Practices such as deforestation for farming, overgrazing, and poor construction techniques have resulted in a rate of soil erosion in China that is among the worst in the world. Climate factors, such as wind and increasing temperatures that increase the rate of glacial shrinkage, also adversely affect soil erosion. Government efforts to control soil erosion have focused on rehabilitation of small river valleys.
Soil erosion occurs when soil is detached and moved by water, wind, or tillage. Scientists estimate that 15 percent of the Earth’s ice-free land surface suffers from soil erosion. Although the area eroded by tillage is not known, of that 15 percent, erosion by water is responsible for about 56 percent, and erosion by wind is responsible for about 28 percent. China, with 3.56 million square kilometers (37 percent) of its land surface eroded to some degree, has one of the worst cases of soil erosion in the world. Soil erosion has been identified as the primary environmental problem in the country. It causes desertification, silts up rivers, lakes, and reservoirs, and aggravates droughts and sandstorms.
Causes
China has every type of soil erosion in the world, including water erosion, wind erosion or desertification, freeze-thaw erosion, landslide, mud rock flow, and hill avalanche. The two prevalent types are water and wind erosion, which occur in all the provinces and autonomous regions in China’s mainland. The most severe soil erosion in China occurs in the Loess Plateau on the middle and upper reaches of the Huang (Yellow) River, where 450,000 square kilometers out of a total area of 640,000 square kilometers are subject to erosion. The soil loss from the Loess Plateau is more than 2.2 billion tons annually.
A vulnerable ecosystem and unfavorable climate changes have been identified as two of the causes of China’s soil erosion. As the least-industrialized region with the lowest population density in China at barely two persons per square kilometer, the Qinghai-Tibetan Plateau, the “roof of the world” at an average elevation of 4,500 meters above sea level, experienced a sudden rise of temperature beginning in the 1970s. As of February 2007, the average winter temperature had gone up by 1.4°C from the historical average of minus 4.4°C, while the winter temperature in the regional capital Lhasa rose by 6°C. Along with records showing the temperature rise are records showing shrinkage of glaciers at an annual average rate of 131.4 square kilometers over the past three decades. Some scientists predict that the glacial areas on the plateau, which equal five times the area of France, will dwindle by nearly one-third by 2050. Elsewhere, a research station of the Chinese Academy of Sciences at Xilingol League in Inner Mongolia documented that in the twenty-four years up to the year 2000, 12 centimeters of topsoil were lost to wind erosion.
But human activity is believed to be the main culprit in soil erosion. Historical records indicate that most of the eroded areas once were covered with lush woods but were denuded through the centuries because of wars and miscalculated development, such as deforestation for farming, indiscriminate logging, overgrazing, mining, and road construction without consideration of water and soil conservation. An investigation of the Three Gorges Reservoir area indicates that farming on mountain slopes accounts for 60 percent of the total soil erosion in the area. Most eroded areas are caught in a vicious cycle in which soil erosion has destroyed the land’s natural productivity, but because of the pressures to sustain an ever-growing population, poor land use practices are continued, resulting in further damage to the ecosystem. No wonder the areas that are subject to severe soil erosion are commonly poverty-stricken.
Rehabilitation
China began its efforts to control soil erosion in the 1950s when the State Council established under it the Water and Soil Conservation Committee. Now the Ministry of Water Resources is responsible for steering the work of water and soil conservation and coordinating comprehensive utilization of water resources. Under the Law on Water and Soil Conversation and other water-related laws, programs have been planned to carry out water and soil conservation and eco-environmental improvement in key areas, including the middle reaches of the Huang River, the upper reaches of the Yangzi (Chang) River, sandstorm areas, and grassland areas.
Although government officials openly admit that the trend of worsening soil erosion has not been fundamentally checked, control efforts have never stopped, with some local achievements witnessed, especially in the rehabilitation of small watersheds or river valleys. Such rehabilitation efforts feature integrated planning, which takes into account the land and resources capacity with regard to population size, and the pursuit of a sustainable mode of development that is appropriate to local reality while allowing the ecosystem to restore its function effectively. The comprehensive rehabilitation of small river valleys, which normally takes five years to accomplish, emphasizes the equal importance of economic, ecological, and social benefits. It has been regarded as the best way to control soil erosion in China.
In Qinghai Province a sapling of dragon spruce takes four years to grow barely 5 centimeters tall, assuming that the sapling survives hostile conditions such as a frost-free period of only seventy days a year, extreme aridity, strong wind, and severe cold in winter plus an altitude of well over 2,000 meters above sea level. Nevertheless, the villagers of Xiaogaoling in Huangyuan County have built, in the fifty-one years since 1958, a green shelter on the mountains surrounding the village of 450 households. The 400,000 trees covering 513 terraced fields have increased the village’s forest coverage from 0 to 40 percent, checked soil erosion, and increased land productivity, with grain yields raising from 1,125 kilograms per hectare to 5,250–6,000 kilograms per hectare (2001). This conservation work has also enabled the village to better withstand natural disasters.
Throughout Qinghai, which occupies one-eighth of China’s land area, the extension rate of deserts has slowed from 13,000 hectares annually in the late 1990s to 2,000 hectares in 2007, thanks to conservation efforts such as Xiaogaoling’s. Nationwide, according to the Ministry of Water Resources, forty thousand small river valleys have been rehabilitated from soil erosion, bringing a total of 900,000 square kilometers of soil erosion under control.
Further Reading
Chen, Y., & Zhou, J. (2002). Studies of comprehensive rehabilitation of watersheds in mountainous areas of western China. Beijing: China Science Press.
Department of Water and Soil Conservation, Ministry of Water Resources. (2007). The water and soil erosion and the control measures in China. Retrieved May 20, 2008, from http://www.mwr.gov.cn
He Xiubin, Zhou Jie, Zhang Xinbao, & Tang Keli. (2006). Soil erosion response to climatic change and human activity during the Quaternary on the Loess Plateau, China. Regional Environmental Change, 6, 62–70.
In China trees come to mighty rescue. (1998). Retrieved February 3, 2009, from http://forests.org/archive/asia/treeresc.htm
Normile, D. (2007, July 20).
Getting at the roots of killer dust storms. Science, 317, 314–316.
Tang, K. (2006). Characteristics and perspectives on scientific discipline of soil erosion and soil and water conservation in China. Science of Water and Soil Conservation, 11.
Wang, J. (2007). “Roof of the world” testifies early global warming. Washington, DC: Worldwatch Institute.
Source: Lei, Xiong. (2009). Soil Erosion. In Linsun Cheng, et al. (Eds.), Berkshire Encyclopedia of China, pp. 2036–2037. Great Barrington, MA: Berkshire Publishing.
Soil Erosion (Shu?t? liúsh? ????)|Shu?t? liúsh? ???? (Soil Erosion)
