The Hsi River itself drains an area of about 127,000 square miles (32.... river mile

More than half of the river's basin is mountainous and lies between 9,900 and 1,650 feet (3,000 and 500 m) above sea level; more than 40 percent of the rest of the basin is occupied by hills between 330 and 1,650 feet (100 and 500 m) high. The Hsi's main headstream is generally considered to be the , which rises in the Yunnan-Kweichow plateau region at an elevation of about 6,900 feet (2,100 m) but drops a total of 5,900 feet (1,800 m) in the first 530 miles (850 km) of its course, which flows in a southeasterly direction through Yunnan province. This section of the river flows for about 400 miles (640 km) through a narrow valley with high, mountainous banks dropping down about 850 feet (260 m). This shortest section of the river is no more than 75 miles long, the river dropping about 50 feet (15 m) in this distance. For almost half its length, the Ch'ien flows through the narrow, rock-strewn Tat'eng Gorge between the cities of Wu-hsan and Kuei-p'ing, at the end of which it ! receives its major right-bank tributary, the Y River, and is then called the Hsn River. This section flows for about 120 miles (190 km) in an easterly direction, dropping a further 55 feet (17 m) and receiving the Jung River on the right bank at T'eng-hsien and the Kuei River on the left bank at Wu-chou (Ts'ang-wu) on the Kwangtung province border. Below Wu-chou, where it enters Kwangtung province, the river is known as the Hsi River. Canton lies west of the point where the Tung flows into the main channel; Hong Kong stands to the east and Macau to the west of the entrance to the Pearl River Estuary, which is about 18 miles (29 km) wide. Covering an area of about 1,500 square miles (3,900 square km) in southeastern Kwangtung province, the delta is a complex network of river branches and channels, divided by islands of alluvial soil and by hills that were once coastal islands. The river contains an abundance of freshwater fish, and the waters of the Pearl River Delta are uti! lized as fishponds. River towns become more frequent in the hi! lly part of the Kwangsi region, where the river is an artery of commerce; towns include Kung-ch'uan, Ch'ien-chiang, Lai-pin, Kuei-p'ing, T'eng-hsien, and Wu-chou. The Hsi River is the great commercial waterway of South China, linking Hong Kong, Canton, Macau, and other delta centres with Wu-chou and the interior. The Hsi River basin contains more than 9,000 miles (14,500 km) of water routes, of which more than 6,800 miles (11,000 km) are in use. Because most of the river branches of the delta are shallow, oceangoing vessels cannot reach Canton but must dock at Huang-pu-chiang (Whampoa), 10 miles (16 km) downstream. river mile