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THE MAIN PROGRESS IN THE HYDRAULIC RESEARCH IN CHINA

By Zhu Erming
(Chairperson of the Executive Board, Chinese Hydraulic Engineering Society)

Abstract

    This paper summarizes the natural conditions, achievements of water resources undertakings and major existing water problems in China, emphatically expatiates upon the major progress in hydraulic research and, in consideration of the requirement of economic and social development for water resources, presents prospects for the development of water resources undertakings in the early 21st century (2030).

1、 NATURAL CONDITIONS AND ACHIEVEMENTS IN WATER RESOURCES UNDERTAKINGS

    1.1 Natural Conditions

    China has a vast territory ranging over 62° of longitude or 5200 km from east to west, and 52° of latitude or 5500 km from north to south, covering the tropical zone, sub-tropical zone, warm humid zone, temperate zone and cold temperate zone. The topography is complicated and presents three obvious steps from the "World Roof" at the western end to the eastern coastal plains. China has a large number of rivers, in which more than 1500 each have a drainage area of more than 1000 km² and have a total length of 430000 km. Most of the large rivers flow from the west towards the east with divides in between in the same direction, thus natural hydraulic links are lacking in the south-north direction. The climate is affected by monsoon and the precipitation varies greatly in time and space. The southwestern regions are rich in hydropower potential, and the northwestern regions are poor in rainfall and suffer frequently from droughts. The total volume of water resources in the country is 2800 billion m³ and the per capita volume is 2170 m³. As affected by the natural and climatic conditions, China suffers frequently from flood, waterlogging and drought disasters, the soil erosion is serious, and the eco-environment is fragile. The natural environment determines the position and role of water resources undertakings in the economic and social development and the eco-environmental protection in China.

    1.2 Achievements of Water Resources Undertakings

    The Chinese nation has a long history of water harnessing. The Dujiang Weir Complex in Sichuan Province, the Zhengguo Canal in Shaanxi Province, the Ling Canal in Guangxi Autonomous Region and the Beijing-Hangzhou Grand Canal were all built Anno Domini and water resources projects of various kinds such the Yellow River embankments were built in later periods. Since entering the 20th century, particularly after the founding of the P. R. China, the water resources undertakings have seen a period of great development. In the last 50 years, a lot of water resources infrastructure has been built. By the end of year 2000, the total length of consolidated and newly-built embankments had amounted to 270000 km; more than 85000 reservoirs had been built with a total storage capacity of 518.3 billion m³, and 98 flood detentions zones had been established with a total detention and storage capacity of 97 billion m³, thus preliminarily creating a flood control engineering system for large rivers and lakes which can control normal floods, protect 40 million ha of farmland, 460 million population, more than 600 cities and major communication lines, industries and mines; the total annual capacity of water supply had amounted to 580 billion m³; the area of irrigated farmland to 55 million ha; the installed capacity of hydropower generation to 76.8 GW; the mileage of river transportation to 110000 km; and the soil erosion area that has been put under preliminary control to 800000 km², thus reducing annual sediment discharged into rivers by about 1.5 billion t. The water resources undertakings in China have played an important role in flood control, urban and rural water supply, hydropower generation, river transportation, water and soil conservation, ecological improvement, harbor, aqua-culture, recreation, etc, thus providing great supports for the sustainable, rapid and healthy economic development, social stability, promotion of the people's living standard, smooth progress of reform and opening-up and the national economic safety and, at the same time, also providing extensive horizons for hydraulic research.

    1.3 The Main Water Problems

    1. Low capacity against flood and long term treats of flood and waterlogging disasters

    At present there are 70% of the cities and 50% of the major embankments are not up to the national standards for flood control, the situation of flood control is still stern and the tasks of flood control are very arduous.

    2. Uneven distribution of water resources in time and space and a big gap between water supply and demand

    As affected by the monsoon climate, China's precipitation varies greatly in time and space. The southern China is rich in water resources but poor in farmland, and the northern China is poor in water resources but rich in farmland. It is very pressing to implement rational allocation of water resources in order to solve the water shortage in the Huang-Huai-Hai region

    3. Severe soil erosion and fragile eco-environment

    According to the second national soil erosion remote-sensing survey, the water erosion area in the country is 1.65 million km² and the wind erosion area 1.90 million km². Therefore, the soil erosion is still very severe and the tasks to harness soil erosion are very arduous.

