Abstract
A study designed to examine the impact of urbanization on the quantity
and quality of groundwater recharge in the Coastal Plain Aquifer,
Israel, is being carried out in the city of Ashdod, where urbanization
in the last 40 years has been one of the most rapid in Israel.
Infiltration processes under different urban land setups are being
compared to those beneath nearby cultivated areas and the undeveloped
sand dunes. Temporal variations in water content at various depths along
the entire vadose zone were measured for two consecutive years at five
sites that represent typical land uses. Water-content measurements were
conducted using a monitoring system that includes flexible time-domain
reflectometry (FTDR) sensors installed in slanted boreholes throughout
the entire vadose zone. The variation in water content enables direct
tracking of the wetting- front propagation velocities, variations in
vadose-zone water storage and calculation of the infiltration fluxes. In
addition to the FTDR system, a new monitoring system that allows
continuous measurements of the water potential and frequent sampling of
the sediment pore water was installed at a sand dune site. This new
system is comprised of vadose-zone sampling ports (VSPs) and FTDR
sensors installed in slanted boreholes. Preliminary results show that in
addition to the expected changes in pore-water pressure due to changes
in water content caused by the infiltration process, increases in
pore-water pressure were detected simultaneously throughout the entire
vadose zone after each of the major rain storms. This pressure wave was
detected each time fast and significant propagation of the wetting front
was observed. Vadose-zone pore water was frequently sampled by a second
VSP system and analyzed for chemical and isotopic compositions
presenting changes in the vadose zone chemical and isotopic profiles
throughout the year.
Original language | English GB |
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Journal | Geophysical Research Abstracts |
Volume | 33 |
State | Published - 1 May 2007 |
Keywords
- 1800 HYDROLOGY
- 1830 Groundwater/surface water interaction
- 1838 Infiltration
- 1866 Soil moisture
- 1875 Vadose zone