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Presentation

2nd Revision

Introduction

 
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:
WB00860_.gif (262 bytes) Frequent flooding threatens harvests and contributes to water erosion of the soils.
WB00860_.gif (262 bytes) The water deficit problem in Northern China can lead to aridification.
WB00860_.gif (262 bytes) 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
Yellow River Flooding
Satellite Image 3
Floods and droughts by Province
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.
Water Use by Economic Sector in China, 1993
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.
Water Use by Economic Sector in China, 1993
Table 2
Related Arguments

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.)