BEIJING, (Xinhua) -- China Tuesday began to implement an ordinance to regulate and control the water volume of the Yellow River, the second longest river in the country.

This is China's first law on water volume control of the long rivers, said Li Guoying, head of the Yellow River Conservancy Committee under the Ministry of Water Resources.

At a press conference of the Information Office of the State Council, Li said the regulation is aimed to strengthen management of the water resources of the Yellow River, realize sustainable utilization of the water resources, improve the ecological environment along the river, and promote the economic and social development of valley areas of the river.

The ordinance stipulates that the water volume of the Yellow River will be under the unified control of the State. It also has specific stipulations on the water allocation, regulation and control, emergency management, supervision and legal responsibilities.

The Yellow River, popularly known as China's Mother river, is the major water resources for the northwest and northern China. The Yellow River plays a vital role in China as it provides water for 12 percent of China's 1.3 billion people, 15 percent of China's farmland and more than 50 large and medium-sized cities.

However, the water level of the river changes remarkably in different years and the river suffers a great imbalance of the water flow in different seasons and regions.

The Yellow River carries more silt than any other river in the world. It was well known as a disastrous river as floods deprived of numerous lives in the past 2,000 years.

The water volume in the river has been shrinking over the past years due to climate changes and degradation of the environment. Some parts of the river were dry for 21 times during the period from 1971 to 1999.

The source water of the Yellow River has dwindled by 23 percent more in the past ten years than the average level in the previous 40 years in northwest China's Qinghai Province, environmental officials said.

Li said China has taken measures to protect water sources and control the total volume used by cities along the Yellow River, which prevented the river from drying up over the past seven years.

The successful experience lays a solid foundation for the making of the ordinance, Li added.