In the school hall of Luxi Academy, Mr. Chen He is teaching students.

Chen He put down the book and paced slowly with his hands behind his back: "Let's discuss current affairs today. In recent years, the Yellow River has flooded many times, and the people are miserable, and His Majesty the Emperor wants to personally patrol the river to investigate the actual situation, so as to formulate a strategy for river control. ”

"Regarding this strategy for governing the river, the princes of the DPRK and China are arguing endlessly. It is said that we should follow the method of our predecessors, focusing on dredging and cleaning up the silt at the bottom of the river; There are also like those advocated by Pan Shiliang, the Shaoqing of Dali Temple, to build high embankments and narrow the river. What do you think of these two remarks? At this time, political discourse is also a compulsory subject in the township examination, so you don't have to be restrained, just speak freely. ”

A student in the front row immediately stood up: "The Yellow River has always been governed by building embankments and dredging, why does this Shaoqing of Dali Temple want to narrow the river?" Once the river is narrow, the water level increases, and once the flood season comes, won't the Yellow River be more likely to burst? What else is there to say about this? ”

"Haven't you ever heard of the water attacking the sand?" Another person disagreed, "This is the theory put forward by Pan Shaoqing. Narrowing the river will increase the water level, but the water flow will also be faster, so that the sediment at the bottom of the river can be washed away, and the river channel can be cleared once and for all, isn't it more convenient and faster than cleaning up the silt? ”

"Where does the Yellow River come from, once and for all! Naturally, it is necessary to desilt regularly and take care of it frequently. As soon as the river is narrow, I am afraid that the sediment has not been washed away, and the flood will come first, and then millions of lives in the middle and lower reaches of the Yellow River will be destroyed. The ancient book uploaded Dayu to control the water, using the strategy of dredging, not following the law of the sages, but what kind of water to attack the sand, isn't it ridiculous? ”

The man was so angry that his face turned red, and he pointed at the other party and scolded: "Pedanty! Time has passed, how can we copy the methods of our predecessors? The construction of embankments and dams can be carried out at the same time as the narrowing of the river channel, and when the sediment at the bottom of the river is washed away, the riverbed is lowered, and the water level will naturally go down. You said that you want to dredge, but the imperial court dredging the Yellow River every year and flooding every year, has it ever improved? ”

"Hmph, with the existing law, the situation will not be worse at least, not to mention that the last time the Yellow River flooded was eight years ago. As for the attack on sand by harnessing water, I have never heard of it before, and if it is really implemented, maybe the Yellow River will collapse immediately in the spring flood this year! ”

"You—incomprehensible! I can't make sense with you! ”

"Okay, okay, class discussions are about things, it's normal to have different opinions and arguments for a while, don't take it to heart." Chen He smiled and came out to play a round, turned his head and saw Gu Yunji on the side smiling and silent, as if he was in his chest, his heart moved, and asked, "Do you have any good strategy for controlling the river?" ”

Gu Yunji stood up and said calmly: "Students have three strategies, in terms of time and years, they can be divided into near, medium and far. ”

There was an uproar in the hall for a while: "There are only two strategies for the adults in the court, and as soon as he came, he said that there were three strategies, so he didn't say big things......

Chen He became interested: "Oh? Let's talk about it. ”

Gu Yunji said: "The nearest strategy is to clean up the silt at the bottom of the river and open up a new river channel to divert the water of the Yellow River. However, as I just said, this year's dredging is cleared, and next year's sediment will be deposited again, and there is no end to the cycle, so this strategy can ensure the peace of the Yellow River for five years at most. ”

"The middle strategy is to narrow the river channel and deepen the riverbed, so that the flow of the Yellow River can be accelerated so that the silt at the bottom of the river can be washed away. However, this strategy also has shortcomings, once it encounters the flood season, if the silt erosion effect of the river bottom does not meet expectations, it increases the risk of outburst. Moreover, the sediment of the Yellow River flows from the upper reaches downstream, and even if the downstream is cleaned up, the sediment problem is not solved, and the possibility of flooding of the Yellow River still exists. This policy is guaranteed for 30 years. ”

