My younger brother Zhuge Liang

Chapter 89 Zhuge Liang's Flood Control
Liu Bei sent Sun Shao to Xudu to take up an official post. It would take at least a month and a half to see the result, as well as the long journey back and forth, and the invitations, gifts and mediation at the court.

During this month and a half, Zhuge Liang obviously had no time to spare. Before Sun Shao was sent out, he had already been rushed by Mi Zhu and Chen Qun to solve difficult problems.

Fortunately, the problems to be solved this time were very novel, allowing Zhuge Liang to apply the mathematics and natural laws he had just learned from his elder brother, so he did not feel it was hard, but rather very interesting and fulfilling.

After sorting out the difficulty of the problems on both sides, Zhuge Liang chose to take two or three days to instruct the ship craftsmen of the Mi Zhu family on how to modify the original ships with bilge keels, as well as add some other small technical improvements to increase navigation safety.

Chen Qun was very depressed at first, and he sincerely asked Zhuge Liang to explain why he favored one over the other.

Zhuge Liang was not targeting people, and pointed out very bluntly: "Brother Zizhong's work is easy and can be done in two or three days, and then the ship craftsmen can start work. Brother Changwen's work requires on-site inspection and survey before we can give a construction plan, so we should start with the easy ones and then move on to the difficult ones."

Chen Qun thought about it, accepted the explanation, and stopped harassing them.

After all, how the canal in Guangling is renovated and how the gates are built are all tied to the geographical environment. In the past three months, Zhuge Liang and Zhuge Jin in Yuzhang were unable to plan and design remotely.

However, shipbuilding and ship modification are not strictly related to geography. The Zhuge family can get a few ships to Yuzhang. They can study and experiment when they have time in the next few months. When they return to Guangling, they can directly give technical briefings and report the answers.

This makes sense.

The craftsmen of Mi Zhu's family quickly learned how to temporarily install a bilge keel, and tried their best to follow the example and clarify the detailed requirements for the streamlined shape of the bilge keel.

We try to reduce the sailing resistance of the bilge keel as much as possible, but there is no way to reduce the maneuverability of the ship and slow down the steering. Increasing the underwater rolling resistance will definitely inhibit the steering.

In addition to the bilge keel, the Mi family craftsmen also learned a reinforced anti-leakage technology that was not available in the Han Dynasty: "soaking hemp in tung oil" -

This thing was something Zhuge Jin randomly saw on TikTok in his previous life. Some bloggers were showing off "traditional handmade shipbuilding techniques". Zhuge Jin just watched it for fun at the time, but he didn't expect to use it after traveling through time, so he taught it to his younger brother.

The specific method is nothing more than wedging materials such as flax/sesame fibers into the gaps between the hull planks with a chisel, and the sesame fibers must be soaked in tung oil. In this way, when the tung oil dries, the waterproof effect of the wooden board joints can be improved by an order of magnitude.

Originally, it was difficult to make the ships of the Han Dynasty absolutely leak-proof. If you went out to sea, you would often find that the inner wall of the bottom cabin and the bottom of the boat were very wet, or even slightly stagnant. You had to occasionally pour out the water with a wooden bucket to prevent it from accumulating more and more. After beating hemp and adding tung oil, the situation can be alleviated a lot.

Although the simple method of beating hemp with tung oil could not reach the level of watertight bulkhead technology used in the later Song Dynasty, it was much better than the one originally used by Mi Zhu, and could probably improve the anti-leakage level to that of the early Sui and Tang Dynasties.

In a nutshell, Zhuge Liang spent three days to improve the anti-leakage performance of seagoing ships by about 300 years, to the end of the Sui Dynasty and the beginning of the Tang Dynasty. He also improved the anti-rolling and wave measurement performance of ships by 800 years, to the level of the Northern Song Dynasty.

Mi Zhu was overjoyed when he received these improvements. Not only could they serve his lord's cause, but they could also serve the Mi family's own maritime business.

