Renewability of groundwater in Changzhou, Jiangsu Province: Based on isotopic technology

This paper is the result of hydrogeological survey engineering.[Object] Changzhou is a typical industrialized city in the Yangtze River Delta. The regional groundwater there had experienced a periodic historical process of overdrafts and prohibitions of mining, resulting in a greatly change in the groundwater dynamic field. Thus, it is necessary to conduct a further study on the renewable capacity of the groundwater of Changzhou. [Methods] Based on the analysis of the existing hydrogeology conditions, the recharge, runoff and discharge conditions of groundwater and the characteristics of groundwater ages are systematically analyzed to evaluate the renewable capacity of groundwater using isotope technology. [Results] The results showed that, 18O and D of the shallow groundwater are more abundant than the deep groundwater due to the evaporation to a certain extent. The recharge time of the deep groundwater with relatively closed storage environment is earlier than that in the shallow groundwater. The shallow groundwater, basically affected by infiltration recharge of modern water, has an active circulation zone of modern water reached to a depth of 40m. As for the ages of the deep groundwater, it varies from less than 2000 to 25000 years, indicating that it is mainly composed of ancient water. [Conclusion] The renewal rate of the shallow groundwater is generally higher than 0.1%/a, and controlled by the storage conditions, surface water recharge and human activities, etc. Weakly, the renewal rate of the deep groundwater is generally less than 0.05%/a, and controlled by the distribution of river ancient channel, exploitation and utilization of human beings, etc. These results can provide scientific basis for protection and utilization the groundwater in Changzhou and other areas in the Yangtze River Delta.