Coastal mudflat resources in China: spatial-temporal evolution, utilization efficiency, and development strategies

Coastal tidal flats represent a crucial land resource, with their quantity and quality continuously undergoing dynamic changes. It is essential to comprehensively investigate the spatiotemporal transition, utilization efficiency, and existing challenges of coastal tidal flats to provide critical support for their sustainable and efficient utilization. According to the main data bulletin of China’s Third National Land Survey, there are 1.512 million hectares of coastal tidal flats in China, and Jiangsu Province accounts for 25.4% of the national total. In recent years, the area of tidal flats in China has generally been expanding slowly, with an estimated accretion rate of 0.02 to 0.03 million hectares per year, primarily driven by anthropogenic activities. China has a long history of tidal flat reclamation, with evolving utilization patterns closely mirroring the socioeconomic development needs across different historical periods. The scale, intensity, and potential of tidal flat exploitation exhibit significant spatiotemporal heterogeneity among various coastal regions. The tidal flats have been utilized through various approaches, including salt production, agricultural cultivation, aquaculture, port-urban-industrial construction, wetland conservation and tourism, as well as renewable energy development. Among these, integrated agriculture-aquaculture systems and renewable energy projects exhibit particularly prominent comprehensive benefits. Due to the complexity of their formation mechanisms and coupled with reclamation policy restrictions, China's tidal flats are currently under-utilized—predominantly for wetland conservation and aquaculture. This limited utilization pattern results in suboptimal efficiency, leaving substantial untapped potential in both ecological and economic value. Based on the national strategy of cultivated land and food security in the new period, it is proposed to promote the efficient and sustainable utilization of tidal flats by strengthening the definition of resource attributes and monitoring their quantitative dynamics, scientifically assessing the potential of different utilization methods, enhancing scientific and technological innovation support, and improving supporting policies.