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TRANSCRIPT
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Integrated surface-groundwater analysis considering groundwater use in Pyoseon region, Jeju island, Korea
Nam-Won Kim*, Il-Moon Chung*, Hanna Na*, Sangyeon Yoo **and Sung-Kee Yang***
* Korea Institute of Construction Technology** Saman Cooperation
*** Jeju National University
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Background & Purpose Integrated SWAT-MODFLOW Application to Pyoseon watershed Results of simulation Conclusion
Content
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Background
Jeju island is the region where the highest rainfall occurs in Korea
The average annual rainfall of the island is about 1,975mm which is the 1.5 times larger than the mean value of 1,283mm for the Korean mainland (Won, 2004).
However, the island has suffered from water shortages mainly due to lacking large perennial rivers and streams
Main water resources is groundwater
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BACKGROUND
The streams in jeju island
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Surface water condition
Most of streams in upper region of watersheds show dried characteristics by means of large portion of recharge which goes to the deep aquifer : no baseflow in the upper area of watershed (losing stream).
On the contrary, groundwater discharge is more and more increasing as approaching to the downstream near to sea.
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Hydrogeology
Jeju island is mainly consisted of volcanic rocks including highly permeable basalts.
Mean transmissivity of permeable formations : 2,008 m2/day (K-Water, 2003)
A number of production wells have been installed.
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The groundwater flow direction
Equipotential lines
GW flow
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Deep recharge and discharge
Precipitation
Inland GW
Jeju GW
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Surface water measurements : Very hard
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SWAT-MODFLOW
Overview
SWAT(Arnold, 1993; Arnold, 1995) is widely used long term runoff model.
SWAT’ groundwater model is a semi-distributed type and thus the distributed parameters such as hydraulic conductivity and output (groundwater level) distributions could not be represented.
The conventional groundwater flow analysis performed by MODFLOW(McDonald and Harbaugh, 1988) often overlooks the accuracy of the recharge rates.
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SWAT-MODFLOW
Integrated SWAT-MODFLOW model
Development of subroutine for exchanging characteristics between HRU(Hydrologic Response Unit) of SWAT and CELL of MODFLOW
On the basis of these stable platforms, the groundwater module in SWAT is replaced by MODFLOW
Then, SWAT-MODFLOW is capable of simulating spatial-temporal GW recharge and stream-aquifer interactions by RIVER package in MODFLOW
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SWAT-MODFLOW
* Kim et al., Development and application of the integrated SWAT-MODFLOW model, J. of Hydrology (2008)
Schematic diagram
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SWAT-MODFLOW Linking RECHARGE in MODFLOW with SWAT
7 7 7 7
7 7 7 7
7 7 7 7
7 5 5
5 55 556 6 6
6 6 6
6 6
64
4 4 4 4
4 4
4 4
4 4
44 913554
SWAT
MODFLOW
HRU별 대수층의 함양량 = 54+44+35+91
소유역의 HRU
소유역의 HRU
MODFLOW의 cell
HRU based recharge
HRU in small watershed
HRU in small watershed
Cell in MODFLOW
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SWAT-MODFLOW
1 m
5
5
4 4 3 3
1 0
-2
23
SWAT
MODFLOW
SWAT의 하천
소유역
MODFLOW의 cell
MODFLOW의 하천
SWAT의 하천유입량 = 소유역 유출량 + 하천-대수층간 물교환량 = 소유역 유출량 + 23 하천-대수층간 물교환량 = 5+5+4+4+3+3+1+0-2
Stream inflow in SWAT =discharge in small watershed +SW & GW exchange(23)
Stream inflow in SWAT
Small watershed
Cell in MODFLOW
Stream in MODFLOW
Linking RIVER in MODFLOW with SWAT
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Pyoseon region
SeongPanAkSamdasu
Pumping Well
Jeju
GyoRae
SungSan
4th GyoRae Br.
SeongEup
ChunMi Br.
EomDeuRik Br.