    4. Serious water pollution and deteriorating water environment

    By now about 38% of the river reaches of the seven major rivers in the country have been polluted to a varying degree, about 30% of industrial wastewater and 80% of domestic sewage are directly discharged into rivers, lakes and reservoirs without any treatment. To facilitate the harnessing of water pollution sources will be put on the important agenda of infrastructure construction in China.

2、 MAN PROGRESS IN HYDRAULIC RESEARCH

    In the last tens of years, China has stick to the thoughts that sciences and technologies are the first productivity, economic development must rely on sciences and technologies and scientific and technologic work must be oriented to economic development, and the large-scale construction of water resources engineering has promoted hydraulic research.

    2.1 Water Resources Research

    The natural precipitation in China is distributed unevenly in time and space with great inter- and intra-year variations, and both consecutive wet and dry years often occur, which is the basic reason for the imbalance between land and water resources and the frequent occurrence of drought, flood and waterlogging disasters. In the last tens of years, China has achieved great progress in water resources assessment, allocation of water resources, water environmental protection, water legislation and water management. Structural and non-structural measures are applied to coordinate the relationship between water and the society, economy, ecology and environment and implement unified planning and management of development, utilization and protection of water resources. The multiple levels, multiple objectives and group decision large system analysis method was applied to the formulation of national mid to long term water plan, national groundwater plan, national water conservation plan, etc so as to promote the foresight for sustainable utilization of water resources. At the same time, the research projects of Macroeconomic Based Water Resources Planning and Management in North China and the Rational Allocation and Ecological Protection in Northwest China were implemented for the areas of serious water scarcity. In order to alleviate the water shortage in some areas, a number of inter-basin and inter-regional water transfer projects have been implemented, such as Datong River-Qinwangchuan and Yellow-Shanxi transfer projects. At present the South to North Transfer Project is being studied, which would cover the four major river basins of Yangtze, Huaihe, Yellow and Haihe.

    At present coordinated planning is being made for the three large systems of water cycle, socio-economy and eco-environment of river basin with the dissipation theory, fuzzy mathematics and artificial intelligence in order to provide comprehensive guarantee of water resources for the regional economic development and eco-environmental protection.

    2.2 Environmental Hydraulic Research

    Water is an important element of the environment and water resources undertakings exert multiple impacts on the environment, in which the positive ones include: control of flood and waterlogging disasters, development of irrigation, improvement of navigation, hydropower development, water and soil conservation, water supply for human beings' life and production, ecology and environment, and the negative ones include: inundation of large areas of land by reservoir construction, resettlement of large numbers of residents, layered distribution of water temperature in large-sized reservoir affecting water ecology, river barriers stopping fish migration, release of low temperature water from reservoir affecting water ecology; excessive upstream water use causing water shortage and river's drying-up downstream, discharge of untreated wastewater upstream causing pollution of river channel downstream, and excessive overdraft of groundwater causing ground subsidence. Therefore, to strengthen water demand and use management, promote water use efficiency, protect and improve the eco-environment is an important task of water resources undertakings.

    1. Water eco-environmental protection

    (1) Conduct scientific zoning of water functions and formulate protection plans accordingloy.

    (2) Carry out targeted water quantity and quality evaluation and make forecast regularly.

    (3) Strengthen the monitoring and information collection on water eco-environment and establish a data base system for water quantity and quality.

    (4) Protect water eco-system and biological resources.

    (5) Strengthen research and water pollution control, and accelerate the progress of water and soil conservation.

    (6) Strengthen legislation for water ecological protection and protect water eco-environment by law.

    2. Hydraulic works environmental protection

    The impacts of hydraulic works on the environment are a complicated system of multiple variables, multiple structures and multiple levels, and are generally evaluated in a comprehensive way according to the varieties, components, elements and measures of environment, covering reservoir inundation, land occupation, induced changes in water and sediment regimes, river regime, storage and release, water table, etc, and impacts of construction. The Law on Environmental Protection of P. R. China was issued in 1979, the Regulations on the Management of Environmental Protection for Capital Construction Project in 1981, and the Regulations on the Environmental Impact Evaluation of Hydraulic Works in 1982, thus establishing a system of EIA for hydraulic works.

    (1) The planning and design of hydraulic works should follow the policy of putting prevention first, combining prevention with remedy and implementing comprehensive harnessing so as to reduce as far as possible adverse impacts on the eco-environment. Reliable protection measures must be adopted for unavoidable impacts.

