Study on coastline changes in the Rizhao area for the past 30 years and their bearing on land use

The Rizhao coastal zone is a place rich in tourist resources, which play important roles in economic and cultural development of the Rizhao city. In this paper, four sets of summer Landsat images in the years of 1988, 2000, 2011 and 2018 are collected for visually interpretation, and the coastline of Rizhao coastal zone is classified according to the diversity index of coastline type and the change rate of the coastline. The maximum likelihood method is adopted to explore the changes in land use in the Rizhao coastal zone for the past 30 years. The results suggest that the length of Rizhao coastline is significantly increased from 1988 to 2018 at an artificial growth rate of about 2.35 km/a, while the length of sandy coastline, on the other side, is decreased at an average rate of 0.56 km/a. The coastline mainly moves toward the sea and most of the intensely expanded areas are closed to the Rizhao Port and Lanshan Port. The cultivated land area of Donggang District and Lanshan District, the overall area of water body and the unused land remain basically unchanged. The construction land is significantly increased in the past 30 years, while the forest land decreased drastically. Human construction activities are doubtlessly the main factor that influence the evolution of coastline and land utilization in Rizhao coastal area. The results of this study may be used to promote the sustainable development and rational utilization of Rizhao coastal zone in future urban planning and policy-making.