The Loess Plateau is a large flat area in north-central China made of loess, a type of fine dust carried by the wind. It lies southeast of the Gobi Desert and is near the Yellow River. The plateau covers parts of the provinces of Qinghai, Gansu, Shaanxi, and Shanxi. The area was shaped by movements of the Earth's crust during the Neogene period. Later, strong southeast winds from the East Asian Monsoon brought dust and sediment to the plateau during the Quaternary period. The main landforms on the plateau include flat areas, ridges, and hills, created by the buildup and erosion of loess. Most of the loess comes from the Gobi Desert and nearby deserts. Wind from the southeast and winter monsoons carried the sediment to the plateau during warm periods. Over time, the sediment was pressed together by the dry climate to form loess.

The Loess Plateau is one of the largest and thickest loess plateaus in the world. It covers about 635,000 square kilometers, which is 6.6% of China's total land area. Approximately 108 million people live on the plateau. Strong winds cause erosion, creating features like wind-carved edges, vertical cracks in the loess, and deep gullies. In recent years, changes in rainfall, plant cover, and natural dangers have occurred. These changes may be connected to human activities in the area. Chinese officials are working to find ways to protect the environment and manage the region sustainably.

Geology

The Loess Plateau has three main types of landforms: loess platform, loess ridges, and loess hills. A loess tableland is flat and has many layers of loess. It is mostly found in the southern part of the Loess Plateau. Loess ridges are formed by erosion and are located in the central part of the region. Loess hills are cone-shaped dunes and are found in the northern part. The landforms of the Loess Plateau are shaped by erosion and the movement of loess.

In the Loess Plateau, landforms often change from rocky mountains to alluvial plains near river valleys. This pattern repeats from the northwest to the southeast of the region. Rocky mountains are much taller than loess deposits. The height and shape of mountains vary depending on their location.

One of the tallest mountains in the Loess Plateau is Mahan Mountain. It reaches about 3,670 metres (12,040 ft) in height, which is 1,300 metres (4,300 ft) higher than the top of the loess layer. The mountain has a flat top and shows signs of old flat surfaces on its summit.

Some mountain slopes, especially the north side, were once covered with forests. The alluvial plains near the base of the mountains are made of alluvial fans. These fans are found at the foot of the rocky mountains.

The size of these plains depends on the amount of water and weathered material from the mountains. Older alluvial fans are covered with wind-blown loess. Farther from the mountains, loess tablelands and loess "Ping" can be found, and these areas connect to the river valley belt.

The river valley belt includes floodplains, river terraces, and riverbeds. Higher terraces are often covered with thick loess. Strong erosion can change these terraces into loess ridges. If erosion is weak, higher terraces may become flat loess tablelands. These flat areas are important for building and farming.

The Mu Us Desert is located in the northwest of the Loess Plateau. A wind-eroded boundary, called a wind escarpment, separates the Mu Us Desert from the Loess Plateau. This boundary shows a shift from loess accumulation to wind erosion. Behind the wind escarpment, ridges of bedrock form lines that run parallel to the wind direction. In the northern part of the Loess Plateau, these ridges point northeast. In the central region, their direction slowly turns north. In the north, ridges are oriented 118° ±14°, while in the center, they are oriented 179° ±11°. This shows the effect of wind erosion.

Winter and spring wind directions during the Quaternary period match modern wind patterns. Studies comparing ancient and modern winds found that wind directions during storms align with the orientation of bedrock ridges. This means that modern windstorms also shape the landforms.

The Yellow River has continuously supplied sediment, which is moved by wind. Wind erosion becomes stronger when it reaches the wind escarpment. The shape of the escarpment increases wind speed.

Because of strong wind erosion, the Loess Plateau is not only a place where loess is deposited but also a source of dust. Wind erosion was especially strong during the glacial period, when there was little vegetation.

The distribution of vertical cracks in loess depends on the structure of the loess, water content, layers, and small land features. These cracks develop both vertically and horizontally.

Vertically, cracks are found in different layers of loess, including layers from the late, middle, and early Pleistocene. These cracks are one of the most important structures in the Loess Plateau. The size and development of vertical cracks depend on the amount of vegetation and the steepness of slopes. Steeper slopes and areas with little vegetation are more likely to have cracks. Many vertical cracks can be seen on the cliffs of tablelands. These cracks and the boundary between loess and ancient soil are perpendicular. In dry loess layers, vertical cracks are found in the wetter parts. This makes it hard to see cracks in deep layers. Water from rain or irrigation moves through cracks and areas with many pores. The cracks in loess layers vary in size, properties, age, and origin. Vertical cracks are found throughout the Loess Plateau. Cracks in landslides can be grouped based on their features.

Original cracks form on major and minor slopes, vertical cliffs, and sides. These cracks do not move or close.

Unloading and weathering cracks are found at the top and edges of slopes or landslides. These cracks are usually open and show little movement.

