Republic of Korea
Korea-7: South Han-gang
Korea-8: Kwang-gang
Korea-9: Geum-gang
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Introduction
The Korean peninsula, about 1 300 km long and 300 km wide, is located between the Yellow Sea and the East Sea on the eastern end of the Asian continent. The eastern coast line of the peninsula runs directly along the skirt of the steep mountain slope range, while the western and southern coast lines indicate curved shapes having wide alluvial plains in places. In general, rivers running to the eastern coast are short and steep in their riverbed gradients. Long stretching rivers with gentle slopes such as the Han River, the Geum River, the Nakdong River, and the Seomjin River, discharge to the southern or western coasts.
Korea is in the moderately humid zone of medium latitudes. It has a definite, seasonal climate which is greatly defined by dry, cold continental air masses during the winter, and humid warm air masses from the ocean during the summer. The average annual temperature is 14 °C (57 °F) along the southern coast, while it drops to as low as 11°C and 8°C (52°F and 46°F), respectively, over the mid and northern climatic zones. The yearly distribution of precipitation is determined by westerly and north- westerly dry winds from the Asian continent in the winter and south-easterly winds from the Pacific Ocean in the summer. Thus the rainfall is concentrated in the summer. Of the annual precipitation of 1 274 mm, approximately 66 % occur during the rainy season from June to September, 16 % during the transition period from April to May and the remaining 18 % during the six months from October to March. As of 1990, the population of Korea was 42 860 000 with a population density of 432 persons/km2. Of a total land area 99 450 km2, farm lands account for 21 379 km2 while forest cover is about 63 762 km2.
The three rivers catalogued in this volume are the Nam Han gang, the Hwang gang, and the Geum gang. They are also the representative rivers with typical hydrologic characteristics in Korea. The Nam Han gang joins the North Han River about 35 km upstream from Seoul, the Capital of Korea. It shows the characteristics of a typical forest basin covered by shadow well-drained soil layers. The Hwang gang is one of the main tributaries of the Nakdong River and is also a representative river flowing through forest, agricultural and urbanized areas of Kyongnam Province. It shows very typical conditions in water supply as well as in water quality. The Geum gang is one of the three main rivers of the country and runs through the central western part of the Korean Peninsula.
Acknowledgements
A working group was established for the preparation of the catalogue as part of the IHP project of 1995 which was supported by the Ministry of Construction and Transportation of the Republic of Korea. The working group members are as follows: Lee, Soontak (Chair), Yeungnam University, Ahn, Sang-Jin, Choongbuk University, and Chun, Byung-Ho, Korea Military Academy. The organizations which have contributed include: River Planning Division, Water Resources Bureau, Ministry of Construction and Transportation, Han River Flood Control Office, Ministry of Construction and Transportation, Nakdong River Flood Control Office, Ministry of Construction and Transportation, Geum River Flood Control Office, Ministry of Construction and Transportation, Korea Water Resources Association, and Korea Water Resources Corporation.
