|Long Distance Water Transfer: A Chinese Case Study and International Experiences (UNU, 1983)|
Yao Bangyi and Chen Qinglian
Management Bureau for Water Conservancy Planning, Ministry of Water Conservancy, Beijing, China
WATER is a necessary resource for production and everyday life. The amount needed increases with production and with improvements in the standard of living. Yet the distribution of water spatially does not usually coincide with human requirements. At a certain stage of water resource development, therefore, interbasin transfers become inevitable.
In China, water is plentiful in the aggregate, but not in terms of area or population. Even more serious is the extreme geographical maldistribution between the water-abundant, land-short south and water-short, land-abundant north. The proposed transfer schemes would seek to correct this by bringing excess water from the Chang Jiang in the south to the arid areas of north and northwest China.
DISTRIBUTION OF WATER AND LAND RESOURCES IN CHINA
In general, water is more abundant in the southeast, along the coast and in the mountains. It is deficient in the northwest, inland and on the plains. This is due to climatic and geographical features, including China's land-ocean configuration.
Areal Distribution of Precipitation
The long-term average annual precipitation in China is approximately 6,000 km³ with an average annual depth of 630 mm. This is less than the world continental average of 800 mm or Asia's 740 mm.
Figure 1 shows the areal distribution of annual precipitation in China. The 500 mm isohyet stretches in a general northeast-southwest direction and divides the country into two parts. To the west lie China's main pastoral regions and some deserts. To the east are the main agricultural areas. South of the Qin Ling and Huai He and east of the Hengduan mountain range lie the main rice growing districts with rainfall in excess of 1,000 mm/annum in most places. The northern part of the Huang-Huai-Hai Plain is semi-humid, with an annual precipitation slightly greater than 500 mm.
Distribution of Stream Runoff
The long-term average volume of stream runoff is 2,600 km³ with an average annual depth of 270 mm, about 45 per cent that of precipitation. This volume ranks fifth in the world behind Brazil, the Soviet Union, Canada and the United States. The depth of runoff is less than either the world continental average of 315 mm or Asia's 324 mm. Per capita runoff amounts to only 2,700 m³, one-fourth of the world average.
The areal distribution of annual runoff is shown in Figure 2. In general, runoff tends to vary in the same way as precipitation, although the coefficient of runoff is less in the north, where there is relatively intense surface evaporation, than in the humid south. Several land surface factors also affect the generation of runoff and thus lead to a more uneven and more complicated areal distribution than for precipitation. South of the Chang Jiang annual runoff exceeds 700 mm, while along both banks of the lower Huang He and in the Hai He Plain it is only 25-50 mm.
The relatively small volume of runoff in the northern rivers is unevenly distributed seasonally and varies significantly from year to year with successive wet years and dry years. Reservoirs with very large capacities are required to regulate the runoff. Dams have already been built on most of the suitable sites in the Huai and Hai river basins. The inadequacy of regulation storage capacity means that a large amount of flood water has to be wasted and discharged into the sea during years of abundant water.
China has a long history of exploitation of groundwater. Rough estimates indicate the long-term safe yield to be approximately 700 km³. Of this, 480 km 3 are distributed in the Chang Jiang basin and regions to the south of it. This reserve has only been utilized in extremely rare instances such as in the Nanyang Basin. Only 70 km³, about 10 per cent of China's groundwater, lie under the one-quarter of the country's cultivated land which is located in north China in the municipalities of Beijing and Tianjin and the provinces of Hebei, Shandong and Henan.
The most extensive extraction of groundwater is in the Huang-Huai-Hai Plain. A large portion of the area north of the Huai He is irrigated by wells. In recent years, excessive extraction of groundwater in some places has produced cones of depression, particularly in the deep aquifers. Some of the cones have even linked together over broad areas. The groundwater in the coastal plain is highly mineralized and some of it is unusable.
Distribution of Water and Land Resources in China
Table 1 presents the cultivated land, population and long-term average annual stream runoff within major river basins in China. The total cultivated area in the Chang Jiang and Zhu (Pearl) Jiang basins constitutes little more than one-quarter of the national total while their runoff is half. Runoff per hectare is 41,700 m³ and 69,750 m³ repectively, while the per capita figures are 2,890 m³ and 4,150 m³.
