The surveillance for data collection in wireless sensor networks (WSNs) setting is recognized as an important application of WSNs. Given an area of interest and a number of wireless sensors, typical problems to be addressed are covering the whole area while prolonging the network lifetime. It is explicitly observed that most existing studies focus on limited case in which the interested area is static. In many WSN applications, however, the areas of interest are dynamic, e.g., deploying sensors to monitor the contaminated area of poisonous material which is fluid or diffusing. Accordingly, this paper turns to solve the Dynamic Area Coverage (DAC) problem. Our work focuses on tackling two key challenges: 1) determine the candidate positions for sensors once the area has evolved, 2) map each sensor to one of the candidate positions to achieve the desirable requirements. Different algorithms are proposed to determine the candidate positions and mappings with constraints. Through extensive simulations, the efficiency and efficacy of the proposed algorithms are well validated.