Presentatie door Peter Vermeulen, Frans Roelofsen, Liduin Burgering en Bennie Minnema (Deltares) voor de iMOD NL Gebruikersdag, tijdens de Deltares Software Dagen- Editie 2017. Woensdag 14 juni 2017, Delft.

1. iMOD Gebruikersdag Deltares | Delft
14 Juni
29 juni 2017
Peter Vermeulen
Frans Roelofsen,
Liduin Burgering
Bennie Minnema

2. Content
29 juni 2017
UZF SFR MNW

3. UZF – Onverzadigde zone
29 juni 2017

4. UZF – Unsaturated Zone
The UZF:
• Simulate water flow and storage in the
unsaturated zone and to include precipitation
(RCH-concept); evapotranspiration; EVT-
concept
1. first unsaturated zone;
2. groundwater within EXDP).
• The approach assumes that unsaturated flow
occurs in response to gravity potential
gradients only and ignores negative potential
gradients (upward capillary flow);
• the approach further assumes uniform
hydraulic properties in the unsaturated zone
for each vertical column of model cells*.
• *MF6 support multiply k-horizons
29 juni 2017

5. UZF – Unsaturated Zone
29 juni 2017
Method of characteristics:
• velocity of a wave;
• the change in water content of the wave
with time;
• the change in water content with depth
behind the wave, respectively.
1. Wetting front – leading wave
2. Drying – traling wave
3. Waves can overtake others
NSTRAIL = number of trailing wave
increments
NSETS2= number of waves (each
precipitation event generate another wave)

6. UZF – Unsaturated Zone
Specific Yield (SY) is the
porosity minus the residual
water content
Permeability – and therefore velocity –
and eventually moisture content is
determined by Brooks-Corey function for
unsaturated permeability

7. UZF – Unsaturated Zone
Grondwater level (red)
Precipitation (blue)
Grondwater Recharge
(green)
Output:
• Net recharge;
• Water balance for the unsaturated zone (precipitation, evapotranspiration,
recharge and overland flow*;
• Detailed output: Prints time, ground-water head, and thickness of unsaturated
zone, and cumulative volumes of infiltration, recharge, storage, change in
storage and ground-water discharge to land surface; series of depths and
water contents in the unsaturated zone.
* Not supported in iMOD implementation

8. UZF – Unsaturated Zone
run 1 2 3 4
CB-
Epsilon
2 2 2 4
EXTWC 0.01 0.10 0.01 0.01
THTI 0.15 0.15 0.01 0.15
Measurement behavior
Extinction Water Content EVT
Initial Water Content

9. UZF – Tutorial
29 juni 2017

10. SFR – Surface Water Routing
29 juni 2017

11. SFR Overview – Concepts
LAYOUT
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𝑄in = 𝑄out
𝑄 = 𝑛𝑤𝑦
5
3 𝑆
1
2
𝑦 =
𝑄𝑛
𝑤𝑆
1
2
3
5
• Exchange Groundwater
• Surface overland flow
• Precipitation
• Evaporation
• External sources
Manning’s Equation
w: width of the stream
y: depth of water in the stream
n: Manning’s roughness coefficient
s: slope of stream

12. SFR Overview – Concepts
LIMITATIONS
29 juni 2017
 No storageterm;
 No damping of waves;
 Steady state for each timestep (quasi-transient approach);
 Uniform flow, driven by gravity and predefined flow directions (per timestep
adjustable though;
 Distribution at branching must be specified:
 Fixed amount taken from a stream (extraction)
 Up to a specified flow rate is diverted to the stream;
 Only above a specified flow rate in the stream the flow is diverted;
 The diversion rate is assigned by a predefined fraction;
 All flow is diverted in excess of a specified flow (flood control).
10.0
11.0
12.0
13.0
14.0
15.0
01
00:00
01
12:00
02
00:00
02
12:00
03
00:00
03
12:00
04
00:00
04
12:00
05
00:00
05
12:00
06
00:00
time
waterlevel[m]
unsteady steady

13. SFR Overview – Concepts
EXCHANGE WITH GROUNDWATER
29 juni 2017
Q, q: leakage flux, exchanged amount of water
c: leakage coefficient as ks / d;
w: interface width as function of river stage
L: length of stream
h: head difference between river stage hr and groundwater
level hg
d: sediment layer thickness of river bed
kS: hydraulic conductivity of riverbed
q
q1
q2
Δh
Δh1
Δh2
infiltration
drainage
𝑄 =
𝑘 𝑠 𝑤(ℎ 𝑟)𝐿
𝑑
Δℎ
𝑐 =
𝑘 𝑠
𝑑

