Artificial Recharge of Fresh Water in the Belgian Coastal DunesAlexander Vandenbohede, Luc Lebbe and Emmanuel Van HoutteResearch Unit Groundwater ModellingGhent University, BelgiumIntermunicipal Water Company of the Veurne region (IWVA)

Very low mineralisation of source water for recharge: 50 mg/l

Extraction wells surrounding pondsInfiltration of 2.5 million m/yearExtraction of 3.5 million m/year

Borehole measurements

Sedimentological data

Head observations

Chemical data

Tracer test3D density dependent flow transport modelling

MOCDENS3D Visual MOCDENS3D

Hydrochemistry

Hydrosomes (water bodies) Important processes

Fresh water heads

Fresh water heads

Fresh water heads

Replacement of dune water withrecharged water

Residence times of recharged water

Residence times of recharged water

Hydrochemistry

Hydrochemistry

Hydrochemistry

Conclusions More water is extracted less water dune water is extracted

Positive effects on drawdowns Natural groundwater flow is partially restored Ecological implications

Conclusions Extracted water is mix of artificial recharged water and dune water

Extracted water is mix of water with a large spectrum of residence times (30 days to 5 years)

Conclusions Source water for artificial recharge is of very low mineralisation 50 mg/l vs 500 mg/l for dune water

Distinct water types: dune water, extracted water, recharge water, recharged water in aquifer

Most important reactions: carbonate dissolution consumption of oxygen/nitrate oxidation of sulphide minerals