The delta formed by the alluvial waters of China's Pearl River where it enters the sea in central Guangdong. It is composed of three small deltas formed by the Xijiang, Beijiang and Dongjiang alluvial areas, covering an area of ??approximately 11,300 square kilometers. Among them, the Xijiang and Beijiang deltas account for 1/10. It was formerly known as the Yuejiang Plain. Referred to as the Pearl River Delta. Located on the eastern coast of Guangdong Province, China, it is a general name for the large delta formed by the Xijiang and Beijiang rivers and the small delta formed by the Dongjiang river. It is a delta complex with radial branches. It is in the shape of an inverted triangle, with the base being a line from Sanshui City in the west, Guangzhou City in the east to Shilong, and the apex at Yamen Bay. It covers an area of ??approximately 11,000 square kilometers. The alluvial layer is thin, generally 20 to 30 meters. The ground is undulating and surrounded by hills, mountains and islands, accounting for 30% of the area. The central part is a plain, distributed in the south of Guangzhou City, the north of Zhongshan City, the east of Jiangmen, and the west of Humen. The average annual sediment load of the Pearl River system reaches more than 80 million tons, and the delta near the river mouth is still extending to the South China Sea. In the estuary area, it can extend by an average of 10 to 120 meters per year, making it one of the key reclamation areas in China. The concept of "Pearl River Delta" first originated in the early 1990s. In the late 1990s, the concept of the "Greater Pearl River Delta" emerged based on the "(Little) Pearl River Delta". In 2003, the concept of "Pan-Pearl River Delta" was proposed. At this point, the "Pearl River Delta" actually encompasses the concepts of "Little Pearl River Delta", "Greater Pearl River Delta", and "Pan-Pearl River Delta" that are both distinct from each other and closely related to each other.