Loess And The Huang He: A Pollution Story

The Loess Plateau, a highland area in north-central China, is a plateau formed of loess, a clastic silt-like sediment formed by the accumulation of wind-blown dust. The Huang He, or Yellow River, is a river that passes through seven present-day provinces and two autonomous regions in China. The Loess Plateau surrounds the Yellow River and includes parts of the Chinese provinces of Qinghai, Gansu, Shaanxi, and Shanxi. The river is notable for the large amount of silt it carries, with 1.6 billion tons carried annually at the point where it descends from the Loess Plateau. The riverbed has been raised several meters above the surrounding ground due to excessive sediment deposits. This has led to the river being called the 'Earth Suspended River'. The Loess Plateau contributes 90% of the sediment load of the Huang He, affecting river navigation, seasonal floods, and water quality for the middle and lower portions of the river.

The Loess Plateau's soil is highly susceptible to erosion due to sparse vegetation, heavy rainfall, and gullying

The Loess Plateau is a plateau in north-central China formed of loess, a clastic silt-like sediment formed by the accumulation of wind-blown dust. It is located southeast of the Gobi Desert and is surrounded by the Yellow River. The Loess Plateau is part of the Central East Asian Forests subrealm and is made up of three ecoregions: Central China Loess Plateau Mixed Forests, Huang He Plain Mixed Forests, and Bohai Sea Saline Meadow.

The Loess Plateau's soil is highly susceptible to erosion due to several factors, including sparse vegetation, heavy rainfall, and gullying. Firstly, sparse vegetation cover on the plateau has been a significant contributing factor to soil erosion. Human activities, such as farming on steep slopes, have exposed the loess materials, making them more vulnerable to erosion. Overgrazing has also led to land degradation and reduced vegetation cover. In addition, the steep slopes and poor vegetation coverage have favored the development of vertical loess joints, further exacerbating erosion.

Secondly, heavy rainfall and storms in the region have intensified soil erosion. The pulsed events of rainstorm erosion on the Loess Plateau are well-documented. Rainfall, particularly in the form of rainstorms, is the primary driving force behind soil erosion on hillslopes. The high-intensity and short duration of heavy rainstorms accelerate storm runoff erosion, leading to gully erosion on the slope surfaces. The infiltration-excess runoff in the loess hilly region further contributes to the erosion process.

Lastly, gullying, or gully erosion, is another critical factor in the susceptibility of the Loess Plateau's soil to erosion. While vegetation measures can help control erosion on gentle slopes, gully erosion in loess hilly areas with high valley density and deep dissected valleys cannot be effectively mitigated by vegetation alone. The combination of heavy rainfall and gullying accelerates the erosion process, making the Loess Plateau highly susceptible to erosion.

The soil erosion in the Loess Plateau has had significant impacts on the Yellow River. The middle stream of the river passes through the plateau, where substantial erosion takes place. The large amount of mud and sand discharged into the river from the eroded plateau contributes to the Yellow River being the most sediment-laden river in the world. The excessive sediment deposits have raised the riverbed several meters above the surrounding ground, earning it the name "Earth Suspended River."

The Yellow River is the most sediment-laden river globally due to the large amount of mud and sand discharged from the Loess Plateau

The Yellow River, also known as the Huang He, is the world's most sediment-laden river. This is due to the large amount of mud and sand discharged into the river from the Loess Plateau, a highland area in north-central China. The plateau, which covers parts of Qinghai, Gansu, Shaanxi, Shanxi, and Henan, is the largest continuous deposit of loess in the world. Loess is a clastic silt-like sediment formed by the accumulation of wind-blown dust, giving the river its characteristic yellow colour.

The Loess Plateau is characterised by its high elevation, averaging about 4,000 feet (1,200 metres) above sea level. The loess forms a continuous deposit on the land, ranging from 165 to 260 feet (50 to 80 metres) deep in most places, but reaching up to 1,000 feet (300 metres) in some areas. The plateau's height and morphology vary across its expanse, with one of its highest mountains, Mahan Mountain, reaching an elevation of around 12,040 feet (3,670 metres).

The Loess Plateau is subject to substantial erosion due to several factors. Firstly, the sparse vegetation and intense summer rainfall contribute to significant water erosion, creating deep ravines, gorges, and barren hills in the landscape. Additionally, human activities such as farming on steep slopes, overgrazing, mining, and construction further exacerbate soil erosion. The region's agricultural activities, which make up more than 70% of slope land usage, expose the loess materials, making them susceptible to being washed away by heavy rainfall and storms, leading to serious soil erosion.

The Yellow River's middle reaches, which pass through the Loess Plateau, contribute 92% of the river's silts. The river carries an estimated 1.6 billion tons of silt annually as it descends from the plateau, with 1.4 billion tons being transported to the sea each year. This excessive sediment load has raised the riverbed several meters above the surrounding ground, earning it the name "Earth Suspended River". The high silt content in the river has significant impacts on river navigation, seasonal flooding, and water quality for the middle and lower portions of the river.