Out of gratitude to the Zhuge family and realizing the huge potential of the Zhuge family to curry favor with them, Mi Zhu could not help but propose that his family's merchant fleet give the Zhuge family a 10% stake in the profits, and in the future, the Mi family's maritime trade profits would be distributed as dividends every year.

Zhuge Liang was embarrassed to take it at first, but he was influenced by his elder brother's thoughts in this life. His elder brother often taught him in the past few months that it was right to accept money for technological improvement and it did not violate the gentleman's way. It might even inspire people all over the world to work together and come up with new things to benefit the people.

In addition, Mi Zhu even began to inquire about Zhuge Liang's "whether he was married or engaged". Zhuge Liang was afraid of more trouble, so he calmly accepted the 10% share and said that he would not take it for nothing. If the Zhuge family had any new improvements in navigation and shipbuilding technology in the future, they would take the initiative to cooperate with the Mi family.

As for Mi Zhu's question, Zhuge Liang only said:

"I was able to escape from Jingzhou thanks to the help of an old friend. I have already made a marriage promise. A gentleman should keep his word.

Besides, my eldest brother is already 22 years old and still unmarried, so why would I discuss this matter and disrupt the order of seniority in the family?"

This reason was very legitimate, so Mi Zhu didn't say anything else.

……

After spending three days dealing with Mi Zhu and letting the Mi family's shipbuilders work on the ship by themselves, Zhuge Liang came to Chen Qun to fill another hole that his elder brother had dug last year:

Control the water in Han Canal and solve the saline-alkali land problem in Guangling County!

Neither side was polite and modest. Chen Qun reported how he had used the 40,000 soldiers and their families who had immigrated from Xia Pi County to provide relief in the past winter.
How much of the canal channel in the southern section of the Hang Canal has been renovated, and how much new polder has been built and how much irrigation and water storage capacity has been increased in the area of Sheyangze near the canal during the dry season.

These situations are similar to the measures Zhuge Liang took to control Pengli Lake in Yuzhang.

Because of Chen Qun's governance, during the winter off-season last year, Guangling County added hundreds of thousands of mu of fertile paddy fields (Han mu, converted to mu in later times by multiplying by about 0.3), enough for tens of thousands of laborers to cultivate. The irrigation conditions were also very good, and if the saline-alkali land could be managed well, it would all be top-grade paddy fields.

Zhuge Liang spent three or four days on a quick tour, running from Guangling County to Sheyang County. After inspecting all the way, he had a general idea of the situation.

"River regulation, silting up polder fields and dredging reservoir capacity are all done very well and there are no problems.

So, the remaining difficulty is how to build a gate for the Hangou Canal to prevent the backflow of seawater during high tide of the Yangtze River? "

After Zhuge Liang finished his inspection, he summarized in one sentence the difficulties that Chen Qun still could not solve.

Chen Qun couldn't help but smile bitterly when he heard this: "Don't make it sound so easy. What do you mean by 'I just don't know how to repair the gate'? The difficulty of this matter is beyond my expectation.

Last year I also thought about it, thinking that I could ask skilled craftsmen and water management officials to build the canal locks myself. But after I started, I realized how difficult it was. "

Zhuge Liang checked casually: "Is it that the gate is difficult to open and close? Or is it leaking? Or is it that it can't withstand the water pressure difference on both sides and will be washed away? I think it shouldn't be washed away. There are so many dams and cofferdams that won't be washed away. If we want to reinforce it, it should be easy to do."

Before the Han Dynasty, building dams to block floods was not uncommon, so Zhuge Liang felt that it was not a problem of not being able to block the water.

Chen Qun replied, "It's definitely not a matter of collapse. I consulted skilled craftsmen and tried various reinforcement methods. It is possible to make the gate withstand the erosion of the water.

