Gao Pragmatic quietly listened to Zhang Jin's relays of Zhang Siwei's investigation results back then, and knew more about his cheap uncle's ambition and ability, and only then did he interrupt Zhang Jin's words slightly: "After so many years of flood control embankment repair, is it effective?" Or rather, how effective is it? ”

Zhang Jin smiled bitterly: "The effect is some, at least the floods of the Yongding River in this dynasty are not as frequent as they were in the previous Yuan Dynasty." The lord has done a detailed investigation of this, saying that in the ninety-eight years of the former Yuan Xiangguo, the Yongding River flooded twenty-two times, and I have been in the Ming Dynasty for more than two hundred years, and the Yongding River flooded fifteen times. ”

"Then why do you have such an expression?" Seeing him with a wry smile, Gao pragmatic asked, "Let me guess...... Although the number of water disasters seems to be less, each time the harm is greater? ”

"The master said that the trouble lies in the fact that the Yongding River was mainly governed by embankments in the past dynasties, and in the end, the entire Yongding River was diverted." Zhang Jin pointed to the frozen Yongding River and said: "The lord said, before the Shang Dynasty, the Yongding River passed through Babao Mountain after leaving the mountain, crossed Kunming Lake to the northwest and entered the Qing River, and went to sea through the North Canal. Later, about the time of the Western Zhou Dynasty, the main stream was placed from the north and south of Babaoshan to Zizhuyuan, passed the pond, and entered the North Canal along the direction of the Ba River to reach the sea. Between Spring and Autumn to the Western Han Dynasty, the Yongding River goes south from Jishuitan, obliquely exits the inner city through Beihai and Zhonghai, and enters the North Canal through Longtan Lake, Empress Dowager Xiao River and Liangshui River. From the Eastern Han Dynasty to the Sui Dynasty, the Yongding River has moved to the south of Beijing, that is, from Shijingshan to the south to the vicinity of the Lugou Bridge and then to the east, between Majiapu and Nanyuan, and flows southeast through the Liangshui River into the North Canal. After the Tang Dynasty, the Yongding River below the Lugou Bridge was divided into two branches: the southeast branch was still between Majiapu and Nanyuan; The southern branch began to flow along the Feng River, and then gradually swung westward, once swinging to the Xiaoqing River-Baigou line. Since the establishment of the southern branch, the southern branch has become the mainstream. ”

It is understandable that the diversion is pragmatic, but he doesn't understand how this diversion was thought to be in trouble by the Zhang family's master and servant, so he frowned and asked: "That is to say, if there is no solid embankment repeatedly built between Shijingshan and Lugou Bridge over the years, it is completely possible for the Yongding River to flow eastward or northeast after leaving the three stores?" ”

Zhang Jin said: "Yes, the lord has checked and verified, saying that the Northern Song Dynasty Duangong planned to march into the army to crusade against the Youji Prefectures occupied by the Khitan in the second year, and Song Qi, the secretary of the Ministry at the time, made a suggestion: 'The water of the Sangqian River belongs to the northern corner of Yancheng and turns around the west wall. If the army goes to the city, this water is weighed in the northeast of Yandanling, and it is poured into the Gaoliang River, and the Gaoliang bank is narrow, and the mulberry water will overflow. It can be introduced into the suburbs of Tingdian in the east of the stationing temple, and it spreads for more than 100 miles in three or five days, that is, Youzhou is separated in the south of Shui. He believed that if the Song army was allowed to divert the water of the Yongding River around the north of Youzhou City, it would separate Youzhou from the Liao army. The lord believes that judging from the location of the place names mentioned above, the Sanggan River at that time should have flowed from the south of Shijingshan to the east, running to Yancheng, that is, the northwest corner of Youzhou, and then turning south around the west wall of the city and flowing southward. This river channel is also the foundation of the Jinkou River dug by the Yongding River water in the Jin Dynasty. Until the end of the Golden Dynasty, the river still existed. In the second year of Yuan Zhizheng, when Polo Timur and others proposed to open the Jinkou River again, Xu Youren, the prime minister of Zhongshu Zuo, strongly opposed it, saying: "The mountains and rivers of the west are high and steep, and when the Jin is destroyed, it flows into the suburbs in the north of the capital (that is, the capital of Jinzhong). Today, it is in the southwest of the capital, which is different from the past. It can be seen that the Lugou River at the end of the Jin Dynasty flows from the north of the Zhongdu City to the east. ”