The total cultivated area in the Huai He and Hail He basins is 24 million ha, one-quarter of the national total, while the natural runoff is only 81.3 km³, onethirtieth that of all China. This averages a mere 3,450 m³/ha or 370 m³/cap, less than one-seventh the national average.
THE UTILIZATION OF WATER RESOURCES IN CHINA
The Utilization of Water Resources in China and Estimated Water Needs at the End of this Century
Although China has made use of its water resources from very early times, progress was rather slow until the 1950s. Since then a large number of water conservancy projects have been constructed. More than 80,000 reservoirs of all sizes were built prior to 1979 with a total storage capacity in excess of 400 km³ (approximately 30 to 40 per cent that of the United States or the Soviet Union). The total storage of the 300-plus large and medium-size reservoirs alone is about 300 km³. Of the 48 million ha currently under irrigation, about 17 million ha is in reservoir irrigation districts, approximately 11 million ha is in well irrigation districts and about 20 million ha is irrigated by other means. Less than half the cultivated land in China is now under irrigation. Moreover, field distribution works are relatively deficient, irrigation techniques are backward and the rate at which water supply can be guaranteed is not high. A rough estimate of the present amount of water used each year in farm irrigation is 300 to 400 km³ while industrial water consumption is one-tenth that, only about 30 to 40 km³.
With the realization of China's four modernizations, industrial and agricultural water uses will increase significantly, especially in industry. If the target of 1/15 ha of irrigated land per capita of agricultural population is reached by the end of this century and if the rate of guaranteed irrigation is increased in a rational manner, it is estimated that irrigation water use will exceed 500 km³. Estimated industrial and domestic consumption, based on the gross national product target for the year 2000, may be around 100 km³, making for a total usage of 600 km³. This comprises 20 to 25 per cent of China's total water resources and is nearly twice the present level of water use. The rate of utilization of water resources in the Huang-Huai-Hai Plain is currently relatively high and water use will increase greatly in the future. Despite further increases in the utilization rate of the region's runoff and the adoption of water-saving measures, the long-term plans of the pertinent provinces and municipalities estimate the normal dry year water deficit to be around 70 km³ by the end of the century. We must rely on the transfer of water from the Chang Jiang to solve this problem.
Table 1. Land and Water Resources in Some Major Basins in China
|River basin||Annual stream runoff||Cultivated |
|Runoff per |
|Name of |
|Total volume |
|Percentage of |
The Current Status of Water Resources in the Major Rivers of Eastern China and Future Trends of Development
Chang Jiang. The long-term average annual runoff of the Chang Jiang is about 1,000 km³ and ranks third in the world. Stream flow is lowest from December to February with monthly average discharge at a minimum in January, 10,400 m³/sec. The historical low monthly average is 6,730 m³/sec.
Large reservoirs such as the Danjiangkou and the Tuoxi have been built in the drainage basin and others such as the Wuqiangxi are planned. These reservoirs play a certain role in regulating runoff. At present a relatively small portion of Chang Jiang water is utilized in agriculture or industry. With the completion of a number of large reservoirs and hydroelectric power stations in the future, increasing industrial and agricultural water usages will be supplemented even in the low flow period by maintaining normal levels of discharge. The Chang Jiang is therefore a reliable source of water for transfer to the north.
Huang He. The Huang He is the second largest river in China. Over 4.3 million ha of cultivated land in this basin has been brought under irrigation. The long-term average natural runoff is 56 km³/annum but in the ten years from 1969 to 1978 the actually observed runoff was only 37.4 km³/annum at Huayuankou station. This was about 10 km³ less than the observed value in the early 1950s. The volume discharged into the ocean during the three months from April to June was only 3.5 km³, due in the main to increases in irrigation water use in the upper and middle reaches. The excessively low precipitation of recent years has also had some effect. According to the estimates of the relevant agencies, industrial and agricultural water use in the upper and middle reaches may increase to approximately 30 km³/annum by the end of the century. This will reduce the longterm average runoff in the lower reaches to a mere 26 km³/annum.
