1. High Resolution Global Scale
Groundwater Modelling
Department of Physical Geography – Faculty of Geosciences
Rens van Beek
Inge de Graaf, Edwin Sutanudjaja, Yoshi Wada & Marc Bierkens
Limits to global groundwater
consumption: effects on low
flows and groundwater levels

2. 2
De Graaf et al., 2014

3. 3
Simulated water stress index for 2000 (Wada et al., 2011)

4. Towards a high resolution global hydrological model
4
Global-scale simulations at 5 arc minutes (~10 x 10 km at equator)
River discharge Domestic water use

5. What has been the effect of abstractions on groundwater levels?
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• Simulation of groundwater head
dynamics;
• Lateral flow (exchange between cells)
cannot be ignored at finer spatial
resolutions.
Challenges to the construction of a
physically based global-scale groundwater
model:
• Quality of available global datasets:
- Surficial hydro-lithology;
- Aquifer thickness estimates.

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Model lay-out
• 5’ resolution;
• Steady-state;
• Offline coupling to MODFLOW;
• Coupling to iMOD under construction.
Sutanudjaja et al., 2011

7. Land-surface model
Available global datasets
Gleeson et al. 2010
Hartmann and Moosdorf 2012
Hydro-lithology
Conductivity
Model Input
Groundwater recharge
Surface water levels
• Imposed as average long-term levels for
lakes, reservoirs and lakes;
• Based on discharge for rivers and imposed
by means of the RIVER package using
uniform conductivity;
• DRAIN package is used where no main river
channel is available.

8. 8
range
Land surface
Sediment basin
50 m
Floodplain elevation
range
1) 𝐹′ 𝑥 = 1 −
𝐹 𝑥 − 𝐹𝑚𝑖𝑛
𝐹𝑚𝑎𝑥 − 𝐹𝑚𝑖𝑛
F’(x) is spatial frequency
distribution of elevation above
the floodplain
2) Associated Z-score
𝑍 𝑥 = 𝐺−1(𝐹′ 𝑥 )
Where G-1 is the inverse of the
standard normal distribution.
Sediment basin aquifers: delineation and depth (1)

9. 9
3) Using case studies in the US
• range of aquifer thickness
• average coefficent of variation
• Aquifer thickness is assumed
to be log-normally distributed
(positive skew)
4) 𝑙𝑛𝐷 = 𝑈(𝑚𝑖𝑛; 𝑚𝑎𝑥)
𝑌 𝑥 = 𝑙𝑛𝐷 × (1 + 𝐶𝑣𝑙𝑛𝐷Z x )
𝐷 𝑥 = 𝑒 𝑌(𝑥)
dmax
dmin
Sediment basin aquifers: delineation and depth (2)

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Cumulative probability of aquifer depth

11. Average simulated aquifer thickness

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Transmissivity (m2d-1)
0.5 5 15 40 >100
𝑇 𝑥 = 𝑘0 𝑒−𝑧//λ
𝐷(𝑥)
0
𝑑𝑧
Aquifer-scale transmissivities

13. Steady-state water table depth
13

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Validation on groundwater wells
0.25-2.5 320- 640 > 640
Observed GW heads
Sediment
basins
All wells

15. 15
Validation on groundwater wells
0.25-2.5 320- 640 > 640
Observed GW heads
Sediment
basins
All wells
Relative residuals
𝑅 𝑟𝑒𝑙=
𝐻 𝑠𝑖𝑚−𝐻 𝑜𝑏𝑠
𝐻 𝑜𝑏𝑠

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0.01 0.1 1 10 100 1000 Years
- Months years decades centuries millennia
Flow paths and travel times

17. • Suitable method to develop aquifer schematization and properties for data
poor environments;
• The large scale-distribution of groundwater levels is captured; starting
point to assess groundwater level fluctuations;
• Confirms the relevance of including lateral flow in global scale hydrological
models at finer resolutions.
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Conclusions
 What is the effect of past and future abstractions on
groundwater levels?
Major limitations, currently being addressed:
• Steady-state;
• Single, unconfined layer;
• Coupling of surface and groundwater.

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Thank you for your attention
http://www.hydrol-earth-syst-sci-discuss.net/11/5217/2014/hessd-11-5217-2014.pdf

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Europe USA
Validation
groundwater depths