14. SFR Overview – Concepts
COMPUTING WATERLEVELS
1. Interpolation between given levels;
2. Manning‘s Equation with a rectangular cross-section;
3. Manning‘s Equation with a 8-point cross-section;
4. Function assuming stream depth and width can be related to
streamflow by an equation;
5. Table with values of depth and width for given streamflows.
29 juni 2017

15. SFR Implementaton in iMOD
DATA STORAGE
29 juni 2017
ISG-RIV ISG-SFR
RIV-package SFR-package
BDGRIV BDGSTR
ISG-RIV
Four attributes per calculation
points, many calculation points per
segment allowed – interpolation
over the segments by iMOD
Eleven attributes per calculation
points, only two calculation points
per segment – interpolation over the
segment by the SFR package
Exchange flux between surface-
and groundwater
Exchange flux between surface-
and groundwater
Stream Stages, -Depth, -Width and
-Discharges

16. SFR Implementaton in iMOD
DATA STORAGE
29 juni 2017
S1
S2
S3
S4
S5
S6
S8
S7
Transient connections, riverbed width, -conductivity
and -thickness, calculation options, runoff flow
Connection and flow
direction
Cross-sections Discharge-
width/depth relations

17. SFR Implementaton in iMOD
CONNECTIONS
29 juni 2017
Functionality
to
interactively
select the
down- or
upstream
connected
stream
diversion
Flow direction
Connection
S1
S2
S3
S4
S5
S6
S8
S7

18. SFR Implementaton in iMOD
GRIDDING FOR SFR PACKAGE
29 juni 2017
Intersection with
modelling raster
S1
S2
S3
S4
S5
S6
S8
S7
S1
S2
S3
S4
S5
S6
S8
S7
Segment is splitted into 6 reaches
for the model

19. SFR Implementaton in iMOD
RESULTS
29 juni 2017
Stream Depths (m)
Stream Discharge (m3/sec)
Transient results:
 Stream Depth;
 Stream Width;
 Stream Stage;
 Stream Discharges
per segment written in ISG-file

20. SFR Implementaton in iMOD
RESULTS
29 juni 2017
Select more segments, S1,
S2, S6 and S8
S1
S2
S3
S4
S5
S6
S8
S7
Visualize Stream Levels, Stream
Depth, Stream Width or Stream
Discharges over the selected
segment in a profile
S1
S2 S6
S8

21. SFR Implementaton in iMOD
RESULTS
Visualize Stream Levels,
Stream Depth, Stream
Width or Stream Discharges
for a) the selected segments
or b) all segments in the 2D
plot
Select any available date to
display the corresponding
results
.. or rasterize
the results to
conventional
IDF files

22. SFR Implementaton in iMOD
RESULTS
SFR Implemented in IMOD – adapted ISG file – not in RUN file only in
PRJ file
29 juni 2017

23. SFR Tutorial
29 juni 2017

24. MNW – Multi-Node Well
29 juni 2017

25. MNW – Multi-Node Well
The Multi-Node Well package is used to:
• simulate ``long'' wells that are connected to
more than one model layer;
• distribute the abstraction rate vertically
proportional to the transmissivity adjacent to
the well screen;
• when a hydraulic head gradually drops below
the top of a well screen the yield of this
shallow part of the well will also gradually
drop – so: effective extraction can be
different than entered extraction.
29 juni 2017

26. MNW – Multi-Node Well
However:
• differences between the volume of a cell
and the volume of a well-bore;
• differences between the average
hydraulic properties of a cell and those
immediately adjacent to a well
not expected that the computed head for
the node of a finite-difference cell will
accurately reproduce or predict the actual
head or water level in a well at that
location.
29 juni 2017

27. MNW – Multi-Node Well
Head losses:
Solved by computing a hydraulic head in the
cell such that it equals the computed
hydraulic head at the well minus a head
loss term*:
Thiem Equation:
Skin OPTION:
this option allows for formation damage or
skin corrections at the well
29 juni 2017
* MNW support more options that are not
supported by the iMOD GUI

28. MNW – Multi-Node Well
The MNW package can deal with intra
borehole flow and computes a realistic
head loss at the well, this makes the
package mostly applicable for multi-
layered unconfined systems.
29 juni 2017

29. MNW – Implemented in iMOD
29 juni 2017
MNW as IPF-file (with- or without associated TXT-files) in PRJ file not
in RUN file

30. MNW – Tutorial
29 juni 2017

31. Contact
29 juni 2017