Water Resources of Mainland China

5.13

Water Resources of Mainland China

J Chen, J Niu and L Sun, The University of Hong Kong, Pokfulam, Hong Kong, P.R. China Ó 2013 Elsevier Inc. All rights reserved.

5.13.1 Introduction 5.13.2 Water Resource Status in Seven River Basins 5.13.2.1 Yangtze River 5.13.2.2 Yellow River 5.13.2.3 Songhua River 5.13.2.4 Pearl River 5.13.2.5 Huai River 5.13.2.6 Hai River 5.13.2.7 Liao River 5.13.3 Some Key Water Resource Issues 5.13.3.1 Floods 5.13.3.2 Droughts 5.13.3.3 Soil Erosion 5.13.3.4 River Sedimentation 5.13.3.5 Water Quality 5.13.3.6 Groundwater Overdrafting 5.13.4 Possible Influences of Climate on Water Resources 5.13.4.1 Observed Climate Variations 5.13.4.2 Temporal Change of Water Resources 5.13.4.3 Glacier Melting 5.13.4.4 Future Water Resources 5.13.5 Tackling the Water Resource Problems 5.13.5.1 South-to-North Water Diversion Project 5.13.5.1.1 Eastern Route 5.13.5.1.2 Middle Route 5.13.5.1.3 Western Route 5.13.5.2 Three Gorges Project (TGP) 5.13.5.3 Water Resource Management in the Pearl River 5.13.5.3.1 Water Allocation Framework 5.13.5.3.2 Key Water Projects 5.13.5.3.3 Future Water Demand 5.13.6 Concluding Remarks Acknowledgments References Web References

5.13.1

Introduction

Mainland China has a total terrestrial area of 9.6 million km2, with a large range of both latitude and longitude. Its topography is characterized by high elevation in the southwest in association with the Qinghai–Tibetan Plateau and low altitude in the east (see Figure 1). Large areas in eastern and southern China are affected by oceanic air currents in summer and by continental air currents in winter, resulting in dry winters and wet summers. Because of geographic and climatic factors, China is vulnerable to severe floods and droughts. The average annual precipitation in China (see Figure 2) is 650 mm year 1 (i.e., 6177.5 billion m3 year 1 in total), which is less than the world land surface average of 800 mm year 1; moreover, the spatial and temporal variations of precipitation are large (Ministry of Water Resources of China 2009). Generally, the precipitation decreases from the southeast coast,

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with 1800 mm year 1, to the northwest inland, with 50 mm year 1 (Figure 2), while the Himalayan Mountains in the southwest are associated with high precipitation. The wet season in southern China lasts from April to September; in the north, it lasts from June to September. The range of the ratios of annual rainfall between a wet year and a dry year for different regions is 2–8, and sequences or clusters of the wet or dry years do occur (Ministry of Water Resources of China 2009). The total water resources in China amount to approximately 2800 billion m3 year 1, which accounts for 6% of the world total water resources; the volume of water resources in China ranks sixth in the world, after Brazil, Russia, Canada, USA, and Indonesia (Ministry of Water Resources of China 2009). However, since the population of China reached 1.37 billion in 2010, the average amount of water resources per capita is 2100 m3 year 1 (see Figure 3), which is less than one-third of the world average; this number ranks 121st in the world. Therefore,

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196

Figure 1

Water Resources of Mainland China

Geographic location of China and major river basins.

China has one of the lowest averages of water resources per capita in the world (Ministry of Water Resources of China 2009). Of the annual runoff (2738.8 billion m3 year 1), the minimum basic flow needed for the support of river ecosystems is approximately 867 billion m3 year 1, while flood water (which cannot be used as a water resource) accounts for 1051 billion m3 year 1; hence, the maximum usable volume of water in mainland China is approximately 882 billion m3 year 1, which is 28% of the annual runoff (Wang 2007, 2010). In mainland China, water resources are unevenly distributed spatially and seasonally. The Qinling Mountains–Huai River line is generally regarded as the geographical dividing line between South and North China (see Figure 1). The average water resources are 560 billion m3 year 1 (1100 m3 year 1 per capita) in South China (including the Yangtze River, the Pearl River, Southeast River basins, and Southwest River basins), and 204.5 billion m3 year 1 (359 m3 year 1 per capita) in North China (including the Songhua River, the Liao River, the Hai River, the Yellow River, and the Huai River); the south is comparatively water rich.

Along with economic development, population growth is the dominant driving force for water demand increase. Figure 4 shows the change in national population and gross domestic product (GDP) in mainland China (National Bureau of Statistics of China 2011) from 1950 to 2010. It is worth noting that the population growth rate in the central and western regions of China is faster than the eastern region for the period from 1978 to 2003 (National Population and Family Planning Commission of China 2007). In 2006, water supply in China was 579.5 billion m3, with surface water accounting for 81.2% and groundwater 18.4%, respectively (Ministry of Water Resources of China 2006). This was 5.5 times the water consumed in 1949, with an annual increase of approximately 3% over the period from 1949 to 2006. Moreover, in 2007, the amount of water resources per capita was 2156 m3 year 1; this number is expected to decline to 1875 m3 year 1 per capita when the projected peak population reaches 1.5 billion around 2033 (Xie et al. 2009). Figure 5 shows the categories of water use in 1999 (Ministry of Water Resources of China 1999) and 2008 (Ministry of

Water Resources of Mainland China

Figure 2

197

Major districts of China and spatial distribution of annual average precipitation.

8000

7328

7000 6000

Water per capita (cubic meter)

5000 4000 3000 2100 1646

2000

636

1000

456

272

170

Hai River Basin

Beijing City

0 World

China

Northeast Yellow River Huai River China Basin Basin

Figure 3 Water resources per capita in the world and mainland China in 2006. Adapted from Wang, H., 2010: Water Resources Callenges and Policies in China. Public Lecture, Hong Kong.

198

Water Resources of Mainland China

2

4.5 4

1.8 National population (billion) GDP (10 trillion yuan)

3.5 3

1.4

2.5 1.2 2 1

GDP

National Population

1.6

1.5

0.8

1

0.6

0.5

0.4

0 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 Year

Figure 4 National populations and GDP from 1950 to 2010 in mainland China. Adapted from National Bureau of Statistics of China, 2011: China Statistic Yearbook. China Statistics Press.

(a)

Ground water 19.1%

Other 0.4%

1999 ( 561.3 billion m3)

Urban domestic Ecosystem sector Rural domestic 0.0% 4.8% sector 5.3% Industry 20.7%

Surface water 80.5%

(b)

Ground water 18.3%

Other 0.5%

Irrigation 69.2%

2008 ( 591.0 billion m3) Ecosystem 2.0%

Urban domestic sector 7.2%

Rural domestic sector 5.1% Industry 23.7%

Surface water 81.2%

Figure 5

Irrigation 62.0%

Sources of water supply (left panel) and water use by different sectors (right panel) in mainland China in (a) 1999 and (b) 2008.