Moreover, after the sluice gates were closed and water began to be stored, within just one or two days, the water level at the sluice gate rose to the same level as the water source from Huaiyin upstream, and the water became still and no longer had any force.

However, once the gates were built too solid, they were difficult to open and close. After the peak tide every day, it took a lot of manpower to open the gates for navigation, which was almost as laborious as digging a dam.

When they tried to close the gate the next day, it was still not tight, so they had to fill the gaps with sandbags and try every possible way to reinforce it to prevent leakage. Over time, the river channel was repeatedly blocked, and it became difficult for ships to enter and exit the canal, which was not worth the loss.

But if the gate is not built so solidly, it will always leak and never close tightly. I have tried for four months and exhausted all methods. Maybe Ziyu thought the problem was too simple at the beginning. I have never heard of anyone being able to build a gate for the canal since ancient times. "

After listening to Chen Qun's detailed statement, Zhuge Liang was not worried at all. Instead, he felt relieved.

Before he came, he discussed many possible situations with his eldest brother during the months in Yuzhang, and he was really afraid of encountering some strange troubles.

But Chen Qun seemed to have worked very hard, and his efforts over the past few months were not in vain. He solved all the other minor problems, leaving only the ultimate big problem of "the gate leaking or difficult to open and close."

This is like a top student doing a test paper. He is not afraid of difficult questions, but is afraid of questions that are complicated and test his attentiveness.

It would be very comfortable if he had a clumsy but diligent and careful student as his partner, who would check and eliminate all the small and low-level mistakes, leaving only the final questions that would pull in the points for the top student to help with.

Zhuge Liang was confident and said, "Since this is the only major problem, let's go to the gate construction site tomorrow to inspect it carefully, and then gather all the original craftsmen together to work together."

Chen Qun had no other choice but to agree.

……

The next day, the group arrived at the gate construction site on the side of the Han Canal, more than ten miles southeast of Guangling City.

Chen Qun recruited thousands of laborers to do the work, as well as dozens of city builders and carpenters, and technical officials from the Gongcao, many of whom were senior and experienced in building city walls and repairing dams.

A large group of people surrounded the construction site, comparing and inspecting the scene bit by bit, and working together to find a solution.

Zhuge Liang took a closer look and saw at a glance that the experimental gate left by Chen Qun had two obvious problems.

Zhuge Liang first asked: "How does your gate open and close? Does it rotate along the door axis? Or is it pushed or pulled left and right?"

Chen Qun gave a look, and immediately an old official from the Engineering Department came over to answer: "This door opens and closes by rotating along the door axis, but we have also tried pushing and pulling it left and right. Both of them leak and cannot be closed tightly. Even if it is closed tightly at the beginning, it will gradually leak under the water pressure all day long."

Zhuge Liangliang said, "In fact, the simplest and most reliable way to open and close the gate is to lift the gate up and down. However, the canal is too wide, not as wide as the city gate, and there is no way to build a tower across the two sides of the canal to hold the gate.

Of the remaining two methods, pushing and pulling is more reliable. If the gate is rotated to open and close, once there is silt, boulders or sunken ships blocking the riverbed on the fan surface where the gate passes, it will not be able to open and close. Pushing and pulling left and right only requires clearing space for the two slides, and it is also convenient to slightly pile up and reinforce the inside and outside of the gate.

The old official in Gongcao didn't have much of an opinion on this question. They were out of ideas and would try anything. This young man spoke eloquently, and although he sounded a bit iron-fisted, it seemed that his basic skills were very solid.

The old craftsmen and clerks nearby also began to develop some trust in Zhuge Liang.

Zhuge Liang then struck while the iron was hot and continued to point out the key problem: "After confirming the use of sliding gates, you still did not seal it tightly. I think the key is that your two gates are too flat, so they cannot withstand the heavy pressure.

The two doors on the left and right were almost parallel to each other. Even if a horizontal bar similar to a door bolt was added in the middle to reinforce it, how much pressure could it withstand? It was no wonder that it was immediately loosened and leaked under the scouring of the river and the sea tide.

