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Shallow rainwater lenses in deltaic areas with saline seepage
- Source :
- Hydrology and Earth System Sciences, 15, 3659-3678, Hydrology and Earth System Sciences, Vol 15, Iss 12, Pp 3659-3678 (2011), Hydrology and Earth System Sciences 15 (2011), Hydrology and Earth System Sciences Discussions, 4, 8, 7657-7707, Hydrology and Earth System Sciences, 15, 3659. European Geosciences Union
- Publication Year :
- 2011
- Publisher :
- Copernicus GmbH, 2011.
-
Abstract
- In deltaic areas with saline seepage, freshwater availability is often limited to shallow rainwater lenses lying on top of saline groundwater. Here we describe the characteristics and spatial variability of such lenses in areas with saline seepage and the mechanisms that control their occurrence and size. Our findings are based on different types of field measurements and detailed numerical groundwater models applied in the south-western delta of the Netherlands. By combining the applied techniques we could extrapolate measurements at point scale (groundwater sampling, temperature and electrical soil conductivity (TEC)-probe measurements, electrical cone penetration tests (ECPT)) to field scale (continuous vertical electrical soundings (CVES), electromagnetic survey with EM31), and even to regional scale using helicopter-borne electromagnetic measurements (HEM). The measurements show a gradual mixing zone between infiltrating fresh rainwater and upward flowing saline groundwater. The mixing zone is best characterized by the depth of the centre of the mixing zone Dmix, where the salinity is half that of seepage water, and the bottom of the mixing zone Bmix, with a salinity equal to that of the seepage water (Cl-conc. 10 to 16 g l−1). Dmix is found at very shallow depth in the confining top layer, on average at 1.7 m below ground level (b.g.l.), while Bmix lies about 2.5 m b.g.l. The model results show that the constantly alternating upward and downward flow at low velocities in the confining layer is the main mechanism of mixing between rainwater and saline seepage and determines the position and extent of the mixing zone (Dmix and Bmix). Recharge, seepage flux, and drainage depth are the controlling factors.
- Subjects :
- zoet water
semi-confined aquifer
Groundwater flow
spatial variation
netherlands
water availability
infiltration
lcsh:Technology
Rainwater harvesting
delta
coastal aquifer
groundwater
Leerstoelgroep Bodemnatuurkunde
Saltwater intrusion
lcsh:Environmental technology. Sanitary engineering
lcsh:Environmental sciences
lcsh:GE1-350
groundwater-flow
seepage
lcsh:Geography. Anthropology. Recreation
Groundwater recharge
Leerstoelgroep Bodemnatuurkunde, ecohydrologie en grondwaterbeheer
Soil Physics
ecohydrologie en grondwaterbeheer
watervoorziening
drained lowland catchments
Infiltration (hydrology)
GM - Geomodelling
fresh water
interface
kustgebieden
flux measurement
EELS - Earth, Environmental and Life Sciences
Geosciences
drainage
Geology
sampling
saline water
Earth & Environment
fresh
rainwater
temperature effect
precipitation
coastal areas
lcsh:TD1-1066
salinity
field method
electromagnetic field
water depth
saltwater intrusion
Geomorphology
in situ measurement
salt tolerance
WIMEK
climatic change
lcsh:T
water supply
surface water interactions
klimaatverandering
Saline water
zout water
neerslag
lcsh:G
Ecohydrology and Groundwater Management
Soil Physics, Ecohydrology and Groundwater Management
numerical model
Groundwater model
Groundwater
Subjects
Details
- ISSN :
- 16077938 and 10275606
- Volume :
- 15
- Database :
- OpenAIRE
- Journal :
- Hydrology and Earth System Sciences
- Accession number :
- edsair.doi.dedup.....069e2ce2d8cd85cb059ebae7b0e4f50d