Groundwater ModelingGroundwater ModelingStudy case : Study case : Central Plain of ThailandCentral Plain of Thailand

Werapol BejranondaDepartment of Geohydraulics and Engineering Hydrology

University of Kassel, Germany

December 16, 2009December 16, 2009

ContentsContentsStudy Area / Groundwater hydro.Study Area / Groundwater hydro.

MethodologyMethodology

Groundwater ModelingGroundwater Modeling

Application of the modelApplication of the model

Study AreaStudy Area

GW BasinsGW Basins

Upper Central GW Basinof great central basin

•Agricultural

*The first upper centralregional GW Model

Lower Central GW Basinof great central basin

•Industrial•Agricultural

Bangkok(Capital)

Hydrogeological map ofupper central GW basin

Geological Map of Thailand

Study AreaStudy AreaStudy Area Boundary

Surface WaterSurface Water

4 Main Streams-Yom Rive-Nan River-Ping River-Sakaekrang River

cover 5 main surface-water basins

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50 0 50 100 150 200 Kilometers

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1750000 1750000

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Study AreaStudy Area

Project study area covers 6 Provinces

47,000 km2

KPP

SKT

UTD

PSL

PCT

NKS

Existing Conjunctive UseExisting Conjunctive Use•Irrigation areaIrrigation area•Rainfed areaRainfed area•Personal GW pumpsPersonal GW pumps

Study flowchart

Math-Model Design

Review Conjunctive Use in study area

Conceptual Groundwater Model

Calibration and Verification

Modeling Result

GW Use Pattern Analyze

Space Dimension- Irrigation Area- Surface Basins- Aquifer Types

Time Dimension- Water Situations- Seasons

Groundwater Uses

Surface Water Balance Analysis Result

Surface Water Uses

Surface Water Shortage

Industrial/Private Use

Agricultural Use

Domestic Use

Questionnaires

- Groundwater Levels- Hydraulics Properties- Recharge

Field Investigationand

Literature Review

Applications

GW use ??GW use ??Field data collectionField data collection ( (pumping behaviorpumping behavior))

area crops/year season pumping/crop day/pumping hours/day

irrigation 2.5dry 6.0 2.6 19.3

wet 3.8 2.3 19.3

rainfed 2.0dry 6.5 3.1 22.0

wet 3.1 2.1 16.0

pilot area(irrigation)

2.3dry 5.4 4,9 20.4

wet 3.5 4.5 23.8

Layer ClassificationLayer Classification

Flood Deposit & Low Terrain

High Terrain

GW Model(MODFLOW)

2 Layers Conceptual Model

Upper Layer (Semi-confined)

Lower Layer (Confined)

10 km. 10

km Upper : 320 grids

Lower : 346 grids

Upper Layer

Lower Layer

Recent Flood Plain Deposits

Rock

Low Terrace Deposits

High Terrace Deposits

thickness 100-300 m.

thickness 40-100 m.

Calculation MethodCalculation Method1.1. Steady Calibration : 2003Steady Calibration : 20032.2. Transient Calibration : 1993-2003Transient Calibration : 1993-20033.3. Model Verification :2003-2005Model Verification :2003-2005

1.Steady Statefor Hydraulic Conductivity

2.Transient State for Specific Storage

1993 2003

3.Verification

2005

Calibration Calibration & &

VerificationVerification15

20

25

30

35

40

45

50

55

60

15 20 25 30 35 40 45 50 55 60

Computed vs. Observed ValuesH e a d

Co

mp

ute

d

Observed

10

20

30

40

50

60

70

80

10 20 30 40 50 60 70 80

Computed vs. Observed ValuesTra ns. H e a d

Co

mp

ute

d

Observed

Calculation

Average Error (m)

Root Mean Square Error(m)

Calibration Calibration (Steady)(Steady)

-0.-0.9797

27.27.55

Calibration Calibration (Transient)(Transient)

3 .83 .833

45.45.33

VerificationVerification

(Transient)(Transient)17.17.77

53.53.44

Steady

Transient

Watersituation

water demand : SW : GW(all in dry season)

Wet 1 : 0.49 : 0.27

Normal 1 : 0.32 : 0.36

Dry 1 : 0.47 : 0.52

Drought 1 : 0.63 : 0.68

Aquifer typespump yield

GW useto demandM3/hr

flood deposits 10-20 17%

Low terrace deposits 5-12 7%

high terrace deposits 1-10 2%

Basinwater demand : SW : GW

Irrigation area rain-fed area

Ping 1 : 0.54 : 0.08 1 : 0.83 : 0.17

Yom 1 : 0.90 : 0.01 1 : 0.87 : 0.13

Nan 1 : 0.53 : 0.30 1 : 0.97 : 0.03

Chaophraya 1 : 1.00 : 0.02 1 : 0.99 : 0.01

Sakaekrang 1 : 0.83 : 0.01 1 : 0.99 : 0.01

all basins 1 : 0.62 : 0.17 1 : 0.93 : 0.07

Irrigation condition water demand : SW : GW (all in wet year)

rainy season dry season whole year

irrigation area 1 : 0.74 : 0.05  1 : 0.50 : 0.29 1 : 0.66 : 0.13

rain-fed (no irrigation)  1 : 0.98 : 0.02 1 : 0.54 : 0.46 1 : 0.94 : 0.06

GW UseRatios

Space Dimension

Time Dimension

Conjunctive Use Patterns

0%

5%

10%

15%

20%

25%

30%

35%

40%

Wet Dry Wet Dry Wet Dry Wet Dry Wet Dry Wet Dry Wet Dry Wet Dry Wet Dry Wet Dry

1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Ra

tio

of

Gro

un

dw

ate

r U

se t

o T

ota

l w

ate

r d

ema

nd

(%

)

400

600

800

1000

1200

1400

1600

1800

2000

2200

2400

1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Wa

ter

Use

(Mil

lio

n m

3 /yea

r)

Surface Water Use

Ground Water Use

Surfaceand

GroundwaterUse

Ratio ofGroundwater Use

to total water demand

Different GW Level from Different GW Level from Calculation ApproachCalculation Approach

33

34

35

36

37

38

39

40

2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 Year

Gro

un

dw

ate

r L

ev

el

(m M

SL

)

gw level with conjunctive pattern approach

gw level with average pumping rate approach

gw level with 0.7% growth-rate approach(3) conjunctive patern

(1) average pumping rate(2) 0.7% increasing pumpinge rate

Groundwater Level in Mae Nam Yom basin

17

19

21

23

25

27

29

2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025

Gro

un

dw

ater

Lev

el (

m.M

SL

)

Groundwater Level

Moving average12-month moving average

Application#1 : GW Level in pilot areaApplication#1 : GW Level in pilot area GW yield awareness

Simulated asDrought year

Agricultural well yield

Application#2 :Application#2 :Regional GW tableRegional GW table

2005 2018

Simulated groundwater table using conjunctive use ratio

Questions & AnswersQuestions & Answers