How important is Poyang Lake?

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Overlooking the panoramic view of Poyang Lake. Photo / NASA official website

Poyang Lake. What's wrong?

Poyang Lake is in a hurry!

On July 11, in the water level well of Xingzi Station, the landmark hydrological station of Poyang Lake, the water level of the lake reached 22.74m, exceeding the 1998 flood water level 13cm, breaking through the historical extreme value since hydrological records began, and the flood control work of Jiangxi Province entered a state of war.

The flood has affected 5.213 million people in Jiangxi Province, affecting an area of 455700 hectares of crops and causing direct economic losses of 6.49 billion yuan.

What is more worrying is that at present, the water level of Poyang Lake is still rising, with an area of 4206 square kilometers, the largest in 10 years. According to the inference of relevant experts, according to this rising rate, the area of Poyang Lake is very likely to surpass Qinghai Lake, from the second largest lake in China to "the largest lake in China" briefly, and the flood control pressure of cities in the lower reaches of the Yangtze River is also increasing with the expansion of the area of Poyang Lake.

On July 11, 2020, Poyang Lake, where the water level continues to rise, shows Shoe Mountain on the top and Nanji Township in Nanchang on the bottom. Picture / people's Vision

Why Poyang Lake?

During the subsequent 20 million years of the Himalayan movement, the mountains continued to rise and became Mount Lushan today. While the basin continued to sink, the earliest Poyang Lake was formed, that is, Peng Lize recorded in the documents of Qin and Han dynasties. After the Han Dynasty, the main river of the Yangtze River moved southward, the north of Penglize gradually shrunk into many small lakes, while the south gradually developed into the scale of Poyang Lake today.

Because Poyang Lake is an overflowing, throughput and seasonal lake in the Yangtze River basin, its size is "erratic", forming a unique landscape of "high water is a lake, low water is like a river". Specifically, the lake facies appears in the flood season, and its area can reach more than 4125 square kilometers when the water level is more than 20 meters; in the dry season, the river facies appears, and when the water level is 12 meters, its area is only 500 square kilometers.

The relationship between Poyang Lake and its water system and the Yangtze River. Cartography / Paprika

The sharp rise in the water level of Poyang Lake has a lot to do with the Yangtze River.

When the Yangtze River galloped eastward from the Qinghai-Tibet Plateau, it recruited troops and horses all the way, bringing many rivers on both sides of the strait under its command, and when it flowed to Hukou County, the northernmost part of Poyang Lake, the demarcation point between the middle and lower reaches of the Yangtze River, seven of its eight major tributaries had been accepted. Recently, the Yangtze River, which is "full of flood", is like a drunken man with a stomach full of wine. When he sees Poyang Lake, he can't wait to open his mouth and release part of the flood into Poyang Lake. As a result, Poyang Lake was overwhelmed and the water level rose sharply.

But it is also unfair to throw all the pots with rising water levels in Poyang Lake to the Yangtze River.

Two days ago, northern Jiangxi was repeatedly hit by torrential rain or torrential rain, with precipitation more than three times that of previous years, and the cumulative rainfall of Xiuhe River, Raohe River and Poyang Lake region was as high as 300-500 mm.

The continuous rainfall has sent the topic of "the reappearance of Lushan Falls, the flow of water pouring down from a height of 3, 000 feet, a magnificent landscape" on Weibo. But now it seems that when the five major rivers in Jiangxi are rushing to Poyang Lake, continuous rainfall seems to be more harmful than the magnificent waterfall landscape.

Poyang Lake, the "lifeline" of the middle and lower reaches of the Yangtze River

There are few tributaries in the lower reaches of the Yangtze River, and Poyang Lake is the last reservoir before the Yangtze River enters the lower reaches. If the water level of Poyang Lake continues to rise and the flood discharges, the harm to the Yangtze-Huaihe River and Taihu Lake basins in the lower reaches of the Yangtze River will be unimaginable. To guard Poyang Lake is to keep the safety of the cities in the lower reaches of the Yangtze River.

Poyang Lake has a prominent position in the middle and lower reaches of the Yangtze River, and has a second to none and irreplaceable important position in Jiangxi Province.

First of all, Poyang Lake and its water system have made great contributions to the economic development of Jiangxi. It is no exaggeration to say that Poyang Lake and its water system have fed the sons and daughters of Jiangxi on their own.

When the swift water of the Yangtze River and the rivers of Ganjiang, Xiushui, Xinjiang, Raohe and Fuhe flow into the flat and open Poyang Lake, a large amount of sediment is deposited, giving birth to fertile fields here. Jiangxi people built fields around lakes, raised fish and planted rice here. In the Song Dynasty, Jiangxi "endowed millet lost to the capital as the best in the world", and has become a rich and comfortable "land of fish and rice".

The west road in the south of the Yangtze River. Cartography / Paprika

The big grain growers in Junqiao Town, Hukou County, Jiujiang City are ploughing the early rice fields. Picture / people's Vision

Throughout the economic development trend of Jiangxi from the pre-Qin period to modern times, we will find a magical phenomenon: when the area of Poyang Lake expands to the maximum, it happens to be the stage of Jiangxi's economic rise and development, and when Poyang Lake gradually shrinks, Jiangxi's economy is also gradually retrogressing.

Secondly, Poyang Lake and its water system and wetlands have also made great contributions to the regulation of Jiangxi's regional climate.

Due to the great fluctuation, Poyang Lake presents a variety of wetland landscape distribution patterns, such as lake wetlands, beach wetlands, river wetlands, marsh wetlands, lakeside wetlands, delta wetlands and artificial wetlands, which effectively regulate the climate of Jiangxi. Therefore, it is known as "the kidney of Jiangxi".

The white crane population living around these wetlands accounts for about 98% of the world's total, and is home to the largest overwintering white crane population in the world. In addition, hundreds of thousands of rare migratory birds come here every winter. There are 30000 wild geese we know best, which is home to the largest population of wild geese in the world.

In 1992, Poyang Lake was listed in the list of important wetlands in the world, and the main protection objects were rare migratory birds and wetland ecosystems.

In the wetland of Poyang Lake in Yongxiu County, two herons are at loggerheads, competing for food. The creativity of picture / picture worm

However, thousands of years of sediment deposition, man-made reclamation of the lake, overfishing and other activities have made the water storage capacity of Poyang Lake smaller and smaller-which is also one of the reasons for the rise of Poyang Lake water level.

After the disaster, the flood control and drought relief headquarters of Jiangzhou Town, Jiujiang City issued an open letter calling on Jiangzhou young adults to return home to fight the flood. In just two days, 1500 Jiangzhou people who work outside have returned to their hometown. May the heroes be safe and the mountains and rivers be safe.