| dc.description.abstract | The algal reefs along the Taoyuan coastline, when covered by sediment, can alter the reef′s topography, habitat conditions, and the survival status of the reef organisms. Therefore, the proportion of sediment coverage on algal reefs is an important scientific data for habitat monitoring. This study utilizes traditional topographic measurement and drone modeling methods to quantify the changes in the area and volume of sediment coverage, and analyzes the fractal characteristics to understand the topographical changes and the differences in fractal features within the study area.
This research focuses on the algal reef area at Guantang Industrial Port along the Taoyuan coast. It collects drone aerial modeling data from The research team of Professor Huang Zhi-Cheng from August 2021 to July 2024, along with artificial RTK single-point measurement data and orthophoto images from environmental monitoring reports from 2001 to 2024, to understand the long-term sediment coverage situation in the study area. By comparing the Digital Surface Models (DSM) generated from drone aerial photography with the artificial RTK single-point measurement data, this study evaluates the applicability of different measurement techniques, analyzes terrain elevation changes, and uses orthophoto images to analyze changes in sediment coverage area. Simultaneously, fractal dimension (FD) analysis is employed to study the geometric features of the algae reef area at different scales, exploring the distinctions between reef and sand and the possibility of multiple fractals.
The results show that in the G1 area, from 2001 to 2024, the average change in sediment coverage area after 2018 was smaller than before 2018, ranging from 67% to 80%. Between 2021 and 2024, the correlation between the changes in the sediment coverage area and volume in the G1 area was higher than that in the G2 area. In the G2 area, the average change in sediment coverage area after 2018 was smaller than before 2018, ranging from 39% to 48%, and between 2021 and 2024, the sediment coverage on the landward side showed an increasing trend, but changes below the mid-tide level in the intertidal zone were not obvious. The correlation between the changes in sediment coverage area and volume was smaller than in the G1 area. As for the fractal analysis, the fractal dimension value of the reef body was higher than that of the sand body, but it could only distinguish the boundaries between larger reef bodies and sand bodies. The surface elevation of the sand body might be too similar to that of the reef body, leading to misclassification. | en_US |