Shulou(Shulou.com)11/24 Report--

This article is from the official account of Wechat: Earth knowledge Bureau (ID:diqiuzhishiju), by Luo Fang Yue.

The original title: "Shaanxi Province, can not do without it."

Author: true fruit juvenile cake

Drawing: fruit / proofreading manuscript: Gu Hanying / Editor: fruit

The Yellow River, the mother river of the Chinese people. Starting from the Bayan Kara Mountains in Qinghai Province, she spanned 5464 kilometers and finally converged into the Bohai Sea in Dongying Kenli District, Shandong Province. As the largest tributary of the Yellow River, the Weihe River, located at the base of the "several" shape in the hinterland of the Yellow River, is the mother river of the Shaanxi-Gansu-Ningxia people.

The Weihe River can seal the "several" shape by a little bit, ▼.

Weihe River Basin is located in the center of China, ▼.

What does the Weihe River look like? How did it become clearer and clearer?

To clear the source of the Weihe River, the north and south separated the Weihe River in ancient times, which originated from the Qingyuan River in Weiyuan County, Gansu Province. after flowing through the Loess Plateau, it entered the Tianshui Basin, and then went out of Baoji City to the Weinan River Basin in the east. After passing Xianyang, Xi'an, Weinan and other big cities, finally injected into the Yellow River in Tongguan County, Shaanxi Province.

The upstream bird and mouse mountain is better known.

Further south, there is actually Qingyuan River ▼.

In the eyes of many people, the vast Guanzhong Plain is synonymous with the flow of the Wei River. But in fact, the Weihe River basin includes not only Baoji City, Yangling demonstration Zone, Xianyang City, Xi'an City, Tongchuan City and Weinan City in Shaanxi Province, but also Yan'an City in Northern Shaanxi Province. There are 84 counties (cities and districts) in Gansu Province, including Dingxi, Pingliang, Qingyang, Tianshui and Guyuan in Ningxia Hui Autonomous region.

Weihe River nourishes not only ▼ in Guanzhong Plain.

Like most rivers, the continuous flow of the Weihe River requires power from the upper reaches. By converting the potential energy into kinetic energy to ensure that the amount of water is sufficient to compensate for the consumption caused by evaporation and leakage, the river is finally formed.

At present, there are still differences in the formation and evolution of the Weihe River. Some people think that the Weihe River is the ancient channel of the Yellow River, while others think that the Weihe River is the "mother river" of the Yellow River, that is, before the Yellow River appeared, the Weihe River flowed to the ancient Sanmen Lake. Although the views are different, it is certain that there is an important relationship between the formation of the Weihe River basin and its geological foundation and primitive geomorphology.

Tongguan stands at the confluence of the two rivers

You may also wonder which one appeared first, the Yellow River and the Weihe River over the past thousand years.

In the geotectonic location, most of the Weihe River Basin belongs to the Weihe River Basin. The basin is located in the convergence zone of plate system. It is bordered by the Ordos platform in the north, the East Qinling orogenic belt in the south and the southwest Ordos fault system in the west. The Yanshan movement occurred in the Mesozoic Jurassic period, which led to the fault depression of the Weihe basin and expanded to the west. After that, during the Cenozoic Himalayan movement, the Weihe basin extended eastward to the Fenhe basin.

Over the course of millions of years, geological movements were carried out intermittently. When the local crust rises, the current erosion intensifies and the river cuts down; when the earth's crust is relatively stable, the river often undergoes lateral erosion and accumulation, so it develops continuously.

It can be said that the geomorphology of the Weihe River basin is the largest tributary of the Yellow River formed by the tectonic movement at the end of the Yanshan Movement and the Himalayan Movement, and then after climate change, water erosion and man-made influence.

The largest tributary of the Yellow River was not formed in a day.

Today, the Weihe River basin covers an area of more than 134700 square kilometers, and its water system is distributed asymmetrically in Guanzhong, with obvious differences between the north and the south.

