Geoscience Reference
In-Depth Information
DYNAMIC AND CHEMICAL EVOLUTION OF
GROUNDWATER SYSTEM IN QUATERNARY AQUIFERS
OF YANGTZE ESTUARINE REGION, CHINA
BAOPING SONG
∗
, ZHONGYUAN CHEN
†
and ZHENG FANG
‡
∗
Department of Resources and Environment, Shijiazhuang College
Shijiazhuang, China
†
Department of Geography, East China Normal University
Shanghai, China
‡
Shanghai Institute of Geological Survey, Shanghai, China
As a part of groundwater flow system of Yangtze Delta plain, the groundwa-
ter in Yangtze estuarine region flows much slowly due to closed circumstance.
However, during the last several decades, the groundwater dynamic environ-
ment has been changed seriously, especially for the II-aquifers, because of heavy
groundwater withdrawal and artificial recharge. In order to reveal the evolution
pattern of groundwater system under natural condition and human activities,
some geochemical methods and groundwater flow model are applied in this
study, supported by a large database on groundwater chemistry, artificial dis-
charge/recharge, and hydrogeology. The results show that three groundwater
flow systems can be recognized. Under the natural condition, groundwater
evolves in manner of dilution by rainwater in shallow system but in manner
of mixing and cation exchange in middle system, and in manner of cation
exchange in deep system.
1. Introduction
The Yangtze Delta plain, one of the most important economic zones in
China, is located in the eastern coast of China. The delta is composed of
Quaternary sediments with a big thickness of 100 m in the western plain
and more than 400 m in the estuarine depocenter,
1
where abundant ground-
water resources have provided important support for economic develop-
ment. Shanghai region, occupied major area of the estuarine region, is this
study area.
The previous hydrogeological survey
2
distinguished one phreatic aquifer
and five confined aquifers in the estuarine region. The confined aquifers were
marked, respectively, as I-V downward shown briefly in Table 1.
Most previous studies started from early 1950s and focused primarily
on groundwater resources assessment, groundwater flow model limited in
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