The river in Baoshan | Wu Jianguo

A corner of Shanghai Wusongpao Taiwan National Wetland Park, which was once a slag backfill beach and an iron sand quarry. Photo: Xinhua News Agency

In the spring of 1975, tens of thousands of middle school students from Baoshan County came to Baoshan Central Hospital in batches to participate in the "Fly Selection" physical examination, and I had the honor of becoming one of several qualified people. From the suburban countryside to the county armed forces department to review the body, fill out the political review form, Aunt Qian Yanru arranged for us to stay in the county government guest house. I was 16 years old, and the first time I left my parents to come to the county town, everything was so new and strange. There is a river in front of the guest house, and whenever you see the tide rising and falling, and seeing the weeping branches of poplar trees gently swaying on the river, it feels like you are still at home.

In the next twenty years of flying, whenever I went anywhere, I saw the river, and I remembered the river in my hometown. In almost every city, there is a river known locally as the Mother River, and the host will praise their Mother River from the perspective of historical geography, cultural legends, folk customs and so on. But in my heart, the river of Weibao Mountain is the most beautiful. The beauty of the river in Baoshan lies in the law of tides: the tide rises and falls, and the tide falls, and such flowing water is alive. On the eve of the new century, I returned to Baoshan, which was a real landing, and I couldn't wait to find the river that was imprinted in the heart of a teenager.

1.

The ancient town of Luodian is named after Luo Sheng's shop here to form a market. It was around 1350 A.D., nearly seven hundred years ago. Luodian is within the administrative division of today's Baoshan, and is the first place in Baoshan District to become a city and a town. At that time, choose a sunny sunset, stand on the arch bridge and look northeast, today The direction of Yuepu Yangxing Wusong is still in the direction of the rolling Yangtze River tide, and the clear shoreline nearby is extending west-south along the direction of today's Hutai Road.

Luodian stood firmly in front of the waves of the Yangtze River, the ultimate reason was the Nine Peaks and Twelve Mountains behind him, and the land plate that had been formed in Songjiang Qingpu Jiading. The direction of the Yangtze River flow in this area of the estuary, under the action of the moon and the gravitational force of the sun, a regular stop rise occurs, the tide and the fresh water discharged by the Yangtze River are combined, and the water level in this area rises rapidly, which is the tide of the Yangtze River estuary, which rises twice a day, and then the rapid discharge in the tide after two flat tides.

Most of the sediment brought by the upper reaches of the Yangtze River is rapidly precipitated and condensed underwater in the half hour of the flat tide, which is the formation characteristic of the alluvial plain. The accumulation of silt is a long process, gradually growing up to sea level over time... The concept of the river begins at this moment: at low tide, the water quickly recedes, the water left on the mud surface, because the roots of the grass, reeds, wild white and poplar trees are rooted in the soil, blocking the flow of water, the roots of these plants are relatively compacted, the flow direction of the water will avoid them, the water rushing east and west on the mud surface, looking for a low level on the tidal flat, even if it is a shallow watermark, will follow the traces of this flowing water, find the Yangtze River in the deep water area. And the traces of this flowing water are the beginning of the river. At low tide, the discharged water will flow along this path to the deep water area, and there are many tributaries, so that the amount of water that converges on this waterway determines the width and depth of the river, and at the time of high tide, the water flows up from the river and then reaches all the small rivers.

As a river, the status is thus determined. Therefore, the river of Baoshan is a tidal river, and the density of the tidal river channel must be the highest.

2.

The Wusong zero point is the earliest established elevation datum in China. After 1860, an artificial water level station was set up on the Huangpu River in Zhanghuabang, which was less than three kilometers away from the Yangtze River. Based on the record of water level observations between 1871 and 1900, the elevation of the lowest water level was determined. The significance is that the concept of altitude in China began with Wusong in Baoshan, Shanghai. Until the 1950s, the state measured the average sea level in the Yellow Sea, thereby determining the zero-meter reference point of China's altitude, known as the Chinese elevation or the Yellow Sea elevation. In 1985, China's elevation was 1.717 meters lower than Wusong's elevation. Compared with the elevation of this country, the highest elevation in Shanghai is DajinShan, which is 103.7 meters, Tianma Mountain in Songjiang, is 98.2 meters, and the east coast of Chuansha and Nanhui is -1 meter. However, the determination of water level elevation throughout China still uses the Wusong zero point. For the people of Baoshan, the most intuitive is the water level clock built here in Wusongkou in 1912, its zero indication plus 1.717 meters, which is the zero altitude of the land under our feet today.

The altitude of the Baoshan area varies, most of the area is around 2 meters, while in some parts of the Tsukiura area, the altitude is -2 to -3 meters. For example, on the fifteenth day of the sixth month of the lunar calendar, the highest water level indicated by the Wusong water level clock is 4.153 meters, and at this moment, the altitude of the tide level is 2.436 meters, and the ground level of the entire territory of Baoshan is below the water level. Therefore, the construction of the bank is the foundation for the survival and life of the ancestors of Baoshan Mountain; the construction of the embankment along the Yangtze River to block the water is the painful knot and heavy burden of the people living in this land. Until the 1930s, the progress of modern industry, the machine was used to dig mud to build shores, the Yangtze River levees became unprecedentedly tall and indestructible, and after liberation cement was widely used, in every estuary connecting the Yangtze River, large sluices were built, including the Huangpu River connected to the Algae Hama, and all its estuaries were also built sluices. To this day, the total number of sluice gates used and abandoned in Baoshan is difficult to count.

