| Abstract |
Like in many parts of the world, the electricity demand in Southern Thailand is still steadily increasing due to ongoing industrial development and international tourism, as many people visit the wonderful beaches and mountains every year. On the other site Southern Thailand hosts more than 30 hot springs, surface manifestations of active geothermal systems at depth, providing a potential source of regenerative energy with almost zero CO2 emission. To tap this potential a better understanding of the geothermal systems at depth is required. Besides other methods, e.g. geophysical, geochemical data of hot spring water can provide information about the subsurface, for example, to estimate the minimum temperature expected at depth, to infer the chemical character and homogeneity of the hot water at depth, and to determine the source of the recharge water. From this boundaries of different geothermal systems at depth can be delineated taken into account available surface geological aspects; this has been attempted for Southern Thailand. The 30 hot spring sites are located in following provinces, Chumphon (CP), Ranong (RN), Surat Thani (SR), Phang Nga (PG), Krabi (KB), Trang (TR), Phatthalung (PL), and Yala (YA), and they are consecutively numbered. Surface temperatures range from 40 to 80 °C and pH values of all water samples are in a normal range between 6.7 and 8.4. For a total dissolved solid (TDS) content is in general moderate with some quite high exceptions, SR1, SR3, KB2, KB4, and TR2; mostly related to higher Na+ and Cl- content and to a minor extent Ca2+, K+, and SO42-. These five hot springs are all more or less influenced by shallower marine water ingression as their locations are relatively close to an estuary or a major river system connecting to the ocean. Most of the hot spring water samples are illustrated that waters are Ca–Na–bicarbonate rich waters and classified into Ca2+–Na+–K+–(Mg2+)–HCO3- water, but excepted waters from KB and SR systems are indicated a high chloride concentration. Difference between silica and cation geothermometers clearly indicate and separate mixing of the original hot waters with near surface groundwater. From the synthesis of all available geochemical data and geological evidence hot springs in Southern Thailand can be grouped into four major geothermal systems: (1) RN-PG along two major faults zones, (2) SR-CP, (3) KB-TR, and (4) PL. YL is an isolated hot spring in the south near the Malaysian border. Only the RN-PG group provides hot water with lower TDS content and shows a fairly high potential for electrical energy generation. |