After the Great East Japan Earthquake in 2011, the Japanese government reconstructed coastal protection facilities to mitigate extreme disasters and coastal erosion. However, the substantial compression of coastal zones poses a challenge in coping with sea level rise, while maintaining a sustainable coastal ecosystem. To clarify the impact of environmental factors and sea level rise on coastal ecosystems in highly developed regions, this study integrated field surveys, geo-detector analysis, and coastal inundation models into the research framework. It explored the relationship between environmental factors and vegetation patterns and predicted the inundation areas and vegetation survivorship of 12 transects in the study area from 2030 to 2150. The results indicated that the distance from the tide embankment (DTE) and elevation (DEM) were the main driving factors, and the combination of the potential of hydrogen (pH) and DTE had a major impact on vegetation coverage. Notably, the distribution of vegetation was positively correlated with the width of the coastal zone, and when the width was less than 60 m, vegetation could not survive. With sea level rise, almost no vegetation will survive until 2150. Appropriate coastal width and height are conducive to maintaining the sustainability of coastal ecosystems.