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Vegetation coverage is an important indicator to reflect the ecological environment status of the lower Yellow River floodplain and its changes mirror natural evolution and the effect of human activities on the ecological environment. The county-level administrative area involved in the wide beach area of the lower Yellow River was used as the research area, and the seven periods of Landsat in 1987, 1994, 1998, 2003, 2008, 2013 and 2017 were used as the remote sensing data source. It used the pixel dichotomy method based on the NDVI index to obtain vegetation coverage and classification. It used the methods of univariate linear trend analysis, transfer matrix method, center of gravity transfer model and correlation analysis to analyze the spatial and temporal changes of vegetation coverage in the study area and the influencing factors. The results show that the overall vegetation coverage in the broad beach area of the lower Yellow River and along the area has shown an overall improvement trend in the past 30 years. The gap between the vegetation coverage in the beach area and the vegetation coverage in the coastal administrative areas are gradually decreased after 2003, and it achieves an overtake in 2017. The annual change of vegetation coverage presents an obvious “bimodal” characteristic. The channel contraction and the development of urbanization have an important impact on the inter-annual changes in vegetation coverage. [ABSTRACT FROM AUTHOR]

In order to analyze the spatial-temporal variation along the wide floodplain of the Lower Yellow River, using Landsat time-series data, the temporal and spatial changes of grass wetland habitats along the wide floodplain of the lower Yellow River of 2000 and 2015 were interpreted by utilizing the modification of normalized difference water index method. The disturbing factors of grass wetland habitats were analyzed in conjunction with the activities of water and sediment along the Yellow River channel. The results show that from 2000 to 2015, the habitat area of grass wetland along the beach area has been decreased and grass wetland habitats tend to migrate downstream. At present, the upstream runoff is concentrated, and the peak value of the corresponding hydro logical pulse is as high as nearly 3 meters, which is not conducive to the stable succession of wetland habitat vegetation along the beach area. In addition, human activities such as agricultural cultivation and sand digging along the beach area also seriously affect the stable development of grass wetland habitats. Based on the analysis of the water and sediment activities along the beach area, the total area of grassland wetland habitats along the Yellow River floodplain area is 247.41 km², accounting for only 9.01% of the total area of the wide beach area. [ABSTRACT FROM AUTHOR]