Groundwater dynamics play a crucial role in landscape rehydratation. However, there is still a big gap in the understanding of the groundwater flow dynamics. Heterogeneities and dynamics are often underestimated and therefore not taken into account. They are of crucial input for successful management and design of measures like weirs and level-controled drainage systems. The bulk of the mass of mass often is transported through only a small layer or section within the aquifer and is in cases of seepage into surface water very dependent to rainfall, evapotranspiration and occurring tidal effects. This study contains the use of novel real-time iFLUX sensors to map the groundwater flow dynamics over time. The iFLUX sensor provides real-time data on groundwater flow rate and flow direction. It consists of multiple bidirectional flow sensors that are superimposed. The sensor probe can be installed directly in the subsoil, riverbed or monitoring well. The measurement setup is unique as it can perform measurements every second, ideal to map rapid changing flow conditions. The measurement range is between 0,5 and 500 cm per day. The City Walls of Damme are a nature reserve of 140 hectares, located near walls of Dam-me. Specific measures were taken to achieve the rewetting of grasslands and swamp forests. A unique real-time hydrological measurement network supports the measures. The network consists of several iFLUX flow sensors to map infiltration, drainage & horizontal flow, combined with a network of groundwater and surface water level, salinity and meteo data. The project also includes a dune ridge infiltration to create an inland freshwater reserve in the coast and raise the freshwater table in order to counter the salinization of the coastal zone. The iFLUX sensing network is being expanded in that zone. Flux sensors in combination with EC sensors will continuously monitor the infiltrated freshwater bubble and its surroundings.

1. iFLUX 1
Innovative real-time sensing of flow dynamics in
groundwater to map effectiveness of
water level management
Presenter: Goedele Verreydt
Turquoise – Seminar Water level management 10 Nov 2022

2. iFLUX 2
Filling the gaps!
Complexity of soil and groundwater
1. Reactive and indirect instruments
2. Simulate with complex models
Need for detailed knowledge
about groundwater flows and
flow patterns, especially at the
interfaces

3. iFLUX 3
iFLUX sensing (r)evolution
Novel, unique real-time flux sensors
▪ Flow velocity & direction, 0.2-
200 cm/dag
▪ Real-time measurement via
microfluid thermal flow chip
▪ Horizontal & vertical probes
▪ In combination with soil
moisture, groundwater levels
and quality parameters: real-
time nitrate, conductivity, pH,
Redox, …

4. iFLUX 4
Microfluid flow chip
Vertical sensor probe

5. iFLUX 5
0 50 100
mm
5
Horizontal sensor probe

6. iFLUX 6
WLS 2.0: Romboutswervepolder

7. iFLUX 7
WLS 2.0: Romboutswervepolder
- Vernatting van graslanden en
moerasbossen om biotopen te
behouden en te beheren
- Monitoring impact van vernatting
& droogte; uniek inzicht geven in
de waterbalans
- Potentieel kreekruginfiltratie?
- Meteo station, 32 druksensoren,
14 CTD sensoren, 12 opp.water,
debieten inlaatpunten
- 8 Horizontale & 8 verticale flux
probes
- Live dashboard

8. iFLUX 8
WLS 2.0: Romboutswervepolder
Horizontal sensor
Vertical sensor in
Romboutswerve

9. iFLUX 9
WLS 2.0: Romboutswervepolder
De combinatie van sensoren biedt unieke mogelijkheid om kwaliteit én kwantiteit te koppelen en onze inzichten in de
grondwaterstromen en waterbalansen substantieel te wijzigen

10. iFLUX 10
Interesting findings
▪ Changes in horizontal flow (direction &
magnitude) following day/night cycles
→ Evapotranspiration? Influence canals?
▪ When the horizontal flow direction is reversed, the
vertical flow increases or decreases respectively
WLS 2.0: Romboutswervepolder

11. iFLUX 11
Interesting findings
▪Clear correlation with precipitation as well
as groundwater levels
▪There is always a strong vertical exfiltration
flux upwards. Impact canals?
WLS 2.0: Romboutswervepolder

12. iFLUX 12
Interesting findings
▪ The level of the Leopoldskanaal clearly also has a
day-night regime whose correlation and impact on
the seepage in the Romboutspolder should be
further investigated.
WLS 2.0: Romboutswervepolder

13. iFLUX 13
▪ First insight in complex dynamics
▪ Added value of real-time flux
▪ Interesting day-night variations
▪ Romboutswerve seems to have more
draining than irrigation function
water balance model
First conclusions: Romboutswervepolder

14. iFLUX 14
www.ifluxsampling.com
Founders & Managers
Goedele Verreydt
goedele@ifluxsampling.com
+32 473 83 64 62
Tim Op ‘t Eyndt
tim@ifluxsampling.com
+32 473 83 64 62
Wetenschapspark UAntwerpen
Incubator Darwin
Galileilaan 15
2845 Niel
Bedankt!
Vragen?