Czech University of Life Sciences in Prague

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• Czech University of Life Sciences in Prague
• Faculty of Agrobiology, Food, and Natural
  ResourcesDepartment of Water Resources
• Hydrogeological Modelling of Different Scenarios
  of Groundwater Movement and Discharge in the
  Watershed of the River Labe in North-west
  Bohemia
• by
• Svatopluk Matula, Getu Bekere Mekonnen, Kamil
  Neetril, Kamila pongrová
• International Conference on Water Policy 2009
• Prague, June 22-26, 2009

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Study area
The study area (Decín)
The Model area
The River Labe
Map of the Czech Republic
N
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Study area (continued )
The river Labe
The Creek Jilovisky
Meeting point of the Creek Jilovisky and the
River Labe
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Objectives of the study

• General objectives
• ? To understand the relationship between the
  river water level and groundwater level.
• ? To apply simulation model using Visual MODFLOW
  software for the practical application.
• Specific objectives
• ? To study river-aquifer interactions
• ? To investigate the situation of small solid
  soil particles as a result of river aquifer
  interaction.

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Why this study was performed?

• The boat navigation has significant difficulties
  with the low water level for the boat
  transportation.
• A weir is planned to be constructed in Decín for
  increasing water level of the River Labe

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Hypotheses

• With the increasing the water level in the river,
  direction and the speed of the grondwater flow
  supposed to be changed.
• Groundwater table will rise up and the small
  solid soil particles might change their direction
  of movement across the porous system.

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Methodology

• Cases of simulation
• 1. Steady state simulation
• For model calibration.
• For comparison of out put results.
• 2. Transient state simulation
• Scenario 1 The first three days.
• Scenario 2 The next three months.
• During each scenario, the situation of the
  surface and ground water interaction was
  investigated.

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The conceptual model
GHB (the creek Jilovisky)

• 400ha
• 100 row
• 100 column
• 20m of nodal
• spacing
• 30m thick
• Recharge 221mm/yr

CHD-boundary condition
Active cells
Head observation wells
Model Y-coordinate (m)
Inactive cell
CHD- boundary condition (THE River Labe)
Model X-Coordinates in (m)
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The conceptual model (continued )
Location of Particles
Model Y-coordinate (m)
Model X-Coordinates in (m)
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Results and discussions

• Steady state simulation results
• General groundwater movement
• Before construction of the proposed weir,
• velocity vector map, and
• head equipotential contour map show that the
  direction of ground water movement is towards the
  River Labe.
• The pathlines show that particles move towards
  the river.

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Results and discussions (continued )
-Pathlines -Velocity vec. -Head contour map
530 days/500m
Model Y-coordinate (m)
Model X-Coordinates in (m)
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Results and discussions (continued )
Crossection view in row 35
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Results and discussions (continued )

• Calibration of the model

Calibration residual head in tag window
Calibration bubble maps of residual head
-Ve residual (Cal-obs)
K4E-4m/s Total P 30 Effective P15
7E-4m/s
4E-4m/s
4E-4m/s
Model Y- coordinate in (m)
ve residual
3E-4m/s
Model X-Coordinates in (m)
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Results and discussions (continued )

• Calibration graph of scatter plot of calculated
  vs. observed heads

• The line of 95 conf. inter. is totally below the
  line yx
• The model is under- predicting
• Necessary to calibrate the model

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Results and discussions (continued )

• Polygons of different estimated K values based on
  measured values
• Keeps heterogeneity of the
• natural aquifer.
• The color is conventional applied by the
  software ? not related to the K values.

4E-4 m/s
7E-4 m/s
5E-4 m/s
6E-4 m/s
Model Y- coordinate in (m)
3E-4 m/s
Model X-Coordinates in (m)
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Results and discussions (continued )

• After running the model for the different input
  values of saturated hydraulic conductivity (K)

Tag maps of residuals after calibration
Bubble maps of residuals after calibration
-ve residual
Model Y- coordinates (m)
ve residual
Model X-Coordinates in (m)
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Results and discussions (continued )

• Comparison of residual (sign and size) before and
  after calibration

Before calibration
After calibration
-ve residual
-ve residual
Model Y-coordinates in (m)
ve residual
ve residual
Model X-Coordinates in (m)
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Results and discussions (continued )

• Calibration graph (scatter plot) after calibration

• The line xy is within 95 conf. int. and 95
  interval
• We can proceed to compare the means of observed
  and simulated hydraulic heads

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Results and discussions (continued )

• Statistical test for calibrated data (hydraulic
  heads)
• Null hypothesis Any given residual is equal to
  the mean residual.
• Paired samples t-test in the table below
  indicates that the significance value (p-value)
  of 0.612 is greater than the sig. level (alpha
  0.05), we cannot reject the null hypothesis.
• Therefore, the null hypothesis is accepted and
  there is no statistical difference between the
  means of cal. obs. heads.
• The significance of statistical test indicates
  that the model is simulating well and is ready to
  be used for further transient simulation.
• SPSS result for Paired
  samples t-test

P(0.612) gt0.05
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Results and discussions (continued )

• Transient state simulation Results for 1st
  scenario (3rd day)

Direction
Magnitude

• The river is recharging the aquifer.
• The velocity of ground water is reduced near the
  river.
• ?because of reduction in hydraulic gradient.
• Particles move towards the river at very low
  velocity
• compared to the natural situation.

Model Y-coordinates (m)
Model X-Coordinates in (m)
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Results and discussions (continued )

• Transient state simulation result for 2nd
  scenario (94th day)

Direction
Magnitude

• Groundwater
• direction is towards
• the river with
• highly reduced
• velocity.
• The reduction in velocity is felt in the whole
  model area
• after 94 days.
• Particles tend to
• stay in the aquifer.

530 days
Model Y-coordinates (m)
Model X-Coordinates in (m)
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Conclusion

• Direction of ground water flow and particles
  movement

Before construction of weir (Steady State
simulation)
After construction of weir (Transient State
simulation)
1st Scenario(3rd day)
2nd scenario (94th day)
Model Y- coordinates in (m)
Model X-Coordinates in (m)
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Conclusion (continued)

• Seepage velocity of ground water flow and
  particles movement

After construction of weir (transient state
simulation)
Before construction of weir (Steady state
simulation)
1st Scenario(3rd day)
2nd scenario (94th day)
Model Y- coordinates in (m)
Model X-Coordinates in (m)
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Conclusion (continued)

• Groundwater level increases

Groundwater depth below top of aquifer before
construction of weir
Groundwater depth below top of aquifer after
construction of weir
Model Y- coordinates in (m)
Model X-Coordinates in (m)
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Conclusion (continued)

• Groundwater level increases..time series graph

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Recommendations

• Periodically reducing the height of the weir
• ?Reduce the recharge from the river to the
  aquifer.
• ?Facilitate the drainage of ground water by the
  river.
• Continues protection of the aquifer from the
  pollution by the external effluents of industries
  in the city.
• Pumping the ground water of the aquifer
• ?For consumptive uses- depending on the quality
  of the water.
• ?Draw back facilitate river recharge to
  aquifer.
• ? increase probability of
  ground water contamination.

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THANK YOU FOR YOUR ATTENTION!