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Arguments - Impact |
| Water |
| China's water
problems critically affect food production. We can identify three major impacts. (1) There
are water deficits in northern agricultural areas, particularly in the North China Plain.
Groundwater extraction in this area has led to falling groundwater levels, which has
already affected soil moisture. (2) China has a history of widespread flooding in its
intensively cultivated floodplains, especially along the Yellow and Yangtze Rivers. (3)
Water pollution from industrial and urban areas is becoming a major problem for
agricultural water use. |
| Short Description of the Problem |
| China's water
problems affect agriculture mainly in three respects: |
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Frequent flooding threatens
harvests and contributes to water erosion of the soils. |
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The water deficit problem in
Northern China can lead to aridification. |
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Water pollution is having an
increasing impact on agriculture. |
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| Discussion |
| Flooding |
Flooding is a severe
problem in certain river basins and downstream lowlands, such as along the Yangtze river
(see Satellite Images 1, 2, and 3). China's food production is certainly affected by these
floods, in part because farmers have moved into previously unused floodplains. In 1996
three provinces, Hunan, Hubei and Hebei, were hit particularly hard by floods in the
middle reaches of the Yangtze basin. In these provinces, between 1.2 and 1.6 million ha of
land were affected by floods (see Figure 1 and Table 1).
Flooding certainly contributes to fluctuations in China's grain production and thus
threatenes a stable food supply of the population. However, natural disasters have always
been part of a farmers live. In fact, there is indication that modern flood mitigation
technology can significantly reduce the flooding risk for China's farmes, despite much
higher rural population density than in the past (see the chapter on intervention possibilities).
Increased emergency buffer stocks for grain and improved food logistics, including a more
flexible grain import policy, can greatly reduce the impact of flood-related harvest
failure. |
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Satellite Image 1
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Satellite Image 2
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Satellite Image 3 |
Figure 1 |
| Water shortages / Droughts in Northern China |
In the
North and Northwest China's agricultural sector is affected by severe and increasing water
shortages. Rainfall is insufficient and rivers frequently run dry. These water resource
deficits, especially in downstream areas, are exacerbated by inefficient irrigation
systems in upstream areas. Experts estimate that poorly maintained and badly managed
irrigation systems lead to water losses of up to 60%.
The water deficit problems in the rivers of Northern China (especially in the lower part
of the Yellow River, which now runs dry several months of the year) are caused by a number
of factors; including a possible decline of precipitation in the catchment areas due to
climate change. There is also clear evidence that water extraction for irrigation and
urban consumption has increased significantly along river systems in Northern China,
especially along the middle and lower parts of the Yellow River.
Water deficit, however, is not only a volume problem. More often, it is a timing problem.
While floods frequently affect the floodplains of Northern China during the monsoon
season, the rivers dry up for several months during the dry season. Obviously, this
problem could be reduced by building more reservoirs and dams. |
Table 1 |
| Water pollution |
Water
pollution from industry and urban sewage systems is becoming a serious problem in some
agricultural areas that depend on irrigation. China has by far the highest total emissions
of organic water pollutants in the world. They are equivalent to the emissions of
the USA, Japan, and India combined (see Table 2). About 80% of the industrial
wastewater discharge is untreated. Recycling of industrial water is limited and
water conservation techniques are rarely used. Water consumption by industry per unit of
industrial output is substantially higher in China than in developed countries. It was
estimated that in 1993 China had an annual total discharge of 35.6 billion cubic meters of
untreated wastewater (United Nations ESCAP, 1997). If we assume that each cubic meter of
wastewater typically contaminates some 14 cubic meters of natural water, China polluted
some 498 billion cubic meters of natural water, equivalent to almost 18% of the country's
total water resources.
Industrial and urban water pollution includes all kinds of oil products, heavy metals
(such as lead, mercury, or cadmium), phenol compounds, cyanide, arsenic, chlorinated
hydrocarbonates, sulfates, and nitrates. While all these water pollutants are serious, it
is the heavy metals, in particular, that pose a major risk for agriculture. They can
accumulate in irrigated fields and enter the human food chain with serious consequences
for public health. |
Table 2 |
| Related Arguments |
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Water Resources: Trends
Impact Data Quality Prediction Error Intervention Possibilities
Intervention Costs
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Revision 2.0 (First revision published in 1999)
- Copyright © 2011 by Gerhard K. Heilig. All rights reserved. (First revision: Copyright © 1999 by IIASA.) |
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