Abstract of the proposal

Surface water has long been the main water supply in the Pearl River Delta (PRD), thus, there has been very limited study of groundwater supplies. However, the increasing demand for fresh water coupled with deterioration in river water quality as a result of rapid urbanization and industrialization, means that groundwater is now being considered as an alternative water source. Much of the groundwater in the PRD is, however, saline and water with salinities over 10 g/l has locally been encountered 40 km away from the current coastline. In some areas, groundwater in the shallow aquifer is fresh whereas that in the deeper aquifer is saline. Thus, the formation and migration of the saline groundwater is a problem not only of scientific interest but also of major importance in coastal groundwater resource management. We speculate that the abnormally high salinity in the PRD may be largely related to palaeo-seawater intrusion in recent geohistory. We propose to study the nature and origin of the elevated salinity and the chemical evolution of groundwater in the PRD aquifer system using a multidisciplinary approach integrating Quaternary geology, hydrogeology, hydrogeochemistry, isotope hydrology, and basin-scale variable-density transport and flow modelling.