Downstream irrigation districts diverting the Huang He in the two provinces of Henan and Shandong have drawn off approximately 10 km³/annum in recent years. Because of the large amount of water so diverted, flow was cut off in the estuary of the Huang He in seven years during the 1970s for a total of over 70 days. The longest stretch in a single year was 20 days. According to the long-term plans of the two provinces, future water diversions may increase to about 25 km³/annum. This would mean that the lower reaches would be dried up for nearly all the year. Of course, this is not acceptable. Moreover, a certain amount of discharge into the ocean is necessary every year to meet sediment transport and ecological requirements. Thus, from a long term viewpoint, there is no water in the Huang He for long-distance diversion. In the near future, however, it is possible to transfer a share of water to replenish the Hai He during the winter by staggering the irrigation seasons and avoiding the period of high sediment concentration.
Huai He. The present area under irrigation in the Huai He basin is 7.3 million ha. Water resources of the basin are utilized relatively intensively. The Huai has a long-term average annual natural runoff of 53 km³. At present it is felt that this amount of water is insufficient in normal dry years. Since 1970 the river has ceased flowing several times in the stretch below Bengbu. From October 1977 until the middle of 1979, Jiangsu Province pumped 21 km³ of water from the Chang Jiang to make up the water-use deficit in the lower reaches of the Huai He. At the present level of water use the total volume of water is sufficient in normal years, but during dry periods and the peak irrigation period it is necessary to pump supplementary water from the Chang Jiang. With further increases in industrial and agricultural water use in the basin, the lack of water will become very serious in dry years and water will be insufficient even in normal years. In the future we must increase the scale of pumping from the Chang Jiang to replenish the Huai and gradually extend the area receiving supplementary water towards the west and north.
Hai He and Luan He. The drainage basins of the Hai and Luan He cover a total of 320,000 km², of which 190,000 km² is mountainous and 130,000 km² is in the plains. At present approximately 5.3 million ha are under irrigation. The longterm average annual natural runoff amounts to 28.3 km³. Of this, 20.9 km³ originates in the mountains and only 7.4 km³ stems from the plains. Over 1,000 reservoirs of various sizes have been built in these basins, with a total storage capacity in excess of 21.7 km³. Large increases in industrial and agricultural water use have caused the entire basin's discharge into the ocean to decrease gradually, from an average of 22.3 km³/annum between 1950 and 1959 (15.9 km³ from the Hai He basin) to 13.8 km³/annum between 1960 and 1972 (Hai basin: 10.1 km³). In recent years there has been a further decrease in discharge into the ocean to 7 to 8 km³/annum (from the Hai basin: 3.5 to 4.5 km³). In dry years only about one km³ enters the ocean and most of this is from the Luan He basin.
There is some discrepancy in different agencies' estimates of the extractable groundwater. The relevant provinces and municipalities feel that the present degree of exploitation of groundwater is already rather high.
It is difficult or uneconomical to increase further the rate of utilization of mountain runoff in the Hai and Luan He basins. It is even more difficult to utilize the runoff of plains rivers due to the lack of sufficient storage capacity. At present the lower reaches of most tributaries in the Hai and Luan He systems run dry for a long period during the non-flood seasons. Even during the flood season, the amount of water is quite small except in abundant years. Water is insufficient for agricultural uses in the eastern part of the plain. Water deficiency has become increasingly severe in municipalities such as Tianjin and has already affected industrial and agricultural production as well as the daily lives of the people.
PLANNING AND RESEARCH ON SOUTH-TO-NORTH WATER TRANSFER
Much attention has consistently been paid in China to the planning and research on south-north water transfer. In the early 1950s the pertinent agencies did some of this work in conjunction with the river basin plans for the Chang Jiang and the Huang He. Later various tentative ideas were brought forward and preliminary surveys made of some of the proposed transfer routes. In addition, symposia and scientific research conferences were held one after another with some degree of success. Since the beginning of the 1970s the problems of drought and water deficiency have become ever more salient, especially in large and medium-sized municipalities such as Tianjin, which has been seriously affected by water shortages. In consequence, the question of northward transfer of Chang Jiang water was again placed on the agenda and the agencies concerned once more began to do research on the interbasin transfer of water.
First studied was diverting water from the Huang He. Because the amount of water that can be transferred over a long distance is small, this can only be used as an emergency measure. In addition there are numerous difficult problems such as siltation which have to be solved. In order to solve the problem of water deficiency once and for all it is still necessary to transfer water from the Chang Jiang. Therefore, acting on the basis of the original long-term plans and in keeping with current circumstances, the agencies concerned first studied the route involving pumping water from the lower reaches of the Chang Jiang and submitted a preliminary planning report in 1976. They then organized an initial examination. At the same time, research was renewed on the transfer route from the middle reaches of the Chang Jiang. A survey was made on the route transferring water from the Danjiangkou Reservoir and a working plan was drafted for a long-term programme. Exploratory investigations were also made once more of routes diverting water from the upper reaches.
