Using Borehole Prospecting Technologies to Determine the Correlation between Fracture Properties and Hydraulic Conductivity: A Case Study in Taiwan

This study conducted different borehole prospecting techniques for hydrogeological investigations of fractured rock at three active landslide sites in southern Taiwan. Borehole televiewer logging, flowmeter logging, and packer hydraulic tests were performed to quantify various hydrogeological parameters including fracture width, fracture angle, flow velocity and hydraulic conductivity. The dependence of hydraulic conductivity on fracture properties was evaluated by correlation analysis. While a high positive correlation was found between hydraulic conductivity and fracture width (r = 0.89), and flow velocity (r = 0.87), no correlation with fracture angle was observed. In addition, it is worthwhile to note that the product of fracture width and flow velocity showed a strong correlation with hydraulic conductivity (r = 0.97). The regression analysis also revealed that a power law relationship, with a coefficient of determination of 0.83, exists between the hydraulic conductivity and the product of fracture width and flow velocity. The rationality of this relationship was carefully verified by using another group of geophysical borehole measurements. The results demonstrated that it is capable of predicting the hydraulic conductivity of fractured rock based on borehole televiewer and flowmeter logging results.