Groundwater Modeling Course

by Dr.-Ing.Phatcharasak Arlai Program of Civil and Environmental Engineering Nakhon Pathom Rajabhat University and Dr. Manfred Koch University of Kassel 20th – 22rd of October, 2008

Content of Presentation 1. General Aspects of Groundwater Modeling 2. Groundwater Modeling Protocol 3. Details of GW Modeling Protocol 4. Introduce PMWIN 5. Applications of PMWIN

1. General Aspect of Groundwater Modeling
Introduction
Advancement of Physical, Chemical, Hydrology of Groundwater
develop computer capacity
Numerical Modeling  the groundwater hydrology works + since 3 decades ago.
Groundwater problems = Quantity + Quality + Space + Time





Quantity = pumping >> natural yield Quality = leakage + intrusion + upconing Space = Some places (abundant) or the other places (no gw) Time = Dry (Deficit)

1. General Aspect of Groundwater Modeling

1. General Aspect of Groundwater Modeling
In USA, emergency programs to cope with contaminated problems , e.g., leakage from gas stations, septic tanks, pesticide, etc.
Emergency program??? Thailand????
The other contaminations, seawater-/saltwater intrusion.

1. General Aspect of Groundwater Modeling
Land settlement

1. General Aspect of Groundwater Modeling



  

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1. General Aspect of Groundwater Modeling
Many questions in the groundwater works
How will the groundwater level be in the next 20 years?
How many CMD can we sustainably extract the groundwater from an aquifer ?
How does the water level in a river effect to the groundwater in a shallow aquifer?
Etc.

GW modeling Protocol

Groundwater Modeling

1. General Aspect of Groundwater Modeling
Groundwater Model
Physical Model

1. General Aspect of Groundwater Modeling
Groundwater Model
Mathematical Model

1. General Aspect of Groundwater Modeling
Mathematical Model applies mathematic expressions to calculate the physical mechanism of groundwater system
Groundwater Flow
Solute Transport
Heat Transport
Land Subsidence

1. General Aspect of Groundwater Modeling
Solute Transport

1. General Aspect of Groundwater Modeling
Heat transport

1. General Aspect of Groundwater Modeling
Land Subsidence

1. General Aspect of Groundwater Modeling
Groundwater flow expression

Conventional 3-D Groundwater flow Eqn.

1. General Aspect of Groundwater Modeling ∂h =0
Steady State: ∂t

Parameters for the steady state 1.K or T (only confined aquifer) 2.Grid characteristics 3.Physical characteristics of stratigraphic unit, e.g., top-, bottom elevation, aquifer type and so on. 4.Temporal parameters

1. General Aspect of Groundwater Modeling ∂h ≠0
Transient: ∂t

Parameters for the transient 1.K or T (only confined aquifer) 2.S {Unconfined- (Specific yield) or Confined (Storage Coefficient) aquifer} 3.Grid characteristics 4.Physical characteristics of stratigraphic unit, e.g., top-, bottom elevation, aquifer type and so on. 5.Temporal parameters

1. General Aspect of Groundwater Modeling
Layer Type

2. Groundwater Modeling Protocol
Modeling Protocol
Purpose of Model
Conceptual Model
Computer Code
Model Design
Calibration
Sensitive Analysis
Model Verification
Prediction
Predictive Sensitivity Analysis
Presentation of modeling design and result
Postaudit
Model Redesign

3. Details of GW Modeling Protocol
Purpose of Model: the purpose will determine what governing equation will be solved and what code will be selected.
Conceptual Model: Hydrostratigraphic unit and system boundaries are identified.
Computer Code: Can it accurately describe the physical processes occuring in porous media?
Model Design: The conceptual model is put into a form suitable for modeling
Calibration: is to establish that the model can reproduce field-measured heads and flows.

Details of GW Modeling Protocol
Sensitivity Analysis: is performed in order to establish the effect of uncertainty on the calibrated model
Model Verification: is to establish greater confidence in the model by using the set of calibrated parameters and stresses to reproduce a second set of field data.
Prediction: quantifies the response of the system to future events.
Predictive sensitivity analysis: is done to quantify the effect of uncertainty in parameter values on the prediction.

