In the morning, it was sunny and cloudy. On the observation deck (observation deck) on the simple third floor of the state government, Li Li was using a telescope to observe the movements and stills of the wilderness in the south.

This is a "high power telescope", so when placed on a tripod, you can see the movements of a person's arm several miles away clearly.

In the wilderness to the south, five or six miles away from Hanshan Nansaiyue, a long dragon runs across the east and west, which is a large number of young and strong men digging ditches.

The ditch looks like a straight line, but it is actually an arc, an arc that goes around the southern end of Hanshan Weir.

It is unknown where the eastern section of this ditch will eventually extend, but where the western section of the ditch is connected, Li Li can guess: it is connected to the "Pengcheng Reservoir" reservoir area.

The word "reservoir" is no longer used now, so Li Li changed it to "Pengcheng Lake".

As long as this ditch is deep enough, it can drain the water from "Pengcheng Lake". In addition, another ditch being excavated on the north bank of Si Shui, one south and one north, can drain the water from "Pengcheng Lake".

When the water is gone, Pengcheng's "sea turn into mulberry fields", and Hanshan Weir has also become an earth wall. The surging Qi army can flood Pengcheng and Hanshan.

At that time, I would have been captured alive because of a failure to break through and took me to Yecheng to parade. At that time, the city will probably not be empty...

Li Li thought so, and there was movement in his ears.

It was the sound of metal hitting. Li Li turned his head and saw Zhang Ying carefully considering it with a Luoyang shovel.

Li Li left the telescope, sat aside, drank tea, and asked, "Is this thing useful? Just drilling on the ground and you can bring up a lot of soil."

Zhang Ying put down the Luoyang shovel that was still covered with some mud and sincerely praised: "It is indeed convenient. In the future, the foundation survey will be twice the result with half the effort."

"You don't need to use this thing when you survey the copper mine veins in Le'an in the future. It's really a good idea."

"June, why is this item called Luoyang shovel?"

Li Li said vaguely: "This matter is a long story, and I don't know where to start."

Thanks to the popular tomb robbers, Li Li learned of a drilling tool called "Luoyang Shovel". Although he did not plan to do anything "Golden-Touching Captain" or "Faqiu General", it did not prevent him from using this tool for "geological exploration".

After Zhang Ying arrived in Hanshan, he walked around a few times and raised a very serious question: Hanshan Weir has a huge flaw, which is simple and fatal.

That is, the enemy can mobilize labor to dig ditches in suitable areas on both sides of the north and south, and directly discharge the water stored in the dam into the lower reaches of the river. In this way, the water storage function of Hanshan Imperial can be invalidated.

Li Li is already prepared for this. He will not place his life on a mysterious plan to think of it but not conduct a field investigation.

"First, look at the trends of Hanshan and a series of small hills around." Li Li dipped his hands in water and drew a schematic diagram on the table.

"Si Shui flows from west to east here, a horizontal line, Hanshan and a series of hills, like folds, it travels north and south, and it is a vertical line."

"What does this mean? It means that there may be folded areas on the terrain on both sides of the Si Shui River in the Hanshan area, which are north-south and are not obvious on the surface, but under the soil, it may be like a stone wall, and Si Shui flows eastward from the gap in this fold."

"Of course, this is a conjecture, and there must be empirical evidence."

"From the beginning of the year to now, we have roughly touched the geology of Hanshanyan on both sides of the north and south sides. This place has a gravel layer and rock layer that is not very deep. Although it can dig a trench, it is not easy to dig a trench deep."

Li Li took it to the map and explained his arrangement.

"The terrain of this area determines that if they want to dig a trench around Hanshanyan to release water to the lake area, the ditches they dug cannot be shallow, and they will inevitably touch the gravel layer or even rock layer under the soil layer. This is not easy to dig, just like digging a plank road on a stone wall."

"Although it can be done by burning water, it will not take a short time to complete a drainage channel that is deep enough. Even if it is barely dug, as long as the water level in the lake area drops a little, the bottom of the ditches will be higher than the water surface and there will be no more water discharge."

"The fish pond we dug outside the north and south Ershi were actually not very deep, and they..."

Li Li drank a cup of tea and continued: "And they mobilized a lot of manpower and material resources, dug the ditches with confidence, and had to overcome the terrain first, and the amount of earthwork would not be small."

"After digging the gravel layer, the project progress will be very slow, let alone what to do if you dig the rock layer."

"It may be possible to complete it after more than a year of digging, but it is impossible to complete it in one or two months. Look at the past half month, the opponent has not even had a tentative attack, and we don't have to hurry."

Zhang Ying understood: "Your Majesty's cleverness, and I admire you."

"Don't praise me like this, no, don't think I'm a god with complete plans, and you have to say it if you have any questions."

"It's good this time. If there are some things I didn't expect, and you think I thought, wouldn't that flaw be left behind?"

It is winter now, and the Qi army has arrived at the two borders north and south of Hanshanyan. Although the two sides have not yet fought, the offensive and defensive battle in Pengcheng has begun.

Qi Jun’s first choice is to dig ditches to drain water, drain "Pengcheng Lake" and make Hanshan Weir directly ineffective.

Wu Xiang, who was stationed in Pengcheng, sent ships to investigate everywhere and found that the Qi army was already catching water. He built warships upstream of the Si Shui River. It seemed that the other party was also preparing for a water battle.

