A systematic study of interactions between sustainable development goals (SDGs) in Hainan Island

The 2030 Agenda for Sustainable Development issued by the United Nations is an important foundation for countries to achieve common economic, social and environmental development. Important progress has been made in the evaluation of the Sustainable Development Goals (SDGs) in Hainan Island; nevertheless, there is still a lack of understanding around the trade-offs and synergies between the SDGs. Studying the trade-offs and synergies between Hainan Island's sustainable development goals is of great significance for the coordinated development of these goals and the promotion of the construction of free trade ports. Therefore, based on the United Nations Sustainable Development Assessment System and the existing SDG indicator system on Hainan Island, this paper identifies and quantifies the trade-offs and synergies within and between SDGs and targets on the county scale. Based on the different impacts of different spatial, dimensional and geographical directions, the results show the following: (1) Hainan Province made good progress on multiple SDGs between 2010 and 2021. (2) The most significant synergies between SDGs exist between SDG1 (No Poverty) and SDG10 (Reduce Inequalities), while the most significant trade-offs exist between SDG2 (Zero Hunger) and SDG4 (Quality Education). (3) Obvious spatial characteristics in trade-offs and synergies exist, with the highest level of synergy being in the Haikou and Sanya Economic Circles and their surrounding areas, and in the central region of Hainan Island which has a higher level of trade-offs. (4) The synergistic effect between the SDG targets and indicators in Hainan is much greater than the trade-off effect: the four aspects of people's livelihood improvement, economic development, resource utilization and environmental quality all show synergistic effects in different regions.