Have you never built an arch bridge? Don't you know that a bridge must be built in an arched shape so that it can withstand the load of carriages and horses? If a bridge with a large span is built completely flush from top to bottom, how can it withstand the heavy pressure?
Therefore, this gate should also be built like an arch bridge, so that the slide grooves of the left and right doors form an angle. When the doors are finally closed and collide with each other, they will arch to the left and right. Moreover, the top angle of the arch should face the side with higher daily water pressure.

And once the angle is made, the contacting side of the two doors does not need to be completely smooth. It can be made into a jagged shape, and then put together to fit into each other with mortise and tenon joints, and then put on a tight gate bolt. The more the tide washes, the tighter the gate will be. Unless it is actively pulled to the sides, it will not leak easily. "

As Zhuge Liang spoke, he picked up a branch and drew a "V"-shaped structure on the ground. The gate originally built by the craftsmen was in the shape of a "I" with no angles on the two sides.

After listening to Zhuge Liang's explanation, several relatively less knowledgeable craftsmen all had their eyes light up: Yes, why didn't we think of learning from the compression-resistant structure of the arch bridge? If a two-stage V-arch is made, it will definitely be able to withstand the water pressure of the tide, right?

However, the oldest official with a white beard, Gongcao, was not easily intimidated by Zhuge Liang's advice.

He just shook his head helplessly, revealing an expression of "young people are really unreliable", and sneered: "You have never seen the scene of Guangling tide flowing back into the Han Canal, right? This method is just assuming. If the gate is made into two sections with arched mortise and tenon joints, it is not difficult.

But have you ever thought about which direction the arch tenon should face? If it is low tide, the water level of the Yangtze River is much lower than the water level of the Huaihe River and Sheyang Lake upstream, so it is higher in the north and lower in the south. If it is high tide, it may be higher in the south and lower in the north.

When building a bridge with an arch to resist pressure, one prerequisite is to ensure that only the arch back is under pressure. If the pressure direction is suddenly to the south and suddenly to the north, once the arch belly is under pressure, the gate will collapse immediately!

Just like a chicken egg, when you hold the eggshell tightly in your hand, it is not easy to break the eggshell, because the eggshell is arched outward. But when the chick breaks out of the shell, how weak is its strength? It is easy to break the shell by chiseling from the inside of the eggshell. The gate built by this method will be as fragile as a chicken egg when the arch is under pressure! "

The old official had obviously been involved in flood control for many years and was very experienced. He also had great prestige among the engineers in Guangling. After hearing the problem he pointed out sharply, everyone, including Chen Qun, could not help but frown and worry.

However, Zhuge Liang was still prepared. Facing everyone's doubts, he still said with wisdom: "This question is very well raised, but it is not impossible to solve it. In fact, we can completely increase the estuary where the canal connects with the Yangtze River from one to two, and dig an additional river channel next to it. When digging, we must accurately measure the water level difference between the Yangtze River and the Huai River on both sides of the connection.

In this way, in the future, one of the two connection points between the Hang Canal and the Yangtze River can always ensure that the water level of the Yangtze River is higher than that of the Huaihe River/Hang Canal. The gate on this opening can withstand the heavy pressure from the Yangtze River to the Han Canal from south to north.

The other opening ensures that the water level of the Huaihe River/Hanggou is always higher than that of the Yangtze River. Even when the Yangtze River is in high tide, the water level is only at most equal. In this way, most of the time, this gate only has to bear the heavy pressure from north to south.

In the future, only canal boats sailing from south to north will be allowed to pass through estuaries where the water pressure is from south to north. In this way, the boats can float downstream without even paddling or towing. When the water level rises, river boats can directly enter the Han Canal without having to change boats, which also saves manpower for loading and unloading.