Water Resources of China 2008). In both years, irrigation accounts for more than 60% of use; industry is the second largest user and accounts for more than 20% of water used. The ratios of water use for urban domestic and industry sectors in 2008 are 3% larger than those in 1999. Therefore, urbanization has become another factor driving the water demand increase; it is expected that the urban domestic water demand will further increase because the urban population will reach 55– 66% of total national population by 2020 (Xie et al. 2009). The continuous growth of China’s population and economy, leading to higher water demand and associated water-related

environmental issues, makes the study of water resource vulnerability extremely important. The possibility of further changes in climate provides a further imperative of exploring and understanding the characteristics of water resources in mainland China.

5.13.2

Water Resource Status in Seven River Basins

There are more than 50 000 rivers in China with drainage basin areas larger than 100 km2; of these, more than 1500 have basin

Water Resources of Mainland China

Table 1

199

The seven major rivers in mainland China (Qian 1994)

River

Length (km)

Basin area (km2)

River’s destination

Population in 2004 or 2005 (millions)

Yangtze River Yellow River Songhua River Pearl River Huai River Hai River Liao River

6397 5464 2308 2214 1000 1090 1345

1 808 500 752 443 557 180 453 690 269 283 263 631 228 960

East China Sea Bohai Gulf Heilong River South China Sea Yangtze River and Yellow Sea Bohai Gulf Bohai Gulf

440 113 62 99 172 130 35

areas larger than 1000 km2. Most rivers in China are fed by rainfall, and some rivers are partly fed by snow or glacier melting water. The seven major rivers in mainland China are the Yangtze River, the Yellow River, the Songhua River, the Pearl River, the Huai River, the Hai River, and the Liao River (see Figure 1). Table 1 lists the basic hydrological information of these seven river basins. Note that city names, river gauge station names, and dam names given in the following text are marked in Figures 1 and 9–11. The total area of the seven major river basins (the Yangtze River, the Yellow River, the Songhua River, the Pearl River, the Huai River, the Hai River, and the Liao River) is approximately 45% of the total land area of mainland China (see Figure 1). However, the volume of water resources of these basins is approximately 64% of the country’s total, with approximately 80% of the total population living there. Table 2 lists the basic information on the water resource status of these seven river basins; the amounts of annual water resources per capita are calculated based on the population in 2004 for the Pearl River basin and 2005 for other six basins. The threats of water shortage over the Hai River, the Huai River, and the Yellow River basins are obvious (Table 2). The following sections briefly introduce the seven river basins one by one.

5.13.2.1

Yangtze River

The Yangtze River is the largest river (in terms of the length, basin area, and streamflow volume; see Table 1) in China and the third longest river in the world. The basin area is 1.8 million km2 and the length of the mainstem is 6397 km. The Yangtze River basin runs through 19 provinces (including autonomous regions and municipalities), namely Qinghai, Tibet, Sichuan, Gansu, Shaanxi, Yunnan, Chongqing, Guizhou, Guangxi, Guangdong, Hubei, Hunan, Henan, Anhui, Jiangxi, Zhejiang, Fujian, Jiangsu, and Shanghai (see Figures 1 and 2).

There are many tributaries, such as the Min River, the Wu River, the Xiang River, the Han River, the Huangpu River, and so on; among them, the Han River is the longest one. The Qutang Gorge, Wuxia Gorge, and Xiling Gorge of the river are known as the Three Gorges (Sanxia in Chinese). The population over the basin reached 0.44 billion in 2005, which is more than 30% of the total national population of China. The river basin is located mainly in subtropical climate zones, and seasonal and interannual variations of the runoff in the mainstem are large. As an agricultural production base, the rice product in the basin accounts for up to 70% of the total in China. The potential hydropower capacity of the river reaches 250 000 Million Watts (MW). The river has abundant fish resources, with about 500 fish species. Consequently, the water resources in the Yangtze River basin make a great contribution to the agricultural and economic development in mainland China. The streamflow of the Yangtze River is relatively stable (Lu 2004). Nevertheless, the Yangtze River basin is vulnerable to floods and droughts, especially in its middle stream and downstream regions. For example, a serious flood that occurred in 1998 over the entire river basin submerged an area of more than 0.2 million km2 and caused an economic loss of 166 billion RMB Yuan (about US$ 20 billion in 1998 equivalent) (Yin and Li 2001). The drought that occurred in 2011 in the middle and lower reaches of the river was the worst since 1961; the economic loss due to the 2011 drought was 14.9 billion RMB Yuan (about US$ 2.3 billion in 2011 equivalent), and the farmland affected totaled 40 000 km2.

5.13.2.2

Yellow River

The Yellow River is the second largest river in terms of both the basin area (752 443 km2) and length (5464 km) in China. The river runs through Qinghai, Gansu, Sichuan, Ningxia, Inner Mongolia, Shanxi, Shaanxi, Henan, and Shandong provinces

Table 2

Status of water resources in the seven major river basins (Qian 1994)

River

Amount (km3 year 1)

Depth (mm year 1)

Amount (km3 year 1)

Depth (mm year 1)

Annual groundwater (km3 year 1)

Annual total water resources (km3 year 1)

Annual water resources (m3 year 1) per capita

Yangtze Yellow Songhua Pearl Huai Hai Liao

1936 369 279 897 283 178 190

1071 464 500 1544 860 560 551

951 66 74 336 74 29 49

526 83 133 741 225 91 141

246 41 12 112 39 27 19

961 74 88 471 96 42 58

2181 655 1419 4758 558 323 1657

Annual precipitation

Annual river runoff

200

Water Resources of Mainland China

(see Figures 1 and 2). The population in 2005 over the basin was about 0.113 billion. The river is well known worldwide due to soil erosion and sediment problems. Most of the river streamflow comes from upstream Lanzhou City. The runoff yield decreases downstream from Lanzhou City to Hekouzhen station due to the evaporation and leakage losses. The runoff yield increases in the region from Hekouzhen station to Taohuayuan station. However, from Huayuankou station to the river outlet, there are significant water losses along the river channel; the river bed in this part is higher than the surrounding land surface, resulting in a so-called suspended river. This suspended river raises the vulnerability of the region to floods. In 1958, the river reach between Sanmenxia and Huayuankou stations experienced the worst flood since 1919; the Beijing–Guangzhou railway, which is the main transport route in mainland China, was interrupted for 14 days. In addition, based on the historical records, the Huayuankou station for the period of 1946–88 and the Sanmenxia station for the period of 1953–88 experienced decreasing trends of the annual mean and annual maximum discharge (Lu 2004). On the other hand, because the western and northern parts of the river are located in arid and semi-arid areas, where the annual rainfall is less than 250 mm year 1, basinwide droughts are easily triggered. Furthermore, for the period of 1972–97, the downstream area of the river suffered from dried-up river courses; in 1997, such a situation lasted 226 days, and the annual economic loss was more than 1.1 billion RMB Yuan (about US$ 0.13 billion in 1997 equivalent). This dry situation also brought many other environmental and ecological problems, such as land desertification, aquatic ecosystem stress, water quality degradation, and so on.