    (2) In the planning and design, impacts on the eco-environment should be fully studied as an important element for the rational selection of design schemes, resident relocation plans and operation rules.

    (3) Construction must not start before the EIA report for the project is approved.

    (4) The system should be fully implemented that the environmental protection measures are designed, constructed and put into operation at the same time as the main works. The acceptance of environmental protection measures should be taken as a component of project completion acceptance.

    (5) The monitoring and management of eco-environment during operation should be taken as a component of project management.

    (6) In the formulation of the EIA report for hydraulic works, representatives from related areas and sectors, experts and the public must be invited to participate and an effective supervision mechanism should be established.

    3. Major progress in water environmental research

    (1) Observation has been made of pollutant diffusion and transportation for the main reaches of large rivers and studies have been carried out on the range and concentration distribution of offshore pollution belt and mutual impacts among multiple waste outlets.

    (2) Studies have been made on the impact of regular waves on re-oxygenation coefficient for each system of the river dissolved oxygen model and the model for oxygen production of algae photosynthesis and methods for the determination of parameters have been determined.

    (3) Studies of basic theories have been made on the pattern and rate coefficient of adsorption and resolution of suspended substances to metals in water of heavy metal quality.

    (4) Long term, systematic studies have been made on thermal pollution mainly with physical models for cooling water of thermal power plants to put forward the measures to overlap intakes and outlets of cooling water. Studies have also been made with multiple hydraulic and thermal models for cooling water of nuclear power plants.

    (5) Studies have been made on groundwater pollution and purification measures, offshore pollution, self-purification of pollutants, and analysis and simulation techniques for diffusion.

    2.3 Studies of River Channel Evolution and Sediment Movement

    Soil erosion is severe in many river basins in China. The rivers carry huge quantities of sediment and river sediment movement directly affects river configuration. Therefore, long term observation, studies and harnessing have been made for river sediment movement. The Chinese scholars have achieved a number of theoretical, semi-theoretical, semi-empirical and empirical results, and have made breakthrough progress in the studies of cohesive sediment running-up, high sediment content flow movement, density flow and mud-rock flow by combining the mechanical theories with statistics and physical chemistry.

    In the aspect of river channel evolution, the theories of sediment movement and geomorphology have been applied to study the laws of scouring and sedimentation of natural rivers. The alluvial rivers are divided into five types: straight, curved, serpentine, braided and wandering, and harnessing measures have been adopted according to the evolution laws to achieve good results. The sediment movement at river mouth is affected by river flow, tidal flow and waves. The studies of river mouth are focused on the development of river mouth delta and the formation and variation of sand barriers and bars. Long term observation has been made to provide a scientific basis for the harnessing of river mouth.

    In the aspect of engineering sediment, the focus has been put on the studies of reservoir sediment, water complex sediment, river channel and lake sediment, sedimentation at tidal gates and sediment induced abrasion of water turbine. A series of theories and experiences have been produced for sediment treatment, such as the theories of "storing the clear water and discharging the muddy to regulate water and sediment" for reservoir operation, "forward diversion and lateral sediment discharge" to separate water from sediment for the layout of water complex, "diverting flood for warping irrigation to improve soils, warping on the front and back to consolidate embankment" to utilize sediment resources, "carrying out transportation in static water and scouring sand regularly" to solve sedimentation of navigation routes.

    While solving the sediment problems for river channel and hydraulic works, theoretical studies and technical development of mathematical simulation, physical model and prototype model observation have been promoted in the fields of river basin sediment generation, river channel modeling, laws of sediment movement at river mouth and coast, experiment on high sediment content water flow, and the results have been extended and applied effectively.

    2.4 Studies of High Water Head Ship Lock Hydraulics

    China has many large rivers, a large number of lakes, reservoirs and coastal lines connected to river mouths. Those waters provide favorable conditions for the development of river shipping and river-sea joint shipping. The total length of the rivers open to navigation is about 110000 km. The water resources in China vary greatly in time and space and the river sediment problem is serious, therefore, in order to develop river shipping, studies must be made on many scientific and technological issues. During the construction of ship locks of the Gezhouba Project, a lot of studies and experiments were carried out to solve the issues and problems, such as sedimentation affecting navigation, the harnessing of the Nanjinguan navigation channel and hydraulics of high water head ship locks. The Nanjing Hydraulic Research Institute established an experimental tank for non-steady flow and made 1:10 model experiments for extra-large valve in combination with mathematical models to optimize gate shape; at the same time, studies were made on the shape of valve intake, water inflow and ventilation of internal shaft in combination with prototype observation of the Gezhouba lock, etc to solve the problems of current vibration and cavitation erosion.

