Back analysis of high density resistivity method in the water-bearing karst cave

In high-density electrical prospecting, karst caves may show different electricity resistivity (ER) characteristics due to the nature of cave fillings. When a cave is empty, its ER value appears extremely high, when being completely filled with water this value could be very low. However, for an unsaturated karst cave, the resistivity range is difficult to judge via ER data interpretation. By constructing different models with various cave moisture contents, forward modeling using the method of least square at geoelectric sections were conducted, compared with the different geoelectric response characteristics of their inversion imaging model. The results showed that the resistivity of water-bearing karst cave decreases with increasing water content. On the geoelectircal section the range of low resistance expanded with the amount of water increased, which was strongly distinguishable. Exploration data derived from the field work further has verified the validity of the simulated results shedding light on the significance of the model application and a better understanding of electrical analysis method for underground cavern detection.