Sliding cracks are inside landslides. These cracks are step-like and show large movement.

Collapsible cracks form when uneven settling happens during rain or irrigation. These cracks are far from the edges of tablelands and show clear movement.

The horizontal development of vertical cracks can be divided into four stages.

In the early stage, original cracks, unloading cracks, and weathering cracks are present. Most cracks here are weathering or unloading cracks. These cracks are empty and not filled.

In the next stage, cracks are less common. They are filled with fine sand, showing that water has moved through and sediments have settled.

In the underdeveloped stage, very few or no cracks are found.

In the final stage, no cracks are present. The loess is very dry, with an average moisture content of 16.22%.

Gully erosion is a major source of sediment. If an area has gullies, it means the land is seriously degraded. In the Loess Plateau, gullies contribute 60% to 90% of sediment in hilly areas. To measure the impact of gullies, scientists study changes in their volume.

There are three types of gullies in the Loess Plateau: floor gullies, hillside gullies, and valley bank gullies.

In conclusion, the shape of the Loess Plateau was influenced by tectonic movements since the Neogene period. Later, during the Quaternary period, the East Asian Monsoon helped form loess and other eroded features. However, human activities have caused many areas to become more eroded.

Loess is not the same as silt. Loess is yellow sediment carried by wind from dry or semi-dry areas during the Quaternary period. About 6% of the world’s land is covered with loess. Loess records past climate and environments.

The Chinese Loess Plateau is one of the largest

Climate and environment

The population of the Loess Plateau has grown since the 1600s. In 2000, the population reached 104 million. The fast increase in population has caused some environmental problems in the Loess Plateau. One example is deforestation. People cut down trees to create more land for farming and use the wood for fuel and building materials. This is why the amount of forest cover has dropped sharply. There are more unusual and severe natural events in the Loess Plateau. These may be linked to changes in climate and the environment.

Natural hazards connected to the Loess Plateau include dust storms, floods, droughts, locust swarms, and landslides.

Dust storm events are increasing and becoming stronger. The dust can travel very far. It affects places like Korea, Japan, and even the European Alps. Dust storms can have serious effects. They can cover large areas of farmland, harm human breathing, and cause the death of animals and people.

The number of floods and droughts is closely connected. This is because more frequent droughts show that weather patterns have become more extreme. At the same time, the number of floods also increases. The frequency of floods and droughts is rising in an unusual way.

The Loess Plateau is more likely to experience locust swarms because the climate has become cooler and more humid. Locust swarms can destroy farmland and reduce the amount of crops grown.

Between 1965 and 1979, more than 1,000 landslides in the Loess Plateau were caused by earthquake shocks and heavy summer rains.

Sustainable development

The Loess Plateau experiences one of the world's worst soil erosion problems. Soil erosion in this area is influenced by several factors, such as the amount of plants covering the ground, rainfall, wind strength, and climate. However, human activities have been the biggest cause of soil erosion in recent years. Historical records show that forest cover on the Loess Plateau decreased to one-eighth of its original amount over the past 3,000 years. This decline reached its lowest point in 1949, leading to soil erosion of 3,700 tons per square kilometer each year. The northern and eastern parts of the region were once covered in forests.

The population in the Chinese Loess Plateau tripled between 1949 and 2000, reaching 104 million people by 2000. More than 70% of sloped land is used for farming. Farming on steep slopes exposed the loose soil to erosion. Heavy rain and storms wash away the soil, causing serious erosion. In 1999, it was found that most grasslands were overgrazed and faced land degradation. Mining and construction also contributed to soil erosion.

To reduce soil erosion and promote sustainable farming, reforestation efforts began in the 1960s. In 1999, the Institute of Soil and Water Conservation introduced a plan for eco-agricultural construction. The plan included four main strategies:

• Restoring vegetation, such as grass and shrubs.
• Creating terraced farmland for essential grain crops.
• Planting more cash crops and trees.
• Managing livestock farming.

Conservation and sustainable development efforts are divided into three stages:

In 1999, the Chinese government started the Grain for Green restoration project, supported by the World Bank and the United Nations. The project banned farming on hillsides and free grazing, offering farmers grain and cash to convert farmland into grassland or forests. In the early 2000s, grain production dropped, causing debates about food security. The government later adjusted the program, and production recovered. The first Loess Plateau restoration project cost $252 million by 2007.

From 1975 to 2015, restoration projects in the Beiluo River Basin, in the southwestern part of the Loess Plateau, turned farmland into grassland and forests. This effort increased forest cover by about 18% and raised the basin’s ecosystem service value by roughly 54% (about $3.2 billion). From the program’s start to 2020, the Jinghe River watershed saw restored forests and grasslands on hills, improving soil and water conservation and ecosystem services. Overall, forest cover increased by 15,000 square kilometers on the plateau from 2007 to 2017.

Between 2000 and 2024, the Loess Plateau experienced a warming climate with slightly more rainfall.