, which is due for completion at the end of 2019, and which can
accommodate up to 125,000 drums (Figure 2). As the silo, and the engineered-vault, facilities
are to be co-located at the WLDC, the individual and integrated safety assessments of these
facilities are being undertaken. In addition, construction of the trench disposal facility is also
planned for VLLW, generated in large volume in the process of decommissioning NPPs in the
near future [4].
Figure 2. Plan for the 2nd stage expansion of the Wolsong LILW Disposal Center.
3) Geological Setting
The topography of the study area shows an overall decreasing altitude from the west
to the east (Figure 2) [5]. As the valleys and ridges extend eastward, small streams flow from
the highlands in the west into the East Sea. In the vicinity of the estuaries, coastal deposits
and small-scale alluvial deposits form. In the study area, the runoff of the small, short stream
channels only flow during the wet season, and cease during the dry season.
Geologically, the study site and surrounding area belong to the Gyeongsang
supergroup, and consists of Cretaceous sedimentary rocks (shale and sandstone), Tertiary
diorite, granodiorite, biotite granite, feldspar porphyry, rhyolite, and basaltic andesite and
porphyritic dacitic andesite formed by tertiary volcanic activity (Figure 3). The first stage
cavern-disposal facility is located in an area of granite, while the second stage surficial
1st Stage Disposal Facility
Surface Facility
ShinWolsong NPP #1&2
2nd Stage Disposal Facility
Project Duration : 5 yrs
Disposal Area : Approx .44,800㎡ (160m×280m)Disposal Capacity : 125,000 drums
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disposal facility is predominately located in an area of sedimentary rock. Substantial fractures
and faults occur in both the granite and sedimentary rock areas.
- Groundwater flow
At the Gyeongju site, groundwater mainly moves through the granite and
sedimentary rock factures and flows from mountainous areas in the west to the East Sea in
the east (Figure 4). Figure 4 was plotted using groundwater heads (amsl, m) level data
recorded measured in April 2008, prior to construction of the radioactive waste repository.
Additionally, the highlands and streams bind the groundwater systems as the eroded hills are
geomorphologically bound by the rivers.
Figure 3. Geology of the study area.
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Figure 4. Groundwater head contours (amsl, m) in the study area.
- Fault Distribution
Fractures in the study area were classified as either deterministic faults observed on
the land surface or as background fractures identified through underground investigation. A
total of 7 major faults and 6 minor faults ranged in length 0.172–1.4 km and in width 0.2–7 m
(Figure 4). Using the minimum fault length as a cut-off value, background fractures were
defined as those having a length of 172 m or less. A stochastic realization of the background
fracture was generated for the three-dimensional DFN model considering the location,
direction, length, and width of the faults and borehole fractures (Table 1).
Table 1. Properties of the deterministic faults in the study area.
Fault No. Z21 Z22 Z23 Z31 Z32 F31 F33
Strike
/dip
N75°W
/50°SW
N60°E
/55°SE
N80°E
/64°SE
N60°E
/72°SE
N63°W
/65°SW
N25°W
/61°NE
N25°W
/60°NE
Damage
zone (m) 7.9 4.8 5.6 8.3 2.2
0.2–10.0
(ave. 5.0)
0.6–8.0
(ave. 5.0)
Length (km) 1.1 1.4 1.26 0.73 0.8 0.65 0.75
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References
[1] The National Assembly, The Radioactive Waste Management Act, in Korean (2008)
[2] The National Assembly, The Nuclear Safety Act, in Korean (2011)
[3] IAEA, Classification of Radioactive Waste, GSG-1 (2009)
[4] KORAD, Analysis for the applicable scheme of the IAEA's new classification of
radioactive waste, in Korean (2012)
[5] Cheong, J.-Y.; Hamm, S.-Y.; Lim, D.-H.; Kim, S.-G. Hydraulic Parameter Generation
Technique Using a Discrete Fracture Network with Bedrock Heterogeneity in Korea. Water,
9, 937 (2017)
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Trip 8. Maisan geologic park and Wine cave
Site 1. Muju Meoru wine cave
The Muju Meoru Wine Cave locates in the area of Jeoksangsan Mountain,
Bukchang-ri, Jeoksang-myeon and is surrounded by a beautiful natural landscape and various
cultural heritages. The Jeoksangsan Mountain consists of Cretaceous volcanic and
sedimentary rocks. Visitors can enjoy the taste and charm of sanmeoru (wild grape) wine here.
