The present situa-tion and changing characteristics of the shorelines along Tianjin-Hebei coastal areas and proposal for protection

Based on 3-period remote sensing images covering the whole study area, field investigations and two case studies of both Binhai New Area and Luanhe Estuary, which consist of the historical shorelines back to the 1870 and the 1950 as the basal lines and year by year remote sensing images since 2000, the present shorelines of Tianjin-Hebei coastal areas are interpreted and classified for their characteristics and the causes of changes. The results show that the total length of the present shorelines of Tianjin-Hebei coastal areas is 894km, which can be divided into three types, i.e., natural shoreline of 90km, semi-developed shoreline of 329km, and the artificial shoreline of 475km. Multi-temporal data comparison shows that shoreline changes were dominated by natural factors before 1950, but after 1950 it was gradually dominated by intensifying human activities with the climax in 2010. In the global sea-level rise and regional land subsidence background, the natural trend of shorelines should be characterized by landward retreat; nevertheless, with the human activities, the shorelines are showing anti-natural trend of seaward movement. As a new land margin, the reclamation area will be affected firstly by increasingly enhanced marine influence, and thus monitoring and protection must be carried out immediately. Taking into account long-term needs of both development and enviornmental protection, the authors suggest re-defining the regional shorelines and giving their new function, including delineation of the red line and restoration of some semi-developed sectors to their natural properties.