Gao Pragmatic frowned slightly when he heard this, and thought to himself: How can you repair and repair upstream? In this way, after the embankment is built upstream, it is stable, but won't the downstream suffer?

Gao Shishi didn't ask out loud, Zhang Jin had already continued: "The lord has consulted the official Xiu "Tujing Chronicles" in the Hongwu period, which records that the situation of the Yongding River from the former Yuan to the founding period of the Ming Dynasty is: 'Out of the Lugou Bridge, southeast to Kandankou, Chong Break Scattered, and then divided into three: one of them diverts to the southeast, from the boundary of Daxing County to Xinhedian in Beixiang, Duzhou (that is, Xinhe Village on the west bank of the Nanliangshui River in Tongzhou District), and flows northeast, reaching Gaolizhuang in Tongzhou, and entering the Bailu River; One of them passes through Daxing County Qingrun Store (now Qingyun Store) in the southeast, and passes through Dong'an County ......; One of them passes through Liangxiang, Gu'an, Dong'an, Yongqing and other counties in the south...... It merges with the Bailu River and enters the sea. In other words, the Yongding River used to swing up and down the city of Beijing at that time, but since we built a large number of embankments, it has never flowed to the east and northeast. Although the embankment between Shijingshan and Lugou Bridge often burst during the flood season, they were quickly repaired and blocked, and the north of Lugou Bridge never became the main river channel to the east. In other words, the Yongding River is now just a river that 'passes' from the southwest corner of Beijing's suburbs. ”

Gao pragmatic said secretly: You have been talking for so long, just want to say that the Yongding River flows through solidification? I want to see it...... What you meant with a wry smile before must be because of the solidification of the river, which has led to changes in the ecological environment of the surrounding area, right?

"What happened after the Yongding River only went south?" Gao pragmatically pondered: "Lack of water in the north? ”

Due to the blockage of stone embankments or stone banks and the elevation of the riverbed caused by sediment accumulation, the surging river water can only flow straight downstream, and it is difficult to replenish enough groundwater through natural infiltration, which will make the swamps, lakes and springs on these ancient rivers shrink or even disappear, and the groundwater level drops sharply.

"Young Master Cousin sees thousands of miles." Zhang Jin praised and echoed: "The Yongding River does not go through the north of Beijing, which directly affects the water supply on the Yongding River Qinghe Ancient Road and the Jingou River Ancient Road in Beijing, and now, the water volume in these areas has been significantly reduced. The old man said that in the past, the foot of Yuquan Mountain was originally everywhere to see the spring gushing, its water into streams, lakes, densely spread in Yuquan Mountain, hot springs, Haidian area, has always been the important water source of the dynasties to build the capital, water diversion to help the water, open the field for irrigation, and build the palace, but after the major repair of the Beijing West Dam in this dynasty, it began to decline significantly. ”

Zhang Jin sighed lightly: "The master also said that the Jinshui River, which flowed into the Taiye Pool alone from Yuquan Mountain in the former Yuan Dynasty, has now been completely annihilated and abandoned; The inner and outer Jinshui rivers that surround the Forbidden City are actually just two small canals leading from Shichahai. The inner city rivers and lakes such as Shichahai (Jishuitan), which rely only on this water source, are shrinking due to the decrease in water from the upstream. From the former Yuan to the present day, it has been nearly half. In the former Yuan Dynasty, as the end point of the Grand Canal, the 'Haizi' (the name of the Yuan people for the pond) that was once lined with ship masts and sheltered from the water has now been encroached upon by large areas of streets and rice fields; The Tonghui River, which once brought glory to the north-south water transportation, has also been difficult to operate and unsustainable. ”

When Zhang Jin said this, he suddenly fell silent.

