Li Chao took Cheng Qian's pen and paper and quickly drew the mountains and rivers around Hanjing in his notebook, such as the Han River, the Danjiang River, the Tang River, the Baihe River, the Hanjing River, Xiangyang, etc. Pen, fun, and www.biquge.info

It's a few simple strokes, but the location is accurate.

"We are here to intercept the Danjiang River and build a reservoir so that we can also use the water of the Danjiang River to irrigate the Hanjing Plain. At the same time, after the impoundment of the Danjiang River, after the water level increases, the navigation capacity is also improved, so that through the Danjiang shipping, the transportation traffic between Hanjing and Chang'an is also greatly improved. ”

Of course, Li Chao wants to block the Han River and the Danjiang River, but it's not just that.

"Your Highness, look here, this is the Fangcheng Pass in the north of Hanjing, the junction of Henan Road and Shannan Road, the boundary between the Yangtze River Basin and the Huaihe River Basin, the boundary between the Hanjing Basin and the Central Plains Plain, and the boundary between the Funiu Mountains and the Tongbai Mountains."

On this continuous high mountain range, a pass suddenly appeared here in Fangcheng, which the locals called Fengkou. This pass is 30 miles long from east to west, 40 miles wide from north to south, and the ground on both sides is as high as 60 or 70 zhang.

The special geographical environment makes Fangcheng a traffic artery for Jingxiang in the south and the Central Plains in the north.

From Hanjing to Luoyang, this is the only way to go.

Because Funiu Mountain is the watershed of the Yangtze River and the Huai River, there is no direct waterway between Hanjing and Luoyang. And waterway transportation, which is the highway of this era, is extremely important for traffic and transportation.

The high Funiu Mountain blocks the waterway. But this mountain pass has become a possibility to communicate the north and south of the water and land.

"As long as we build a dam on the Baihe River, then divert the Danjiang Mountain into the Baihe River, and then excavate the Fangcheng Pass, we can divert the water of the Baihe River into the Shahe River, into the Cai River, directly to Bianzhou, Henan, and connect the Yellow River with the Grand Canal and the Huai River."

Cheng Qian was dumbfounded after hearing this.

"Teacher, Fangcheng Pass is a continuous mountain, which is the watershed of the Jianghan River. How could the water of the White River flow backwards to Henan? Cheng Qian felt that Li Chao was telling a joke.

Li Chao didn't tell a joke, although the Song Dynasty did fail to build the Xianghan Cao Canal in history, and failed twice. But that's because they're just blocking the White River, which doesn't have enough water. In later generations, the south-to-north water diversion project of the century project successfully passed through the Fangcheng Pass.

At that time, the Danjiang River was used to pass through the Baihe Pass.

The plan of the Song people needed to dig seven zhang of the low pass, and later generations only needed to dig a little more than two zhang through the south-to-north water diversion project of the pass.

Digging a two-zhang deep river channel is not a difficult and incompleteable project, after all, it is only a few dozen miles. Even if you want to dig the section of the river from the deep Baihe River to the pass, it is only more than 100 miles. In total, there are about 150 miles to be dug, and only the section of the pass is to be dug two zhang deep, and the rest are borrowed from the old river, which only needs to be dredged.

The key is to build dams and divert water.

"Teacher, can this really be done, it only takes two zhang to get through the pass?"

"It's about two feet long." Li Chao corrected.

Cheng Qian was already extremely excited, and he knew very well the importance of opening up this canal. The Sui Dynasty excavated the Grand Canal to connect the north and the south. Among them, the Bianqu, that is, the canal section that connects the Yellow River and the Huai River, plus the canal section from the Huai River to the Yangtze River, has completed a transportation artery operation in the north and south, and the north-south transportation is greatly convenient.

But this canal is in the southeast.

