潮间带是海岸带陆域向海延伸的前沿地带，对海陆交互作用响应敏感，冲淤多变，生物多样性脆弱。黄河三角洲潮间带属于淤泥质潮滩，地形平缓、面积宽广，长时间序列的实地监测难度较大。美国NASA的Landsat 卫星自1972年至今已连续运行了 40 年，对其遥感数据进行解译是研究潮间带环境变化的有效手段。

    本文利用1973-2012年30景 Landsat 影像，以黄河三角洲潮间带为研究区域，使用支持向量机监督分类方法识别海陆，提取黄河三角洲潮间带岸线；并计算 NDVI，进行阈值分割来提取潮间带植被的覆盖范围。对岸线、植被时空分布的提取结果进行了统计和分析。

    研究发现，1973-2012 年，黄河三角洲潮间带岸线在现行黄河入海河道流域整体向海淤进 12km, 并在清水沟、清八汊口依次形成两个尖沙咀；莱州湾西侧岸线后退趋势明显，幅度达7km，渤海湾南侧岸线也略有后退；莱州湾西南侧、渤海湾西南侧岸线在 5km 范围内剧烈摆动，冲淤趋势不明显。其中，黄河现行入海河道流域经历了1973-1996年迅速淤积、1996-2000年受到侵蚀、2001-2010年继续向海推进的三个过程。侵蚀的发生主要源自于1996年黄河来水来沙量急剧降低及入海河道由清水沟改道清八汊口。

    在各个区间出现人工岸线防护建筑之前，潮间带植被呈现出依据岸形变化向岸线延伸的趋势。植被分布延伸最快、面积增长最大的是岸形变化最大的黄河现行河道流域，且增长呈现出先向河道两侧后沿河道的趋势。在其他岸形变化较小的区间，植被到海岸距离基本稳定，延伸缓慢。当孤东至刁口流域、莱州湾西南侧岸线出现人工地物后，植被分布以人工地物为界不再向海延伸。

Intertidal zone is the foreland where land extends to sea. It is sensitive to marine-terrestrial interactions, always experiencing erode and deposit and fragile in biodiversity. The slit tidal flat in the Yellow River Delta is broad and slopes gently, it is difficult to conduct in-situ, long time continuous monitoring in this area. From 1972 to the present, Landsat satellites of National Aeronautics and Space Administration of the USA has been operating for 40 years, it is an effective mean to study the dynamics of the slit tidal flat in the Yellow River Delta. 

In this study，30 Landsat images from 1973 to 2012 were collected to analysis the changes of coastlines and vegetation coverage. Coastlines were extracted from the identification of land and sea, using supervised classification of support vector machine; normalized difference vegetation index were calculated and applied into threshold segmentation, so that the vegetation coverage can be categorized. Statistics were then taken to analyze temporal-spatial variation. 

It is found that, during 1973-2012, the shoreline of the current Yellow River estuary silted into the sea for 12km as a whole, and formed two Tsim Sha Tsui at Qingshuigou and Qingba; the shoreline of the Laizhou Bay west showed a significant retreating trend of 7km, while the south shoreline of the Bohai Bay also retreated slightly; the southwest shorelines of the Laizhou Bay and Bohai Bay swung violently within 5km and the siltation trend was not significant. Besides, the current Yellow River basin has experienced three processes of the rapid siltation in 1973-1996, the erosion in 1996-2000, and the moving-forward to the sea in 2001-2010. The reasons why the erosion happens lie in the sharply-decreased water and sand volume of the Yellow River since 1996 and the transformed Yellow River course from Qingshuigou to Qingba. 

Before the shoreline bulwark’s occurrence, intertidal vegetation presents a trend of extending to the shoreline based on the changes in shore shapes. In the estuary with the biggest change in the shore shapes where the vegetation distribution has a fastest extension and the area enjoys a fastest growth, the growth shows a trend of first running vertically and then along the river course. In the regions where the changes in shore shapes are small, the distance between the vegetation and the sea shore is basically stable and shows a slow extending trend. When man-made features occur 

between Gudong and Diaokou, and at the southwest shoreline of the Laizhou Bay, the vegetation distribution is bounded by man-made features and will no longer extend to the sea.