130 Korea (Republic of) – 8
Hwang-gang
Map of River 128oE
36oN
o 128 E Geographical Survey, MOC Korea
Table of Basic Data
Name: Hwang-gang (in Nakdong River) Serial No.: Korea – 8 Location: Kyungnam Province, Korea E 127° 40′∼128° 22′ N 35° 28′∼35° 55′ Area: 1 325.6 km2 Length of the main stream: 116.9 km Origin: Mt. Sambong (1 302m) Highest Pt.: Mt. Togyusan (1 614 m) Outlet: Nakdong River Lowest Pt.: River mouth (14.8 m) Main base rocks: Cretaceous to Middle mesozoic, Igneous rocks, Metamorphism rocks, Alluvial layer, Weathered stone Main tributaries: Kochangwi River (248 km2), Kachun River (116.9 km2), Sannae River (54.7 km2), Hwanggye River (44.6 km2) Main lakes: None Main reservoirs: Hapchun (790 × 106 m3, 1989 ) Mean annual precipitation: 1 149.8 mm (1960∼92) Mean annual runoff: 18.5 m3/s at Hapchun (1 039.7 km2) (1961∼95) Population: 153 750 (1993) Main cities: Hapchun, Kochang Land use: Forest (70.42 %), Rice paddy (7.19 %), Other agriculture(15.14 %), Urban ( 3.86 %) (1996)
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1. General Description
1.1. General Description
The Hwang-gang is one of the main tributaries of the Nakdong River which flows through the southern part of the Korean Peninsula. Originating from Mt. Sambong (1 302 m), the river drains an area of 1 325.6 km2, has a length of 116.9 km, and flows into the middle part of the main Nakdong River. The basin has an average annual precipitation of 1 150 mm and the mean annual discharge at Hapchun (1 039.7 km2) during the period 1961~1995 is 18.5 m3/s (1.77 m3/s/100 km2). The population in the basin in 1993 was 153 750. One of the main hydraulic structures in the basin is the Hapchun Dam, built in 1989, that can store 790 x 106 m3 of water. The river segment above Kochang is considered the upper stream which is mountainous with narrow and terraced paddy fields. Between Kochang and Hapchun is the middle stream, and that below Hapchun is the lower reach. The middle and lower streams flow through narrow plains between high mountain areas in the north and the west.
2. Geographical Information
2.1. Geological Map
METAMORPHIC ROCK
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2.2. Land Use Map
2.3. Characteristics of the River and the Main Tributaries
Highest peak Length [km] [m] Cities Land use No. Name of river Catchment area Lowest point Population (year) [%] [km2] [m] Mt. Togyu Hwang River 116.9 Kochang City, etc 1 1 614.3 (Main River) 1 325.6 39 371 (1996) 5.3 Mt. Kumwon Kochangwi River 26.0 Kochang City, etc 2 1 352.0 (Tributary) 248.0 39 371 (1996) F (70.4) 180.0 P (7.2) Mt. Biak Kachun River 33.7 U (3.9) 3 1 125.7 (Tributary) 116.9 A (15.1) 150.5 L (0.3) Mt. Kumsung Hwanggae River 16.5 O (3.1) 4 590.0 (Tributary) 44.6 32.3 Mt. Mita Sannae River 8.5 5 662.1 (Tributary) 54.7 9.5 F : Forest L: Lake, river, marsh P: Paddy field U : Urban; O: Orchard A : Agricultural field (vegetable field, grass field)
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2.4. Longitudinal Profiles Elevation (m)
Distance (km)
3. Climatological Information
3.1. Annual Isohyetal Map and Observation Stations
Based on the data of Ministry of Construction
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3.2. List of Meteorological Observation Stations
Mean annual Mean annual Elevati Observation Observation No. Station Location precipitation evaporation on [m] period items2) [mm] [mm]1) N 35° 40' 00″ 284* Kochang 224.9 1961~present 1 164.5 1 214.1 P(TB) E 127°55' 00″ N 35° 40' 00″ 285* Hapchun 30.9 1961~present 1 243.2 1 245.4 P(TB) E 128° 10' 00″ N 36° 46' 00″ 159** Wongyang 300.0 1962~present 960.8 - P E 127° 54' 00″ * : Serial number used by Ministry of Construction ** : Weather Office, Korean Meteorological Agency 1) Measured by small pan (20cm pan) 2) P: Precipitation; TB: Tipping bucket with recording chart
