[A-HW20] Advances and Emerging Methods in Tracer Hydrology

[AHW20-P03] Development of Hydrogeological Tracer Technology – An Example at HeShe Research Site

*Ching-Yi LIU¹, Po-Yu Chuang¹, Yeeping Chia², Yung-Chia Chiu³, Chien-Chung Ke¹ (1.Advanced Geological Research Task Force, Sinotech, Inc., 2.Department of Geosciences, NTU, 3.Institute of Earth Sciences, NTOU)

Keywords:tracer test, conductivity, temperature, DTS, fractured rock

Tracer tests are wildly used in the hydrological technology, various types of tracers are used for different purposes. Commonly used tracers such as NaCl or heat, provide a convenient method to detect the preferential flow paths in fractured rocks. In this study, we used three methods, NaCl, nanoscale zero-valent iron (nZVI or ‘nano-iron’) and heat, to study the preferential flow path at HeShe research site. The tracers are released in the injection well, under natural gradient or forced gradient, in order to understand the behaver of groundwater flow. Sensors are placed in the injection well and the observation wells. For NaCl tracer, conductivity sensors are used; for nZVI tracer, conductivity sensors and magnet array are used; for heat tracer; temperature sensors and distributed temperature sensing (DTS) are used for observation. After bring out a series of tracer tests, results from different tracers suggests that there are two to three preferential flow path at this site. Also, a downward flow was found during the natural gradient tracer test at this site. This study has demonstrated that integrating different types of tracer tests, has the potential to characterize preferential flow paths in fractured rock.