The north tributary is obviously diverted from the trunk in a feathery shape.

On the south side, ▼ is blocked by Qinling Mountains.

Originated from the north bank tributary of the Loess Plateau, it has a long history and a large catchment area, showing a dendritic water system from northwest to southeast, and finally converges into the Yellow River. Among them, the largest tributary of the Weihe River, the Jinghe River, and the second largest tributary, the Beiluo River, with a basin area of 45000 square kilometers, are all developed on this side.

At the confluence of the Jinghe River and the Weihe River, the color gap is obvious.

This is the origin of the idiom "distinct".

Compared with the north bank, the tributaries of the south bank of the Weihe River appear to be less "public". The south bank of the Weihe River is the steep Qinling Mountains, the short and urgent tributaries are distributed in the dressing water system, the specific drop of the river bed is large, and the catchment area is small. However, it is such a short-flowing river that has formed a "Qinling 72 valley" like a wandering dragon, which has become a good place for Sanqin residents to recuperate. In addition, the Bahe River, the longest tributary in the south, has also become a valuable resource for ecological conservation in Xi'an.

The urban development of Xi'an has long been integrated with the Bahe River.

From the east-west flow direction, the Weihe River basin can be divided into three sections, namely, the narrow valley, the fast current, the source of the full-length 433.4km to the upper reaches of Baoji Gorge, the wide channel, the scattered flow, the middle section of the full-length 176.6km from Baoji Gorge to Xianyang Railway Bridge, and the lower Guanzhong section with reduced specific drop, river siltation and full-length 208km.

Adding these three sections together, it is the total length of the main stream of the Weihe River basin-- only 818km. Compared with the Han River (1577 km) and the Jialing River (1345km), which are tributaries of the Yangtze River, this length is really not a major river.

Although it is the first tributary of the Yellow River

It doesn't stand out in terms of the length of the river.

(the following picture shows a rough comparison of the length of the three rivers, not the real geographical location) ▼

However, I do not know whether it was the reason why the fertile fields of Guanzhong, which was formed in the middle and lower reaches, created the Zhou, Qin, Han, Tang and other powerful dynasties. From ancient times to the present, the "temper" of the Weihe River is not small.

In the run pass of Weihe River, the flood irrigation area in China is one of the countries with the most flood disasters in the world. During the two millennia from 206BC to 1949, there were 1029 floods, almost once every two years. Among them, the Yellow River is the most serious. According to statistics, the Yellow River has made more than 1500 breaches in history, with an average of one breach every three years and a major diversion every 100 years.

As the largest tributary of the Yellow River, the Weihe River is also prone to flooding. The jingle widely circulated in the middle and lower reaches of the Weihe River: "heavy rain, light rain and nine waterlogging in ten years" is proof of this.

With the volume of the Yellow River, every flood disaster occurs

Will cause irreparable damage to the natural environment and normal human life.

According to historical records, there were 135 floods in the main stream of Weihe River during the 417 years from 1532 to 1949, with an average of one flood every 3.2 years. Among them, the flood occurred in 1895, which led to the northward shift of the main channel of the Weihe River and the northward extension of the largest tributary of the Bahe River into the Weikou River for nearly 4250 meters.

As a sandy river supplied by Rain Water, the average annual runoff of the Weihe River is 10.37 billion cubic meters. The flood season of the Weihe River is from July to October every year. Among them, the amount of water in July and August can account for 70% of the total water in the flood season. A large amount of water will not only bring flooding to the lower reaches, but also aggravate erosion and erosion in the basin, endangering the production and life safety of people on both sides of the river.

(photo: official website of Shaanxi Daily) ▼

Since ancient times, people began to transform the Weihe River to build irrigation canals and transfer water across regions to control floods. One of the most famous is the Zheng Guoqu built by the Korean hydrologist Zheng Guo during the warring States period. In 246 BC, in order to consume the manpower and material resources of Qin, South Korea sent Zheng, a spy, to dig canals in the State of Qin, which took a total of 10 years (246-237 BC) to build water.

