Ecological Compensations for Damed Rivers

Dong Zheren

（Chair of Global Water Partnership - China） 

Abstract

The stresses of dams on river ecosystems are analyzed based on river continuity characteristics. It is pointed out that the pros and cons of dam construction should be comprehensively evaluated in the compound ecosystem of nature, society and economy. It is feasible to implement ecological compensations for damed rivers by adopting bioengineering methods. It is suggested to conduct value evaluation of river ecosystem services for decision-making of large hydraulic and hydroelectric projects. 

Recently some domestic experts criticize the hydropower development plan on rivers of southwest China. They protest to “preserve a healthy river”. Some others argue the construction of dams in China while the Western Countries are decommissioning dams. It can be seen that the debates on dam construction initiated in the Western Countries in 1970’s has spread to China after 30 years. 

According to statistics of International Congress on Large Dams (ICOLD), there are 49697 dams all over the world by the end of 2003, which are higher than 15 m or their reservoir capacities are larger than 1 million m^3[1]. China, USA, former Soviet Union, Japan and India have the most dams in turn. Therefore, it is reasonable that communities of all circles of China are concerned about the effects of dam construction on ecology along with the improvement of ecology consciousness.  

This paper mainly discusses the following topics. Do dams have any negative effects on river ecosystems? How to evaluate the pros and cons of dam construction on social economic benefits and the health of natural ecosystem? Is it feasible for damed rivers to be compensated and what are the compensation standards？ 

1. The Stresses of Dams on River Ecosystems 

Dam projects play important roles in satisfying the demands of human community for flood control, power generation, irrigation, water supply, navigation, etc. and guaranteeing community security and economic development. Dams have dual influences on ecosystem. In one aspect, reservoirs can provide abundant water for the growth of biology and mitigate the impacts of large floods on ecosystems. This is beneficial for river ecosystems. On the other hand, dams have disturbances on river ecosystems. Disturbances from nature and human society are defined as “stresses” in ecology. The stresses of hydraulic projects on river ecosystems are represented mainly in two aspects: one is the channelization of natural rivers and the other is their discontinuity^[2]. The negative impacts of dam projects belong to the second problem, i.e. discontinuity in the direction of water flow. Here the “river continuum” concept is used to illustrate that river ecosystem is an open and flowing one. Its continuum means not only the continuity in the sense of river hydrology, but also the continuous characteristics of nutrient substance transportation, which is very important for biology community ^[3]. Taking a river as a carrier, nutrient substances interchange, diffuse, transform, accumulate and release along with the changes of floods and low flows in natural hydrological cycle. The aquatic and terrestrial organisms along a river survive and multiply and accordingly form a diversiform and orderly biotic community, which includes the continuous vegetation in terraqueous interlaced zones, fishes migrating from estuary to the upper reaches and waterfowl and amphibian continuously distributed along rivers, etc. Biotic community and habitats compose a river’s ecosystem with perfect structures and functions. 

Studies have indicated that periodic changes of flood is a special signal for the biology around rivers to breed, spawn and migrate, which means that rivers are responsible for transferring life information. In a word, rivers are carriers of material flow, energy flow and information flow in ecosystems. River continuum consists of not only hydrological continuity of streams, but also the continuity of mass transportation, nutrition substances, biotic community as well as information flow.  

Daming causes river discontinuity and as a result radically changes its natural evolution process that has a history of ten thousands or millions of years and its continuity pattern. 

Impacts of dams on river ecosystem mainly consist of two respects, i.e. negative effects caused by dams or reservoirs themselves and stresses on ecosystems during reservoir operations. The former mainly causes the changes of river geomorphology features of the upstream and downstream of a dam. The latter mainly leads to man-designed cycle of natural hydrology.

Firstly a river valley is turned into a reservoir, original habitats of land and hills are fragmentized and terrestrial animals are forced to migrate. Original forests, meadows, croplands of reservoir area and garbage, chemical fertilizer are completely submerged under water. Flowing river is turned into a relatively motionless man-made lake. Water velocity, depth, temperature and current boundary conditions are all changed Reservoir has apparently temperature-zoned characteristics. Because of sedimentation and river nutriments trapped in the reservoir, alga propagates in the surface water easily and this will cause water bloom. The growth of large foliage becomes fade because of the spread of alga, while the dead algae sink in the bottom and be rotten and consume oxygen there. Water body with low dissolved oxygen may cause aquatic organisms to be suffocated. In tropical and subtropical areas, lots of greenhouse gases as CO₂, CH₄, etc may be produced after forests are submerged in reservoirs. Because reservoir water is very deep and sunlight in deep water is feeble, photosynthesis there is accordingly weak. The quantity of living organism production in a reservoir, compared with that in a river, is much lower and its self-recovery capability is feebler to withstand outside disturbances. In addition, any dam without fishways is a fatal barrier for migratory fish. In the downstream of a dam, the increase of sediment carrying capacity of discharged water makes riverbank be scoured intensely and therefore may cause the alteration of river regimes. Because of sedimentation and trapped nutriments, rules of transportation and diffuseness of nutriments may also change in downstream river corridor of a dam. All these elements will cause the alterations of biotic habitat features. 

