Why are terraced fields widely used in eastern Sichuan?

Terraced fields are widely used in eastern Sichuan primarily to maximize arable land in the region's uneven, hilly terrain and to effectively control soil erosion.123

The eastern basin is characterized by a rugged landscape of low, rolling hills and high ridges. Because the bedrock in this area is soft and weathers easily, it is relatively simple for farmers to construct long, narrow strips of terraced land, even on steep slopes. These terraces serve several critical functions:42

• Erosion Control: By building level terraces supported by walls, farmers can hold back water and prevent the topsoil from washing away during the rainy season.3
• Water Management: Terraces act as reservoirs that catch and retain rainwater, allowing for increased infiltration and more uniform distribution of water for crops. This is further supported by the dongshuitian (winter water-storage field) system, which stores water in fallow fields for use in the spring.52
• Land Maximization: The method allows for the cultivation of crops on land that would otherwise be unsuitable for farming, ensuring that even small or steep plots contribute to food production.163