Xiaolangdi Dam 小浪底 opens the floodgates

 The purpose of opening the floodgates to send millions of tons of silt downstream of the Yellow River. Bystanders are dwarfed as they stand watching a tremendous rush of water gushing through gaps in a dam in China, part of a carefully-choreographed operation to remove silt from the Yellow River in Luoyang, in the Henan province. This annual operation sees more than 30 million tonnes of silt sent downstream a year, with more than 390 million tonnes shifted this way over the last 13 years.
 The Xiaolangdi Dam (小浪底) is a dam in Jiyuan, Henan Province, China, and impounds the Yellow River. The facility is located about 20 km to the northwest of Luoyang. It has a total installed capacity of 1,836 MW and generates up to 5.1 TWh annually with the help of six 306 MW turbines. The dam stands 154 m tall and 1,317 m wide, and cost US$3.5 billion to build. Constructed in 1994, Xiaolangdi Dam regulates water and silt flow annually. The Dam is a multi-function project designed for flood control, ice control, dredging, industrial and municipal water supply, and hydroelectric power generation.
 

The Change of Boundary in Tang Dynasty China

大唐边疆的变化

The Tang Dynasty 唐朝 (618 AD - 907 AD)was an imperial dynasty of China preceded by the Sui Dynasty and followed by the Five Dynasties and Ten Kingdoms Period. It was founded by the Li (李) family, who seized power during the decline and collapse of the Sui Empire.

The Tang Dynasty, with its capital at Changan (current day Xian), the most populous city in the world at the time, is generally regarded as a high point in Chinese civilization—equal to, or surpassing that of, the earlier Han Dynasty—a golden age of cosmopolitan culture. Its territory, acquired through the military campaigns of its early rulers, was greater than that of the Han period, and it rivaled that of the later Yuan Dynasty and Qing Dynasty. In two censuses of the 7th and 8th centuries, the Tang records estimated the population by number of registered households at about 50 million people. Yet, even when the central government was breaking down and unable to compile an accurate census of the population in the 9th century, it is estimated that the population had grown by then to about 80 million people. With its large population base, the dynasty was able to raise professional and conscripted armies of hundreds of thousands of troops to contend with nomadic powers in dominating Inner Asia and the lucrative trade routes along the Silk Road.

In the Tang census of the year 754, there were 1,859 cities, 321 prefectures, and 1,538 counties throughout the empire.