Monitoring tidal flats boundaries through combining Sentinel-1 and Sentinel-2 imagery

Abstract

Tidal flats are a critical habitat to support a large population of wildlife. It is the habitat of fish, shellfish, birds and mammals, providing the necessary material and energy for the survival and reproduction of a large number of biological populations. The monitoring of tidal flats boundaries is important for the regional biodiversity and coastal sustainability. Since the SAR data is hard to distinguish tidal flats and land part, the existing efforts of monitoring tidal flats is mainly based on optical data with low tide level. However, the effects of frequent cloud cover and foggy weather constraint its large-scale application for monitoring the position and extent of tidal flats. Here we presented a new method for monitoring tidal flats by combining Sentinel-1A with low tide level and optical Sentinel-2A images with high tide level, taking the Fuqing city in Southeast China as the study area. A spectral index integrating Sentinel-1 and Sentinel 2 and a simple threshold-based method were proposed, and we found it efficient for rapid tidal flats monitoring. The result showed that a combined use of Sentinel-1A and Sentinel-2A data has a great potential for extraction and monitoring tidal flats in the coastal zones.