Flood Analysis in Geum River & Countermeasure Establishment Flood Analysis in Geum River & Countermeasure Establishment the 8th Hydro Asia 2014 Hydraulic and Hydrology Session 1

2 1 Climate Change in Korea

1 In 100 years : Temp. 5℃ ↑, precipitation 17% ↑ 2 times more than global warming 0.74 ℃ [Change of Global Mean Temp.] 1.7 ℃ [Change of Mean Temp. of Korea] (Source : KMA, Institute) Climate Change in Korea

Water management under Changes & Challenges Frequency, Intensity of Flood & Drought increase - Flood damage (billion Won) : 123.6(’71)→1,990.4(’05) Evaportranspiration & Water demand etc. increase Regional rainfall deviation & uncertainty increase Typhoon intensity & Heavy rain increase - Typhoon intensity : 984→960hpa, 24hpa↓/36yr - Heavy rainy days : 20→31days, 11days↑/50yr 1 Climate Change in Korea

2 2 Climatic & Geographical Characteristics in Korea

The 70’s : 1,225mm → Recently : 1,465mm, 19.6% ↑ Since the 1970, drought with every 5-7 years Annual Precipitation : 1,277mm 2 Climatic Characteristics – Precipitation trends ,0071, ,061 1,016 1,383 1,409 1,736 1,611 1,669 1,791 1,908 Trough : ㎜ (60.7%) Monsoon : ㎜ (24.3%) Typhoon : ㎜ (14.9%) Trend 5yr 6yr 7yr 1465mm 1225mm

Effective Water management is absolutely required Trough : ㎜ (41.4%) Monsoon : ㎜ (36.7%) Typhoon : ㎜ (21.9%) Precipitation During Summer Season (JJAS) : ㎜ (65% of the Total) 2 Climatic Characteristics – Monthly precipitation

Annual Precipitation : Global 1.6 times Water per Capita : Global 1/6 times 1,277 2, , , , ,794 1,690 4,933 1,220 4, ,530 2 Climatic Characteristics – Water per capita

Mountainous with Steep slope Korea land Seasonal discharge variation is very severe (Flood season : much water ⇒ flood, Dry season : small water ⇒ drought) 2 Water per capita Geographical Characteristics

2 3 Geum Gang River & GRRP (River Restoration Project)

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3 Youngju dam Hwasun Damyang Han Riv. Seomjin Riv. Nakdan Youngsan Riv. Chilgok Gangjeong Goryeong Gangjeong Goryeong Dalseong Hapcheon Changnyeong Changnyeong Haman Gangcheon Yeoju Ipo Seungchon Juksan Dam Weir Flood Retention Res. Barrage Expansion Barrage Expansion Introduction of GRRP Andong-Imha connection Andong-Imha connection Gumi Sangju Bohyeon dam Bohyeon dam Nakdong Riv. Barrage Expansion Barrage Expansion Project Dredging : 43 million ㎥ Multi-purpose Weir : 3 Bank Reinforcement : 117 ㎞ Embanking Agr. Res. : 30 Farmland Remodeling : 17 Small Hydro-power : 3 Eco-stream : 199 ㎞ Bike Road : 301 ㎞ Basin Area : 9,912 ㎢, Basin Length : 397 ㎞ Geum Riv. Baekje Sejong Gongju

3 Geum Gang River & GRRP(River Restoration Project) Riverbed and Water Level Profiles of the Geum River Estuary barrageDaecheong dam Sejong weir 137 ㎞ Gongju weir Baekje weir 24.2MCM 15.5MCM 5.7MCM length depth

3 Geum Gang River & GRRP(River Restoration Project) Status of Weirs in the Geum River Sejong-weirGongju-weirBaekje-weir Weir Length(m) Capacity(10 6 m 3 ) Hydropower plants Capacity ( ㎾ ) 2,3103,0002,640 Fishway(ea) 121 Sejong-weirGongju-weirBaekje-weir

2 4 TEAM PROJECT

4 MISSION □ Find various solutions to flood problems at target areas □ and Verify your solution !

4 TEAM PROJECT Target area

4 TEAM PROJECT Target area

AREA 1 4 TEAM PROJECT NO NO Length : L=2,860m (No ~ No ) Bank top level: Right(7.75m~9.16m), Left(-) Flood Level : EL. 6.76m ~ EL. 7.47m (100year return period) Cultivated Land Altitude: EL. 3.70m ~ EL. 3.75m FLOW

AREA 1 4 TEAM PROJECT NO NO Problems : Sudden river narrows, Non-bank area(left side) - Frequent flooding at cultivated land - River bed sedimentation at direct downstream by Bottleneck phenomenon - Oppose the river improvements by local residents Riverbed sedimentation FLOW Non-Bank area

AREA 2 4 TEAM PROJECT Length : L=1,890m (No ~ No ) Bank top level: Right(8.55m~9.23m), Left(10.00m~10.36m) Flood Level : EL. 8.01m ~ EL. 8.35m (100year return period) BANK

AREA 2 4 TEAM PROJECT BANK Problems : Sudden river narrows - Concerned about right-bank erosion by speedy flow velocity - River bed sedimentation at direct downstream by Bottleneck phenomenon

DEM at target areas □ Modeling Analysis using 1-D (HEC-RAS,…) & 2-D (CCHE-2D, MIKE,..) tool Go! Go! Go! Move! Move! Move! □ Given data : A river bed measurement data (CAD-type) Frequency flood discharge at target point Other necessary data for analysis..

□ Segregation of duties Go! Go! Go! Move! Move! Move! TEAMTarget areaRemarks 1Area1 2Area2 3Area1 4Area2 5Area1 6Area2 - Elemental analysis => joint execution(3 teams) - Find solution => each team - Verify solution => each team □ 1 target area for 3 teams

Go! Go! Go! Move! Move! Move!