A method for performing an electrosurgical procedure at a surgical site on a patient includes continually sensing electrical and physical properties proximate the surgical site that includes acquiring readings of tissue electrical impedance with respect to time at the surgical site； identifying the minima and maxima of the impedance readings with respect to time； and correlating the minima and/or the maxima of the impedance readings with hydration level and/or hydraulic conductivity in the tissue at the surgical site. The method also includes controlling the application of electrosurgical energy to the surgical site to vary energy delivery based on the step of correlating the minima and/or the maxima of the impedance readings with the hydration level/or and the hydraulic conductivity in the tissue at the surgical site. The process may be an ablation process.
