Source: The Library Of Congress Country Studies
The Himalayas form a natural boundary on the southwest as the Altai Mountains do on the northwest. Lesser ranges branch out, some at sharp angles from the major ranges. The mountains give rise to all the principal rivers.
North of the 3,300-kilometer-long Great Wall, between Gansu Province on the west and the Greater Hinggan Range on the east, lies the Nei Monggol Plateau, at an average elevation of 1,000 meters above sea level. The Yin Shan, a system of mountains with average elevations of 1,400 meters, extends east-west through the center of this vast desert steppe peneplain. To the south is the largest loess plateau in the world, covering 600,000 square kilometers in Shaanxi Province, parts of Gansu and Shanxi provinces, and some of Ningxia-Hui Autonomous Region. Loess is a yellowish soil blown in from the Nei Monggol deserts. The loose, loamy material travels easily in the wind, and through the centuries it has veneered the plateau and choked the Huang He with silt.
Because the river level drops precipitously toward the North China Plain, where it continues a sluggish course across the delta, it transports a heavy load of sand and mud from the upper reaches, much of which is deposited on the flat plain. The flow is channeled mainly by constantly repaired manmade embankments; as a result the river flows on a raised ridge fifty meters or more above the plain, and waterlogging, floods, and course changes have recurred over the centuries. Traditionally, rulers were judged by their concern for or indifference to preservation of the embankments. In the modern era, the new leadership has been deeply committed to dealing with the problem and has undertaken extensive flood control and conservation measures.
Flowing from its source in the Qing Zang highlands, the Huang He courses toward the sea through the North China Plain, the historic center of Chinese expansion and influence. Han people have farmed the rich alluvial soils of the plain since ancient times, constructing the Grand Canal for north-south transport. The plain itself is actually a continuation of the Dongbei (Manchurian) Plain to the northeast but is separated from it by the Bo Hai Gulf, an extension of the Huang Hai (Yellow Sea).
The country's longest and most important waterway, the Chang Jiang is navigable over much of its length and has a vast hydroelectric potential. Rising on the Qing Zang Plateau, the Chang Jiang traverses 6,300 kilometers through the heart of the country, draining an area of 1.8 million square kilometers before emptying into the East China Sea.
The Hai He, like the Zhu Jiang and other major waterways, flows from west to east. Its upper course consists of five rivers that converge near Tianjin, then flow seventy kilometers before emptying into the Bo Hai Gulf. Another major river, the Huai He, rises in Henan Province and flows through several lakes before joining the Chang Jiang near Yangzhou.
Inland drainage involving a number of upland basins in the north and northeast accounts for about 40 percent of the country's total drainage area. Many rivers and streams flow into lakes or diminish in the desert. Some are useful for irrigation.