In the future, only ships going from north to south will be allowed to sail in estuaries where the water pressure is from north to south. The same principle applies. Natural drifting can save effort. "

As Zhuge Liang spoke, he casually drew a map on the ground. The mouth of the canal is now east of Guangling City, and Zhuge Liang casually drew a line.

The Han Canal was diverted westward from the north of Guangling City, forming a branch that connected to the moats on the west and north sides of Guangling City. It then headed southwest and finally connected with the Yangtze River about 20 to 30 miles upstream.

When Chen Qun and the old officials from the Engineering Department saw this plan, they were immediately shocked.

What is the idea behind this? Are they going to dig a 30-mile branch road out of the 280-mile-long Hangou Ancient Canal? This would require a lot of construction, right?
However, Chen Qun reacted quickly. He soon realized that when Zhuge Liang gave the signal, he borrowed a part of the moat on the northwest side of Guangling City. If the overlapping part could be omitted, it would only take about ten miles to dig. This construction volume was still acceptable.

Digging a river channel of more than ten miles is equivalent to digging the moat of Guangling City again. With tens of thousands of corvées and a few months of work, we can achieve some small results. If the method is confirmed to be feasible, we can gradually widen it later.

And if it is really possible to divert the canal ships traveling north and south, and divert the water levels at the estuaries, to ensure that each estuary only has to bear the water pressure in one direction, and there will not be a situation where "the water level is high in the north and high in the south at different times", then the arched gate connection method seems to be really feasible.

Chen Qun thought about it and quickly grabbed the old clerk in charge and asked, "Mr. Qin, do you think this method is feasible? If the river mouth is really diverted, can the arch gate withstand the one-way water pressure at any river mouth?"

The old official felt his lips dry and the mental pressure was too great. He did not dare to jump to conclusions. Finally, he just struggled and said:
"The key is to see if there is anyone in the world who can measure so accurately, and really make it so that after changing the river mouth, the water level of the Yangtze River at the new river mouth is always higher than that of the Huai River! And we can't leave too much margin and deliberately let the Yangtze River water rise too much, otherwise it will not be able to close the gate after opening! We can only allow the Yangtze River water to be just a little bit higher. If someone can guarantee this, it is not difficult to build an arch gate!"

After the old official finished speaking, other workers and old craftsmen also echoed him, saying that the difficulty of this idea was not in the construction, but in measuring the water level "altitude" - although there was no word "altitude" in the Han Dynasty, they expressed that meaning.

After collecting everyone's opinions, Chen Qun returned to Zhuge Liang and spread his hands, saying, "Mr. Kong Ming, you have a good plan, but it seems that no one in the world can measure the water level between two points on two rivers that are far apart so accurately."

Zhuge Liang didn't say much about this question, but just said: "Leave it to me, but you also need to give me a few compass stones for measuring the level. These stones are too heavy, I didn't bring them from Yuzhang, but I have all the other tools."

Chen Qun was confused and had to go find a professional: "What is a compass stone?"

Many craftsmen nearby were also confused. Finally, the old official named Qin remembered and said with sudden enlightenment:

"Could it be the kind of cross-grooved stone that was used to level the four sides of the cross-shaped tomb passage when the emperor's mausoleum was built? As long as the tomb is higher than the direction along the cross groove of the compass stone, it can be guaranteed that it will not be flooded after it is built?"

Zhuge Liang was a little surprised when he heard this, and nodded in approval: "You also know the specific use of this thing? Then why didn't you think of using it to measure the altitude? Wouldn't it be enough to just change it slightly?"

The old official surnamed Qin was shocked when he heard this: How could this change slightly? You think it's too simple, right? I can't imagine it at all!

However, since Zhuge Liang could say this, he believed it at least 90%. He quickly whispered to Chen Qun:

"It seems that what Mr. Zhuge said is probably true. Although I don't know how he did it, I have never heard of a craftsman who measured the height of the tomb and the groundwater level for the emperor's mausoleum making a wrong measurement and causing the emperor's mausoleum to be flooded. Mr. Zhuge's method evolved from this, and with the addition of the divine calculation method, it may really work."

