Nowadays, monitoring of vast environments and gathering their information by wireless sensor networks has become popular. A challenging issue of these networks is storage and retrieval of events and detected data by the network nodes. The problem uprises when the sensor network has an irregular and complex shape and includes some holes with no node inside. The data are concentrated toward the boundaries of these networks leading to unbalance storage which reduces network efficiency. This problem is solved in this study by consideration of data storage on the medial axis of the network. The simulation results depict good improvements of the results obtained by the proposed method compare to those obtained by the base methods. Smaller total traffic complexity and hotspot effect are obtained by the proposed method.