5.13.2.3

Songhua River

The source of the Songhua River is the Tianchi Lake on Changbai Mountain. The basin area is 557 180 km2, and the length is 2308 km (Table 2). The population over the basin was 62 million in 2005. As it is located at the mid-temperate climate zone, evapotranspiration is relatively low. The Songhua River at Harbin station experienced an increasing trend of the annual minimum discharge for the period of 1898–1987 (Lu 2004). Since 1950, floods have occurred in 1953, 1956, 1957, 1960, 1969, and 1998. For the 1957 flood, high-intensity rainfalls occurred in July and August, and the number of days with continuous rainfall reached 45. About 4 million people were affected and 81 people died. The economic loss was 0.24 billion RMB Yuan (about US$ 0.1 billion in 1957 equivalent). In 1998, the river experienced another serious flood; the maximum water level reached 120.89 m and the associated discharge was 16 600 m3 s 1 at Harbin station on August 22. For the basin, this flood was the worst in the twentieth century. On the other hand, during the period of 2000–03, the mainstem of the Songhua River endured severe low water levels (the lowest being 110.07 m at Harbin station), and the droughts resulted in the reduction of industrial and agricultural outputs.

5.13.2.4

Pearl River

The total basin area of the Pearl River is 453 690 km2 (part of the river basin, 11 590 km2, is located in Vietnam), and the

length of the mainstem is 2214 km. The population over the basin was 99.35 million in 2004. The Pearl River is situated in a tropical to subtropical monsoon climate region. The average runoff is 336 km3 year 1, making it the second largest river in terms of streamflow volume in China; the annual runoff generation rate (about 0.74  106 m3 year 1) is the highest among the seven major rivers in China. A decreasing trend has been identified for annual minimum discharge at Wuzhou station for the period of 1915–84 (Lu 2004). Historically, the basin has suffered from frequent floods and most of the river’s major tributaries have experienced severe floods (e.g., 1979 flood in the East River, 1982 flood in the North River, and 1998 flood in the West River); serious basinwide floods also occurred in 1915, 1968, 1994, and 2005. For the period of 1990–2005, the total economic loss over the basin caused by floods reached 345 billion RMB Yuan (about US$ 41.7 billion in 1998 equivalent). Droughts also frequently occur over the basin, especially for the southwest region (e.g., severe droughts occurred in 1963 and 2010). In addition, due to the droughts, persistent seawater intrusion has threatened freshwater supply in the Pearl River delta.

5.13.2.5

Huai River

The Huai River basin area is 269 283 km2, and the mainstem length is 1000 km. The Huai River runs through Henan, Hubei, Anhui, Shandong, and Jiangsu provinces (Figures 1 and 2). The river in the lower reach has three branches. One enters into the Yangtze River at Sanjiangying station near Yangzhou City in Jiangsu province; another enters into the Yellow Sea through the North Jiangsu Irrigation Canal; the third one flows into Haizhou Bay through the Huaishu River (a comprehensive water resource utilization project). The total population over the basin was 0.172 billion in 2005. The average population density is about 639 per km2, ranking first among the seven major river basins in China (Huai 2011). The Huai River at Bengbu station showed a decreasing trend in the annual minimum discharge for the period of 1915–86 (Lu 2004). Due to the significantly changed geography of the Huai River basin in history, water flow in the middle stream cannot easily flow into the downstream region. Water-related hazards, such as floods and droughts, have frequently occurred in the basin. From 450 CE (Common Era) to 1950, on average, there were 94 floods per century over the basin; droughts occurred 260 times, with a frequency of 1 per 1.7 years (Hai 2011). In the 1991 flood, the area of farmland inundated was 55 160 km2, and the population affected was 54.23 million. The economic loss in 1991 was 34 billion RMB Yuan (about US$ 6.39 billion in 1991 equivalent). Two severe droughts occurred in 1966 and 1978, associated with an annual average rainfall of 579 mm and 601 mm, respectively, compared to 911 mm year 1 for the long-term average; the area affected by each of the droughts was about 33 330 km2.

5.13.2.6

Hai River

The basin area of the Hai River is 263 631 km2, with the length of mainstem of 1090 km. It is located in semi-arid and semi-humid areas. There are 25 large- and medium-scale cities in the basin, including Beijing and Tianjin, and the total population over the

Water Resources of Mainland China

basin reached 0.13 billion in 2005. The average population density is about 410 per km2 (Hai 2011). The streamflow volume has greatly decreased since 1980. Due to the serious overexploitation of groundwater, large-scale land subsidence has occurred in the downstream area of the basin. Also, many tributaries are dry for most of the year. Meanwhile, water pollution has worsened in conjunction with the reduced streamflow.

5.13.2.7

Liao River

The Liao River has a basin area of 228 960 km2, and a mainstem length of 1345 km. The total population over the basin was 35 million in 2005. The basin area and annual runoff (14.8 km3 year 1) are the smallest among the seven major rivers in China. The Liao River has a high sediment load because many parts of the river flow through powdery loess, which is ranked third behind the Yellow River and Hai River. A decreasing trend of annual mean discharge has been observed at Xiaoheyan station in the Liao River for the period of 1955– 98 (Ren et al. 2002). During the past 100 years, 50 floods occurred over the basin; drought events occurred almost every year in the east of the basin (i.e., the Xiliao River basin). In the 2005 flood, 1.34 million people were affected and 1400 km2 of farmland was inundated; the economic loss was 7.4 billion RMB Yuan (about US$ 0.92 billion in 2005 equivalent).

5.13.3

Some Key Water Resource Issues

Since 1949, more than 51 extreme floods and 18 widespread and severe droughts have occurred in mainland China. Floods and droughts in China are high frequency, with large spatial extent as well as heavy losses of life and societal property. Specifically, the Yellow River delta, the Yangtze River delta, and the Pearl River delta are vulnerable to storm surge, seawater intrusion, coastal flooding, shoreline erosion, and loss of wetlands. Other water resource issues in mainland China include water environment deterioration, soil erosion, river sedimentation, and groundwater overdraft. In the previous section, some water resource issues in the seven major river basins were introduced. The following sections will review some key water-related issues in mainland China.

5.13.3.1

Floods

Floods are one of the most serious disasters frequently occurring in China. Due to the great variation in meteorological, topographical, and geological features over the territory, about two-thirds of the land area of China is subjected to different types of floods. Table 3 lists the distribution features of historical floods in mainland China. The continental monsoon climate influences most of China. Rainfall in the territory is mainly formed by two types of weather systems (Qian 1994). The first is the westerlies rain belt system, including fronts, extratropical cyclones, tangential lines, and low vortexes. The other is the low-latitude tropical weather system, which includes mostly tropical cyclones and typhoons. The principal source of flood disasters in China is rainstorm floods; other types of floods include snow melt floods, glacier ice melt floods, and the floods caused by storm surges in coastal regions.