Details of GW Modeling Protocol
Presentation of Modeling Design and Results: Clear presentation of model design and results is essential for effective communication of the modeling effort.
Postaudit: After modeling is completed, new field data are collected to determine whether the prediction is correct or not.
Model Redesign: Typically the postaudit will lead to new insights into system behaviors which may lead to changes in the conceptual model or changes in the model parameters

4. Introduce PMWIN
PMWIN “Processing Modflow: A Simulation System for Modeling Groundwater Flow and Pollution”
PMWIN was designed as a pre- and postprocessor with the goal of bringing various codes together in a complete simulation system.
The code developers are “Wen-Hsing Chiang and Wolfgang Kinzelbach”
IBM = “Immer bis mittle Nacht”

4. Introduce PMWIN MODFLOW and PMPATH PMWIN

MT3D, MT3DMS and MOC3D PEST and UCODE

4. Introduce PMWIN
Groundwater flow: MODFLOW-88 (McDonald and Harbaugh, 1988) or MODFLOW-96 (Harbaugh and McDonald, 1996a, 1996b)
Advective transport model: PMPATH (Chiang and Kinzelbach, 1994, 1998)
Solute transport model: MT3D (Zheng, 1990), MT3DMS (Zheng and Wang, 1998), MOC3D (Konikow et al., 1996)
Inverse Model: PEST (Doherty et al., 1994) and UCODE (Poeter and Hill, 1998)

4. Introduce PMWIN
The Density package (Schaars and van Gerven, 1997) was designed to simulate the effect of density differences on the groundwater flow system.
The Horizontal-Flow Barrier package (Hsieh and Freckleton, 1992) simulates thin, vertical low-permeability geologic features (such as cut-off walls) that impede the horizontal flow of ground water.
The Interbed-Storage package (Leake and Prudic, 1991) simulates storage changes from both elastic and inelastic compaction in compressible finegrained beds due to removal of groundwater.

4. Introduce PMWIN
The Reservoir package (Fenske et al., 1996) simulates leakage between a reservoir and an underlying groundwater system as the reservoir area expands and contracts in response to changes in reservoir stage.
The Streamflow-Routing package (Prudic, 1988) was designed to account for the amount of flow in streams and to simulate the interaction between surface streams and groundwater.

4. Introduce PMWIN
Reservoir Package

4. Introduce PMWIN
The particle tracking model PMPATH uses a semianalytical particle tracking scheme (Pollock, 1988) to calculate the groundwater paths and travel times. PMPATH allows a user to perform particle tracking with just a few clicks of the mouse. Both forward and backward particle tracking schemes are allowed for steady-state and transient flow fields. PMPATH calculates and displays pathlines or flowlines and travel time marks simultaneously. It provides various onscreen graphical options including head contours, drawdown contours and velocity vectors.

4. Introduce PMWIN
PMPATH

5. Applications of PMWIN Example 1
Aquifer: two stratigraphic units
The West and East sides are bounded by rivers, which are in full hydraulic contact with the aquifer and can be considered as fixed-head boundaries.

5. Applications of PMWIN Example 1
The hydraulic heads on the west and east boundaries are 9 m and 8 m above reference level : Geostatistics
Kxy1 = 1x104 m/s and Kxy2 = 5x104 m/s
Kz = 10% of Kxy
Effective Porosity = 0.25
Top elevation = 10 m.
Recharge rate = 8x10-9 m/s
How much can the pumping rate be? So that the contaminated area lies within the within the capture zone of the pumping well.

5. Applications of PMWIN
Steady state simulation

5. Applications of PMWIN
Create a new model: Specify the project name

5. Applications of PMWIN
Assign model data: Grid

5. Applications of PMWIN
Assign model data: Grid/Mesh size

5. Applications of PMWIN
Assign model data: Grid/Layer type

5. Applications of PMWIN
Assign model data: Grid/Boundary condition
IBOUND = Flow B.C.
IBUND = Solute Transport B.C.

5. Applications of PMWIN
Assign model data: Grid/Boundary condition

Assign B.C. = -1, constant head which represent the water level in two rivers.

