Abstract
Karsts are important sources of water, and it is crucial to determine their water volume and quality. The Ravansar karst spring in Kermanshah province is a significant water resource with a substantial water volume in the area. The source of this spring is the carbonate rock unit from the Cretaceous period and is affected by tectonic changes and faulting caused by movements related to Zagros folding. In this study, geophysical methods of microgravity, electrical resistivity, and induced polarization have been utilized to identify the feeding sources of Ravansar spring and the extent of karst development in the limestone units. The microgravity method was employed to generate the residual gravity anomaly map of the area, as the decrease in density and increase in porosity resulted from karstification. The minimum residual gravity values are associated with caving and karstification. As a result, the gravity anomalies of the range were examined, and three-dimensional modeling was conducted on the gravity data. In this manner, we were able to identify not only cave-shaped voids and spacious cave chambers, but also sub-structures and micro-karstification in carbonate rocks. The most significant finding from the field survey is the detection of low gravimetric values, indicating relatively large holes and chambers that are previously unknown and inaccessible from ground level. These findings are consistent with known collapse and sediment infill features, as seen in surface sinkholes, cavities, and karstification systems.In addition to the gravimetric method, electrical resistivity and induced polarization surveys (IP & Res) were conducted to explore the subsurface geology in the chosen area. The purpose of this research was to visualize karst cavities and identify areas at risk of land subsidence due to cavity collapse. The field dataset comprised two electrical profiles acquired using a dipole-dipole electrode configuration. The resistivity data was inverted using a two-dimensional algorithm based on the least square’s technique with a smoothing constraint. Geophysical surveys and field surveys show that the holes and karsts in the area are related to tectonic phenomena and faulting and are conduits for transporting water to the Ravansar spring.