The wine tunnel was used as a working tunnel to build the Muju Water Power Plant. The
working tunnel is now remodeled for maturing and storing wine, in order to increase the
income of wild grape farms and to boost the regional economy. In the wine tunnel, you can
enjoy wine tasting and buy wines at 15% off market prices. You can also enjoy the wind foot
bath.
Site 2. Muju pumped Storage power plant (Jeoksangsan Mountain)
Muju Pumped Storage Power Plant South Korea is located at Jeoksang Mountain,
Muju-gun, Jeollabuk-do, South Korea. This infrastructure is of TYPE Hydro Power Plant
with a design capacity of 600 MWe. It has 2 unit(s). The first unit was commissioned in 1995
and the last in 1996. It is operated by Korea South East Power Co., Ltd (KOSEP).
Jeoksangsan Mountain (1,034m) shows steep rock walls and red maple trees around
cliffs make the mountain look like a giant red skirt in the fall.
Near to the Plant, there is Electric Power Public Information Hall in which some
exhibitions about electricity industry are displayed. And there is Muju Meoru Wine Cave as a
tour attraction as well.
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Site 3. Maisan Geopark
1) How the Jinan Basin and Maisan formed
Maisan locates in the southeastern margin of the Jinan Basin in the northern
boundary of the Yeongnam Massif (Fig. 1). The Jinan Basin is one of the Cretaceous pull-
apart basins in South Korea and formed by sinistral strike-slip movement along the
Yongdong-Gwangju fault system (Fig. 2). The sinistral strike slip movement was expected to
occur due to the southwards compression caused by the collision between Siberian and
Manchuria blocks during the Cretaceous (ca. 130~100Ma) (Fig. 3). Many other pull apart
Cretaceous Basins also developed along the sinistral strike-slip fault systems (the Gongju-
Eumseoung and Yongdong-Kwangju faults system). Later the Jinan Basin uplifted to form the
Noryeong mountain range due to the compression which may be related with dextral strike
slip fault movement which is expected to be caused by the collision between Indian plate and
Eurasian plate at the Cenozoic (ca. 55~25Ma) (Fig. 4).
The Jinan Basin is bounded by two strike-slip faults, the Kwangju and Jeonju faults. The
basement rock of Jinan Basin is Precambrian granitic gneiss and Jurassic granite (Shimamura,
1924; Kim et al., 1984). The Jinan Basin shows asymmetrical half-graben geometry in cross-
section (Baag and Kwon, 1994) and consists of non-marine sedimentary rocks, such as
conglomerate, gravelly sandstone and shale, with more than 10 km in thickness (Shimamura,
1925; Son, 1969; Jang, 1985; Hong. 1981; Gwag, 1990; Lee, 1992). Sedimentary rocks in the
Jinan Basin were interlayered or overlain by Cretaceous basalt, andesite, andesitic tuff,
rhyolite, rhyolitic tuff (shimamura, 1924; Son, 1969; Hong, 1981; Jang, 1985; Gwag, 1990;
Kim et al., 1984; Lee, 1992). Some Cretaceous igneous rocks such as quartz porphyry and
andesitic and rhyolitic hypabyssal rocks intruded the sedimentary rocks (Fig. 1).
The sedimentary rocks in the Jinan Basin consists of four formations: the Sansudong
Formation (sandstone, black shale, 600m thick), Dalgil Formation (tuffs, black shale and
tuffaceous shale, 1,000m thick), Manducsan Formation (conglomerate, sandstone, black shale,
andesite, tuffaceous shale, tuffs, and marlstone, 800m thick), Maisan Formation
(conglomerate, 1500-2000m thick) (Fig. 1). Reedman and Um (1975) named these
formations as the Jinan Group. The four lithofacies units had been considered as the
stratigraphical units with different depositional age (Shimamura, 1929; Son, 1969; Reedman
and Um, 1975; Chang, 1982). However Lee(1992) reported that the four formations in the
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Jinan Basin are corresponded to contemporaneous heteropic facies deposited in laterally
different sedimentation environments and can be divided into the Upper and Lower
sedimentary sequences with different depositional age implying two Basin forming stages.
