"At present, the matter of drilling wells is nearing the end, and this year's drought is not expected to have a serious impact on the agriculture of our county. However, students believe that this year's drought should be a profound lesson. Sage Cloud: Water conservancy is the lifeblood of agriculture. If we do not pay attention to the construction of water conservancy infrastructure, then it will be too late to cling to floods and droughts. Su Hao talked eloquently.

"Water conservancy is the lifeblood of agriculture...... Fang Mengjin twisted his beard and repeated gently, "That's a good thing." It's just that...... Anyway, which saint said this, why has the old man never heard of it? ”

It's strange if you hear about it, unless you have crossed over once in the old age, Su Hao teased in his heart. He also said it smoothly, and took the supreme instruction as a sage's speech to the Ming Dynasty. He didn't explain Fang Mengjin's questioning, but just smiled and said: "This is what the students read in the idle books, and the students feel that although it is not what Confucius said, the truth is still worth pondering." ”

Han Wendao: "This water conservancy matter, since the county took office, has never been ignored, every year to recruit conscription to repair the river. In just two years, the county has successively repaired the Nansha embankment, Xiongfang embankment, Doumen embankment, Xiaogang embankment, and countless small repairs, accumulating more than 30 miles, which is a thing for all to see. It seems unfair to say that the county usually does not pay attention to water conservancy construction. ”

Su Hao nodded and said, "Master Han, these projects you mentioned, the students have already seen them when they checked the files in the workshop, and they are indeed indispensable." However, the students thought that the main purpose of building these dams was to prevent the river from bursting and causing disasters, and such water conservancy projects were a little passive. ”

"Changing it means to say......" Fang Mengjin dragged his long voice and asked Su Hao to continue.

Su Hao said: "The students went to the countryside this time, and by the way, they also learned about the hydrological situation in the south of Fengcheng. In the south of the county seat of Chang'an, Changle two townships, the mountains are continuous, and the abundant and rich two rivers originate in Si. Listen to the old man, located in Changle Township of Luoshan, the main peak of the old fairy peak, up to hundreds of zhang, surrounded by mountain peaks, there are three stacks of Baizhang waterfalls, among which the nine curved streams and incense burner water, for many years do not know, is the source of abundant water and rich water, for many years irrigated the ten thousand hectares of fertile land in Fengcheng County. ”

Han Wen said: "What you have changed is very true. The three-fold waterfall of the old fairy peak, this county has also been to observe, it is indeed magnificent. It's a pity that there was no rain for a long time in the past few months, and the two rivers of abundance and abundance are also on the verge of drying up, and only some waterfalls and springs cannot support the water of the whole county. ”

Su Hao clapped his hands and said, "This is the situation I want to talk about." Lord Han, the two rivers of Fengshui and Fushui both originate in Luoshan. During the rainy season, flash floods flow down the river, damaging many fields downstream. In the dry season, there is too little water in these two rivers for downstream irrigation. If we can build a couple of reservoirs upstream......"

"What is a reservoir?" Fang Mengjin asked with a frown. There are too many new words in Su Hao's mouth, which makes Han Wen and Fang Mengjin a little uncomfortable.

Su Hao scratched his scalp and thought about it, and finally found a suitable word, and said, "Uh...... It should be similar to Pitang. ”

The so-called Pitang is a kind of water storage facility in ancient China, which is equivalent to the reservoir of later generations. The history of the construction of Pitang by ancient Chinese can be traced back to the pre-Qin period. By the time of the Ming Dynasty, the construction of Pitang in southern China was very prosperous, taking Jianning Mansion in Fujian Province as an example, there were more than 500 Pitang in Pucheng County, 252 in Jian'an County, 140 in Songxi County, and dozens of other counties.

However, due to the limitation of technical conditions, the storage capacity and irrigation capacity of Pitang in ancient times are very limited, and the Pitang that can irrigate more than 20 hectares of cultivated land is generally considered to be relatively large-scale. Water storage facilities of this scale could not even reach small reservoirs in later generations, that is, they were equivalent to the level of small mountain ponds.

Listening to Su Hao talk about Pitang, Fang Mengjin said: "Pitang I also know that in Changle and Chang'an townships, there are also more than a dozen Pitang, but these Pitang can also store some water in the rainy season for irrigation in the dry season. A pond is irrigated with a few hectares at a time, and at most twenty or thirty hectares, which is really a drop in the bucket for the farmland of the county. ”

Su Hao said: "The reservoir I am talking about is actually just similar to Pitang. The biggest difference between it and Pitang is the difference in water storage. A large reservoir should have a storage capacity of more than one million cubic abbots. During the rainy season, it can lock in the flood water so that it cannot be discharged. In the dry season, it can release water to irrigate downstream farmland. With such a reservoir, the people of our county will be able to ensure harvest during drought and flood, and they will no longer have to rely on the weather for food. ”

"Millions of cubic abbots of water! Can such a huge Pitang really be built? Han Wen couldn't help but get up from the stool, he propped his hands on the public case, leaned forward, and stared at Su Hao with his eyes, as if he wanted to see if he was joking.