The sluice gate regulation controls the flow of water entering the river, keeps the tide out of Baoshan Mountain, and perfectly plays the function of drainage. This is conducive to human habitation and survival, to the cultivation of farmland and stable harvest. However, blocking the natural flow of the tide, many rivers have become backwater, so that the function of shipping is gradually exhausted, and the social ecology has changed from slow rowing to convenient land travel! In the process of road construction, building bridges is the biggest investment, and burying the river is the easiest way, that is, in this time period, most of the small rivers are filled in. The second peak of the landfill channel was in the 1950s, when schistosomiasis was discovered in the south of china, and the snail was the source of infection for this terrible disease, and the snail grew in a small river where the water flowed still. The third peak of the landfill river was in the early 1970s, when the country's population peaked, food was scarce, the river flats were turned into fertile land, and the biggest obstacle to agricultural mechanization was the ditch. Since then, almost every production team has abandoned the ship and purchased tractors. The fourth stage is the large-scale development of this era, whether it is industrial projects or residential projects, in a sense, the landfilling of rivers and the reconstruction of flowing water pipelines. Today's young people in Baoshan will not believe that beneath the bustling north wing commercial street, there is originally a river with rolling waves.

The rivers of Baoshan that we see today have been "modified", and the characteristics are: one is to straighten, the original direction is basically gone; the other is that the end of each river is a sluice gate. Such a river, which only has the function of water storage and irrigation, basically loses the function of shipping and the exchange of water bodies in the tidal tides of the Yangtze River. After countless small rivers were buried, the only rivers in Baoshan today are: Fernandohama, Lianqi River, Gujing River, Chuansha River, Malu River, Meipu, Beisitang, Shapu, Zoumatang, Yangjing, Xincha River, Taopu, Ximitang, Dongjingjing, Xisitang, Nansitang, Dijing, Panjing, Yangshenghe... These rivers rarely intersect with each other, but they eventually flow to the Yangtze River.

3.

Most of the estuaries of rivers have tidal laws, Hangzhou Bay near the mouth of the Yangtze River and the northern irrigation estuary, the kinetic energy of the tide is huge, only because the concentration of chloride (salt) in the water body reaches more than 3000 mg / l, and when the tide rises, it is rejected outside the sluice gates of each tributary. The estuary of the Yangtze River benefits from the huge amount of water coming from upstream, the time of the annual salt tide is only one week or less, and the relative concentration of chloride is below 300 mg/L, but this is the chloride content that is fatal to plants on the land and freshwater aquaculture. Therefore, at the mouth of the Yangtze River, the South Confluence of Chuansha on the south bank, the Qidong in Jiangsu on the north bank, and Chongming Island and Hengsha Island, which face the East China Sea, have maintained a high degree of vigilance and cannot let the salty tide pour into the river. Baoshan is the area least affected by salt tide in the estuary of the Yangtze River (the longest time was in February 2004, when the salt tide arrived at the Chenhang Reservoir in Baoshan District), which is almost completely freshwater tidal environment, which is a gift from The Heavens to this area of Baoshan.

On the west coast of the Pacific Ocean, areas with completely freshwater environments, tidal kinetic energy, and well-defined tidal laws may only exist in Baoshan District, Shanghai. Traced back to the next door to Taicang Nantong, due to insufficient tidal kinetic energy, it is impossible to complete the water exchange of rivers on land during a tidal process. Only Baoshan has such unique natural conditions, therefore, only Baoshan can do the article of the tidal river.

Even existing rivers can be replaced in a single tidal wave throughout Baoshan. However, the feeling of the citizens today is that the river in the area is always static, it is rare to see the opening of the gate to release water into the river, the water quality of many tributary rivers is blackened, and the river surface is full of green algae, but the sluice gate is still tightly closed. Therefore, some citizens suggested: at the middle and low tide levels, open the sluice gates and let the currents in the Yangtze River naturally enter and exit our rivers.

If the floodgates are opened to a limited extent, allowing the current of the Yangtze River to enter baoshan from the sluices along the Yangtze River and the Huangpu River and the Algae Hama – the extent of this basin has reached parts of Putuo and Jiading Districts, with a total area of more than 600 square kilometers – purely from a livable point of view, such as the first or fifteenth day of the first lunar month, starting at seven o'clock in the morning, the river in front of you, the river begins to rise; at 12 o'clock in the afternoon, it rises to the upper edge of the riverbank, and the wind blows softly, and the waves in the river splash under your feet Then the river began to recede gradually, and by 6 o'clock in the evening, in the shallow water of the riverbed, small fish and loach were cruising, the river slopes were crawling with snails, the river mussels spitting out clear water from the mud cracks, and the frogs jumping around on the grass... At 7 p.m., the river began to rise again, and the full tide was in the dream of the Baoshan people! Such a river, such a rise and fall, can make the self-purification ability of the water on the land and in the river channel to the extreme. The crops growing on this land will have the least pests and diseases, and the people living here will have the most peace and nourishment in their hearts!

Because of water in the world, everything flourishes and life continues. Baoshan is a city because of water, and prospers because of water; compared with a river flowing from a source, the water of the tidal river rises and falls, and it has more vitality. In the land of Baoshan, the river is sacred, and every primordial river is formed in the synergy of nature, and her life is connected with all living beings on the shore. Today, we guard every river and love her as if it were our own life, because following their names, even in the distant future, there will still be people who can read the river of Baoshan and the story of an era.

2021/8/8

Author: Wu Jianguo

Editor: Qian Yutong