201

Table 3 Statistical information of floods occurring in the period of 1840–1949 (Flood Control and Drought Relief Headquarters, and Nanjing Research Institute of Hydrology and Water Resources (FCDRH and NJRIHWR) 1997) Spatial coverage

Number of years

Percentage %

Whole country North and south Central North South Other regions Total

4 6 25 15 1 59 110

3.6 5.5 22.7 13.6 1.0 53.6 100

Generally, in mainland China, flood disasters in the eastern region are mainly caused by rainstorms and coastal storm surges. The western region is primarily subject to mixed-type floods from snow and glacier melting and local rainstorms. The economically developed eastern and southern parts (see Figure 2), which possess approximately 35% of the national cultivated land, 70% of the national agricultural and industrial products, and more than 50% of the national population, are most seriously threatened by floods (Wang 2010). The total loss caused by floods in China was approximately 1.5% of the GDP for the period of 1990–2010 (Liu 2009). For example, in 1998, 4185 people lost their lives in mainland China due to the unusually high rainfall in the wet season (World Socialist 2005). In 2005, 1660 people were killed in the flood season (National Bureau of Statistics of China 2006). In 2007, 177 million people were affected by the nationwide floods, resulting in more than 1200 deaths, 0.12 million km2 of croplands ruined, and more than 1 million houses destroyed; the direct economic loss was over 100 billion RMB Yuan (US$ 12.82 billion in 2007 equivalent) (National Bureau of Statistics of China 2008).

5.13.3.2

Droughts

In normal years, due to huge water demands from various water consumption sectors in mainland China, water shortage is 25 billion m3, accounting for 4% of the national total demand. In dry years, the water shortage can reach 30–40 billion m3, which is 6% of the total demand. Three-quarters of the national water shortage occurs in North China, and the region with the worst water shortage is the Hai River basin. In the Hai River basin, the situation has been deteriorating since the 1950s, becoming severe since 1980 as reflected in the record of annual runoff (see Figure 6). The total loss resulting from drought disasters in mainland China was about 1% of the GDP for the period of 1990–2010, or about 300 billion RMB Yuan (about US$ 36.23 billion in 2000 equivalent) (The Ministry of Water Resources 2010). Table 4 lists the statistical information (Flood Control and Drought Relief Headquarters, and Nanjing Research Institute of Hydrology and Water Resources (FCDRH and NJRIHWR) 1997) of drought disasters on agriculture in different river basins; it shows that the drought-influenced areas and droughtresulted damages in the basins of the northern region are normally much higher than in the Pearl River in the southern region. During the periods of 1949–90 and 1971–90, the

202

Water Resources of Mainland China

Runoff (billion cubic meter)

30 25

North Part of Hai River South Part of Hai River Poly. (South Part of Hai River) Poly. (North Part of Hai River)

20 15 10 5

0 1956 1960 1964 1968 1972 1976 1980 1984 1988 1992 1996 2000 Year Figure 6 Annual runoff variations in the Hai River. Adapted from Shen, D. J., 2010: Climate change and water resources: evidence and estimate in China. Curr. Sci., 98, 8.

highest drought impact in northern China occurred in the Yellow River basin, followed in decreasing order by the Songhua River, the Liao River, the Huai River, and the Hai River (FCDRH and NJRIHWR, 1997). In 2010, southwest China (including Yunnan, Sichuan, and Guizhou provinces, Guangxi Zhuang autonomous region, and Chongqing municipality) suffered from the worst drought in six decades; it lasted 6 months and resulted in serious drinking water shortages and crop damages. According to statistics from the China Foundation for Poverty Alleviation (CFPA), the direct economic loss of the drought was more than 35 billion RMB Yuan (about US$ 5.12 billion in 2010 equivalent), and more than 2 million people were reduced to poverty levels. The drought affected about 5000 km2 of natural reserves, and shrinking wetlands and water shortages for wildlife were reported by the Yunnan provincial forestry bureau (China Daily 2010). In 2011, the worst drought in 50 years hit the midstream and downstream areas of the Yangtze River basin. Precipitation in the regions (including the Anhui, Jiangsu, Hubei, Hunan, Jiangxi, and Zhejiang provinces and Shanghai municipality) was 30–80% less than that in normal years. The surface area of the largest freshwater lake in mainland China, Poyang Lake in Jiangxi province, shrank to just 16% of its average. The difference between areas of cropland damaged (referring to where the crop production is reduced by more than

Table 4

30%) and areas of agriculture affected (referring to where crop production is reduced by more than 10%) by droughts depends not only on the variation of meteorological conditions, but also the irrigation efficiency and the irrigation intensity of farmlands. The ratio of cropland damaged to total agriculture area affected in northern China is more than 0.5, while the ratio in the Pearl River basin in the southern China is less than 0.4 (FCDRH and NJRIHWR 1997). Moreover, Ge et al. (2011) estimated the water footprint for each province (or autonomous region) in mainland China, in which the water footprint is defined as the total volume of freshwater consumed for producing the goods and services (Hoekstra et al. 2009). With reference to the water footprint, the extent of water shortage in Tianjin, Beijing, and Shanghai municipalities, Ningxia autonomous region, and Hebei and Shanxi provinces are the worst in mainland China.

5.13.3.3

Soil Erosion

Soil erosion is an important factor in influencing river sedimentation and water quality. The total eroded area in China amounts to one-sixth of the territory (Qian 1994). A large amount of fertile soil from farmlands is eroded and transported into the rivers and seas. The eroded areas are mainly found in the Loess Plateau in North China, the Yunnan–Guizhou

Droughts over the major river basins (FCDRH and NJRIHWR 1997) Agriculture affected rate

Average during 1949–90

Crop damaged rate

River basin

Agriculture affected rate (%)

Crop damaged rate (%)

Crop extinction rate (%)

Max (%)

Year

Max (%)

Year

Songhua and Liao Hai Huai Yellow Yangtze Pearl

12.3 9.9 10.7 16.2 10.3 9.6

7.1 6.5 5.6 11.3 5.6 4.0

0.7 0.5 0.3 1.5 0.8 0.8

54.2 30.6 33.9 33.6 26.1 26.1

1982 1965 1978 1987 1959 1988

41.8 18.3 22.8 27.0 15.7 18.6

1989 1986 1988 1987 1978 1963

Water Resources of Mainland China

Plateau in southwest China, and the hilly and mountainous regions in South China (Figure 2). The area of the Loess Plateau is 340 000 km2 with an annual precipitation ranging from 300 to 600 mm year 1. Within the loess area, the gullied plateau regions and the gullied-hilly regions, amounting to 250 000 km2, have the highest erosion rates. Due to the high storm intensity, sparse vegetation cover, and steep slopes, soil erosion in the Loess Plateau is rampant and results in a distinctive geomorphological landscape (Qian 1994). The erosion rate ranges from 5000 to 10 000 t km 2 year 1 on slopes and from 15 000 to 20 000 t km 2 year 1 in gullies. The Karst region of the Yunnan–Guizhou plateau with an eroded area of about 340 000 km2 is another region of extensive erosion, and it has an annual precipitation of 1000 mm year 1. Eroded areas account for about 54% of the Yellow River basin, with a normal surface area erosion rate of 2500 t km 2 year 1. Based on sediment transport observations, the most seriously eroded area in the Loess Plateau has an erosion rate of 5000–8000 t km 2 year 1, which is the highest in China and the main source area for sediment in the Yellow River basin. In the Yangtze River basin, the eroded area is about 570 000 km2, and the annual soil loss is about 3500 to 4000 t km 2 year 1. The region of most serious erosion is in the upper stream of the Yangtze River, from Dukou City to Yichang City. The eroded areas in the Hai River, the Huai River, the Songhua River, and the Liao River basins are about 104 000 km2, 56 000 km2, 180 000 km2, 128 000 km2, and 59 000 km2, respectively. Overall, soil erosion is a serious issue in sustaining water resource security in mainland China, and measures for protecting the land surface and preventing soil erosion are necessary. To this end, there are numerous engineering projects implemented in mainland China. For example, the Grain-for-Green project for western China took off in 2000; the project aims to turn low-yielding farmland back into forest and pasture to reduce soil erosion and restore ecological balance in the western region.