    2.5 Studies of High Speed Flow Energy Dissipation

    There are many high water head flood relief structures in China. Table 2-1 shows the existing high water head and large discharge relief structures and Table 2-2 shows those under construction and to be constructed. Because of the high dam, large discharge, high flow velocity and narrow channel, energy dissipation and scouring prevention are the most outstanding issues for high water head flood relief structures. Many types of energy dissipation structures have been developed through model experiments, theoretical analysis, prototype observation, etc. with consideration of practical conditions of engineering structures.

Table 2-1 Existing high water head, large discharge flood relief structures in China

Basic data					Relief structures
No	Dam	Dam type	Dam height (m)	Discharge (m³/s)	Openings on dam			Spillway No.–width´ height	Tunnel No.–width´ height
No	Dam	Dam type	Dam height (m)	Discharge (m³/s)	Surface Opening No.–width´ height	Middle Opening No.–width´ height	Deep Opening No.–width´ height	Spillway No.–width´ height	Tunnel No.–width´ height
1	Shuikou	PG	101	51800	12-22´15		2-5´8
2	Panjiakou	PG	107.5	42600	18-15´15		4-4´6
3	Shuifeng	PG	106	40000	26-12´6.5			10-9´10	D8.6
4	Ankang	PG	128	37000	5-15´17	5-11´12	4-5´8
5	Yantan	PG	111	33400	7-15´21		1-5´8
6	Yunfeng	PG	113.75	24230	21-11.0´7.5		4-4.25´4.25
7	Ertan	VA	240	23900	7-11´11.5	6-6´5	4-3´5		2-13´13.5
8	Geheyan	GV	151	23458	7-12 ´18.2	6-6´5	4-4.5´6.5
9	Fengtan	GV	112.5	23300	13-14´12		1-6´7
10	Tianshengqiao I	ER	178	21750				5-13´20	1-6.4´7.5
11	Wujiangdu	PG	165	21350	4-13´18.5		2-4´4.4	2-13´18.5	2-9´10.44
12	Manwan	PG	126	20910	5-13´20		2-5´8		1-12´12
13	Baozhusi	PG	132	16060	2-15´17.3	2-13´15	4-4´8
14	Sanmenxia	PG	106	15100		12-3´8	8-3´8		2-8´8
15	Guxian	PG	125	13894	5-13´16.5	1-6´9	2-3.5´4.23
16	Huanglongtan	PG	107.5	13300	6-12´10		1-5´6	Emergency 10´12
17	Xin’anjiang	PG	105	13200	9-13´10.5
18	Dongfeng	VA	173	12580	3-11´7	2-5´6 1-3.5´4.5		Left 1-15´20	1-12´17.5
19	Baishan	GV	149.5	11000	4-12´12		3-6´7
20	Bikou	TE	101.8	9550				1-15´16	Left 1-9´8 Right 1-8´10
21	Liujiaxia	PG	147	9220			2-3´8	3-10´8.5	1-8´9.5

Table 2-2 High water head, large discharge flood relief structures under construction or to be constructed in China

Basic data					Relief structures
No	Dam	Dam type	Dam height (m)	Discharge (m³/s)	Openings on dam			Spillway No.–width´ height	Tunnel No.–width´ height
No	Dam	Dam type	Dam height (m)	Discharge (m³/s)	Surface opening No.–width´ height	Middle opening No.–width´ height	Deep opening No.–width´ height	Spillway No.–width´ height	Tunnel No.–width´ height
1	Three Gorges	PG	183	102500	22-8´17	2-18´11 raft floating	23-7´9
2	Dachaoshan	PG	115	23800	5-14´17.8		3-7.5´10
3	Xiaolangdi	TE	154	17063				3-11.5´17	3-D14.5 3-D6.5 1-10´11.5 1-10.5´13
4	Xiluodu	VA	273	50311	8-12.5´18		7-5´6
5	Xiangjiaba	PG	161	48680	5-19´26	7-7´11
6	Longtan	PG	216	35500	7-15´20		2-5´8
7	Nuozadu	ER	258	35300				10-15´20	2-5´8.5
8	Goupitan	VA	225	26950	6-16´15	7-6´7	2-6´7
9	Xiaowan	VA	292	20683	5-11´15	6-6´5			2-10´12
10	Shuibuya	ER	232	15243			2-4´5	5-14´21.5
11	Pubugou	ER	186	9780				3-12´16	1-9´9 1-12´7.5 (transformed from diversion tunnel)

