Abstract
Estimating surface elevation changes in mangrove forests requires a technique to filter the mangrove canopy and quantify the changes underneath. Hence, this study estimates surface elevation changes underneath the mangrove canopy through vegetation filtering and Difference of DEM (DoD) techniques using two epochs of unmanned aerial vehicle (UAV) data carried out during 2016 and 2017. A novel filtering algorithm named Surface estimation from Nearest Elevation and Repetitive Lowering (SNERL) is used to estimate the elevation height underneath the mangrove canopy. Consequently, DoD technique is used to quantify the elevation change rates at the ground surface, which comprise erosion, accretion, and sedimentation. The significant findings showed that region of interest (ROI) 5 experienced the highest volumetric accretion (surface raising) at 0.566 cm3. The most increased erosion (surface lowering) was identified at ROI 8 at −2.469 cm3. In contrast, for vertical change average rates, ROI 6 experienced the highest vertical accretion (surface raising) at 1.281 m. In comparison, the most increased vertical erosion (surface lowering) was spotted at ROI 3 at −0.568 m. The change detection map and the rates of surface elevation changes at Kilim River enabled authorities to understand the situation thoroughly and indicate the future situation, including its interaction with sea-level rise impacts.
Highlights
In the mangrove forest region, the environment is very dynamic because of dense canopy vegetation and the tidal inundation that causes the surface elevation to be partially submerged, especially during high tide and the highest astronomical tides (HAT)
All epochs have been analysed for RMSE error to determine the accuracy of each result based on the previous GCP table
unmanned aerial vehicle (UAV) photogrammetry data could be used as the primary data for estimating surface elevation underneath a mangrove canopy
Summary
In the mangrove forest region, the environment is very dynamic because of dense canopy vegetation and the tidal inundation that causes the surface elevation to be partially submerged, especially during high tide and the highest astronomical tides (HAT). Terrestrial laser scanners (TLS), electronic distance measurement (EDM), and other surveying equipment that needs a tripod are hardly set up in this terrain. The study only looks at the surface of the mangrove canopy and ignores the hidden features beneath it. Any physical changes on the ground are hidden by mangrove vegetation, especially from an aerial view, and these obstacles have inspired this study. To quantify surface elevation changes on sites with small-scale areas, a few terrestrial measurements such as physical surveys, erosion pins, and the surface elevation table–marker horizon (SET-MH) method are commonly used
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