The Jinan Basin has abundant felsic and intermediate volcanic rocks. Son (1969)
correlated the felsic volcanic rocks in the Jinan Basin to the Sakugi Series relevant to
Campanian to Maastrichan. Jang (1985) correlated the andesitic rocks to lower Yucheon
formation (Albian) in the Gyeongsang Basin. Although they suggested different ages for the
felsic volcanic rocks and andesites in the Jinan Basin, they are interlayered each other.
LA-MC-ICPMS age dating on the zircons from sedimentary and igneous rocks indicates
followings. The sedimentation in the Jinan Basin had started at least from 97.7Ma and
continued until 89.47Ma. During the sedimentation, basalt or basaltic andesite extruded at 90-
92 Ma and later rhyolitc and andesitic magma intruded the Jinan Basin at 90-89 Ma and 85-
84 Ma respectively.
Later the Jinan Basin uplifted to form Noryeong mountain range due to the
compression which was related with dextral strike slip fault movement. This fault movement
is expected to be caused by the collision between Indian plate and Eurasian plate at ca.
55~25Ma.
The above information indicates that Maisan consisting of conglomerate were
deposited under the lake as a part of the Misan formation in the southeastern margin of the
Jinan basin during the formation of the Jinan pull apart basin at 97~84 Ma and then may be
uplifted at ca. 55~25 Ma as a part of the Noryeong mountain range.
2) Tafoni on conglomerate cliff and a culture of stone
Maisan is famous because it has two mountain peaks showing the unusual
topography, the shape of horse ears, and mainly consists of conglomerate as a part of the
Maisan formation (Fig. 5). Grain size of conglomerate is pebble to cobble which show well
developed roundness. The pebbles and cobbles are almost Precambrian gneiss and Jurassic
granite which were supplied from the basement rocks around the Jinan Basin. During the
formation of the Jinan basin, very steep slope due to normal faulting may have formed in the
southeastern Jinan basin which caused the supply of the pebbles and cobbles forming the
Maisan formation. During uplifting of the Jinan basin, steep conglomerate cliff formed. On
the cliffs, many tafonis were developed. Tafoni is expected to be formed by several
mechanisms; one is the injection of water into the rocks which dissolve cementing materials
such as calcareous in the matrix of conglomerate out of the conglomerate and the other is a
frost wedge action which fracturs conglomerate by the volumetric expansion of freezing
water. Those activities decreases coherence of conglomerate resulting separation of cobble or
pebble grains out of the conglomerate. Over the years the holes formed by separation of
pebbles and cobbles were combined to form a big hole, tafoni. Some tafoni are big enough to
build small temple (ex. Gogeumdang) or pavilion in them (Fig. 7a, b). Beneath the western
peak (Ammaibong Peak) of the Maisan, there are around one hundred stone pagodas with
temples which is called Tapsa (Fig. 7c). It is said that these stone pagodas were built using
boulders collected from all over the Korean Peninsula. These pagodas underwent many
storms but they have been well preserved without falling. This makes the Maisan more
mysterious.
3) Dividing water systems resulting differentiation of ecosystem
Maisan formed as a part of the Noryeong mountain range acts as a ecological barrier
dividing the Kumgang and Seomjingang water systems. As a result, the Coreoleuciscus
splendidus living in the Geumgang water system is different from that in the Soemjingang
water system. In addition, the Geumgang and Mangyeong-Dongjingang water systems are
also divided by the Unjangsan with NNE direction, the mountain formed by volcanic activity
during the formation of the Jinan basin (Fig. 8). As a result, diverse ecosystem have been
established in and around Maisan.
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Figure 1. (a) Tectonic map of the Korean Peninsula (after, Oh, 2006 and Lee et al., 2016).