    (1) Bottom flow (jump) energy dissipater. It dissipates energy through hydraulic jump to make upstream flow connect downstream flow steadily. This type of energy dissipaters is used in the Yanguoxia and Puxi projects constructed in the 1960s and the flood and sediment relief gates of the Gezhouba Project. Flaring pier-cushion pool joint energy dissipater is used for the high water head flood relief structures of the Ankang and Wuqiangxi projects constructed after the 1980s. Aerated pier-cushion pool and T-shaped pier-cushion pool joint energy dissipaters are also applied, which can reduce the length of cushion pool and promote the efficiency of energy dissipation.

    (2) Submerged bucket dissipater. With this kind of dissipaters energy is dissipated through the rapid diffusion as induced by the spiral mixing function of bottom spiral flow and surface flow of overflow dam. Practices of years show that surface flow dissipates a small amount of energy and has a large speed, thus causing bank scouring over a long distance. Therefore, better dissipation effects can only be achieved with supporting dissipaters, in which flaring pier is one of the most effective ones.

    (3) Ski-jump energy dissipater. With this kind of dissipaters, a trajectory bucket at the end of overflow dam is used to make the jets discharge in air to collide and diffuse and, after dissipating a part of dynamic energy, fall into a downstream cushion pool to dissipate energy through diffusion, turbulence and rolling. There are many types of trajectory bucket, and the common ones are continuous type, differential type, diffusion type, oblique deflecting type, torsional type, high-low sill type, etc. Multiple types of ski-jump dissipaters have been used for about 100 high dams, such as Xinfengjiang, Zhexi, Liuxihe, Wujiangdu, Baishan and Longyangxia projects, and have greatly reduced downstream scouring.

    (4) Contracting energy dissipater. It is formed by sudden contracting side walls or blocks to create diffusion in both the longitudinal and verticdal directions, thus achieving significant energy dissipation. A flaring pier contracting dissipater is used in the Ankang Project to make the length of the cushion pool reduced by more than one third. For the overflowing dam of the Wuqiangxi Project, flaring piers are used to create longitudinal diffusion and traverse contraction of jet and bottom release openings are provided in the water free area of dam surface to increase release capacity and promote energy dissipation. In this way the length of cushion pool is reduced by 60%. Slit-type buckets of different contracting ratios and deflecting angles are used in the Dongjiang, Dongfeng, Longyangxia, Nanyi and Xiongdu projects to achieve satisfactory energy dissipation effects.

    (5) Stepped joint energy dissipater. With this kind of dissipaters, water flow becomes aerated, slowed down, mixed and turbulent along the steps on dam slope or spillway surface to dissipate energy, and good effects are achieved in combination with energy dissipation from longitudinal diffusion created by flaring piers on dam crest. This kind of dissipaters is used in the Shuidong and Dachaoshan projects, etc and is being considered for some dams under design. The steps themselves cannot dissipate energy significantly, but can promote aeration to reduce cavitation and can achieve good results jointly with flaring piers.

    (6) Dissipater in flood relief tunnel. It includes many types such as orifice plate type, vertical shaft type and vortex flow type. In the Xiaolangdi Project three orifice plates are used in the flood relief tunnels and energy is dissipated step by step by using the orifice plates to create contraction, then diffusion, and further contraction and diffusion repeatedly. In the Shapai Project, vertical shaft vortex flow energy dissipation in flood relief tunnels is applied, that is, reservoir water flows into a vortex chamber at the inlet of vertical shaft to create vortex flow entering the vertical shaft. Within the shaft frictional force of free vortex flow against the side wall and internal shearing and resistance forces of the flow dissipate a large amount of energy. After entering the horizontal free flow section, the vortex flow continues to dissipate energy significantly.

    (7) Dam crest water fall-cushion pool energy dissipater. Cushion pool is applied to both the Liuxihe and Ertan arch dams, with which a spillway on dam crest throws the jet downstream far from the dam site. The jet dissipates a part of dynamic energy in air and most of dynamic energy is dissipated in the downstream cushion pool.

