Why are dikes and polders important in coastal Jiangsu?

Dikes and polders are essential in coastal Jiangsu because the province is the lowest and flattest in China, with most of its area lying at a very low elevation above sea level.1

These structures serve several critical functions:

• Flood Protection: Much of the province consists of an alluvial plain crisscrossed by an intricate network of rivers, canals, and lakes. Dikes are necessary to protect these low-lying areas from flooding.1
• Land Reclamation and Cultivation: In coastal regions that sit below the high-water level, polders—areas reclaimed from the sea and protected by dikes—are used to create land suitable for cultivation.12
• Systematic Development: Since the early 20th century, the systematic development of polders and extensive canalization has been used to completely alter the landscape, transforming tidal or water-covered areas into productive agricultural land.1

By managing water levels and preventing the encroachment of the sea, these engineering efforts allow for intensive land use in a region that would otherwise be vulnerable to its low-lying topography.13