AnJwaRiver
JinPyeongRiver
GaSiRiver
Song River
ChunMi River
Surface observation station
Weather observation station
Rain observation station
Groundwater Well
Study Area
River network
SeongPanAkSamdasu
Pumping Well
Jeju
GyoRae
SungSan
4th GyoRae Br.
SeongEup
ChunMi Br.
EomDeuRik Br.
AnJwaRiver
JinPyeongRiver
GaSiRiver
Song River
ChunMi River
Surface observation station
Weather observation station
Rain observation station
Groundwater Well
Study Area
River network
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DEM
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LAND USE
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SOIL CLASS
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Samdasu Pumping Well
Zone1
Zone2
LONGITUDINAL GROUNDWATER LEVEL
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PUMPING WELLS (N=198)
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CHB(Constant Head
Boundary)
No-flow Boundary
No-flow Boundary
K-Zone1K-Zone2
K-Zone3
Samdasu Pumping Well
AQUIFER ZONING / BOUNDARY CONDITION
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SURFACE RUNOFF SIMULATION (R2=0.65)
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SEPARATION of SW / GW
River bed
GroundwaterLosing stream
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Gwlevel(El.m)
GW CALIBRATION
OBS.
CAL.
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150
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200
1/1
/04
2/1
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12/1
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1/1
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2/1
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3/1
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4/1
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5/1
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6/1
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2/1
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3/1
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5/1
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6/1
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7/1
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8/1
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9/1
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10/1
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11/1
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12/1
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Time(days)
GW
leve
l(Gl,
m)
-3
2
7
12
17
22
27
Rec
harg
e(m
m)
GroundWater LevelRecharge
SIM. RECHARGE vs GW LEVEL (R=0.87)
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Re-100 - 3435 - 6869 - 102103 - 136137 - 170171 - 204205 - 238239 - 272273 - 306No Data
N
EW
S
DISTRIBUTED GW RECHARGE (OCT. AVE.)
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FDCs with various PUMPING scenarios
Q (Current rate) / 10Q / 20Q
: Low flow rate 0.18CMS -> 0.15CMS -> 0.10CMS reduces 17%, 45% respectively
0.01
0.1
1
10
100
1000
0% 7% 14% 21% 27% 34% 41% 48% 55% 62% 69% 75% 82% 89% 96%
Dis
char
ge (c
ms)
Probability
Pumping
Pumping (10)
Pumping (20)
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Water Budget change (3, 13 subwatersheds)
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Sustainable additional groundwater resources
10Q / 20Q reduces the groundwater to Sea
: secures 60Mm3 /1000Mm3
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GW level variations
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GW recovery in alluvial aquifer
10Q -> Stop : Prompt recovery
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10Q -> Stop : Slow recovery
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GW recovery in rock aquifer
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GW Time series at a single cell (SWAT-K)
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GW level distribution (SWAT-K)
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CONCLUSION
Integrated SW-GW analysis in Jeju island is performed
Annual groundwater recharge rate in the Pyoseon basin is about 53%
Impact analysis due to increasing Q scenarios- Recorvery tests show that 10Q / 20Q
Sustainable additional GW resources in Jeju island could be secured
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Thank you
This work is financially supported by 21century Frontier Research Program(code 2-2-3).
Slide Number 1Slide Number 2 Background BACKGROUND Surface water condition � Hydrogeology�Slide Number 7 Deep recharge and discharge Surface water measurements : Very hard SWAT-MODFLOW SWAT-MODFLOW SWAT-MODFLOW SWAT-MODFLOW SWAT-MODFLOWPyoseon regionSlide Number 16Slide Number 17Slide Number 18Slide Number 19Slide Number 20Slide Number 21Slide Number 22Slide Number 23Slide Number 24Slide Number 25Slide Number 26Slide Number 27Slide Number 28Slide Number 29Slide Number 30Slide Number 31Slide Number 32Slide Number 33Slide Number 34 CONCLUSIONSlide Number 36