The south-to-north transfer is a magnificent project to transform nature. It involves numerous scientific and technical problems which must be researched and solved. Many of China's scientists are interested in this matter and the government has also devoted much attention to it, listing the engineering techniques involved and ecological effects as key items for scientific research. Some initial results have already been obtained on some of these topics.
Transfer Route Schemes
In the past, agencies have proposed numerous route schemes, some of which have remained on paper while others have had some work done on them. If we leave out obviously irrational schemes or those which do not solve the problem adequately, these proposals can be lumped together into three groups, depending on whether the water is transferred from the upper, middle or lower reaches. These are termed the West, East and Middle routes respectively. Figure 3 shows their locations.
The West Route is the generic term for the various proposed routes which divert water from the upper reaches of the Chang Jiang into China's northwest. These routes traverse the Qinghai-Xizang (Tibetan) Plateau or its edge, transferring water from either the Tongtian He or from the Jinsha Jiang and other tributaries of the Chang Jiang. Some work was done on looking into these schemes in the late 1950s and exploratory studies are now being carried out. Measured simply in terms of the severity of drought conditions, the northwest is the most deficient in water. With water the cultivated area could be expanded and forestry, animal husbandry and industry could be developed more fruitfully. But all of these water transfer projects are enormous and difficult and none of them can be carried out in the short term.
The Middle Route and the East Route (see Figure 4) would both supply water to the Huang-Huai-Hai Plain, the former mainly to the western portions of the plain and the latter chiefly to the eastern parts of the Huai He and Hai He plains as well as to coastal regions. The areas supplied by these two routes are independent of each other and it is generally considered that they cannot be treated as substitues.
At present there is some controversy over which route should be developed first. Nevertheless, both routes have the same conditions for proceeding from small to large and from near to far and developing benefits one stretch at a time. Hence we may carry out planning and research on the one hand while bringing the advantages of each scheme into full play on the other, gradually expanding its scope and making full use of it. In practice, this is what is now being done.
MIDDLE ROUTE SCHEMES
The Chang Jiang Basin Planning Office and the Huang He Commission carried out preliminary studies of this route as early as the 1950s. In this scheme, the water of the Han Jiang may at first be diverted northward from the Danjiangkou Reservoir. Once the Sanxia (Three gorges) Reservoir is built on the Chang Jiang, additional water will be diverted from it.
Water Conditions for Transfer from the Han Jiang
The Danjiangkou Reservoir, on the middle reaches of the Han Jiang, is a key multipurpose project used for flood control, irrigation and the generation of power. The requirements of transferring water northward from the Han Jiang were considered in its planning and designing stages. The reservoir is to regulate the headworks of the Middle Route canal.
In the original design of Danjiangkou, the dam crest elevation was 175 m above sea level, the normal pool level 170 m, total storage 33 km³ and useful storage 16.4 to 19 km³. The first stage was completed in 1973, with a dam crest elevation of 162 m, a normal pool level of 157 m, a total storage of 21 km³, useful storage of 9.8 to 10.2 km² and a power station with an installed capacity of 900 MW.
The reservoir controls a catchment area of 95,000 km², 60 per cent of which is in the Han Jiang basin. The long-term average streamflow discharge above the dam site is 1,200 m³/sec with an average annual runoff of 37.9 km³, 75 per cent of that of the entire basin. Most of the area above the dam site is mountainous where little water is used. Even if more water conservancy facilities are developed, there will be no great reduction in runoff.
Table 2 presents the volumes of water which may be transferred to the north from the Danjiangkou Reservoir. It is based on 49 years of hydrological data and takes into consideration irrigation and navigation requirements in the lower reaches of the Han Jiang below the reservoir.
Preliminary plans are for the control irrigation area of the Middle Route scheme to be in excess of 6.7 million ha. In diverting Danjiangkou water it is planned to first develop 5.1 million ha, of which 0.73 million ha will be added to areas irrigated by the Tongbai He, 1.6 million ha to eastern Henan Province and 2.8 million ha to the area north of the Huang He and west of the area irrigated by the East Route. Calculating on the basis of present irrigation norms it will be necessary to supply 20 to 24 km³ of supplementary water. We have also looked into the water required in the subregions. Industrial water use is estimated at 7.4 km³.