(b) Geological map of the Jinan area (after, Lee, 1992 and Hong et al., 1966 and Kim et al.,
1984 and Kim et al., 1973). Abbreviations are as follows: GM = Gyeonggi Massif; OMB =
Okcheon metamorphic belt; TB = Taebaeksan Basin; YM = Yeongnam Massif.
Figure 2. (a) The simplified tectonic map of the Northeast Asia during the Cretaceous.
(b) The distribution map of the Cretaceous Basins and strike-slip fault system in the South
Korea Peninsula. KFS: Kongju-Eumsung fault system, YFS: Yongdong-Gwangju fault
system, 1: Cheonsuman Basin, 2: Eumsung Basin, 3: Gongju Basin, 4: Tongli Basin, 5:
Jungsori Basin, 6: Muju Basin, 7: Jinan Basin, 8: Gyeokpo Basin, 9: Haenam Basin, 10:
Neungju Basin, 11: Gyeongsang Basin. (after Lee et al.(1999) and Geology of Korea, (1998)
and Ryang, (2013)).
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Figure 3. (a) The final collision process of Asia during Jurassic to Cretaceous (after Lee et al.,
2011); (b) the distribution map of the Cretaceous basins and strike-slip fault system in the
Korean Peninsula with the direction of pushing force (red arrows) due to collision; (c) the
schematic diagram showing the extension force occurred in the area between two sinistral
strike slip faults; (d) the schematic diagram showing the formation of Jinan basin due to the
extensional force.
Figure 4. (a) Regional stress map of the East Asia due to collision along the Himalayan
collision belt (after Cho et al., 2014), (b) the distribution map of the Cretaceous pull-apart
basins and dextral (thin red arrow) strike-slip fault systems due to eastwards compression
(thick red arrow) in the Korean Peninsula, (c) the schematic diagram showing compression in
the area between two dextral slip faults, (d) the schematic diagram showing uplift of
sedimentary basin due to compression
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Figure 5. The panoramic photographs of the Maisan (a, b)
and outcrop photo of Maisan conglomerate (c).
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Figure 6. (a) The panoramic photograph of the tafonies on the Maisan
and (b) the model for the formation process of tafoni.
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Figure 7. The photographs of the cultural of stone around Maisan;
(a) Gogeumdang, (b) Suseonlu and (c) Tapsa..
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Figure 8. The map of mountain ranges and water systems in the South Korea and species
differentiation of the Coreoleuciscus splendidus due to building of Noryeong mountain range.
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References
Gwag, J.H., 1990. Depositional Environment of the Maisan Conglomerate Formation
(Cretaceous) in the Southern Part of the Jinan Basin. M.Sc. Thesis, Seoul National Univ.,
Seoul, 99 pp.
Lee, D.W., 1999, Strike-slip fault tectonics and Basin formation during the Cretaceous. The
Island Arc, 8, 218-231.
Lee, S.H. and Chough, S.K., 1999, Progressive changes in sedimentary facies and stratal
patterns along the strikeslip margin, northeastern Jinan Basin (Cretaceous), Southwest Korea:
implications for differential subsidence. Sedimentary Geology, 123, 81-102.
Lee, S.H., 2017, The time of sedimentation and volcanic activity of the Jinan Basin and
change of magma chamber depth during formation of the Baekdu volcano. Master thesis,
Chonbuk National University, Jeonju, 141 p.
Lee, Y.S., Han. H.C., Hwang. J.H., Kee. W.S. and Kim. B.C., 2011, Evidence for significant
clockwise rotations of the Korean Peninsula during Cretaceous. Gondwana Research, 20,
904–918.
Lee, Y.U., 1999, An analysis of the xnergy for the elevation of the Cretaceous Jinan Basin,
Journal of Korean Earth Science Society, 20, 437-443.
Lee, Y.Y., 1992, Stratigraphy, depositional environments, and evolution of the cretaceous
Chinan Basin. Ph.D thesis, Seoul National University, Seoul, 287 p.
Oh, C.W., Lee, B.C., Lee, S.H., Kim, M.D., Lee, B.Y. and Choi, S.H., 2016, The tectonic
evolution and important geoheritages in the Jinan and Muju area, Jeollabuk-do. Journal of the
Geological society of Korea, 52, 709-738.
