North China Plain

(also Great Lowlands of China), one of the largest plains in Eastern Asia, in China. It is washed by the Yellow Sea in the east and bounded by the Yen mountains in the north; the Taihang range in the west, whose eastern slopes break up into steep terraces up to 1,000 m high along the side of the plain; and the Tongbai and Dabie ranges in the southwest. The lower course of the Yangtze River flows along the southern edge of the plain. The area of the plain totals approximately 325,000 sq km. At the foot of the western mountain belt, which is made up of ancient alluvial fans, the plain has an elevation of approximately 100 m. The elevation descends to 50 m or less along the seacoast. This part of the plain is completely flat, with insignificant slopes and an abundance of shallow depressions that are periodically filled by floodwaters. Many depressions have become swamps and have shallow lakes. The Shantung mountains are located within the eastern portion of the plain. The North China Plain is composed of very deep alluvial deposits, principally redeposited loesses.

In addition to the Huang Ho, the major rivers are the Hai Ho, Huai Ho, and Luan Ho. All rivers follow the monsoon cycle with abrupt seasonal flow variations. Peak summer river discharges are often 100 times greater than the spring minimums. The constant discharge is exceptionally great, as is the accumulation of river alluvium. Because of this, in some places the riverbeds, including that of the Huang Ho, have risen 10 m above the surrounding terrain and thus threaten to break through shore protection structures during heavy floods. The plain has been subjected in the past to frequent floods caused by river overflows, which have been great disasters for the population. In the 1950’s large hydraulic projects were built to control the flow and to utilize the river waters for irrigation. The plain is traversed from north to south by the Great Canal.

The North China Plain has a subtropical monsoon climate. Cold dry air emanating from the inland regions of Asia prevails during the winter. Average January temperatures are -4° C to -2° C in the north and 8° C to 12° C in the south. The summer is hot and rainy, with average temperatures of 25° C to 28° C in July. Precipitation amounts to 400-500 mm annually in the north and 750-1,000 mm annually in the south. There is a marked difference between the summer maximum and the meager precipitation during the winter (2-3 percent of the yearly total) and transitional seasons. The onset and ending of the summer monsoon season and its intensity vary greatly from year to year and thus give rise both to periodic severe droughts and to long heavy downpours. The broad-leaved forests, mixed with subtropical evergreens in the south, which had formerly grown on the North China Plain, no longer exist. Small groves of ash, poplars, thujas, and pine have been planted among the agricultural fields. Rich alluvial soils, greatly changed by cultivation, are predominant. The plain area, notable for its high degree of agricultural development, is the most important region for the growing of wheat, cotton, peanuts, and tobacco. The plain has an extremely high population density; numerous rural population centers and cities (among them, Peking; Tientsin, and Chinan) are concentrated here.