Investigation of the hydraulic connection between the upper storage reservoir and the underground powerhouse in the Hongping Pumped Storage Hydroelectric Powerstation

Abstract

Field tracer tests in fractured rocks were performed to investigate the hydraulic connection between the upper storage reservoir and the underground powerhouse in the Hongping Pumped Hydroelectric Storage Powerstation (HPHSP). Data from tracer measurement points indicated the appearance of multiple peak values during the course of tracer migration, which revealed multiple water pathways in fractured aquifers owing to the development and intersection of fractures and faults. Also, complex hydrogeological structural systems were proposed according to geological data from borehole logs and outcrops seen in the exploration adit. These structures revealed the different permeability and strong heterogeneity of the fractured media and can, therefore, explain the existence of a concentrated water-conducting passage from the upper storage reservoir to the underground powerhouse. Multiple peak values in the field tests were examined using a laboratory cross-fracture experiment involving tracer migration and numerical simulation based on transition probability. According to the observed data and the numerical results, the laboratory model and simulation method can capture the characteristics of groundwater flow and tracer migration in fractured rocks.