Reedman A. J. and S. H. Um, 1975, The Geology of Korea. Korea Institute of Energy and
Resources, 139p
Shimamura, S., 1925, Geological Atlas of Chosen (Korea; 1:50000). Chinan and Cheonju
sheets. Geol. Surv. Korea, No. 5.
S.K. Chough, Y.K. Sohn, 2010, Tectonic and sedimentary evolution of a Cretaceous
continental arc–backarc system in the Korean peninsula: New view, Earth-Science Reviews,
101, 225-249.
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Song, H.-Y. and Bang, I.-C., 2015, Coreoleuciscus aeruginos (Teleostei: Cypriniformes:
Cyprinidae), a new species from the Seomjin and Nakdong rivers, Korea. Zootaxa, 3931,
140-150.
Woo, K.S., 2014, Qualification and prospect of national and global geoparks in Korea.
Journal of the Geological Society of Korea. Journal of the Geological Society of Korea, 50,
3-19.
Yi, S.H., Yun, H.S. and Lee, J.D., 1998, Palynofacies of the sansudong formation (lower
cretaceous), Jinan Basin, Korea. Journal of Paleont. Society of Korea, 14, 1-13.
Yin, A. and Harrison, T.M., 2000. Geologic evolution of the Himalayan-Tibetan orogen.
Journal of Annual Review, Earth Planetary Science 28, 211-280.
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Trip 9. Baengnyong Cave
1. What is a limestone?
The surface of the Earth is composed of three rock types such as igneous,
metamorphic, and sedimentary rocks. The sedimentary rock is the rock that sediments
deposited in the river, lake or sea, buried deeply due to continuous sedimentation, and turned
into rocks by the influence of water with various chemical compositions due to high
temperature and pressure. The limestone was mostly deposited as carbonate sediments on the
seafloor, thus belongs to the sedimentary rock.
In the East Asia or the coastline of Caribbean, Guam or clear and warm sea of the
subtropical area, we have often seen the beautiful underwater scenery of coral reefs in the
Bahamas, Great Barrier Reefs in Australia, and many small islands in South Pacific. Coral
reefs are forming by corals, calcareous algae, bivalves, and other many organisms, secreting
calcium carbonate minerals (CaCO3; named as calcite and aragonite) in tropical and
subtropical regions. When these shell-making organisms die and pile up at the bottom of the
sea, the calcium carbonate which constitutes the hard part (skeleton) of the organisms such as
bones and the shells will be left and form carbonate sediments. Limestone mostly consists
of calcite.
The limestone can be found throughout the Korean peninsula, however most
limestone is distributed in the eastern central parts such as Yoeongwol, Jeongseon, Taebaek,
Gangneung areas of Gangwon Province, the Danyang area of Chungcheongbuk Province, and
Mungyeong of the Gyeongsangbuk Province (Figures. 1 & 2). Most limestone is lower
Paleozoic (Cambrian to Ordovician) in age. Also small limestone areas can be found in the
Uljin and Pyeonghae areas of Gyeongsangbuk Province, the Igsan area of Jeollabuk Province,
and the Hwasun area of Jeollanam Province. It is also reported near the DMZ in Gyeonggi
Province. This means that limestone caves are always possible to be found in these areas. The
limestone area in North Korea is even larger, mostly distributed in Pyeongannam and
Pyeonganbuk Provinces. Thus it is likely that there can be more limestone caves in North
Korea than South Korea.
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Figure 1. Geologic map of Korea.
Figure 2. Karst distribution of Korea.
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2. Karst landforms
The limestone is easily dissolved by rain or groundwater so a unique shaped
topography can be developed where the limestone is widely exposed on the surface. This
topography is called the ‘karst landform’. Karst topography can be more easily formed if the
limestone is porous or contains weak cracks (called joints) for rainwater to percolate down.