    2.6 Studies of Technologies of High-velocity Flow Aeration for Cavitation Erosion Reduction

    Because there are irregularities on the surface of spillway left from construction, cavitation erosion often occurs to high-velocity relief structures. Since the 1970s studies have been carried out on technologies of aeration for cavitation erosion reduction, applying the shapes of spillway surface and aeration measures recommended by model experiments to real projects and making prototype observation. Observation results further show that the designed hydraulic indexes are rational and the effects of aeration to reduce cavitation erosion are significant. In the last tens of years, research, design, construction and management agencies have made joint efforts to carry out experiments, prototype observation and theoretical analysis, thus achieving development and improvement in the studies, design and application of technologies of aeration for cavitation erosion reduction. Since the 1980s aeration cavitation reduction measures have been applied to almost all high water head relief structures in China. The Codes for the Design of Spillway issued in 1990 stipulates that aeration cavitation reduction measures shall be applied to water relief structures with a flow velocity of more than 35m/s. During the same period, in-depth studies have also been carried out on pulse pressure and current vibration of high-velocity flow with measures to reduce erosion adopted accordingly.

3、 PROSPECTS FOR THE DEVELOPMENT OF WATER RESOURCES UNDERTAKINGS IN CHINA

    Water resources engineering is important infrastructure for the national economic and social development and is thus of overall and strategic significance. With the economic and social development new requirements are being put forward and the water resources undertakings will enter a new era.

    3.1 Requirements

    1. Provide safety against flood for the economic and social development.

    2. Provide water supply for food safety, urban and rural domestic use and production.

    3. Provide a good water environment and water ecology.

    4. Provide clean hydropower for the adjustment of energy structure and implement "West to East Power Transfer".

    5. Harness the rivers for water transportation.

    6. Realize development of water resources undertaking coordinated with economy, society, ecology and environment.

    3.2 Basic Thinking

    The water resources undertakings in the new era should seriously implement the strategies of sustainable development and prospering the country by relying on sciences and education, correctly deal with the relationships between water resources undertakings with economic and social development, ecological improvement and environmental protection. The principles of comprehensive planning, taking all factors into consideration, and looking into the root causes while solving a problem should be implemented, and comprehensive measures of river and lake harnessing, hydropower generation, water and soil conservation, rational development, optimized allocation, high efficiency utilization, effective protection and strengthened management of water resources should be adopted to provide powerful support and an important guarantee for the coordinated economic, social and eco-environmental development and ensure a sustainable, stable and healthy development of the socialist modernization of China.

    3.3 Goals and Objectives

    The goals and objectives for water resources undertaking in the early 21st century (2030) are:

    1. Establish a sound comprehensive flood control system. Through the establishment of flood control engineering system and non-structural measures, the standards of flood control and capacity against flood and waterlogging will be promoted step by step, and the standards of main protection areas against flood will reach a level consistent with the level of economic and social development.

    2. Establish a safe, reliable water supply system. The national capacity of water supply will reach 750 billion m3, water saving will be intensified, the area of irrigated farmland will be increased by 8 million ha, the grain yield per m3 of applied irrigation water will reach about 1.5 kg, and the water consumption per 10000 yuan of industrial output value will be reduced to about 10 m3.

    3. Establish an effective system for water and soil conservation and water resources protection. 50-60% of the water erosion area in the country will be put under primary control and soil erosion will be effectively reduced. Effective protection of water resources will be carried out based on the water functional zoning, the control of water pollution will be strengthened, and the water eco-environment of rivers, lakes and reservoirs will be improved step by step.

    4. Rationally develop hydropower resources in the western regions. A sound mechanism for the development of hydropower resources will be established, that is, conducting rolling development on the basis of river basin by implementing cascade and multi-purpose development. By 2030 the total installed generating capacity of hydropower in the country will reach 130-140 GW and the rate of hydropower potential exploitation will reach 34-37%.

    5. Establish a sound system for water resources management, a comprehensive legal system for water resources and the development, management and utilization of water resources by law will be achieved, unified management of water resources will be realized so as to ensure sustainable economic and social development with sustainable utilization of water resources.

    In the 21st century, the water resources undertakings in China will further develop vigorously and large-scale construction of water projects will open a great horizon for hydraulic research. We hope that the hydraulic professionals in the world will join us in the construction of hydraulic works and hydraulic research and make contribution to the solution of global water issues and problems.