Accelerated expansion of built-up area after bridge connection with mainland: A case study of Zhujiajian Island

Around the world, numerous sea-cross bridges have been constructed for economic reasons. Land use of islands is often influenced deeply after the construction of bridges, especially with the increase of built-up area. Estimating the impact of sea-cross bridges on island land use becomes more and more urgent. In this study, the observed land use and the simulated land use without fixed link to mainland were compared to derive the impacts of sea-cross bridges. The main results are: 1) The land use of island is greatly affected by sea-cross bridges, with growth rate of built-up land 1.59 times higher than that before the bridge construction. Compared with the scenario of without fixed link to mainland, the centroid of built-up area moved about 500 m to the southeast, while the centroid of farmland moved nearly 300 m to the northwest; 2) After being connected with mainland, the island faced serious pressures, such as rapid land use change, explosive growth of tourists and continued stress on the ecosystem; and 3) Future construction of sea-cross bridges forming fixed link between island and mainland should take the economic development needs of the island, the carrying capacity of the island resources and the ecosystem responses into consideration, in addition to the feasibility analysis.