Table 2. Volume of Water which can be Transferred to the North from the Danjiangkou Reservoir
|Scale of reservoir||Transferable volume||Hydropower|
|Storage level |
|Diversion from |
|P = 0.80 |
|Average annual |
According to data from the fifty years between 1929 and 1978, there were only two years of concurrent drought in the river systems of the Han Jiang, the Huai He and the Hai He, only three concurrent drought years in the Han Jiang and the Hai He, and but six years of concurrent drought in the Han Jiang and the Huai He. The infrequency of drought years occurring at the same time is very favourable to interbasin water transfer.
The Main Trunk Canal for Diverting the Han
The total length of this canal will be 1,265 km, of which 481.5 km are south of the Huang He, 6.5 km are in the section crossing the Huang and 777 km are north of the river. The scale of water transport declines gradually from south to north. The discharge is to be 1,200 m³/sec at the diversion canal headworks, 800 m³/sec when crossing the Huang He, 680 m³/sec when entering Hebei Province in the vicinity of Handan and 120 m³/sec when it enters Beijing Municipality. The route slopes from 149 m above sea level at the headworks in the south to approximately 50 m at Beijing, so water can flow by gravity.
Specifics of the route are shown in Figures 5, 6 and 7. The following is a brief account of the canal by sections.
From Danjiangkou Reservoir to the Huang He. After being diverted at the Taocha key works on the left bank of the Danjiangkou Reservoir, water would flow northeast along the northern edge of the Nanyang Basin until it reaches Fangcheng (Town). Then, crossing the divide, it would turn north, generally following the piedmont of the Funiu Shan and pass through Baofeng and Yu counties. When it reaches the northwest of Zhengzhou Municipality, it would cross the Huang He by aqueduct.
The topography along the route is not too complicated, consisting in the main of mounds and low hills without great undulation and some alluvial and diluvial plains. In general the canal line would be excavated through strata of clay, mild clay and loam. A small amount of stonework is necessary at the headworks and the Fangcheng gap and in the vicinities of Baofeng and Xinzheng. Ten crossing projects must be constructed where the trunk canal passes over natural river channels.
From the Huang He to Beijing .After crossing the Huang He the trunk canal proceeds northward along the eastern piedmont of the Taihang Shan, roughly parallel to the Beijing-Guangzhou rail line. High and low alternatives have been compared. The higher elevation tends to be favoured, but further research must be done before a specific route location is determined.
The high line would begin from the north bank of the Huang He and reach Beijing via Jiaozuo, Anyang, Shijiazhuang and Fangshan. Most of the main delivery canal would be on the higher elevations to the west of the Beijing-Guangzhou rail line. The irrigated area which could be controlled by gravity would be large and water supply to the large and medium-sized cities along the route would be convenient. The disadvantages of this route are that it would have to traverse some hilly districts and would cross numerous feeder railways, requiring a great deal of construction.
A low line has been proposed which is identical south of the Qin He, but after traversing that river it falls and moves back and forth across the BeijingGuangzhou rail line. This line lies entirely in the plains and would require relatively little construction. Its disadvantages are that the low elevation of the water transported reduces the area which can be irrigated by gravity and makes it impossible to supply water by gravity to the large and medium-sized cities along the route; and that the land excavated would mostly be good farmland. The soils along the route are generally clay or mild clay. Furthermore, nearly one hundred crossing structures would have to be built where the trunk canal intersects natural river channels.
Projects for Storage and Regulation
In order to reduce the scale of the main canal and to supply suitable amounts of water to industry and agriculture at the appropriate times, a certain number of storage projects will be required. The existing reservoirs along the route can be joined with the main canal in conveying water and bring into full play some of their regulating storage functions. In addition it will be necessary to build some new reservoirs. Among these, the Yanshan Reservoir will play a large role in regulating water used in the irrigated areas of eastern Henan Province.
The diverted water will be used in conjunction with local runoff and groundwater. In years of abundant water in the Han Jiang, irrigation districts may use more transferred water and less groundwater. In Han Jiang dry years, more groundwater will be used and less water will be diverted from the Han.