5.13.3.4

River Sedimentation

Over 40 rivers in China carry a large amount of sediment due to severe soil erosion, and each of them has an annual sediment load of over 10 million t year 1. Data for the seven major rivers and some other rivers in southwest China and inland rivers (Qian 1994) reveal that the average annual sediment load totals 2.687 billion t year 1. The main sediment problems include reservoir sedimentation, sediment at low water head hydro projects and in canal systems, sediment in rivers and lakes, sedimentation in estuaries and below tidal barriers, and abrasion of high-energy particle turbines and hydraulic structures by sediment particles. The annual sediment load transported by the Yellow River is about 1.6 billion t year 1, and the riverbeds in the downstream areas are raised at a rate of 0.06–0.10 m year 1 due to the huge Table 5

203

amount of sediment (Qian 1994). This threatens the river bank safety during the flood season. Above the Hekouzhen station, the catchment area is 360 000 km2, and the sediment yield accounts for 9% of the total, while the runoff yield accounts for 53% of the total. The area between Hekouzhen and Longmen stations is 130 000 km2, and the runoff yield is about 15% of the total, while the sediment yield can reach up to 56% of the river total sediments; it is this area that is the main sediment source in the Yellow River basin.

5.13.3.5

Water Quality

Of the 20 most seriously water-polluted cities in the world, 16 are located in mainland China. Most of the major river basins suffer from severe pollution (Gleick et al. 2008), and about 300 million people have no access to safe water. Table 5 lists the growth rates of water use for the industrial and urban domestic sectors in China since the 1980s. The increase of water use can reflect the growth of wastewater discharge and water pollution. The main features of the water pollution in China are a large volume of wastewater discharge, little treatment, and an increasing trend of pollution. During the period of 1980–2000, the growth rates of wastewater discharge from the domestic sector and industry were 7.1% per year and 5.3% per year, respectively (Wang 2010). In 2006, the wastewater discharge was about 74.1 billion m3 year 1, while the treatment rate was 57% in urban areas and only 23% in rural areas. In 2010, the chemical oxygen demand loading to rivers was 30.29 million t year 1; NH3-N, total nitrogen, and total phosphorus in mainland China discharged into rivers amounted to 1.73, 4.73, and 0.42 million t year 1, respectively (National Bureau of Statistics of China 2010). Following the Chinese National standard for grading water quality, Grades I, II, and III of water are potable and Grades IV and V are acceptable for use by industry and agriculture. For the 2.8 million km of overall river length in mainland China, about 34% has water quality graded as worse than Grade IV (see Figure 7). Regarding the groundwater quality, of the assessment area of 1.97 million km2, about 63% of the water quality is grade IV or V (Wang 2010).

5.13.3.6

Groundwater Overdrafting

Around half of all of China’s wheat is produced in North China, where the water shortage is severe; consequently, groundwater is pumped out to irrigate the croplands. Therefore, groundwater overdrafting is a very common issue in North China, and in some regions it becomes a very serious problem. For example, the groundwater exploitation in Hebei province was 13 billion m3 year 1 in the 1980s, with groundwater table depths of 170–350 m. In the 1990s, the amount was 16 billion m3 year 1, with water table depths of

Growth rates (%) of water use for the industry and urban domestic sectors in China since 1980 (Wang 2010)

Sector

1980–85

1985–90

1990–95

1995–2000

2000–06

1980–2006

Industry Urban domestic

4.7 8.5

5.7 7.2

7.3 6.3

3.4 6.9

1.8 4.9

4.4 6.7

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IV 12% V Grade I II III IV V

Length(km) 19 717 106 781 61 765 33 304 17 925

Worse than V

6%

Worse than V 16% I~III

45 552

66%

Figure 7 Surface water quality in mainland China in 2006. Adapted from Wang, H., 2010: Water Resources Challenges and Policies in China. Public Lecture, Hong Kong.

250–380 m (Shao and Hu 2002). Another consequence of groundwater overdrafting is loss of wetlands. It is reported that 90% of the wetlands in Hebe province have disappeared since 1960, and streams and creeks have been dried up. The largest natural freshwater lake in the Hai River basin, Baiyandian Lake, is losing area and becoming grossly polluted (Griffiths 2006). Regarding urban areas, groundwater overdrafting in the cities of Shanghai (Wei 2006), Beijing (Zhang and Kennedy 2006) and Tianjin (Bai and Imura 2001), for example, resulted in declines of the water tables and groundwater storage. Land subsidence (Yin et al. 2006; Zhang et al. 2008) has occurred in urban areas in association with groundwater overdrafting.

5.13.4 Possible Influences of Climate on Water Resources A temperature increase in China over the past five decades (Piao et al. 2010) has been observed. There are serious potential vulnerabilities to China’s agricultural production due to climate variations; however, no definitive conclusion can be drawn due to the uncertainties involved in climate change projection. It is possible that China’s average temperature will increase further by 1–5  C by 2100 (Meehl et al. 2007), whilst summers are likely to be much warmer (Piao et al. 2010).

5.13.4.1

Observed Climate Variations

Over the Yangtze River basin, the western, eastern, and northern parts show more well-developed increasing trends for the temperature than the southern region for the past 100 years (before 2007) (National Development and Reform Commission of China 2007). There is a seasonality to warming, with the most pronounced temperature increase occurring in winter, especially for the period of 1986–2005 (National Development and Reform Commission of China 2007), with warming in winter (0.04  C per year) being about four times the rate of warming in summer (0.01  C per year). Meanwhile, the warming in northern China is faster than that in southern China. There is no obvious trend on the annual precipitation in the past 100 years in mainland China (National Development and Reform Commission of China 2007). However, since the 1950s, the annual precipitation has gradually decreased, with

an average rate of 2.9 mm per decade, while regional variation is noticeable. The most obvious decease of precipitation occurred mostly in northern China and also in the eastern parts of northwestern and northeastern China, with an average rate of 20–40 mm per decade. Meanwhile, the precipitation significantly increased in southern China and southwestern China, with an average rate of 20–60 mm per decade. The urbanization-induced temporal warming at the two stations of Beijing and Wuhan cities was analyzed (Ren et al. 2007). The study concluded that the annual urban warming accounted for 61.3 and 39.5% of overall warming in the respective cities for the period of 1981–2000. Zhou et al. estimated that the warming of mean surface temperature of 0.05  C per decade is attributed to urbanization in Southeast China for the period of 1979–98 (Zhou et al. 2004). The local urbanization effects on weather variables in South China have also been studied (Chen et al. 2011). It was found that for the period of 1960–2005 the variations of weather variables before and after 1984 are different. Before 1984, there were no significant urbanization effects, and the daily minimum temperature (Tmin), relative humidity (RH), and precipitation (P) steadily increased but the daily maximum temperature (Tmax) decreased, resulting in a considerable decrease in the diurnal temperature range (DTR) and a slight decrease in the surface temperature. After 1984, Tmin and Tmax increased considerably, and an urbanization influence on Tmin, but not Tmax, is observable. The urbanization effect causes an additional increasing trend in Tmin with a rate of about 0.6  C/ decade, and also results in a decreasing trend in both DTR and RH in the urban area. The urbanization influence results in a near-uniform increase of Tmin for all four seasons and a strong decrease of RH in summer and autumn. Moreover, there is no significant change in precipitation at the annual scale, but an increasing rate of 11.8% per decade in summer was detected (Chen et al. 2011). With the urbanization influence, a considerable increase in precipitation is noticeable at the annual scale; specifically, the increasing rates of 18.6% per decade in summer and 13.5% per decade in autumn are observed.