Along the joint planes, deep valley can be easily developed. Very peculiar landscapes such
as cockpits, tower karsts, and karrens are typical karst features. Because rain water plays an
important role to form karst landforms, it is more difficult for karst landform to be formed in
the dry area where the rainfall is low. The typical forms of the karst topography are doline,
uvala, polje, tower karst, cockpit, and gorge, which are formed by the dissolution of
limestone by rain or the water flowing over the surface of the Earth, Also the karren that is
formed by the corrosion of flowing water or soil over the surface of the limestone.
The limestone is distributed in many places all over the world, however there are not
many places that are famous for the karst landforms. The internationally famous places are
“Causse” in South France, Andalusia in Spain, the northern part of Yucatan peninsula,
Jamaica, the northern part of Puerto Rico, West Cuba, middle part of New Guinea, New
South Wales in Australia, Kentucky, Pennsylvania, Maryland, Virginia and Tennessee in
USA, Huanan and Gwangxi Provinces in China, Thailand, Myanmar, Akiyoshidai in Japan.
In Korea, very small areas are characterized by karst landforms. In Korea, Balgudeog near Mt
Mindung of Jeongseon, Gomaru and Donneomi of Pyeongchang, Paegbongryeong which is
at the boarder of Jeongseon and Gangneung are the places where the dolines are well
developed. Noeunjae of Danyang is famous for the well developed karrens. In China,
breadth-taking views are provided along the Li River near Guilin and Stoneforest of
Kunming, thousands of karst towers stand up from the ground. The Ha Long Bay of Vietnam
also shows a magnificent view of the well developed tower karst.
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3. Limestone caves
1) General characteristics
A cave is defined as a naturally formed underground cavity, which is not man-made.
Therefore, manmade tunnel built for road or coal mine is not considered as a cave. These
days, the secret of cave that aroused a curiosity of many people for a long time has been
revealed since many show-caves were developed. Cave could be simply beautiful and
mysterious place for general public. However the natural cave means more than just a
marvelous nature but it is a place that has tremendous scientific values for cavers and
scientists. Recently numerous paleoclimatic investigations have been carried out using cave
speleothems, and biologists are eager to find new microbes or genes in caves.
There is no incoming light into the cave, thus only complete darkness exists if there
is no lighting apparatus. Photosynthesizing plants cannot live in cave since there is no light,
thus the living organisms in cave are totally different from those of the outside. Also in the
cave, there are various forms of very odd, but fabulous speleothems that have been growing
for a long time. Quite often, after you pass through a narrow passage that just allows one
person to barely get through, a huge chamber that is bigger than soccer field may await you.
In some caves, a huge underground stream is flowing fast or several tens of meters-high
waterfall may be dropping, and all of these are beyond imagination for the people who have
not experienced caving.
The cave maintains constant temperature all the year round. But the temperatures of
each cave are different, not by the type of the cave but due to the location of the caves, e.g.,
latitude and altitude, as well as the climate of the surrounding environment. The cave air
temperature in the tropical region is hotter than 25 ˚C (=77 ˚F) all year, similar to the
temperature outside, while the temperature in the polar region is usually below zero degree.
In the temperate region like Korea, the temperature of the cave differs depending on the
regions but normally maintains around 10~15 ˚C (=50~59 ˚F). The temperatures of the
streams or the lakes in caves are commonly similar to the cave air temperature. If the
stream flows into the cave from the outside and flows out, the cave air temperature can be
easily affected by the outside temperature.
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2) Formation of limstone caves
The limestone caves are formed in the limestone. The limestone is mostly composed of a
mineral called calcite made of calcium carbonate. The calcite is easily dissolved by acidic
water. Thus, limestone caves are formed due to the dissolution by lightly acidic rain and
groundwater. Weak acid (carbonic acid) is added into rain by the reaction of water with the
carbon dioxide (CO2) in the air. Then it drops onto the surface of the limestone and slowly
dissolves it. However the weak acid also forms in the soil (in the form of organic acid) where
the plants grow. The organic acid is formed when the dead plants are decomposed and is
included in the percolating rainwater that passes through the soil zone. One of the important
factors that affect the process of the limestone cave formation is the level of the watertable.
