Distribution And Source Of Groundwater Salinity In The Pearl River Estuary

Pearl River estuary owns large amount of tributaries and flows into the sea from eight outlets.There is abundant rainfall in the estuary.The relationships among the groundwater,surface water and precipitation are complex.The estuary is commonly an economy prosperous area and acts as a transition zone from the land to the sea.Saltwater intrusion through surface waterways and aquifers has an important influence on coastal ecosystem.To explore the groundwater dynamics and the characteristics of groundwater salinity,the geophysical prospecting was first conducted in the field.Meanwhile,the water levels and Total Dissolved Solid(TDS)of groundwater of 32 boreholes were measured in Jan and May,2017.In addition,The Cl-,2H?18O?14C were analyzed in the groundwater and surfer water to access the water circulation and the possible source of salt in the Pearl River estuary aquifers.The results are as follows: the groundwater salinity was decreased from the seaside to the inland,and gradually increased from the north to the south.The salty water were distributed in the three fourths acreage of the study area with the TDS in excess of 1g/L.The interaction between the surfer water and the groundwater is weak in the Pearl River estuary.Groundwater was subjected to the stress of seawater,but exchange slowly.The proportion of groundwater that received the recharge from the precipitation and the surface water were different in January and May.Groundwater was mainly supplied by surfer water in January.River was supplied by groundwater weekly in May.The origin of the groundwater salinityis from the ancient seawater which was trapped in the aquifer lens during the development of the Pearl River Delta.