Zheng Guoqu starts from the mouth of the Zhongshan bottle bottle of the Jinghe River in the west, passes through the rivers such as Gushui, Qingshui, Muddy Water, Jushui and lacquer Water, and infuses Luoshui into the income canals such as Shichuan River and Qinghe River along the way. Among them, the canal head project located in Zhongshan is an important hub to ensure the safe operation of the canal.

Even if it is "the trick of tired Qin"

But it is also the first large-scale water conservancy project to be carried out in Guanzhong.

It deserves to be called "the first canal in the world" ▼.

The head of Zheng Guoqu is located at the fault zone on the northern margin of Guanzhong basin, making use of the difference of topography to raise the water level and cut off Jing water into the canal. The fault has a strong tectonic activity in the Cenozoic and continues to uplift in the north, resulting in a strong erosion under the canal of Zheng. In the position below the valley mouth, the unstable loess which is easy to be lost at the diversion mouth is also easy to be washed away under the action of long-term water erosion.

It is such a water conservancy ditch which does not have great advantages in geological conditions, but ensures that a sufficient amount of water enters the Guanzhong irrigation area, and at the same time plays the role of flood discharge and preventing the irrigation area from being flooded, making it a fertile field.

Relying on the heavy history of Zheng Canal and the rich landscapes around it.

Zheng Guoqu Scenic spot has become the first choice for many visitors to explore history and water conservancy culture.

In addition to Zheng Guoqu, many ancient canals, such as Bai Gong Canal, Cao Canal, Chengguo Canal, Longshou Canal and other ancient canals in the Wei River basin, also sheltered one side of the soil and water peace. Although most of the Zheng canals can no longer operate normally, its advanced way of water control provides a reference for later generations to control the Weihe River basin.

Longshou Canal was successfully selected into the World Irrigation Project Heritage list in 2020.

(photo: special feature film of Longshou Canal diversion Luogu Irrigation District) ▼

At the beginning of the 20th century, the famous hydraulic scientist Li Yicheng, the pioneer of modern water conservancy construction in China, put forward the advanced proposition of harnessing the Weihe River on the basis of previous experience. Mr. Li Yicheng believes that the governance of the Yellow River should be carried out in parallel with the upper, middle and lower reaches, which has changed the idea that for thousands of years only focused on harnessing the irrigation areas in the lower reaches of the Yellow River.

On the basis of Zheng Guoqu, he presided over the construction of Jing, Wei, Luo, Mei, eight, Heihe, waterlogging, Guanzhong Bahuiqu. Today, these canals are still benefiting the people along the coast.

Zheng Guoqu was reorganized by Li Yicheng in 1932.

Renamed Jinghui Canal

(figure: www.cnbksy.com) ▼

"the canal irrigates 610000 mu of farmland."

(figure: www.cnbksy.com) ▼

Entering the new century, people still do not stop the treatment of the flood disaster of the Weihe River. In 2015, the three flood diversion areas of Luofu, Changjian and Liuye of the Weihe River regulation project were completed. Subsequently, the emergency flood storage and detention project and the backflow prevention project of the Nanshan tributary of Erhua have also been operated one after another. This wave of operation has enabled the division and control of the trunk and tributaries of the Erhua section of the Weihe River, and we will try our best to prevent the floods that come every year.

The Erhua section of Weihe River belongs to Huayin City.

Now the green mountains and rivers can stay for a long time.

In addition to keeping the water of the Weihe River under control, it is also necessary to make it clear.

In ancient times, the Weihe River was the source of water supply in the hometown of emperors. Today, the Weihe River still carries the rest and recuperation of the people on Qinchuan for eight hundred miles. However, with the aggravation of climate change and man-made influence, the Weihe River basin is facing the shortage of water resources, pollution crisis, substandard water quality in many river sections, poor water quality and so on.

