Toward a Method of Constructing Tidal Flat Digital Elevation Models with MODIS and Medium-Resolution Satellite Images

Liu, Y.; Li, M.; Mao, L.; Cheng, L., and Li, F., 2013. Toward a method of constructing tidal flat digital elevation models with MODIS and medium-resolution satellite images, Journal of Coastal Research, 29(2), 438-448. Coconut Creek (Florida), ISSN 0749-0208. The terrain of tidal flats often varies remarkably over space and time, but few existing methods are capable of producing fine-spatiotemporal resolution digital elevation models (DEMs) for tidal flats. This research aims to fill the knowledge gap and propose a 6-step method to construct tidal flat DEMs by incorporating both moderate-resolution imaging spectroradiometer and medium-resolution satellite images. The six steps include: waterline extraction, water level simulation, height assignment, median filtering, waterline point fusion, and interpolation to DEMs. A case study was conducted at the Dongsha sandbank one of the largest sandbanks among the radial tidal sand ridges of Jiangsu Province, China. The resultant DEMs were compared with the light detection and ranging based DEMs for vertical accuracy assessment. The results show that the proposed method successfully shortens the temporal resolution of DEMs to 3 months, while retaining high spatial resolution and vertical accuracy. An additional analysis of seasonal sediment change for tidal flats based on the proposed method shows that the sediment deposition in the Dongsha sandbank apparently has a semiannual cycle the tidal flats are deposited in winter and eroded in summer. All of these findings are valuable references for researchers and local authorities to conduct research on the evolution of tidal flats and to boost environmental management, coastal protection, and economic exploitation.