Water Quality and Ecological Restoration

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Water Quality and Ecological Restoration

• Bomchul Kim
• Department of Environmental Science
• Kangwon National University

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Contents

• Water quality issues in Korea
• Turbidity in streams and reservoirs
• Water quality survey project in Haean
• Control measures to improve water quality

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Change of water quality issues in Korea

• Before 1970s
• No pollution problems
• No concern about environmental conservation
• In 1980s
• High BOD from sewage
• Fish farms installed in many reservoirs
• In 1990s
• Sewage treatment systems established
• Active operations of fish farms within reservoirs
• Eutrophication problems emerged
• Algal toxins were reported

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Current issues in 2000s

• Turbidity and siltation major ecological hazard
• TMDL of BOD and TP for water quality management
• Phosphorus removal from sewage
• Biological assessment new paradigm
• Automatic monitoring high frequency monitoring

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Turbid water of the Soyang River on flood days
that flows into Lake Soyang (July 15,
2006) Increased rainstorm intensity - Due to
global warming ?
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Two hot spots of turbid water discharge
Haean
Lake Soyang
Jawoon
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Soil disturbance in Haean (2007. Mar.8)
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Making flatter fields for better cultivation a
cause of erosion in Haean
Original slope
Made steeper
Made flatter
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Tilling in Haean basin and the turbidity in Lake
Soyang
Turbidity
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Movement of turbid interflow in Lake
Soyang(result of simulation by CE-QUAL-W2, 1996)
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Turbidity increase in Lake Soyang
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Turbidity problem in reservoirs

• Turbid water lasts 3 months after summer monsoon
  in the Han River.
• Reservoirs are filled with turbid water after
  monsoon.
• Large dams prolongs the duration of turbid water
  in downstream.
• Destroys aquatic ecosystems.
• SAV is reduced.
• Fisheries is reduced.

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Water blooms in Lake Soyang after turbid storm
runoff
ltWet yearsgt
ltDry yearsgt
cyanobacteria
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Phosphorus loading into Lake Soyang
? increasing trend
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Land use vs. water qualityComparison of clean
streams and turbid streams- case study of two
couple sites (in 2006)
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A turbid stream (Jawoon) and a clean stream
(Kyebang)
In 2007
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A turbid stream (Daeki) and a clean stream
(Bongsan)
Result change and reduction of fish and benthos
community
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Water quality survey project in the Haean basin

• Purpose to evaluate effectiveness of soil
  erosion control and diffuse pollution control
• To assess water quality improvement in subbasins
  w/wo erosion control measures
• To assess efficiencies of each erosion control
  method
• To quantify specific export of nonpoint source
  pollution
• Period six years from 2009

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Site of investigation
Chungryounggolan
Seonghwang
Wolsan
Kunjigol
Doonjunggol
Naedong
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Land use in subbasins (km2)
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Water level measurement

• Water level scales were installed.
• Two automatic water level meter (sonic distance
  meter type) and two automatic water samplers will
  be installed in next year.

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Rainfall in 2009
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Pollutograph in rain events
Kunjigol
Wolsan
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Specific export coefficient (kg/ha/event)
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Effect of suspended sediment on fish
No fish is living in the Haean basin
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Table 3. The export loadings(kgyr-1km-2) in
each watershed.

• The amounts of TP exported from these two basins
  were considerably high,
• compared to other many studies

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Control measures of turbid water

• Sociological strategy
• Environmental management
• Agricultural practice

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Struggling to control erosion in Haean
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sometimes in vain
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To protect steep slope
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Food vs. Water

• Disturbed land ? poor water quality
• Conserved ecosystem ? good water quality
• Can we choose only one?
• The goal of Korea.
• even with intensive agriculture ? good water
  quality
• Is it possible?

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Thank you