| 其他摘要 | In recent years, human activities and natural factors have posed a threat of degradation to the tidal wetlands in the Bohai Rim region. It is necessary to accurately grasp the historical and dynamic changes of tidal wetlands, as well as the impact of human activities and natural factors on tidal wetlands. Currently, satellite remote sensing technology has been widely used for monitoring ground surface changes. However, the current use of satellite remote sensing for monitoring tidal wetlands is easily affected by the temporal resolution of remote sensing images and clouds, resulting in inaccurate monitoring of tidal wetlands. Therefore, this study proposed to monitor tidal wetlands based on spatiotemporal data fusion algorithm and applied it to the monitoring of tidal wetlands in the Bohai Rim region. This study firstly compared the effectiveness of three spatiotemporal data fusion algorithms applied to tidal wetlands’ extraction so as to select the optimal spatiotemporal data fusion algorithm suitable for tidal wetlands’ extraction. Then, based on the selected optimal spatiotemporal data fusion algorithm, Landsat data and MODIS data along the Bohai Rim were fused to supplement the sparse original observed Landsat data so as to achieve the goal of constructing remote sensing data cube in the Bohai Rim; and the spatial distribution of tidal wetlands in the Bohai Rim were extracted from the constructed remote sensing data cube by using the pixel inundation frequency algorithm. Finally, detailed analyses were conducted on the spatiotemporal evolution characteristics of tidal wetlands, as well as the impact of human activity and natural factors on tidal wetlands in the Bohai Rim region and its typical areas. The study of tidal wetlands in the Bohai Rim is crucial for maintaining ecological balance, protecting biodiversity, and achieving sustainable development in the Bohai Rim coastal zone.
Main research contents: (1) Study on the construction of remote sensing data cubes along the Bohai Rim: selected the optimal spatiotemporal data fusion algorithm suitable for tidal wetlands extraction by comparing and analyzing the fusion results of different types of spatiotemporal data fusion algorithms applied to the extraction of tidal wetlands, and used the results of the optimal spatiotemporal data fusion algorithm to supplement sparse original observed Landsat data so as to construct remote sensing data cubes for the extraction of tidal wetlands in the Bohai Rim. (2) Study on the spatiotemporal evolution characteristics of tidal wetlands in the Bohai Rim: analyzed the spatiotemporal evolution characteristics of tidal wetlands in the Bohai Rim region and its typical areas. (3) Study on the impact of human activity on tidal wetlands in the Bohai Rim: analyzed the impact of human activity on the landward side of tidal wetlands in the Bohai Rim region and its typical areas. (4) Study on the impact of natural factors on tidal wetlands in the Bohai Rim: analyzed the impact of natural factors such as erosion effect and sedimentation effect on the seaward side of tidal wetlands in the Bohai Rim region and its typical areas.
Main conclusions: (1) This study selected the FSDAF algorithm as the optimal spatiotemporal data fusion algorithm for extracting tidal wetlands. The Landsat-like images generated by the FSDAF algorithm could present the seaward boundary of tidal wetlands, which could be applied to the extraction of tidal wetlands in the Bohai Rim. (2) The overall area of tidal wetlands in the Bohai Rim had decreased from 1986 to 2022. 89.37% of the landward boundary of tidal wetlands in the Bohai Rim had been affected by human activity and moved towards the sea. Human activity and the erosion effect in natural factors had respectively reduced the landward side and seaward side of tidal wetlands, while sedimentation effect in natural factors had increased the seaward side of tidal wetlands. (3) The area of tidal wetlands in Liaoning, Hebei, Tianjin, and Shandong had decreased from 1986 to 2022. The tidal wetlands had been shrinking year by year in space, shifting from contiguous distribution to scattered distribution. The landward side of tidal wetlands in Shandong Province had changed most affected by human activity and nature factors, while tidal wetlands in Tianjin had had the smallest variation due to human activity as well as natural factors. (4) Tidal wetlands in the five typical areas of the estuary of Liao River, Caofeidian, Tianjin Port, the modern estuary of the Yellow River and Laizhou Bay had decreased from 1986 to 2022. The loss area of tidal wetlands in Tianjin Port and the modern estuary of the Yellow River had been the highest and the lowest, respectively. Human activity had had a significant impact on the landward side of the tidal wetlands in Caofeidian and Tianjin Port, while natural factors such as erosion effect and sedimentation effect had had a significant impact on the seaward side of the tidal wetlands in the modern estuary of the Yellow River.
This study proposed to monitor tidal wetlands based on spatiotemporal data fusion algorithm. Spatiotemporal data fusion algorithm was used to construct remote sensing data cube for extracting tidal wetlands in the Bohai Rim. Traditional methods for monitoring tidal wetlands were easily affected by the temporal resolution of remote sensing images and clouds, resulting in lower extraction accuracy of tidal wetlands; the method proposed in this study overcame this limitation and improved the accuracy of extracting tidal wetlands. Based on the proposed method, this study further revealed the evolution characteristics of tidal wetlands in the Bohai Rim, as well as the laws of human activity and natural factors influencing tidal wetlands. The area of tidal wetlands in the Bohai Rim had decreased from 1986 to 2022. Human activity and the erosion effect in natural factors had resulted in a decrease in the landward side and the seaward side of the tidal wetlands, respectively. The sedimentation effect in natural factors had increased the seaward side of the tidal wetlands. |
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