Geography Notes: Population Case Study of China

China's population distribution is described as uneven, with a high percentage of inhabitants located in the eastern and southeastern regions.
High-density areas are coterminous with alluvial plains where intensive agriculture is centered, such as the Yangtze delta, the Pearl River Delta, and the Chengdu Plain (western Sichuan Basin).
In contrast, the western and northern regions characterized by arid and mountainous terrain are sparsely populated.

Precipitation: High population density generally aligns with areas receiving more than a $380\,mm$ ( $15$ inch) isohyet of annual rainfall.
Topography: Populations are concentrated on flat, arable land and near river systems/coastlines.
Geographic Barriers: Sparsely populated areas include the Tibetan Plateau, Gobi Desert, Takla Makan Desert, Altun Mts, and the Himalayas.

Economic: Industrial growth acts as a magnet for populations; internal migration from rural to urban areas has involved approximately $160$ million people seeking higher incomes, as rural earnings were historically $40\%$ lower than urban incomes.
Urbanization: By $2025$ , nearly $1$ billion people are expected to reside in Chinese cities, which will include $221$ cities with more than $1$ million inhabitants.
Political/Technological: Government policies and the construction of new railways and highways have spurred growth in industrial and mining towns within previously underdeveloped regions.
Historical: Ongoing mass migration continues to shift the distribution from rural areas to urban centers.

Implementation: The policy was first implemented in $1979$ as a nationwide birth planning program to control rapid population growth through birth control, contraception, and abortions.
Demographic Impacts: * Significant reduction in fertility and birth rates since the $1980s$ . * Skewed gender ratio resulting in $33$ million more males than females. * Increased occurrences of female abortions, adoptions, and orphans. * A visible decrease in the population aged between $35$ and $44$ years on population pyramids.
Policy Shift: In $2015$ , China introduced a two-child policy to address low fertility rates and demographic challenges.