On the other hand, reservoir operation obeys to the demands for power generation, flood control, etc. and therefore artificializes the hydrological cycle of natural rivers. In a periodically hydrological year of a natural river, living organisms will also present periodically pulsed variations. For instance, in flood season hydrophyte community takes the preponderance in a river, being replaced by hygrophyte after water level descends. This pattern is a kind of pulsed variation of biotic community. It is necessary to artificially regulate runoff to be well-distributed in the whole hydrological year during reservoir operation so as to satisfying the requirements for power generation, flood control and etc. As a result, the hydrological period of a natural river is changed. In the mean time, hydropower plants are subject to the adaptive activities according to load change in an electricity grid. Therefore there is a relatively huge water current change in a day for the short-term operation. All these factors may bring pressure on river corridors. In addition, excess water diversion from reservoirs for water supply and irrigation greatly decreases the water quantity in the downstream of dams and makes river dry up and eventually leads to the degradation of river ecosystems. Besides, resettlement is necessary to build dams. Damming sometimes inundates the historic relics and change natural landscapes. This problem is not merely relates to society, culture, but macroscopically is a compound ecosystem problem. 

The ecosystem of a natural water body is an open system from the point view of mechanism analysis. It continuously exchanges substance and energy with external environment and has the tendency to balance the input and output. Input substances in water body transfers, transforms and outputs to constitute the metabolic process through physical, chemical and biological actions. Rivers, lakes and reservoirs are all the exchanging ponds for transferring and transforming substances in geochemistry cycle process. Relatively substances stay short and flow fast in the rivers. On the contrary, substances stay long and flow slowly in lakes and reservoirs and therefore their inputs of substances are greater than the outputs. The quantities of trapped substances exceed the self-adjustment capacity of the ecosystems. As a result, it will cause pollution, eutrophication, salinization and so on, which are defined as “ecological retardarce.”  

Although dams are different in scale, natural, economic and social backgrounds, and the effects of projects on river ecosystems are also different with varying degrees, the fact is physically existed that dams have stresses on river ecosystems. Along with scientific development and improvement of ecological environment consciousness, in large-scale hydropower development it is not allowed to blench the negative effects of dams on ecosystems. At present, it is necessary to face up to these kinds of negative effects. However it is more important to actively conduct studies on technologies, policies and measures for river’s ecological compensations and to explore a new mode for environment-friendly dam construction.  

2 To choose the optimized strategies in nature-society-economy compound ecosystem 

There are two opposite theories in the fields of international resources and environments. One is defined as resourcism that claims to widely and continuously exploit recycled resources in maximum. The other is defined as preservationism that opposites human residences and economic development in non-exploited areas ^[4]. The focuses of the two theories are on how to deal with economic development of human communities and the maintenance of healthy ecosystems. The former emphasizes the importance of satisfying the requirements of economic development and neglects the importance to maintain a healthy ecosystem for the long-term benefits of mankind. Preservationism emphasizes to maintain the health and sustainability of ecosystems and opposes to any reasonable exploitation and utilization of natural resources, which is impractical for economic development and finally becomes an empty viewpoint. Particularly in developing countries, the exploitation degrees of natural resources are much lower than that in the developed countries. If developed countries force the developing countries to accept their viewpoints, then an opposite situation will be initiated. It can be said that either of the two theories is unilateral. The more actual thinking is to extend the research scale, to put the problem in the compound ecosystem of nature, society and economy, and to analyze how to seek the balance point between satisfying social and economic demands of human communities and causing no or a little damages to ecosystem healthy so as to achieve the target of sustainable development. Discussions of any problem should be based on the specific conditions of different countries. For distinct nature, community and economic statuses, different countermeasures should be taken and there is no universal norm suitable for every country. Moreover, there is only relative and no absolute optimization in the selection of energy resource type and in the comparison of different project schemes. 