5. Applications of PMWIN
Assign model data: Grid/Top

5. Applications of PMWIN
Assign model data: Grid/Bottom

5. Applications of PMWIN
Assign model data: Parameters/Time

5. Applications of PMWIN
Assign model data: Parameters/Initial Hydraulic Head

5. Applications of PMWIN
Assign model data: Parameters/Horizontal Hydraulic Conductivity

5. Applications of PMWIN
Assign model data: Parameters/Effective Porosity

5. Applications of PMWIN
Assign model data: Parameters/

5. Applications of PMWIN
Assign model data: Models/MODFLOW/Recharge

5. Applications of PMWIN
Assign model data: Models/MODFLOW/Recharge

5. Applications of PMWIN
Assign model data: Models/MODFLOW/Well at

Well locates at [25, 15, 1, -1E-10], [25, 15, 2, -1E-10], [25, 15, 3, -0.0012 ]: [col, row, layer]

5. Applications of PMWIN
Perform the flow simulation: Run Modflow

5. Applications of PMWIN
Check simulation:

0.01%

0.01%

5. Applications of PMWIN
Calculate subregional water budget:

Zone 1>layer 1 and Zone 2 > layer 2

5. Applications of PMWIN • Calculate subregional water budget: Output

5. Applications of PMWIN
Produce Output: Contour head

5. Applications of PMWIN
Produce Output: Contour head

5. Applications of PMWIN
Produce Output: Contour head

5. Applications of PMWIN
Apply Advective Transport Model: To delineate the capture zone of the pumping well

5. Applications of PMWIN
Apply Advective Transport Model: To delineate the capture zone of the pumping well

5. Applications of PMWIN
Apply Advective Transport Model: To delineate the capture zone of the pumping well

5. Applications of PMWIN
Apply Advective Transport Model: To delineate the capture zone of the pumping well

5. Applications of PMWIN
Geotechnical Applications: Flow Net and Seepage under a Weir

5. Applications of PMWIN
Geotechnical Applications: Flow Net and Seepage under a Weir
An impervious weir is partially embedded in a confined aquifer.
The aquifer is assumed to be homogeneous with a hydraulic conductivity of the aquifer of 0.0005 m/s and a thickness of 9 m.
The effective porosity of the aquifer is 0.15.
Calculate the flow net and the flux through the aquifer for the cases that




(1) the aquifer is isotropic and (2) the aquifer is anisotropic with an anisotropy factor of 0.2. (3) the 1st case is connected with the slurry wall at the U/S of Weir basement and its length is 4 m downward from the basement.

5. Applications of PMWIN
Geotechnical Applications: Flow Net and Seepage under a Weir/Grid: 2D model (a uniform thickness of 1 m.)
Mesh size: One layer, 65 columns, 9 rows and regular grid space of 1 m.

5. Applications of PMWIN
Geotechnical Applications: Grid/Layer type

5. Applications of PMWIN
Geotechnical Applications: Grid/Boundary Condition

5. Applications of PMWIN
Geotechnical Applications: Grid/Top of layer

5. Applications of PMWIN
Geotechnical Applications: Grid/Bottom of layer

5. Applications of PMWIN
Geotechnical Applications: Parameters/Time

5. Applications of PMWIN
Geotechnical Applications: Parameters/Initial hydraulic head

5. Applications of PMWIN
Geotechnical Applications: Parameters/Horizontal hydraulic conductivity, K= 5x10-4 m/s

5. Applications of PMWIN
Geotechnical Applications: Parameters/Porosity = 0.15

5. Applications of PMWIN
Geotechnical Applications: Models/MODFLOW/Run

5. Applications of PMWIN
Geotechnical Applications: Tool/Presentation

5. Applications of PMWIN
Geotechnical Applications: Models/MODFLOW/Run

5. Applications of PMWIN
Geotechnical Applications: Tool/Presentation

5. Applications of PMWIN
Geotechnical Applications: Tool/Presentation

5. Applications of PMWIN
Geotechnical Applications: Tool/Presentation

5. Applications of PMWIN
Geotechnical Applications: Advective Transport and equipotential head

5. Applications of PMWIN
Geotechnical Applications: Slurry Wall at the U/S of Dam basement

5. Applications of PMWIN
Geotechnical Applications: Slurry Wall at the U/S of Dam basement

5. Applications of PMWIN
Geotechnical Applications: Slurry Wall at the U/S of Dam basement

5. Applications of PMWIN
Geotechnical Applications: Slurry Wall at the U/S of Dam basement



  
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indeed for your attetion
Vielen Dank fuer deine Aufmerksumkeit