Below a certain depth, all the empty spaces within underground rocks (fractures, pores,
cracks, etc.) are always filled with water and this top of the water level in the subsurface is
called as the water table. As rainwater penetrates down below the water table, groundwater
commonly flows horizontally toward the nearby stream, river, or sometimes sea. Commonly
surface water or groundwater that flow through the limestone terrane becomes easily buffered
by the limestone and contains calcium and carbonate ions. Thus, they are usually
supersaturated with respect to calcite as they flow to some extent. However, water can
become quite acidic when horizontally flowing groundwater meets the groundwater
percolating down from the surface. This is why many caves can be developed just below the
water table. Because caves are usually formed near the water table in the subsurface, the
upper limit of the water table becomes lower when the valley gets deeper after a long time.
As the water table lowers, the cave can be developed as multiple levels. But if the caves are
not formed continuously along with the drop in water table and there is a time lag of the cave
formation, there could be several caves with different elevations that are not connected
together. In this cave, the cave formed near the water table will be left as an “old” cave after
the drop of the water table. Therefore, if you see several caves in the mountain, it is
commonly the case that the cave in more elevated areas is older. If the water table is lowered
below the cave, it influences on the cave environment. When the water table is near or in the
cave passage, there will be lots of water flowing inside. But if the water table is below the
cave, the water flowing inside drains down to the lower level. The atmosphere will become
drier as streams are running in the lower level or in the caves with lower elevation. There are
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only drips of water from the ceiling or occasional flow of water during raining period. This
is why water is flowing only in the lower level in the cave with multiple levels.
Figure 3. Location of limestone formation at water table and mixing zone.
3) Cave speleothems
Weak acid rain can be generated by the combination of water and carbon dioxide
forming a carbonic acid. When the acid rain falls onto the limestone area, it penetrates into
the ground and dissolves the limestone. Groundwater will then contain significant amounts of
calcium ions (Ca2+), carbonate ions (CO32-) (usually in the form of bicarbonate ions; HCO3
-)
and carbon dioxide (CO2). When such groundwater comes down and meets the cave, many
chemical reactions can take place. Firstly the carbon dioxide in the groundwater escapes into
the air in the cave and this process is called a ‘degassing’ of the CO2. This happens because
the amount of the CO2 in the air is less than the amount in the groundwater which is charged
with CO2 during the dissolution of the overlying limestone. The chemical reaction always
takes place towards equilibrium between two phases, for example water and air. In other
words, Two phases want to be balanced (equilibrium state) by moving the enriched gas (CO2)
to the depleted phase. As a result of degassing, there are changes in chemical contents, that is,
the amount of calcium and carbonate ions increase rapidly in cave water. The increase in
calcium and carbonate ions will lead to the state of supersaturation with respect to carbonate
minerals, commonly calcite and less commonly aragonite. This means that the more carbon
dioxide degassing from cave water occurs, the more speleothem will form. The rate of
degassing thus controls the rate of speleothem growth. Also there are some speleothems
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formed by evaporation from thin film of water on the surface of walls or speleothems. Some
scientists suggested that a few speleothems may be made by the microorganism such as
bacteria. Various types of speleothems are found in limestone caves and most of them are
named based on their shapes, locations of formation, and their formation process. The
classification of the commonly present speleothems in many limestone caves, generally
accepted at present, are as follows:
- Speleothems formed by dripping water; dripstones (soda straw, stalactite, stalagmite,
column), cave pearl, draperies (curtain, bacon sheet)
- Speleothems formed by the flowing water; flowstone
- Speleothems formed by the seepage water from the surrounding limestone; anthodite (cave
flower), cave coral (cave popcorn), carbonate powder, cave balloon, cave blister
- Speleothems formed in flowing water or cave pool; rimstone, shelfstone, cave pisolite, pool
finger
- Speleothems formed by other causes; cave shield, moonmilk
4. Baegnyong Cave
Baegnyong Cave is located in Pyeongchanggun County, Gangwondo Province in
South Korea. It is precisely located at the boundary of three counties (Pyeongchanggun,
Yeongwolgun, and Jeongseongun counties). This is the only tourist cave for wild caving tour
in South Korea, even though tourists walk over the horizontal passage with a litte crawn at
narrow passages.