5.13.4.2

Temporal Change of Water Resources

The Ministry of Water Resources in mainland China assessed the situation for water resources over two periods, 1956–79

205

10.0 6.3 3.6

5.0

3.1

1.0

0.6 –1.3

0.0 –3.3 –5.1

–5.0 –10.0

–2.2

–5.2

–12.0

Northewest

Southwest

Pearl

Southeast

Yangtze

Huai

Yellow

Hai

Liao

Songhua

–15.0

Nation

Water Resources Evolution (%)

Water Resources of Mainland China

Figure 8 Water resource evolution between 1956–79 and 1980–2000 in mainland China and different river basins. Adapted from Wang, H., 2010: Water Resources Challenges and Policies in China. Public Lecture, Hong Kong.

and 1980–2000. It was found that the precipitation was 10% less, 6.9% less, and 2.6% less in the second period compared with the first period in the Hai River basin, the Yellow River basin, and the Liao River basin, respectively. In contrast, the precipitation was 3, 4.6, 2.6, and 6.5% more in the second period in the Yangtze River, the Songhua River, and the two river basins in southeastern and northwestern China, respectively. Except for the Songhua River basin and the rivers in southwestern China, the annual average potential evaporation was 5.4% less in the second period than in the first period. Shen (2010) indicated that the main reasons for the potential evaporation decrease between the two periods were the change of sunshine percentage, wind speed, and increase in air humidity during the second period. From the assessment of the Ministry of Water Resources, the surface water resources and total water resources in mainland China have increased slightly in the second period, corresponding to the slight increase in precipitation. However, there are spatial differences as reflected by the various river basins, and Figure 8 shows the change in water resources for the two periods 1956–79 and 1980–2000. In the second period, total water resources in southern China increased by 5%; however, the water resources in northern China have clearly decreased, especially for the Yellow River basin, the Hai River basin, and the Liao River basin (Shen 2010). In the Hai River basin, there was a 10% decrease in precipitation, 41% decrease in runoff, and 25% decrease in total water resources. In the Shandong Peninsula of the Huai River basin, there was a 16% decrease in precipitation, 51% decrease in runoff, and 34% decrease in total water resources. Shen indicated that the reason for the water resource decrease in north China is the reduction in precipitation and landscape change (Shen 2010). Comparing the current land covers with those of 50 years ago, 35% of the areas in the Yellow River, Huai River, Hai River, and Liao River basins have been changed; generally, the runoff is decreased by 10–20% in normal precipitation years and by 15–40% in dry years (Shen 2010). Over mainland China, the analysis of the past weather data revealed that heavy rainfall events happened more frequently over northwestern China and in the middle and downstream

areas of the Yangtze River, but not in northeastern China (Zhai et al. 2005). There is a general decrease in terms of rainy days across the country (Piao et al. 2010). The Yellow River is sensitive to drying trends. A persistent decrease in runoff is observed. This is attributed to both climate impacts and overextraction of water for irrigation, industry, and domestic usages. There has been a small increase (not statistically significant) in annual runoff for the Yangtze River since 1960 (Piao et al. 2010). A decrease in runoff has occurred in many gauged headwater catchments in the autumn, whilst a positive runoff trend is observed for the midstream and downstream sections of the Yangtze River, owing to the increasing precipitation in this region. Northwestern China, especially the arid area, has experienced a decline in the occurrence of severe drought, which is evidenced by both rising lake levels and increasing vegetation cover in areas adjacent to deserts (Piao et al. 2010).

5.13.4.3

Glacier Melting

China has 46 377 glaciers, with a total area of 59 425 km2 (Li et al. 2008). The glaciers shrank by 7%, which is equal to 3790 km2, in the Qinghai-Tibetan Plateau in the past four decades (Li et al. 2008). The runoff owing to the glacier melting has increased from 62 km3 in 1980 to 66–68 km3 in 2000 (Li et al. 2008). Piao et al. (2010) presented a case study of glacier retreat and melting influence in the Tarim River basin in Northwest China, showing that the melting of glacier has increased the local runoff by 15% between 1957 and 2000; however, due to rapid development of oases in the basin, the increased runoff can not satisfy the water demand (Hao et al. 2008), and the runoff in the Tarim river mainstem has decreased. Gurung et al. (2011) indicated that changes in snow cover for the western Himalaya are primarily due to interannual variations in circulation patterns as there is the correlation between the amount of annual snowfall and annual seasonal snow cover. Warming in spring and early summer would increase runoff due to glacier melting (Barnett et al. 2005; Liu et al. 2009). Nevertheless, the vulnerability of the glaciers to the warming in

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Figure 9

Figure 10

Three routes of South-to-North Water Diversion Project and four river basins (the Yangtze River, Yellow River, Hai River, and Huai River).

Location of the Three Gorges Dam.

mainland China is still uncertain. Generally, about 5–27 and 10–67% of glacial areas are projected by some researchers to melt by 2050 and 2100, respectively (Shi and Liu 2000; Xie et al. 2006); they project that glacier melt peak would occur during the period of 2030–2050 (Xie et al. 2006; Chen et al. 2005). According to the China Meteorological Bureau, all small glaciers less than 2 km2 would disappear if the temperature increased by 1.9–2.3  C in northwest China.

5.13.4.4

Future Water Resources

Future projections of climate claim a large range of uncertainty on the question of whether northeastern China will continue to confront droughts in the future (Piao et al. 2010). A decrease of drought in northwestern China is projected under the Intergovernmental Panel on Climate Change (IPCC) B1 scenario (Nakicenovic and Swart 2000), while the bipolarity of a drier

Water Resources of Mainland China

Figure 11

Pearl River basin and major dams.

northeast China and a wetter northwest China would further increase under the IPCC A1B scenario (Nakicenovic and Swart 2000). The future river runoffs and water resources in mainland China have also been studied by using projected precipitation changes (Piao et al. 2010; Meehl et al. 2007; Shen 2010). Due to the large uncertainties involved in projected precipitation, no firm conclusions can be given (Meehl et al. 2007). However, it has been suggested that in general, by the end of 2100, the river runoff would be increased over mainland China (Zhang et al. 2007a) by 7.5% under the IPCC B1 scenario, and by 9.7% under the A1 scenario (Nakicenovic and Swart 2000). Annual runoff in the Yellow River basin is projected to increase by 11% (Zhang et al. 2007b) in IPCC A2 scenario (Nakicenovic and Swart 2000) and by 5% in the IPCC B2 scenario (Nakicenovic and Swart 2000). However, these results are dependent on the accuracy of global climate projections, and Gao et al. (2008) suggested that an accurate high-resolution climate model for mainland China is one of the necessary requirements for skillful future climate projections.