Upon its completion, the project will yield considerable benefits. An additional 3.8 million ha of farmland can be brought under irrigation and the rate of guaranteed water supply can be raised on another 1.3 million ha. Of this total of 5.1 million ha receiving benefits, 0.23 million ha will be in Hubei Province, 2.577 million ha in Henan Province, 2.16 million ha in Hebei Province and 0.17 million ha in Beijing Municipality. The amount of water which can be supplied for industrial, mining, municipal and domestic uses will be 7.4 km³. The main trunk canal will also serve as a man-made navigation channel navigable from Beijing to the Danjiangkou Reservoir. From there one can reach Wuhan directly along the Han Jiang, constituting a total channel over 1,600 km. long.
THE EAST ROUTE SCHEME
The East Route scheme refers to the transfer route which transfers water pumped from the lower reaches of the Chang Jiang to north China roughly along the Beijing-Hangzhou Grand Canal. In addition there is a Chaoliu Route which would only provide supplementary water to central and northern Anhui Province. This route will not be discussed here.
The lower reaches of the Chang Jiang provide a guaranteed water source for the East Route. The transfer path would lie entirely in plains areas, simplifying construction, and there are already river channels and many water conservancy facilities that can be made use of. Four large lakes can store and regulate the water. Finally, the canal could also be used to drain excess surface water. The disadvantage of this scheme is the large amount of electricity which would have to be consumed each year to pump water in the section from the Chang Jiang to the Huang He.
Project Scale and Amount of Water Transferred
The transport capacities of existing projects and river channels which must be enlarged to harness the Huai He add up to 700 m³/sec for northward transport south of Hongze Lake and 400-500 m³/sec between Hongze and Dongping Lakes. Based on making full use of the transport capacities of existing river channels and on solving the water needs in those places most deficient in water while appropriately enlarging some of the channels, the designed discharge in the preliminary plans for each stretch is as follows:
Table 3. Designed Water Discharge
|Section||Designed Discharge |
|Chang Jiang to Hongze Lake||1,000|
|Hongze Lake to Luoma Lake||800|
|Luoma Lake to Nansi lakes||750|
|Nansi lakes via Huang He to Linqing||600|
|Linqing to Dezhou||350|
|Dezhou to Tianjin||100-250|
Adjusted calculations based on the above project scale and using data from the 26 years following the founding of the People's Republic of China in 1949 indicate that 30 km³ would be pumped from the Chang Jiang in dry years. During average years 14 km³ would be pumped, to which would be added the excess water from the Huai He. In a long-term average year the amount of water crossing the Huang He could exceed 15 km³.
Water Conveyance Trunk Route Project
The route tentatively selected pumps water from the Chang Jiang in the vicinity of Yangzhou and Taizhou in Jiangsu Province and conveys it northwards roughly along the Beijing-Hangzhou Grand Canal. In some stretches it divides into two or three channels and links together the Hongze, Luoma, Nansi and Dongping lakes. After passing under the Huang He, the water would flow by gravity to Tianjin along the route of the Beijing-Hangzhou Grand Canal.
The total length of the trunk canal route would be 1,150 km, of which 660 km lie to the south of the Huang He and 490 km lie to the north. The highest point along the entire route is the Huang He. The water level at the crossing site is 40 m higher than where the water would be pumped from the Chang Jiang. A total lift of approximately 65 m is planned in 15 stages, requiring the construction of several dozen large pumping stations with a total installed capacity of about 1,000 MW and an annual electricity consumption of 3,0005,000 GWh.
The sections of the trunk line are as follows:
From the Chang Jiang to Hongze Lake. Water would be delivered to Hongze Lake by several paths using the Grand Canal and drainage channels in the lower reaches of the Huai He. In addition to utilizing the existing pumping stations including those at Jiangdu and Huaian, it will be necessary to construct three other stages with five new pumping stations.
From Hongze Lake to Luoma Lake. Two routes would be used to convey water. A main trunk canal with a designed discharge of 600 m³/sec would enter Luoma Lake at Zao He via the Grand Canal and would require the construction of three pumping stages. A secondary trunk canal with a designed discharge of 200 m³/sec would be located west of the middle reach of the Grand Canal and would also require three pumping stages.