According to the scouts' reconnaissance, the Qi army had divided its troops, and some of them were left in Hanshan to "block" the Hanshanliang Army, while the other soldiers headed east. It seemed that they were going to attack Luliang, Xiapi and cut off the retreat route of Hanshanliang Army.

The Qi army did not attack fiercely as soon as it came up, which shows that Emperor Gao Yang, who was in charge of the army, was very clear-headed, like a butcher who killed a pig, made all kinds of preparations before taking action.

The other party was preparing, but Li Li had already prepared, just waiting for a head-on confrontation.

Li Li has absolute confidence in his victory in the offensive and defensive battle. The opponent will definitely not succeed in a short period of time when digging ditches and draining water, because during this period, the soil layer was relatively thin.

And under the soil, there are many stones.

One of the evidences is that there are many stones at the bottom of the Sishui River section in Pengcheng, or it can be said that this is the "stone bottom" and so there are three torrents in the Sishui River section in Pengcheng, which are the "three floods".

These three floods are "Qinliang Hong", "Xuzhou Hong" and "Luliang Hong". They are all because the river channel is narrow and there are stone beams at the bottom of the river, which causes the river to rush.

Among them, Qin Lianghong is said to be a cauldron made by Qin Shihuang salvaged nine cauldrons in Sishui, fishing up a large number of stones at the bottom of the river and piled up the shore.

"Records of the Grand Historian" has a clear record of this history, and Zhang Ying picked it up casually: "There were nine tripods in Zhou, symbolizing the nine states in the world. During the reign of King Nan of Zhou, King Zhao of Qin took nine tripods, and one of them flew into Sishui."

"The First Emperor passed through Pengcheng and left thousands of people to seek it, but he could not get it."

Li Li nodded: "Yes, it can be seen from this that the geological conditions around Pengcheng at this time were relatively thin, unlike later..."

"Later?" Zhang Ying heard Li Li's implication, but he couldn't figure out when "later" was "later".

Li Li was shocked and almost let out a word, so he quickly said vaguely: "The world has changed and the soil has accumulated over hundreds of years. Is the soil layer around Pengcheng not thicker than during the Qin and Han Dynasties?"

Later, of course, it was 'long time'. In that lifetime, he visited Weishan Lake (Weishan Lake is north of Xuzhou, and the southern end is not far from Xuzhou). He learned some geographical knowledge when reading the introduction.

It was probably during the Song Dynasty that the lower reaches of the Yellow River were diverted, and the Huai River was diverted into the sea (entering the Yellow Sea). After the diverted, the Yellow River also seized the Sishui River and passed through Xuzhou (Pengcheng).

More than 700 years later, in the middle of the Qing Dynasty, the Yellow River returned to the old road and entered the Bohai Sea. The old road of Si Shui also disappeared due to long-term silt accumulation.

During this period, Xuzhou became a yellow flood. After every heavy flooding over the past seven hundred years, the silt and sand accumulated repeatedly, slowly raising the terrain of Xuzhou and getting thicker and thicker the soil layer.

The Yellow River seized the Huai River into the sea, causing a series of lakes to appear on the Sishui River in the north of Xuzhou due to repeated siltation and alluvialization.

These lakes are part of the Grand Canal of Beijing and Hangzhou. They gradually grow larger and then connect together, which is the famous Weishan Lake.

Weishan Lake was probably formed in the late Ming Dynasty, so there was no Weishan Lake in this era. Its location was the Sishui River channel and some small lakes along the way.

It is precisely because there is no long-term large amount of silt accumulation after the Yellow River divert that the terrain around Pengcheng is relatively low at this time, and the soil layer around Hanshan is relatively thin.

If Qi Jun wants to dig deep trenches and drain water, he has to 'chew' the gravel layer. If it is deeper, it is a hard rock layer.

In the era without construction machinery, it is not easy to "chew" the gravel layer, and it takes time and effort, making the rock layer even more difficult.

Therefore, the Qi army dug deep trenches around Hanshan to drain the "Pengcheng Lake" due to the terrain and geology, which is difficult to achieve in a short period of time.

The so-called flaw of Hanshanyan just looks like a flaw.

Of course, if you do not stick to digging canals and drainage near Hanshan, this idea can still be realized, but it requires a lot of investigation, understanding the terrain and geology, and selecting the best construction route.

The survey may take one or two years, and the construction may take at least one year. Emperor Qi personally led the army to fight, so how could he have so much time to do this slowly?

Li Li used to pour Pengcheng into a lake, which also referred to the history of Weishan Lake formation. Since the terrain around Pengcheng is now lower than in later generations, what's wrong with turning the surrounding area of ​​Pengcheng into a lake area?

The sun sets in the west, Li Li looked at the afterglow of the sunset outside the window and smiled, "They think we have flaws, but they themselves have many flaws."

Zhang Ying knew what Li Li was talking about, looked out the window and laughed: "Yes, since they don't come to attack, we will force them to attack."

If you think of "Pengcheng Lake" as a circle, the center of the circle is Pengcheng, and the edge of the circle is the lakeside and nearby cities, the important place.

Liang's troops starting from the center of the circle can arrive at any position on the edge of the circle by boat. If the cavalry is put into motion on the shore, the radius of the circle will be larger.

This is the advantage of "inside combat" mentioned by Li Li. So, how many troops should the Qi army, which is in the 'outside combat' situation, have to use to prevent the entire 'round edge'?

If you are not careful, then flaws will be indispensable.
Chapter completed!