3.3. Monthly Climate Data
Station: Hapchun
Observation Period for Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual Item the mean Temperature -1.1 1.2 6.3 12.9 17.8 21.8 25.0 25.5 20.2 13.9 7.1 1.0 12.6 1961∼1995 [°C] Precipitation 23.0 38.7 53.7 112.2 92.4 179.0 278.3 255.1 147.1 52.3 39.9 15.6 1 287.2 1961∼1995 [mm] Evaporation 48.7 57.7 100.0 135.1 161.2 147.6 138.4 145.8 108.5 95.1 59.5 47.8 1 245.4 1961∼1995 [mm]* Solar radiation 6.43 8.16 9.89 12.20 12.98 12.81 10.67 10.81 10.03 8.69 6.77 5.71 9.60 1961∼1995 [MJ/m2/day] Duration of 210 200 242 246 269 224 195 226 203 220 189 204 2 629 1961~1995 sunshine[hr] *measured by 20cm pan
3.4. Long-term Variation of Monthly Precipitation Series
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4. Hydrological Information
4.1. Map of Streamflow Observation Stations
4.2. List of Hydrological Observation Stations
1) Elevation Catchment area Observation No. Station Location Observation items [m] (A) [km2] period (frequency) N 35° 40' 70 Gukko 11.26 1 296 1962~present H1 E 128° 18' N 35° 40' 125 Hapchun 28.38 1 039.7 1962~1986 H1 E 128° 10' N 35° 32' 119 Changni 93.11 925.0 1962~present H1 E 128° 01' N 35° 40' 124 Kochang 172.9 619.0 1962~1987 H1 E 127° 55'
Q 2) Qmax3) Qmax4) Qmin5) Q/A Qmax / A Period of No. * 3 3 2 statistics [m3/s] [m /s] [m3/s] [m3/s] [m3/s/100km2] [m /s/100km ] 70 22.92 2 017 1,429 7.24 1.77 159.50 1960~1995 125 18.50 1 582 1,079 4.31 1.78 152.16 1960~1995 119 16.36 1 342 984 3.82 1.77 145.08 1960~1995 124 10.95 892 516 2.05 1.77 145.24 1973~1995 * : Serial number used by Ministry of Construction; 1) H1: water level in recording chart; 2) Mean annual discharge; 3) Maximum discharge; 4) Mean annual maximum discharge; 5) Mean annual minimum discharge.
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4.3. Long-term Variation of Monthly Discharge Series
Hwang-gang at Hapchun (1 039.7 km2)
) /s 3 m ( e g Dischar
4.4. Annual Pattern of Discharge Series
Hwang-gang at Hapchun (1 039.7 km2) /s) 3 e (m rg a Disch
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4.5. Unique Hydrological Features
Hwang-gang at Hapchun (1 039.7 km2) /s) 3 e (m rg a Disch
Note that Hapchun Dam was constructed in 1989.
4.6. Annual Maximum and Minimum Discharges
Station: Hapchun Catchment area : 1 039.7 [km2]
Maximum1) Minimum2) Maximum1) Minimum2) Year Year Discharge Discharge Discharge Discharge Date Month Date Month [m3/s] [m3/s] [m3/s] [m3/s]
1973 8.20 1 452.0 2 5.5 1984 7.19 1 124.9 1 4.6
1974 7.09 1 024.1 1 5.0 1985 8.29 1 350.4 1 4.6
1975 7.14 1 124.0 2 5.3 1986 8.12 834.2 1 4.6
1976 8.05 1 315.2 1 4.6 1987 9.03 1 095.0 12 5.4 1978 6.28 825.7 1 4.7 1988 7.24 825.2 2 4.6 1979 6.23 1 208.5 1 4.8 1989 7.21 1 427.4 12 5.8
1980 7.12 1 124.2 2 4.6 1990 7.15 901.8 12 5.6 1981 7.05 950.7 1 4.7 1991 7.30 1 154.2 11 5.5 1982 8.07 915.4 1 4.7 1992 7.02 866.5 1 4.9 1983 7.22 802.9 1 4.9 1993 8.17 1 254.7 1 5.8 1), 2) Instantaneous observation by recording chart
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4.7. Hyetographs and Hydrographs of Major Floods
Dongchun 1991 August /s) 3 h) / m e (m rg a Disch Rainfall (m
Hapchun 1993 September /s) 3 h) / m e (m rg a Disch Rainfall (m
Based on the data of Ministry of Construction.
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5. Water Resources
5.1. General Description
The average annual precipitation in the basin is far less than the average for the country. Because the rainfall is mostly concentrated in summer between June and September, the basin is prone to flooding and droughts every year.
