Waterline digital elevation model development to quantify inundation duration and coastal protection of tidal wetlands

Coastal tidal wetlands are sufficiently acknowledged for the supplied vital ecosystem functions, including flood protection and biological conservation. Measuring and estimating reliable topographic data is essential for quantifying mangrove habitat quality. This study proposes a novel methodology for quickly constructing a digital elevation model (DEM) with an instantaneous waterline combined with tidal level records. Unmanned aerial vehicles (UAVs) enabled on-site waterline interpretation analysis. The results show that image enhancement improves the accuracy of waterline recognition and object-based image analysis has the highest accuracy. The waterline DEM (WDEM) performs a more accurate elevation production than UAV DEM, indicating that its application to habitat evaluation and prediction could be more reliable. Hydrodynamic simulations incorporated with the mangrove habitat model were utilized to calculate inundation duration, flow resistance, and vegetation dissipation potential according to the verified WDEM. The larger the mangrove coverage ratio, the stronger the flow resistance, which means that the protective consequence of the mangrove on the natural embankment is evident. The WDEM and nature-based solutions presented facilitate an adequate understanding of coastal protection and promote the potential ecosystem-based disaster risk reduction of mangrove wetlands. [Display omitted] •A novel waterline DEM using remote sensing techniques incorporated with instantaneous tidal levels is proposed.•UAV Image enhancement improved the accuracy of the waterline recognition and the OBIA scheme has the highest accuracy.•The waterline DEM significantly performs better than the UAV-derived DEM in reflecting the spatially hierarchical topography.•The WDEMs combined with hydrodynamic and habitat models effectively quantify the coastal protection of mangrove forests.•The maximum vegetation dissipation potential during typhoon period is approximately 21 % after mangrove restoration.