5.13.5

Tackling the Water Resource Problems

In the following subsections, three examples are introducedd the South-to-North Water Diversion project, the Three Georges project, and the practices for managing the Pearl River water resourcesdto illustrate some measures that have been implemented in order to deal with water resource problems in mainland China.

5.13.5.1

207

South-to-North Water Diversion Project

The spatial distribution of China’s water resources is extremely uneven. The sum of water resources in the Yellow River and the Hai River is less than 6% of the nation’s total water resources, but they need to supply water for approximately 40% of the

total irrigation land. Moreover, since the late 1970s, northern China has experienced rapid urbanization and economic development; to meet urban and industrial demands for water, groundwater in the region has been overexploited. Land subsidence and regional sandstorms have caused serious environmental problems due to the excessive usage of water resources, and the water shortage is extremely serious in northern China. The Yangtze River generates more than 80% of the nation’s total runoff, but its irrigation land area is approximately 30% of the nation’s total. To resolve the uneven spatial distribution of water resources, the largest water diversion project in mainland China, namely the South-to-North Water Diversion Project (see Figure 9), has been planned and implemented. The project is expected to be completed by 2050, and eventually 44.8 billion m3 of water will be diverted to the north region from the Yangtze River basin annually. This large water diversion project will integrate the water resources in the four river basins, which are the Yangtze River, the Yellow River, the Huai River, and the Hai River. The project consists of three water transferring routesdthe Eastern, Middle, and Western Routesdwhich divert 14.8 billion m3 year 1, 13.0 billion m3 year 1, and 17.0 billion m3 year 1 of water to the north, respectively. These three routes are briefly described in the following sections.

5.13.5.1.1

Eastern Route

Construction of the Eastern Route started in December 2002, and the route is expected to be completed by 2030. The Eastern Route is 1155 km long and diverts water from the downstream Yangtze River via the ancient Beijing-Hangzhou Grand Canal. It is the longest canal in the world and the oldest parts were constructed in the fifth century BCE (Before the Common Era). The main purpose of the canal was to transport grain and other commodities to the Huang River, Huai River, and Hai River plains (in Jiangsu, Anhui, and Shandong provinces), to Tianjin, and finally to Beijing. This route has 23 pumping stations, 9 km of tunnels, and 634 m of siphon sections (Water Technology

208

Water Resources of Mainland China

2011). A total of 7.67 billion m3 year 1 of water will be used to irrigate croplands, and 6.66 billion m3 year 1 of water will be used to supply the domestic and industrial sectors.

5.13.5.1.2

Middle Route

The Middle Route is 1267 km long, and its construction started in December 2003. This route is expected to be fully completed by 2030. In this route, water is diverted from the Danjiangkou reservoir on the Han River, which is a tributary of the Yangtze River, via canals near the west edge of the Huang, Huai, and Hai plains to Beijing and Tianjin municipalities through Henan and Hebei provinces. The route is regarded as an optimal solution to mitigate the water resource shortage in northern China. The advantages of the route lie mainly in the good water quality and gravitational force used to drive water from the south to north. The diverted water will benefit the people living in an area of 0.16 million km2, which is mainly composed of the Tangbaihe plain and the middle-western Huang-Huai-Hai plains, and 17 large- and medium-size cities, including Beijing, Tianjin, Shijiazhuang, and Zhengzhou.

5.13.5.1.3

Western Route

The Western Route plans to divert water from the upstream reaches of the Yangtze River to the upper reaches of the Yellow River by a 100-km tunnel through the Bayan Har Mountains. The water diverted by the route will benefit about 0.2 million km2 of irrigated farmlands and the route will provide 9.0 billion m3 year 1 of water for the domestic and industrial sectors. The main advantages of the route are that it can promote the economic development of some relatively less developed regions in northwest China and improve the environment of the Loess Plateau in North China. Nevertheless, due to the difficulties of constructing such a long tunnel and the ongoing dispute about water resources for the upstream areas of both the Yangtze River and Yellow River, the route is still in the planning stages (Sohu 2011).

5.13.5.2

Three Gorges Project (TGP)

The major task of this project is to construct the Three Gorges Dam (TGD). TGD is located in the Yiling District of Yichang City, in Hubei province, and is the largest water project along the Yangtze River (see Figure 10). Construction of TGD started on 14 December 1994, and the dam was completed on 20 May 2006. Mainly, there are four goals to the project. They are to reduce the flood risks in the midstream Yangtze River, to supply water to the midstream and downstream areas of the river, to produce clean energy, and to improve the Yangtze River’s navigation condition from Wuhan to Chongqing (see Figure 10). According to the design, all of the 26 turbines (with 700 MW generating capacity each) were installed and operating by 2009. There are six extra underground turbines, each with 700 MW generating capacity; three of these turbines were installed and functioning by 2011, with the remaining ones to be completed by 2012. With two other turbines of 50 MW as backup power units, the hydropower station of TGD dam has a capacity of 22 500 MW, which is currently the world’s largest hydropower station to produce clean energy. Flooding is a major problem for the midstream and downstream areas of the Yangtze River, where there are

agricultural production bases, millions of people, and important cities such as Wuhan, Nanjing, and Shanghai. TGD can effectively control or minimize floods by using the flood storage capacity of 22 km3 of the Three Gorges Reservoir (TGR). On 20 July 2010, there was a peak flow of 70 000 m3 s 1 into the TGR, and the reservoir water level rose about 3 m within 24 h; after the TGD regulation, the reservoir outflow was reduced to 40 000 m3 s 1, which would not cause flooding downstream the reservoir. The benefit from flood control of the TGR in 2010 was estimated at more than 20 billion RMB Yuan (about US$ 2.93 billion in 2010 equivalent). The reservoir’s operational water level during the dry season is 175 m (above the sea level). On 26 October 2010, this water level was reached for the first time after TGR tried to impound water for reaching 175 m in 2008 and 2009. Accordingly, its target of 84.7 TW hour (TWh) of annual power generation was achieved in 2010. By 16 August 2011, the hydropower plant of TGP had generated 500 TWh of electricity since the first operation of a hydropower generator in 2003. In addition, with the improvement of the navigation condition of the Yangtze River reach from Yichang to Chongqing due to the TGR, the maximum freight capacity of a ship has increased from 3000 tons before the project to 10 000 tons after the project. On 25 December 2011, a historical high was achieved in which an annual total of 100 million tons of cargo was transported through the TGD ship locks. Nevertheless, there are some negative impacts associated with TGP. For example, some archaeological and cultural sites have been submerged by TGR, and 1.3 million people have been relocated. The river ecosystem would have been influenced by regulating natural flow, and the rising and falling of water levels in the range of 145 and 175 m annually has resulted in some geological natural hazards (e.g., landslides). The impoundment of the TGR may impact the downstream lake levels and associated ecosystems, particularly Dongting and Poyang Lakes (Fan 2011). The scouring of riverbeds by water released from TGR is also a negative effect. Moreover, it has been argued that a massive reservoir like TGR might affect the climate systems and trigger more extreme weather and climate events (Wu et al. 2006; Gleick 2008). However, research has confirmed that TGR may influence the weather of the regions only to approximately 10 km away from the reservoir (Zhang et al. 2004).