Chen Qun: "Then hurry up and prepare the tools for Mr. Kong Ming!"

For a time, all the resources around Chen Qun were mobilized, and he decided to take a gamble with Zhuge Liang.

The entire project has been vigorously promoted since the survey stage.

To put it bluntly, Zhuge Liang's plan was not that difficult. The Grand Canal of the Sui Dynasty and the connection between the north and south banks of the Yangtze River during the Tang and Song dynasties were both built into a bifurcated "two-way independent waterway" state.
The purpose is to facilitate the construction of a single-sided pressure-resistant gate, and also to make it easier for ships entering and leaving the river estuary to drift on their own without the hassle of towing.

After the completion of the project, the people benefited for thousands of years, and they continued to benefit from it until the Ming Dynasty. If you visit Yangzhou and Zhenjiang in later generations, you will know that the ancient Grand Canal forked to connect to the Yangtze River.

All of this did not require any incredible construction technology. It was just that the people of the Han Dynasty were too poor in mathematics, surveying, and optical geometry. They could not find the equal water point where the water level of the Yangtze River was just slightly higher or slightly lower than the water level of the canal.

If the water level difference is not properly controlled and this is forced, once the water level of the Yangtze River is too high, the result will be that the Yangtze River will surge into the Han Canal, turning Huaiyang into a Hongze Lake. If the water level at the Yangtze River connection point is too low, the Han Canal will be directly drained by the Yangtze River and become dry and scrapped.

Any ordinary surveyor from the future who worked in a water conservancy department and traveled through time would have been able to measure the relevant geological data and provide it to the people of the Han Dynasty, as long as his professional skills were not too poor.

The contribution of this one surveyor could save 100,000 canal workers from having to do repetitive work for hundreds of years, and also help to manage the saline-alkali land around Sheyang Lake. (However, before the construction is completed, the surveyor and his family members are usually hung up until the final completion to confirm that he has made no mistakes.)

　Note: Some people have been criticizing the Han Canal for not being feasible to build a sluice gate, saying that it is a big cheat. Let me explain it in a unified way. The difficulty is not the kind of sluice gate that "there is a period of time every day when the water levels on both sides of the gate are naturally equal." For example, the Han Canal relies on the fact that the water levels on both sides will be naturally equal at a certain point in time during high and low tides. Zhuge Liang built it, which was just an improvement from the Han Dynasty to the Tang Dynasty. It is completely possible for modern people with mathematical and physical knowledge.

　　The difficult part is the canal locks such as the Three Gorges and Panama Canal, which need to "maintain the water level difference at all times while ensuring navigation". That is, when there is no natural water level equal on both sides of the lock, even after the ship passes, the water level on one side is always high and the water level on the other side is low, and artificial water level regulation and lifting ships are required. Such locks did not exist in my country until the late Qing Dynasty. But the protagonist did not want to build such a complicated lock.

　　So don't just think of the awesome modern locks when you hear the word "lock" and then say it's impossible. Locks are also divided into different levels, and the technical difficulty can vary by thousands of years. The earliest locks were in Lingqu during the time of Qin Shihuang. The technical cheat used by the protagonist is not very big at all, and has a very big limitation, that is, "it can only be used in places where there are obvious rises and falls of the tide."

　　The inland princes who are a little further away from the sea cannot use this technology, so there is no need to worry about other princes benefiting from it after Liu Bei is given the cheat. In the entire Chinese land, at most Sun Ce and Sun Quan have a Jiangnan River, which was dug by the Yue State during the Warring States Period. It connects the Yangtze River and the Qiantang River and is also affected by the tide.

　　-

　　In addition, there are only these two updates today, because there are 10,000 words in total and it would be difficult to break it up.

　　
　
(End of this chapter)