Luoyang to Hanjing, although it seems to be very close, but there is only a land route, and the transportation is inconvenient. If you want to transport a large number of materials to Hanjing, in fact, the most important route is to take the canal, first take the Bianqu, from Luoyang to Sizhou, then Sizhou to Yangzhou, then take the Yangtze River to Jiangxia, and then along the Hanshui to Xiangyang, and then into the Baihe, to reach Hanjing, in fact, it is a huge circle.

The land of Jianghuai also said that it was very inconvenient to take the Yangtze River, Hanjiang and Baihe to Beijing directly, but Hedong, Henan, Hebei, Huaibei and other places had to go around such a huge circle to transport them to Hanjing, of course, it was very inconvenient.

However, water transport is also very important, compared with land transport, the carrying capacity is larger, it is also fast, and the cost is less. The transportation of bulk materials still mainly relies on water transportation.

Therefore, when Li Chao said that he could stop the water of the Danjiang River from being diverted into the Baihe River, build a dam to store water in the Baihe River, dig a city pass, divert the water of the Baihe River through the Shahe River, flow into the Cai River, go straight to Bianzhou, connect the Yellow River and the Grand Canal, and create a new canal, how could Cheng Qian not be shocked.

One hundred and fifty miles.

A short stretch of canal, if it is really dug and navigable, it will be of great significance. In the future, not only Henan and Hanjing will be directly connected, but also the grain and materials of Hedong, Hebei, Huaibei, etc., will also be able to quickly reach Beijing. Even transportation is much faster and easier.

"Teacher, can this really be done?"

"Of course it can be done, the focus is on Danjiang water."

At that time, the Song people used 100,000 manpower to dig through the Fangcheng pass, and the channel was open, but the water was too little to navigate, so it was useless. Li Chao plans to divert water from the Danjiang River, so there is no need to worry about the amount of water.

The whole amount of work is not large, nor is it small.

Including the construction of the Danjiang dam and the repair of the Danjiang reservoir. Build a dam on the Baihe River, dig the Fangcheng Pass, and widen and dig the upper reaches of the Baihe River to the Fangcheng Pass for more than 100 miles, and even some sections of the river should be directly straightened. But if you really want to say it, it's really not a big project.

It's just that there will be more dams on the Danjiang and Baihe rivers in the future, and it will not be so convenient to get through the boat. But this is nothing, all sections of the Grand Canal are also navigable by Doumen.

Li Chao can also build cascade locks for navigation, and set up low dams and gates to discharge excess water when ships pass through the locks.

"If we can really open up the transportation with the Cai River and go straight to Henan, it will be amazing." Cheng Qian said excitedly, "And after the Danjiang water is intercepted, it can also irrigate the Hanjing Plain." Kill more than one stone. ”

Li Chao took a pen and continued to draw on the paper, "The Bianhe River, the Cai River, the Shahe River, and the Baihe River are connected, so that the Grand Canal can be directly connected to Hanjing." Hanjing is connected to the Han River through the White River, and the Han River is connected to the Yangtze River, so that there is no longer only a southeast canal between the north and the south, but also a canal in the west. In this way, the north-south and east-west of Datang will be more convenient to communicate. ”

Li Chao took the pen and continued to draw, this time drawing a line in Jingzhou, connecting the Yangtze River with the Han River.

"What is this?" Cheng Qian asked.

"Your Highness, this is the Jianghan Cao Canal connecting the Yangtze River to the Han River in Jingzhou, with a total length of about 130 li, but after the opening of this Cao River, it can shorten the detour distance between the Yangtze River and the Han River by 1,300 li. 1,300 miles, at least five days can be saved! ”

"In the future, the middle and upper reaches of the Yangtze River will reach Xiangyang and Hanjing, saving more than 1,000 miles of voyage, which is very remarkable. Moreover, such a canal also has the functions of flood control and water diversion for irrigation. ”

Li Chao took the pen and continued to paint, but this time he was painting in Hunan.

"If a Xiangtan Cao River is built here and leads to the Yangtze River, Hanjing and Hunan will also have more convenient transportation and closer connections."