The Loess Plateau is the largest continuous deposit of loess in the world, with layers averaging 165-260 feet thick

The Loess Plateau is a highland area in north-central China, covering parts of Qinghai, Gansu, Shaanxi, Shanxi, and Henan provinces. It is the largest continuous deposit of loess in the world, with layers averaging 165-260 feet (50-80 metres) thick. In some parts of the plateau, loess deposits can be as thick as 1,000 feet (300 metres). The plateau takes its name from loess, the term for deposits of fine-grained, yellowish, windblown soil.

The Loess Plateau is surrounded by the Yellow River (or Huang He) and includes the middle part of its basin. The river is the most sediment-laden river in the world, carrying 1.6 billion tons of silt annually at the point where it descends from the plateau. The plateau's loess has been eroding into the river for thousands of years, giving the Huang He its characteristic yellow colour. The river's high sediment load affects river navigation, seasonal flooding, and water quality downstream.

The Loess Plateau's geomorphology typically changes from rocky mountains to alluvial plains at the piedmont to river valley belts. The height of the mountains varies, with Mahan Mountain reaching an elevation of around 3,670 metres (12,040 feet). The mountain slopes were once forested, but today, the region is mostly devoid of trees due to centuries of agricultural activities, timber harvesting, and environmental damage caused by massive grass fires set during the Ming Dynasty to keep the Mongols at bay.

The Loess Plateau has been an important agricultural region for thousands of years, providing grain, lumber, and livestock to the expanding Chinese empire centred on the Wei River and the Huang He. Today, agriculture remains the most important economic activity in the region, with over 70% of slope land used for farming. However, farming activities on steep slopes have exposed loess materials to erosion. Heavy rainfall and storms can easily wash away the loess, causing serious soil erosion. The Chinese government has implemented programs to control erosion through afforestation and terracing, promoting sustainable farming and soil conservation strategies.

Intensive farming, mining, and construction activities on the Loess Plateau contribute to soil erosion, further polluting the Huang He

The Loess Plateau, located in north-central China, is surrounded by the Yellow River (or the Huang He) and includes parts of the Chinese provinces of Qinghai, Gansu, Shaanxi, and Shanxi. The plateau is one of the most eroded regions in the world, with human activities being the most significant contributor to soil erosion in recent years. Intensive farming, mining, and construction activities on the Loess Plateau have led to soil erosion, further polluting the Huang He.

Farming activities on the steep slopes of the Loess Plateau expose the loess material, which is easily washed away by heavy rainfall and storms, causing serious soil erosion. The population in the region tripled from 1949 to 2000, and with over 70% of the slope land being used for agricultural activities, the problem of soil erosion has intensified. To address this issue, the Chinese government launched the Grain for Green restoration project in 1999, backed by the World Bank and the United Nations. This project banned hillside cropping and free grazing, providing grain-and-cash subsidies to farmers who converted their fields to grassland or forest. While this initiative faced challenges due to initial dips in grain yields, adjustments to the scheme led to a recovery in yields, along with improved soil and water conservation.

Mining and construction activities also play a role in causing soil erosion on the Loess Plateau. The region's unique geomorphology, transitioning from rocky mountains to alluvial plains and river valleys, makes it susceptible to erosion. The higher terraces, covered in thick loess, can transform into loess ridges through strong erosion, while weaker erosion results in the formation of loess tablelands. The flat river basins, important for construction and agricultural activities, are particularly vulnerable to these changes.

The Loess Plateau is known for its massive soil erosion, with over 70% of the area now dominated by gullies and hills due to human-induced accelerated soil erosion in recent centuries. The sediment yield in the Yellow River is closely linked to heavy floods, which act as proxy indicators of intensive surface erosion on the plateau. The river carries an immense amount of silt, with 1.6 billion tons annually at the point where it descends from the Loess Plateau, making it the most sediment-laden river globally. This excessive sediment has raised the riverbed several meters above the surrounding ground, earning it the name "Earth Suspended River."

In summary, intensive farming, mining, and construction activities on the Loess Plateau have contributed to soil erosion, further polluting the Huang He. The combination of human activities and natural processes has led to significant environmental challenges, threatening global food and environmental security. Efforts to address soil erosion, such as the Grain for Green restoration project, aim to strike a balance between human needs and ecological conservation.

The government has implemented programs to control erosion through afforestation and terracing, improving agricultural land use

Soil erosion has various harmful and costly effects, including an increase in sediment in rivers, which can bury crops, damage marine life, and impair drinking water quality. It is therefore important to implement measures to control erosion. One such measure is afforestation—the reforestation of erosion-prone areas can prevent disastrous effects such as sedimentation. Trees planted near agricultural land offer many benefits, including reducing erosion, increasing soil fertility, and enhancing agricultural yields. The more closely an agricultural system resembles a natural forest, the less chance there is of soil erosion.

Terracing is another effective method of controlling erosion. Terracing consists of constructing ridges and channels across slopes to prevent rainfall runoff from accumulating and causing serious erosion. Terracing helps prevent slope erosion by distributing water more evenly across hills, rather than letting it flow to the foot. This reduces both the amount and velocity of water moving across the soil surface, which in turn reduces soil erosion. Terracing also contributes to water conservation, preventing water pollution by reducing sedimentation.

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