Gao pragmatic glanced at him and suddenly understood. Because of the factors that caused this great change, Zhang Siwei may dare to say it, but as Zhang Jin, he does not dare to say it.

When the Ming Dynasty built the city of Beijing, major adjustments were made to the water system: one was to divide a section of the Tonghui River east of Shichahai into the imperial city, so that the Caoyun Wharf could only be moved to the Datong Bridge outside the Dongbian Gate; The second is to build an imperial mausoleum in Changping in the north, and prohibit the use of the nearby springs and water veins as dragon veins, which leads to the upper source of the Tonghui River can only rely solely on the Xishan water system in the area of Yuquan Mountain and Kunming Lake - that is certainly not enough.

Gao Pragmatic turned his head and instructed the two who came with him to continue to stay in the carriage to keep warm, but he got out of the carriage, accompanied by Zhang Jin, walked to the river, looked at the river surging under the ice, and said secretly: The western part of the Yongding River has built a lot of river defense measures, if I want to use it to transport soap, it is basically feasible except for the freezing period, but it is not easy to do during the freezing period.

Although soap can be placed in a remote place in the capital to buy a yard and rebuild a warehouse, and it is not troublesome to build a warehouse itself, if the Yongding River cannot be used in winter, it will affect my several important ideas for the use of coal in the future, which are very important...... What to do?

After all, from Zhang Siwei's various investigations of the water system of the Yongding River that Zhang Jin just relayed, Zhang Siwei was thinking about the governance plan of the Yongding River more than ten years ago, and after Gao Pragmatic listened to this, his focus was always on his own business......

At this time, Zhang Jin remembered one more thing, and said: "By the way, Young Master Cousin, there is a legend in the capital, I don't know if Young Master Cousin has heard of it?" ”

"Legends?" Gao was slightly stunned: "What legend?" ”

"Tales of the Bitter Waters." Zhang Jin looked at Gao Shi and said.

"Bitter water?" Gao pragmatic frowned: "I haven't heard of it, what's going on?" ”

Zhang Jin smiled bitterly: "It is said that when I built Beijing City, Liu Bowen sent the general Gao Liang to chase after the Dragon King and the Dragon Mother to return to the sweet water source, but Gao Liang accidentally pierced their basket full of bitter water, and since then the water in the entire Beijing City has become bitter water...... The drinking water in Gao Ge's hometown must be the water of Yuquan Mountain bought directly from the water seller, and this is also used in the palace, but there are special people in the palace who transport water from Yuquan Mountain. But in fact, the common people can't afford to buy this water, so they can only drink the bitter water in the capital. ”

Gao realized that it must be because Beijing's annual precipitation is not much but the evaporation is strong, and after the surface runoff reduces the recharge of groundwater, the salinity in the soil will be carried to the upper layer with the evaporation of water, making the well water, which is mainly taken from shallow groundwater, generally bitter.

He smiled bitterly in his heart: It's useless for you to tell me this, I'm a little kid, even if there is a way to control the water, no one will listen, not to mention that the cost of water control is huge, what is the use of the court's current financial income the size of cat?

But thinking about it, looking at Zhang Jin's expectant look, Gao Pragmatic couldn't help but comfort: "I have some ideas about how to control the water, but I ...... right now."

Before he finished speaking, Zhang Jin's face suddenly tightened, and he turned his head sharply to look northwest.

Gao pragmatic subconsciously turned his head to look, but he didn't see anything, and couldn't help but be surprised: "What's wrong?" ”

Zhang Jin didn't answer, but ran towards the nearest tree, regardless of the cold on the tree, he put his ear on it, and then his face became worse and worse, turned around and pulled Gao Pragmatic and walked to the end of the carriage.

"Young Master Cousin, there may be a ringing horse."