Monitoring the vertical changes of a tidal flat using a MEMS accelerometer array

Abstract

Tidal flats are constantly affected by the tide and are alternately exposed and submerged. Therefore, it is very difficult to monitor their topographic vertical changes (subsidence or uplifting) as the geographical environment is unique. In this study, a monitoring system based on the Micro-Electro-Mechanical System (MEMS) accelerometer array is proposed for monitoring subsidence or uplift in tidal flats. The optimal arrangement of the MEMS accelerometer array was determined using the non-uniform sampling theorem (frame theory) and the amplitude distribution characteristics of the tidal flat, and was as follows: the arc length interval between the sensors should be less than double the highest frequency of the tidal flat which is a baseband signal. We theoretically proved that the MEMS accelerometer array which satisfies the requirement of the non-uniform sampling with equal arc length could completely reconstruct the tidal flat. The two-dimensional arc model for reconstructing the tidal flat was then presented. To validate and correct the non-uniform sampling conditions obtained, and the calculation model, a test was conducted on a tidal flat in Zhairuoshan Island. The wave period and the vertical change of the tidal flat are measured. The results demonstrate the feasibility of the proposed system for effective tidal flat monitoring.