In the Ming Dynasty, 1 cubic meter of volume units was equivalent to 30 cubic meters in later generations. Su Hao said that a reservoir holds one million cubic meters of water, which is equivalent to tens of millions of cubic meters, which will be considered a medium-sized reservoir in later generations. As a county magistrate, Han Wen has some knowledge of hydrology, and he can imagine how much benefit it will be to flood control for the entire county if a reservoir can be built in the upper reaches of the main rivers in the county—Fengshui River, Fushui River, Xiushui River, Cha River, Baitu River, and Zhushui River.

There are many rivers and lakes in Fengcheng County, and there are as many as 23 large and small rivers in the county, forming a dense water network. In normal years, such a water network is naturally of great benefit to the development of agricultural production, but when it comes to floods, floods and floods are also extremely serious. As described in Wanli's "New Cultivation of Nanchang Mansion Chronicles":

"Fengcheng of the government, known as Zeguo in ancient times, the lower reaches of Juji and Jiangxi, when the water of the five counties, the momentum is like a building, every time the flood rises, the harm is the first to be it, and the confluence is a huge immersion, and the county is in the middle."

During his tenure in office, Han Boon worked on the repair of the embankment in order to minimize flooding. But as Su Hao said, this method is too passive, just waiting for the flood to come, to keep the embankment. If the reservoir can be built directly upstream to stop the flood, as Su Hao envisioned, then the safety of the downstream will be more guaranteed.

"Instead, can you really build this kind of reservoir that stores millions of cubic meters of water?" Han Wen asked solemnly.

If someone else said such a thing, Han Wen's first reaction was to call the official to drive the person out, because he firmly believed that this kind of thing was just a fantasy and could not be realized. But when the words came out of Su Hao's mouth, it was a different matter entirely. After the success of drilling the well, Han Wen's trust in Su Hao is in full swing, who knows how many novel toys this young master has in his stomach?

Su Hao said: "In fact, it is not difficult to build a reservoir, choose a river valley between the mountains, and build a high dam downstream to block water, then the reservoir will become its own." If the dam is 10 zhang high and the valley is 100 zhang wide, then the 5-mile-long river valley will store millions of cubic meters of water. ”

"How can a 10-zhang high dam ensure that it will not collapse for many years?" Fang Mengjin asked on the side.

Su Hao said: "As long as the design is correct and the right materials are selected, what is the difficulty of the 10-zhang high dam not collapsing for a hundred years?" The students had learned from the Yi people how to make cement, which was like mud and was as solid as a rock when it dried up, which was suitable for the construction of reservoir dams. ”

The process of making cement is actually very simple, it is nothing more than roasting limestone and clay together, and then adding some gypsum and grinding it finely. In his previous life, Su Hao had helped cement factories in some places to survey lime deposits, so he had some understanding of the formula and process of cement. Although equipment such as kilns, fans, ball mills and other equipment does not exist at present, its principle is not complicated, and it can be completely solved with the technical level of the Ming Dynasty.

As long as there is cement, Su Hao can build a reinforced concrete gravity dam. At that time, the reservoir did not need to design locks, generator sets and other facilities, and once the embankment was built and a few sluices were installed, wouldn't a medium-sized reservoir be born?

Su Hao did not tell Han Wen that there is another very important part of building the reservoir, that is, geological survey. In particular, gravity dams must be situated with solid rock formations underneath. If the foundation is unstable, the gravity dam will be displaced under the huge water pressure until it collapses. However, this matter is not a problem for Su Hao, he did this in his previous life.

Han Wen said: "This matter is very important, change it, you plan carefully, if it can really be done, then it will be a great achievement for the benefit of all generations, and even the county will follow you." ”

Su Hao hurriedly said: "Lord Han said the opposite, if this matter is to be done, it must be under the wise leadership of Lord Han, and the credit belongs to Lord Han." It is a great honor for students to be able to shine a little light in it. ”

"Haha, it's really talking." Han Wen said with a smile, "You go and plan, the key is how much food you need, and what kind of cement you are talking about, you have to build it first to test the effect." ”

Su Hao said: "The student plans to report to Master Han after he finishes arranging it in the workshop." In addition to cement, steel bars, construction machinery, etc., also need to be designed and manufactured. In addition, the location of the reservoir is also very important, and I estimate that it will take half a year to prepare for the site selection alone. ”

"Half a year is not a long time, and a large-scale project like this is possible to spend ten or eight years." Fang Mengjin said.

Su Hao said: "I think that if you want to do it, you must complete it as soon as possible, one day earlier, and you can benefit the people one day earlier." Master Han, Master Fang, the students want to ask you for a convenience, and during this period, I may arrange for the workshop to do some things. If it's a trivial matter, the student doesn't plan to ask for advice on everything. ”

"You don't have to ask for instructions on everything, just do what you see." Han Wen said, "The county will fully support you." ”

"Thank you, Lord Han." Su Hao said.