It is situated along Donggang River surrounded by beaurifal limestone karst area (Figures. 4
& 5). The Cave has been open to public past 8 years since 2010, and it has about 15,000
visitors annually. It is the cave that is still actively forming with beautifully decorated
stalactites, stalagmites, flowstones, anthodites and many kinds of other speleothems. During
rainy season, the floor can be submerged by water from the Donggang River through the
collapsed hole connected to the river.
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Figure 4. Entrance (arrow) of the Baegnyong Cave at Donggang River.
(copyright, Cave Research Institute of Korea)
Figure 5. Donggang River with karst landform near the Baegnyong Cave.
(copyright, Cave Research Institute of Korea)
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The sedimentary rocks along the Dongang River are composed of the Lower
Paleozoic Joseon Supergroup, Upper Paleozoic Pyeongan Supergroup and Mesozoic Bansong
Supergroup. The carbonate rocks surrounding the cave are composed of the Maggol
Formation which belongs to the Joseon Supergroup. The formation is composed of limestone
and dolomitic limestone which was deposited in the supratidal flat during the Ordovician.
Baegnyong Cave mostly shows horizontal passages, which have developed along the
east-west direction. This cave contains one main passage (Passage A= 785m) and three
branches (B=185m; C=605m; D=300m), thus the total length of the cave is about 1,875m
(Figure 6).
Figure 6. Plan map of the Baegnyong Cave with site photos
(Supplied by the Cave Research Institute of Korea)
Except for the few passages which are influenced by input of Dongang river water,
most passages show more or less constant temperature range (11 to 13.5 ℃), and humidity
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ranges from 70 to 100%. Humidity tends to be higher during the rainy season (summer; from
July to September). Partial pressure of carbon dioxide ranges from 400 to 1,400ppmv, and
tends to be higher during the rainy season, probably due to higher decomposition rate of
organic matter from outside and/or higher degassing rate of carbon dioxide. Cave water
temperature shows a wide range of variation (9.5 to 22.2℃), because the cave water is
directly supplied from the Dongang River into the lower level of the Passage C. The pH
values of cave water ranges from 7.0 to 8.2, indicating that acid rain was buffered with
surrounding limestone before entering into the cave. Trace elements of cave water tend to
show higher concentrations during winter due to higher residence time. Oxygen isotopic
compositions of cave water is also more enriched during winter.
Most of the passages show domal in cross section showing the typical shape of
vadose passage, even though other shapes are also observed. This cave has been mostly
developed along joint planes, whereas some parts of the passages were influenced by strike
directions of bedding planes. Cave sediments are mostly composed of muddy sediments with
minor contributions of sands and gravels where cave streams are present. Mineralogically,
quartz, calcite and illite are dominant minerals in cave sediments.
Various speleothems such as soda straws, stalactites, stalagmites, columns,
flowstones, rimstones, cave pearls, curtains (and bacon sheets), helictites, anthodites, cave
corals, cave shields, and calcite rafts, etc.. are present. Especially, some stalactites and
stalagmites with erratic shapes as well as fried-egg stalagmites are the most peculiar
speleothems in this cave (Figures 7, 8, 9, 10, 11 & 12). All the distribution of the speleothems
are described separately on the floor and on the wall and ceiling. Mineralogy and texture of
the speleothems are shown only for the speleothems collected (already broken speleothems).
Among the speleothems studied, soda straws, stalactites, stalagmites, rimstones, curtains and
rafts are only composed of calcite, whereas cave corals and cave shields are either composed
of calcite or of both calcite and aragonite.
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Figure 7. Carbonate speleothems at the large chamber in Passage A.
(copyright, Cave Research Institute of Korea)
Figure 8. Stalactities, stalagmites, and columns in Passaage A.
(copyright, Cave Research Institute of Korea)
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Figure 9. Erratic stalagmite. (copyright, Cave Research Institute of Korea)
Figure 10. Cave shield and column. (copyright, Cave Research Institute of Korea)
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Figure 11. Bacon sheet. (copyright, Cave Research Institute of Korea)
Figure 12. Flowstone, stalactites, and stalagmites.
(copyright, Cave Research Institute of Korea)