Like the limerick in "washing rice and vegetables in the 1960s, washing clothes and irrigation in the 1970s, fish and shrimp absent in the 1980s, and unbearable smelly water in the 1990s," which was widely circulated on the banks of the Weihe River, the Weihe River has been used as an discharge channel for agricultural and industrial wastewater for a long time.

For sandy rivers

Any kind of water pollution will make things worse.

In the fifties of last century, people began to explore the governance of the Weihe River. During this period, mainly to explore the management of flood disasters, do not pay much attention to ecological problems.

In the 1960s and 1970s, people began to emphasize "taking grain as the key link", combining water control with agriculture, recommending a large number of tree planting, and focusing on the development of agriculture, forestry, animal husbandry and sideline. In the 1980s and 1990s, different from the previous individual projects, comprehensive management measures of small watersheds such as mountain sloping land and gully land were put on the agenda.

Weinan Section of Weihe River Control and guidance Project photographed in 1987

(figure: swj.xa.gov.cn) ▼

In the 21st century, in order to strengthen the efforts to clear the waves of the Weihe River, the scale management of the comprehensive system based on ecological restoration has become the main task, and people have changed the relatively single and other superficial treatment methods in the past. Two three-year action plans for the prevention and control of water pollution have been carried out successively, and the ecological zone of the Weihe River has been established one after another in the area of 512 km long main river of the Weihe River.

Such a beautiful scene

It was still an extravagant hope on both sides of the Weihe River in the last century.

Among them, Shaanxi Province, which occupies nearly half of the Weihe River basin, has contributed a lot to the management work.

During the 12th five-year Plan period, Shaanxi Province spent a total of 21.5 billion yuan on the regulation project of the Weihe River, built 630km of dikes, 150000 mu of ecological wetlands and water surface landscape, and basically improved the flood control system of the Nanshan tributaries in the lower reaches of the Weihe River.

In addition, the construction of artificial wetland landscape such as Xi'an Weihe Caotan Weihe River Ecological Landscape area, Mei County Weihe Wetland Park and Weinan Wetland Park are all important parts of Weihe River ecological management.

With the improvement of ecological consciousness

The city began to combine the treatment of Weihe River to build a modern wetland park.

According to the Water Ecological Restoration Plan of the Weihe River Basin in Shaanxi Province, by 2025, the Weihe River will become a benchmark river for ecology, landscape, culture and prosperity in the tributaries of the Yellow River, and reach a benign man-land relationship with both sides.

From the rich scenery of "eight Rivers around Chang'an" in ancient times, to today's clearer and clearer Wei River, in the long river of time, the Weihe River has constantly nourished the land of Guanzhong and become a well-deserved mother river for the sons and daughters of the three Qin dynasties. With the continuous progress of ecological management dominated by natural restoration and supplemented by artificial restoration, it is believed that the comprehensive environmental conditions of the Weihe River basin will be significantly improved.

Reference:

1. Li Zhichao. (2017). Cenozoic Lithofacies Palaeogeography and Environmental Evolution in Weihe Basin (doctoral thesis, Northwestern University).

two。 Zhang Bo. (2021) Analysis of eco-environmental problems and control measures in Weihe River basin. Groundwater (03), 301-303.

3. Yang Jinhui. (2008). The changes of Weihe River in Guanzhong Plain in Historical period (Master's thesis, Shaanxi normal University).

4. Wang Yifei (2019). Study on performance Evaluation of Ecological Restoration of Weihe River Basin in Shaanxi Province (doctoral thesis, Northwest University of Agriculture and Forestry Science and Technology)

5. Zhao Mei. (2012). Study on the characteristics of stagnant sediments of paleo-flood in the middle reaches of Weihe River (Master's thesis, Shaanxi normal University).

6. Wang Deyao, Liu Yufeng & Guo Lingxia. (2021). Comparative analysis of water conservancy projects between Dujiangyan and Zhengguo Canal. Journal of Xianyang normal University (06), 65-71.

7. Http://slt.shaanxi.gov.cn/ztzl/sxswhstqjsglgc/whstqyw/201707/t20170726_1774165.html

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