A chemical-mechanical polishing system includes a rotatable head for mounting a wafer thereto, a polishing pad mounted to a rotatable platen, and a fluid dispenser for dispensing a fluid onto a surface of the polishing pad. The polishing pad includes an array of piezoelectric actuators. The chemical-mechanical polishing system includes a controller operably coupled to each piezoelectric actuator. The controller measures voltages output by the piezoelectric actuators of the array, determines, qualitatively, a topography of the wafer surface based on the measured voltages, and adjusts an aggressiveness of at least one portion of the polishing pad based on the determined topography. The controller adjusts the aggressiveness by inducing the piezoelectric effect or reverse piezoelectric effect in one or more piezoelectric actuators to adjust a surface topography of the polishing pad.