5.13.5.3

Water Resource Management in the Pearl River

Figure 11 shows the geographic location of the Pearl River basin. Along with the rapid socioeconomic development of the Pearl River delta since the late 1970s, the water demand from the region has dramatically increased and various water problems (e.g., water shortages during droughts, water pollution, and seawater intrusion) have appeared (Cui et al. 2007; Niu and Chen 2010; Wang 2010). To deal with these problems and other issues in the basin, the Pearl River Water Resources Commission (PRWRC) has implemented a series of measures.

5.13.5.3.1

Water Allocation Framework

The water allocation framework established by the PRWRC aims to protect the upstream water sources, to regulate the midstream development, and to harness the downstream

Water Resources of Mainland China

environment (Cui et al. 2007; Wang 2010). The aims of water protection in the upstream are to maintain the water quality, to prevent soil erosion, to recover the polluted lakes, to protect ecological systems, and to enhance the construction of smallto middle-scale water conservancy projects. Water regulation in the midstream area is achieved by the construction of a series of water regulation projects and by increasing the capability of allocating water for maintaining navigation and achieving an ecology-required minimum flow during extreme dry periods. For example, through the National Headquarters on Flood Control and Drought Relief, the PRWRC implemented the release of water from a series of the reservoirs, most of them located in the midstream area, for preventing seawater intrusion in the estuarine areas in early 2005 (Cui et al. 2007). Water harnessing in the downstream area aims to enhance the prevention and treatment of the water pollution, to build a water-saving and pollution-preventing society, to handle the outlet salinity problem, and to conduct optimization projects for the water resource allocation.

5.13.5.3.2

Key Water Projects

The existing key water projects in the Pearl River basin include the Feilaixia, Bailongtan, Baise, Dahua, Yantan, Longtan reservoirs and the Tianshengqiao hydro projects (see Figure 11). A project currently being planned is the Datengxia Dam, which will be a key regulation project to safeguard water supply for Macau city and the Pearl River delta. Regional water diversion projects include the Zhanjiang and Qinzhou projects, and the Xijiang and Hongling projects along with a scheme to divert water to the middle of Guizhou province. Key water-saving projects currently being undertaken include the Mengkaige Irrigation Area and the Youjiang Irrigation Area water-saving projects. Irrigation and drinking water projects are mainly constructed in Yunnan and Guizhou provinces for agricultural irrigation and water supply, and they include the Rundian and Ziqian projects. A special campaign called the Projects with Five Smalls has been launched; these projects include construction of small water pools, small vaults, small dykes, small channels, and small pumps for the effective storing and transferring of water.

5.13.5.3.3

Future Water Demand

By 2030, the projected total water demand over the Pearl River basin in a normal year is 93.9 billion m3 year 1, which is 6 billion more than current demand (Wang 2010). The projected agricultural supply is 56% (53 billion m3), industry demand is 30% (27.7 billion m3), and domestic water is 14% (13.2 billion m3), while the basic flow for in-stream use is 130.3 billion m3. Urban water use is 37.6 billion m3, which is 15.8 billion m3 more than the current demand and approximately 40% of the total protected water use in 2030.

5.13.6

Concluding Remarks

Population growth is the dominant factor of threatening the security of water resources. Since 1979, the one-child policy has been implemented in mainland China. It was estimated that by 2007 China prevented about 400 million births (Anonymous 2011). The efforts to control population growth have

209

undoubtedly mitigated the severity of water shortage. However, the various water resource problems mentioned above are still serious, especially given the prediction of a projected population peak of 1.5 billion around 2033. The strategies and measures for tackling the vulnerability of water resources in mainland China (Wang 2010) include changing from supply-oriented water management to demandoriented management and establishing a water-saving society by adjusting the economic structure and industrial layout. The water resource management authorities are carrying out the strictest water management system and increasing the utilization of other water resources, such as reclaimed water and seawater desalinization. Also, the water resource commissions for the river basins are improving the water regulation, promoting rational water allocation, building necessary water infrastructures, strengthening their water regulation capabilities, promoting the use of information-based technology applications, and strengthening integrated water management. The current situation of water resources and their management in mainland China are not able to meet the increase in demand of water-related usages, such as water supply, protection of the water environment, and prevention of water-related natural hazards, due to population growth, the need to produce food, and the rapid economic development since the late 1970s. Regarding this, Central Document No. 1 in 2011 (Central Committee and State Council 2011), entitled “The Decision on Accelerating the Reform and Development of Water Conservancy,” was issued on 29 January 2011. This document is the first comprehensive policy document on integrated water resource management released by the Central Committee and State Council of mainland China. Water resource management, as the first priority among national infrastructure construction, will be pushed forward by both the central government and local governments. The main tasks identified in Central Document No. 1 include five parts (Central Committee and State Council 2011). Firstly, the water conservancy construction in rural regions and other vulnerable water-related natural hazard areas will be strengthened. Secondly, the harnessing of large rivers and lakes, water resource allocation, and water and soil conservation will be accelerated in a sound manner. Thirdly, significant financial allocation to water projects will be made. Funds for water resources management projects will be raised from multiple channels, and it is expected that a total of 4 trillion RMB Yuan (about US$ 0.6 trillion in 2011 equivalent) will be invested into the water projects for the next 10 years (i.e., up to 2020). Fourthly, the strict management of water resource usage will be enforced, which sets restriction standards for the control of water resource development and utilization, the control of water use efficiency, and the pollution load in water use zones. Fifthly, innovation of the water management system and mechanism will be continuously carried out. It is expected that by 2020 a comprehensive flood control and drought mitigation system in mainland China will be established and urban flood prevention and flood control capacity will have been greatly improved. The total water use for the whole country by 2020 will be limited to 670 billion m3 year 1, and the effective utilization coefficient of irrigation water will reach 0.55. The possibility of the frequent and sudden occurrence of extreme weather events could increase due to climate change,

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and new water-related problems are raised in conjunction with the growth of population and the fast development of China’s economy. Despite the many challenges in water resource management, including the frequent floods, droughts, and deterioration of the water environment, China has made great efforts in flood control, drought relief, and environmental protection in recent years. Both structural and nonstructural measures have been implemented, which include establishing an institutional framework, improving structural facilities, developing emergency plans, strengthening flood forecasting and warnings, issuing laws and regulations, and enhancing emergency management.

Acknowledgments This work was supported by two Hong Kong RGC GRF projects (HKU711008E and HKU710910E). The authors are grateful for the valuable comments and suggestions from two anonymous reviewers.

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