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Groundwater plays an important role as domestic water in the North Plain of Jiangsu Province, China with a total area of 6.37 × 10 km. The characterization and evolution of regional groundwater quality were surveyed and discussed based on the field data, including 597 data collected in the 1980s and 1346 samples analyzed in the 2000s. The evolution of groundwater quality for phreatic, shallow and deep confined aquifers for more than two decades was discussed by comparing the distribution maps of TDS concentration and groundwater hydrochemical facies in different periods. Piper diagrams of water chemical composition showed that there were significant changes for the groundwater quality during the past 20 years, which is mainly attributed to two opposite effects from human activities. On the one hand, agricultural irrigation using the fresh surface water and exploration of the saline groundwater for domestic and industry usage lead to the desalination of groundwater in large-scale areas. On the other hand, groundwater pollution including human waste and heavy use of fertilizers lead to the deterioration of groundwater quality in local areas (e.g., the increase of TDS concentration is an obvious indicator). It is suggested that the groundwater, especially the shallow phreatic water, could be artificially diluted by groundwater exploration and usage, which may provide an important water source to make up for the serious shortage of living water in this study area. However, groundwater pollution such as from nitrogen needs to be controlled as a critical issue to be faced in the next step. [ABSTRACT FROM AUTHOR]

Abstract: Suzhou is located at the lower reaches of the Yangtze River in southeastern Jiangsu, China. It is part of the Su-Xi-Chang area including Suzhou, Wuxi and Changzhou. As one of the most developed areas in China, this region has suffered from severe land subsidence caused by extensive groundwater exploitation since 1980s. The land subsidence was controlled by prohibition of groundwater exploration in the past several years. However, the surface water pollution prompted a new task of how to sustainably utilize the groundwater resource, especially to satisfy the emergency demands of water supply. In this paper, we took Suzhou as a representative case to discuss how to develop groundwater resources while controlling the land subsidence. The relationship between the deformation and the groundwater level was analyzed, with focus on the deformation features after the period of groundwater exploitation ban. The results confirmed the conclusion by Shi et al. (2007, 2008a): even in the period of rising groundwater level, same units may manifest different deformation characteristics, such as elasticity, elasto-plasticity, and visco-elasto-plasticity, at different locations of the cone of depression. A land subsidence model that couples a 3-D groundwater model and a 1-D deformation model was developed to simulate the groundwater level and deformation. A high-resolution local grid (child model) for Suzhou was built based on the regional land subsidence model of Su-Xi-Chang area by Wu et al. (2009). The model was used for a number of predictive scenarios up to the year of 2012 to examine how to develop sustainable use of groundwater resources under the conditions of land subsidence control. Our results indicated that about 3.08×107 m3/a groundwater could be provided as emergency and standby water source while meeting the land subsidence control target of 10mm/a. [Copyright &y& Elsevier]