"The long-term strategy is to carry out afforestation in the Guanzhong area in the middle and upper reaches of the Yellow River. In the land of Shaanxi, the trees are scarce, the soil is thick and loose, and once the wind blows, the yellow sand is all over the sky. Every summer when the rain is abundant, the rainwater rivers wash the ground loess and roll down the muddy water, and finally join the Yellow River, which is the root cause of the Yellow River's sediment problem. If we want to cure the Yellow River, we must plant trees all over the middle and upper reaches of the Yellow River and grasp the soil layer so that the rain cannot wash away. ”

Speaking of this, Gu Yunji paused and said slowly: "This thing cannot be done overnight, it takes the continuous efforts of several generations to see the effect. This policy can be guaranteed for 100 years. Suddenly, he intensified his bite and his tone became excited, "But, if the three strategies are in parallel, the Yellow River can be clear, and it will be safe for thousands of years!" ”

His words opened up the past and the present, and put forward a bold and comprehensive theory, which shocked everyone's hearts, and Chen He listened attentively for a while, and did not speak for a long time.

At this time, a student glanced at him disdainfully and said, "Your Excellency is so head-to-head, you must have been to the Guanzhong area and personally explored the Yellow River?" ”

"I've never been there, I've seen a description of Guanzhong in the book." Gu Yunji bowed slightly. In his previous life, there were pictures, texts, and even documentaries about the geography class on the Loess Plateau, which were so detailed that people could see them in person, where the books of this era could be compared, but he could only say that.

The man sneered: "Then you are talking on paper?" As he spoke, he stood up, "It is the people of Guanzhong down there, as far as I can see, Guanzhong is fertile for thousands of miles, the vegetation is lush, and the trees are sparse like you said, you are just talking nonsense, and you are talking about the near and far strategies, which is ridiculous." ”

Gu Yunji was unhurried: "The Guanzhong Plain is indeed called the south of the Yangtze River, but further north, it is a plateau area. The mountains are rugged and vertical, the soil is loose, there are few trees, such places are more in the middle and upper reaches of the Yellow River, and it is normal for you to live in the Guanzhong Plain for a long time and have not seen it. ”

"Huh, like you've seen it?"

"I've seen it." At this moment, a lazy voice came from the corner.

Su Qi yawned, as if he had just woken up, he stretched his waist and said nonchalantly, "I've seen it." I once went on expeditions with my father, and I went to the Guanzhong Plain and the plateaus in the northern area. Indeed, as he said, there are large tracts of loess, no dense woods, at most a few low bushes. The local people live in caves, and on a windy day, the yellow sand in the sky makes people unable to open their eyes, and their clothes are filled with sand. ”

Dingguo Gong is a military general, and he has been in the border all the year round, and it is not surprising that he went out with the army as his son, and Su Qi's words are very credible. As soon as these words came out, the students from Guanzhong suddenly had nothing to say and sat down reluctantly.

After hearing this, Mr. Chen He looked at Gu Yunji, and felt more and more that this son was extraordinary, and his eyes were blazing: "When you go back, write your river management strategy into an article, remember to be clear and organized, and hand it over to me in the next class." ”

Gu Yunji nodded yes.

After school at noon, Gu Yunji returned to the dormitory after lunch, and saw Su Qi lying on the table fighting crickets, he walked over and said, "Thank you Shizi for speaking for me in class today." ”

Su Qi didn't raise his head: "I'm just telling the truth, I don't mean to speak for you." Seeing the cricket in the bamboo tube tumble over and fall to the ground, he sighed lightly and turned to look at him, "I have seen the land situation in Guanzhong with my own eyes, and I think the strategy you said about river control is very reasonable, and you don't need to thank me for saying it so casually in class." ”

Anyway, he didn't care about Gu Yunji, he went out again with the bamboo tube in his own hands.