During the 21 year period from 1973~1993, major floods with discharges in excess of 100 m3/s or 0.654 m3/s/km2 at Hapchun (1 039.7 km2) occurred 12 times or approximately once every two years. The maximum flood flow of this station has been 1 452 m3/s in 1973 while the minimum flow was 4.5 m3/s in 1976. After the completion of the Hapchun Dam (790 x106 m3) in 1989, it is noticeable that the minimum flows at Hapchun have been decreasing.
5.2. Map of Water Resources Systems
5.3. List of Major Water Resources Facilities
Major Reservoirs Gross Effective Name of Name of Catchment Year of capacity capacity Purpose1) river dam area [km2] completion [106 m3] [106 m3] Hapchu Hwang 235.0 790.0 560.0 I, N, W 1989 n
1) I : Industrial use, W : Municipal water supply, N : Maintenance of normal flows.
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5.4. Major Flood and Drought Experiences
2 Major Floods: at Hapchun (1 039.7 km )
Peak discharge Rainfall [mm] Meteorological Major damages Date [m3/s] Duration cause (Districts affected) 332 Hapchun 1963. 6.20 1 842 Typhoon 6.20~22 Kochang City 371 Hapchun 1964. 7.18 2 453 Typhoon 7.18~20 Kochang City 307 Hapchun 1971. 8.06 1 212 Typhoon 8.06~9 Kochang City
Major Droughts: Period Areas affected Major damages and counteractions Hapchun Supply cut ratio 1974. 8~11 Kochang City at the first stage: 20 % Supply cut ratio Hapchun 1976. 6~9 at the first stage: 10 % Kochang City at the second stage: 20 % Hapchun Supply cut ratio 1979. 9~11 Kochang City at the first stage: 20 % Hapchun Supply cut ratio 1982. 5~10 Kochang City at the first stage: 20 %
5.5. Groundwater and Water Quality
River Water Quality1) at Gukko in 1995
Date Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
pH 7.2 7.3 7.3 7.5 7.4 7.7 7.6 7.7 7.4 7.3 7.4 7.3
BOD [mg/l] 1.9 1.5 3.2 4.5 5.1 5.5 5.3 5.4 4.3 1.7 1.8 2.0
CODMn [mg/l] 1.3 1.6 1.7 2.6 2.6 2.7 2.4 3.2 3.1 1.6 1.5 1.6
SS [mg/l] 11 15 16 16 17 20 35 22 24 20 18 12
Coliform Group 1.7× 2.4× 2.5× 2.4× 2.4× 2.3× 2.5× 2.4× 1.8× 1.1× 2) 2.2×10 2.3×10 2 2 2 2 3 2 2 3 2 2 [MPN/100ml] 10 10 10 10 10 10 10 10 10 10 Discharge 3) 4.21 4.06 5.70 5.50 6.82 8.50 6.40 6.40 4.56 4.50 4.50 4.20 [m3/s] 1) Location of the station : Located near Taegu City from the river mouth. 2) Measurement method : BLGB Method. 3) Discharge on the data observing the water quality.
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6. Socio-cultural Characteristics
The Hwang-gang is located at the center of Olympic Expressway between Taegu and Kwangju, an artistic tourist city. In this basin, Hapchun is the main capital city which is the sightseeing destination in Korea and main center of historic Buddhist Civilization. This basin is also neighboured with the three national parks: Togyusan, Kayasan, Chirisan.
7. References, Databooks and Bibliography Korea Meteorological Administration, (1960-1992): Climatological Report. Lee, S. T., (1986): Optimal Water Allocation Model through Inter-Basin Water Transfer, proceedings of IWRA Beijing Seminar on Inter-Basin Water Transfer, Beijing, China. Lee, S. T., S. W. Kim, H. K. Jee, (1985): A Mathematical Model to Forecast Community Water Demand, Presented at The Vth Water Congress on Water Resources, IWRA, Brussels, Belgium. MOC, (1983): Imha Multipurpose Project Feasibility Report, MOC/ISWACO. NEDECO, (1970): Andong Multipurpose Project Feasibility Report, NEDECO/ WACO. SAEL-KECC, (1980): Taegu Water Supply Project Master Plane & Feasibility Study.
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