Isotope techniques in groundwater contamination studies in urbanized and industrialized areas, Hat Yai Basin

Anthropogenic activities are mainly responsible for changing the hydrological cycle as well as the climate warming. Assessing the impacts of human activities on hydrological environments is becoming a wide-focused topic. In this research, the author attempt to link the urbanization, agricultural development, and the subsequent water resources exploitation with the change of water environments in Hat Yai Basin, southern of Thailand. The source of water for domestic use mainly comes from Utapao River which flows through the area. Now this area is facing the shortage of water in dry season and pollution due to domestic and industrial activities. Isotope techniques in conjunction with hydrological and chemical data can play the important role for identifying recharge mechanism and surface and groundwater interaction. By using the numerical model the information for proper groundwater management can be obtained. As a result, the quality of groundwater in Hat Yai Basin showed that the iron (Fe) content at many locations was higher than the permissible level for groundwater quality standards for drinking purposes in the Notification of the Ministry of Industry. Groundwater from such locations should not be used for drinking. The water types of Hat Yai aquifer were Na-Cl and Ca-HCO3, while that of Khu Tao aquifer and Kho Hong aquifer were CA-Mg-HCO3 and Ca-Mg-HCO3, respectively. The origin of groundwater in Hat Yai aquifer is local rainfall. The origin of groundwater in Khu Tao and Kho Hong aquifers come from ancient rainfall indicating old water and low flow rate. The groundwater is recharged from the zones located in the eastern and western parts of Hat Yai Basin and flows to middle basin and northward to Songkhla Lake. (author)