Geoscience Reference
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Fig. 1. TDS distribution of groundwater in phreatic aquifer (a) and confined
aquifers (b), the coastline during early Holocene is after Yan and Xu.
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In addition, we presume that the saltwater in IV- and V-aquifer could
formed by means of mixing with upper saltwater through leakage flow, the
bases are: (a) marine transgressions from early to middle Pleistocene are
very weak and (b) ions composition of samples in the two aquifers shows
the characteristics of “resonance” and intergradation (see Fig. 2).
4. Hydrodynamic Evolution of Groundwater
Naturally, the groundwater flow is very slow in study area due to the
low hydraulic gradient (ranging from 1/10,000 to 1/100,000) and the finer
sediments. In phreatic aquifer, groundwater ridge lies along the line of
Jiading-urban district of Shanghai-Nanhui-Fengxia (Fig. 1(a)), which is
the highland area. The groundwater renews quickly through dilution by
rainwater, and furthermore, also exchanges with surface water in local
according to hydrogen isotope.
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In confined aquifers, the regional groundwa-
ter flows from north-western to south-eastern relating with glacis of basal
rock. The natural discharge area is located on continental shelf of East