From Luama Lake to the Nansi Lakes. Water would be conveyed by three routes. A main trunk line with a designed discharge of 500 m³/sec would enter the Nansi Lakes at Hanzhuang via the Grand Canal and would require four pumping stages. Two secondary trunk canals with a total designed discharge of 250 m³/sec would require five new pumping stations.
Within the Nansi (Four South) Lakes. Lying within the section from Hanzhuang to the mouth of the Liangji Canal, the present Nansi Lakes can be divided into the upper (north) and lower (south) stage lakes. Between the two is the key Erjiba project. Water in the Nansi Lakes is extremely shallow and the elevation in the north is higher than in the south. The overgrowth of water plants and reeds necessitates the digging of a channel to deliver water with a designed discharge of 600-700 m³/sec and the construction of a pumping station at Erjiba.
From the Nansi Lakes to Dongping Lake. The designed discharge in this stretch is 600 m³/sec. The Liangji Canal, which will be used to convey the water, will have to be expanded and four pumping stages will have to be built.
The project to cross under the Huang He. A tunnel underneath the river in the vicinity of Dongping Lake will be used for the Huang He crossing. The problem of how to cross the Huang He with navigation vessels is still under study.
From the north bank of the Huang He to Linqing.The new Beijing Hangzhou Grand Canal which has already been partially excavated would be enlarged and utilized in this stretch. It would have a designed discharge of 600 m³/sec.
From Linqing to Tianjin. The designed discharge in the two routes would decline gradually from 600 m³/sec to 100 m³/sec. One path would ship water from the Beijing-Hangzhou Grand Canal with decreasing discharge as it proceeds north. It would supply water for storage in Beidagang (Reservoir) near Tianjin. Measures would be taken to cut off and divert seepage water along both banks of the canal and around plains reservoirs in order to prevent salinization of the nearby land that might be caused by the raising of the water table. The other path would require excavating a new stretch of river to carry the water west of the Grand Canal.
Projects for Storage and Regulation
South of the Huang He, the Hongze, Luoma and Nansi lakes have an effective useful storage capacity of 5.8 km³. At present Dongping Lake serves exclusively as a flood-retarding basin for the Huang He and may not be used for storage in the near future.
In the long-range plan for harnessing the Huai He the storage level of these lakes is to be raised. In the long-range water transfer plans these lakes are to be utilized for storage. With rational operating procedures, no conflict with floodwater retention will occur.
There are very few reservoirs north of the Huang He, and they are far from meeting the requirements of regulating the water. Preparations are being made to make use of low-lying depressions to expand and build reservoirs in the plains. At the same time other forms of storage will be utilized to satisfy the requirements of storage and regulation. Engineering and operations for storage measures must be done m strict accordance with the need to prevent salinization.
The multiple benefits of the water transfer project are as follows: (1) The area under irrigation can be expanded or improved by 4.3 million ha, of which 2.3 million ha will be north of the Huang He and 2.0 million ha south of it; (2) 2.7 km³ of supplemental water can be provided for industrial, municipal, domestic and navigational use along the route; (3) With the conveyance of water, the section of the ancient Beijing-Hangzhou Grand Canal from the Chang Jiang to Tianjin could be modernized; (4) The large pumping stations along the route can also be used to drain up to 5,000 m³/sec of excess surface water from an area of 18,000 km². In addition, more water can be used to scour away sediment from all the harbours along the coast of northern Jiangsu Province. Finally, the project would play an important role in the development of aquatic production.
In this chapter we have outlined the preliminary studies which have been done on the long-range plans for China's south-to-north water transfer projects. A water transfer project of this scale involves numerous scientific, technical and economic problems and would have some impact on the natural environment. These must be given full consideration in the planning stages. In particular, repeated research should be carried out on some major scientific and technical problems. For example: what is the magnitude of local water resources in importing areas? How can their rate of utilization be raised in a rational manner? Is it necessary to transfer water in the future? How much? From what area, which drainage basin? Along which route? How can the scientific and technical problems be solved concerning long tunnels, large aqueducts, deep excavations and myriad crossing projects? What are the likely environmental impacts of the water transfer project in the exporting and importing areas? What measures should be taken to solve these ecological problems? What are the overall economic benefits of the water transfer? Is the water transfer project economically feasible? How can the project be managed in a modern way?
We have carried out some preliminary research on these problems, but different parties hold different opinions. The continuation of these matters awaits further ongoing, in-depth research.