基于RS和GIS的黄河口海岸线演变及土地利用研究

摘要

基于RS和GIS技术,利用黄河口1977—2017年的Landsat MSS/TM/OLI影像数据,采用归一化差值水体指数(Normalized Difference Water Index,NDWI)、大津算法(OTSU)以及最大似然分类和目视解译等方法分别提取6个不同时期的海岸线和土地利用类型,分析海岸线演变和不同土地利用类型的动态变化规律.结果表明:40年来黄河口海岸线总体呈递增趋势,从1977年的253.44 km增加到2017年的594.16 km,且时间和空间的变化显著,不同时间段的不同海岸线地段呈现不同的特征,黄河口海岸线变化主要受黄河流路的改变、海水侵蚀、人类活动等影响,入海口流路改变对海岸线的影响尤为明显;时间上,黄河三角洲的土地利用变化表现为自然类型转向人工类型,水体和滩涂等自然类型持续减少,盐田和养殖池等人工类型逐渐增多,盐田面积从74.97 km2增长到298.1 km2,养殖池从21.2 km2增加到761.7 km2;空间上,黄河口整体呈现向海边推进的趋势.%Based on the RS and GIS techniques,the Landsat MSS/TM/OLI image data of Yellow River estuary from the year 1977 to 2017 are used in this paper.The normalized difference water index(NDWI), the Otsu algorithm(OTSU),the maximum likelihood classification and visual interpretation are used to extract six different periods of coastline and land use types.The coastline evolution and the dynamic change law of different land use types are analyzed.T he result show s that:a.coastline in the Yellow River estuary show s the increasing trend in the past 40 years,w hich increased from 253.44 km2in 1977 to 594. 15 km2in 2017.And the changes of time and space are obviously,the different time of different coastline area has different characteristics,the coastline change is mainly affected by the change of flow path,and the Yellow River effect of human activities,water erosion,estuary flow path changes to the coastline is obvious;b.in the time,the land use change in the Yellow River Delta is characterized by the natural type turning to the artificial type.The water and beaches and other natural types continue to decrease.The breeding pool and salt pan as artificial type gradually increase in w hich salt pan area increases from 74.97 km2to 298.1 km2,and the breeding pool increases from 21.2 km2to 761.7 km2;c.in the space,the Yellow River estuary presents a trend w hich propels the seashore.