Chapter 5 Section 4 Caohe in Chang'an and Luoyang

Chang’an was established as the capital in the Western Han Dynasty. By the time of Emperor Wu of the Han Dynasty, due to the continuous increase in the population of Kyoto, the rapid expansion of bureaucracy, and the need to use soldiers to manage the Western Regions, the central government’s food expenditure was very large and the pressure was great.In order to solve this problem, the government of the Western Han Dynasty overhauled water conservancy in Guanzhong in order to develop local agriculture and obtain grain nearby.On the other hand, water transport conditions were improved so that more grain could be transported to Beijing from the eastern part of the main grain-producing area at that time.

In the Western Han Dynasty, grain was transported to Beijing from the east of Hangu Pass, originally via the Weishui River.However, the Weishui River is sandy, the waterway is shallow and tortuous, and the transportation function is very poor.From the east of Chang'an to the Yellow River, the land route is only more than 300 miles, while the tortuous Weihe waterway is more than 900 miles long.Due to freezing and insufficient water, it can only barely navigate six months of the year.Therefore, the annual transportation volume of the Weihe River is very small, and the grain transported from the west to Beijing is only a few hundred thousand shi.During the reign of Emperor Wu of the Han Dynasty, several million shi of grain had to be transferred from the east, and it was urgent to find another way to solve the problem of grain transportation.Therefore, when Da Si Nong (the chief in charge of the country's agriculture) Zheng proposed to dig a straight grain transportation channel in Weinan, Emperor Wu of the Han Dynasty immediately adopted it.Historically, this channel was called Caoqu.

The canal project started in the sixth year of Emperor Wu of the Han Dynasty (129 BC). Xu Bo, a hydraulic engineer from Qi, was responsible for the survey, measurement and alignment, and tens of thousands of military workers were responsible for the construction.The head of the canal is located in the northwest of Chang'an City. It draws the Wei River as the water source, passes through the south of Chang'an City to the east, and runs parallel to the Wei River. water volume.These waterways all originate from the Nanshan Mountains and have very little sand.Cao Canal passes through Baling (where the government is located in the northeast of today's Xi'an City), Xinfeng (where the government is located in the northeast of Lintong County), Zheng County (where the government is located in today's Hua County), Huayang (where the government is located in the southeast of Huayang County), and other counties. It meets the Yellow River near Weishuikou, with a total length of more than 300 miles, and it took three years to complete. , with a circumference of more than 40 miles, the Fengshui and Yu (Haohao) waters are blocked in the storage pool.In addition to being used to drill sailors, digging Kunming Pond can also adjust the water volume of the Cao Canal and supply the capital's domestic water.

The Caoqu Canal has a high navigability. It has always been the main channel for transporting grain from east to west in the middle and late Western Han Dynasty. The annual transportation volume is about 4 million shi in the general period, and 6 million shi in the highest year, which is about 10 times the transportation volume of Weishui River.In addition to shipping, it also has the advantage of irrigating farmland. The irrigated area is about 10,000 hectares, more than double that of Baiqu, and about the same as Chengguo Canal at that time.After the fall of the Western Han Dynasty, the work of transporting grain from east to west no longer continued, and the Caoqu was gradually abandoned due to disrepair.

Luoyang was the capital of the Eastern Han Dynasty, and the focus of the water transportation project moved eastward. A new waterway called Yangqu was dug, and Bianqu was thoroughly treated. Although there is Luoshui in Luoyang that can lead to the Yellow River, most of the riverbed of Luoshui is very shallow and inconvenient for navigation.In order to allow grain ships to reach the capital directly, Emperor Guangwu Jianwu five years (AD 29), under the auspices of Henan Yin Wangliang, started to build a canal.He organized forces to "pass through the canal to divert valley water (a tributary of Luoshui) to the city of Luoyang, and write (eject) Gongchuan to the east." Due to insufficient valley water and improper arrangement of canal lines, although the canal was dug, it was blocked. Nineteen years later, in the twenty-fourth year of Jianwu (AD 48), Da Sikong Zhang Chun once again built a canal near the capital.He learned the lessons of Wang Liang's failure. On the one hand, he increased the water source of the canal, in addition to still diverting the valley water, and attracted the main stream of Luoshui River; , south and east, and then go east to refill Luoshui near Yanshi.This canal is called Yangqu.The second project was very successful. Since the Eastern Han Dynasty, grain ships from the south, east, and north, passing through Hangou, Bianhe, Yellow River and other waterways, and then following Luoshui and Yangqu, can go ashore under Luoyang City.The drilling of Yangqu not only facilitates the government's access to water, but also enables "the people to benefit from it".

However, the largest canal project in the Eastern Han Dynasty was the governance of the Bian River.From the later period of the Western Han Dynasty to the reign of Wang Mang, the boundary water transport system was fragmented due to the repeated breaches of the Yellow River, and some transport channels were completely cut off. The waterway of the Bian River, which evolved from the Dan River, was also often blocked.The Bian River is the main grain road in Luoyang, the capital of the capital. Among the rents and taxes from the whole country to Beijing, those from Henan, Yan, Xu, Yang, Jing and other prefectures accounted for a large proportion, and most of them entered Beijing through this river.Therefore, the Eastern Han court attached great importance to the governance of the Bian River. The most important one was the river and Bian river governance project presided over by Wang Jing and Wang Wu in the 12th year of Yongping (69 AD).The flooding of the Yellow River is the root cause of the blockage of the Bian River, and the governance of the Bian River must be controlled (for details of the river control projects, please refer to the book "Nine. River Control Projects in Past Dynasties").The Bian governance project mainly includes the reconstruction of the canal mouth, embankment, and dredging of the canal.

The Bianhe River uses the water of the Yellow River as its water source, and the main slide of the Yellow River oscillates in the riverbed, so a single diversion outlet cannot introduce river water stably. Diversion.At the same time, the diversion gate was changed from the original wooden structure to a stone structure in order to better control the water inflow.The flood flow of the Yellow River is very large. Even if Biankou is controlled by a sluice gate, excessive flood water will still enter the Bian River, and the Bian River will still burst its embankment and cause disasters.In order to increase the safety factor of the Bianhe River, the two men went upstream, that is, used the "water flow method" to discharge the excess water poured out of the embankment in a controlled manner.From Xingyang to Sishui, the Bian River has a total length of 800 miles. They also comprehensively built embankments and dug deep river beds.After this treatment, the grain storage capacity of Bianhe River has been greatly improved.

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