Dam construction poses threats to river ecosystem, though it can meet many demands for flood control, power generation, irrigation, water supply, navigation and so on. The viewpoint of simply opposing to any dam construction and claiming the decommissioning of dams widely is undoubtedly impractical for economic development of human communities. It is one kind of concept of stopping eating for fear of choking. On the contrary, any action of blenching the stresses of dams on ecosystems and overlooking the compensation for ecosystems will undoubtedly be harmful for the long-term benefits of mankind. There is no engineering technique that has great benefits and no harm in the world. The dialectic thinking is to balance the advantages and disadvantages and to pursue good fortune and avoid disaster. Practices have indicated that the negative effects of dams on river ecosystem can be avoided, alleviated or compensated to a certain extent by adopting structural, biotic and administrative measures. The reasonable way is to make concrete analyses of different problems and seek a relatively optimized project scheme. 

The objectives of dam construction in China are for flood control, power generation, irrigation, water supply, navigation and so on. Most dams have comprehensive benefits. Most high dams take power generations as the main benefits. However compared with low dams, high dams have relatively serious influence on river ecosystems. Following will analyze the impacts of different types of energy resources on environment for the development of hydropower. In 2002, in China the yields of energy resources are 1.387 billion tons of standardized coals. Among them, there is 1.38 billion tons of coal, the first in the world. Total generator capacity is 357 million kW. Power generation quantity is 165.4 billion kWh annually, the second in the world, in which hydropower quantity is 22.8 billion kWh, the forth in the world. China has become the second large country in energy consumption in the world. 

China is facing seriously environmental challenge in the development of energy resources, especially serious atmospheric pollution. The discharge of sulfur dioxide of China is the most in the world and the discharge of carbon dioxide is the second in the world, only inferior to the USA. The energy composition of coal as the major energy resource is the main reason of serious atmosphere pollution. 70% of smoke, dust and carbon dioxide, 90% of sulfur dioxides, 67% of the nitrogen oxides originate from the combustions of coal. Some experts predict that in 2020 the demand for energy resources would be 2.5 to 3.3 billion tons of standardized coal, at least twice that in 2000. The distinguishing feature of Chinese resources makes the situation with coal as the main energy resource invariable for a long period. According to experts’ prediction, till 2020, sulfur dioxides, nitrogen oxides will be up to 40 million tons and 35 million tons separately in the condition of the least contaminant amount coming into being if no measure of desulfurization and denitrification is taken. Up to 2030, China will be confronted with high international pressures in the aspect of global climate warming. 

For other alternatives of energy development, nuclear power development has the problems of security, economy and disposal of nuclear waste. The development of wind and solar energy will be confronted with the problems of high cost per kilowatt and the difficulties to be exploit in large scale. For hydrogen energy, it is still in the primary development phase at present. In the composition of Chinese energy resources, conventional commercial energy resources account 10.7% of that in the world, in which water resources, coal, petroleum, gases take the position of the 1^st, 3^rd, 12^th, 22^nd in the world respectively. Hydropower development degree in China is only 23%, lower than that in developed countries, where 60% or more hydropower resources has been developed, such as 82% in the US, 65% in Canada, 73% in Germany. Hydropower is one kind of recycled clean energy resources without any pollution to atmosphere and wastes. As long as the Sun does not extinguish, water resources will be available. China has plentiful water resources and therefore hydropower development is the certain choice in its energy strategies. Totally 400 million kW hydropower is feasible to be exploited developed in China. If 50% of it is developed, corresponding 600 million tons of coal can be saved annually. This amount is about the 1/2 of the total coal combustions of China in 2002. It is of great significance in decreasing the discharge of greenhouse gases, which is a great contribution in ecological environment protection for not only China but also the world.

It is thus evident that hydropower development has its incomparable advantages from the point of global ecological environment protection by analyzing the influences of different energy resources on environment based on the actual energy composition of China according to the rule that “between possibilities, select the one has more advantages or that has less disadvantages.” In recent years because of the increasing oppositions to dams, hydropower disappears in the list of clean energy in some domestic and foreign reports on energy policies. Obviously this is not objective and scientific.  

3. Feasibility to actualize ecological compensations to damed rivers.  

Oppositions to dams or decommissioning of dams is not the unique choice to protect ecological healthy of rivers. It has been proved to be feasible in principle and practice to construct environment friendly dams by conduct ecological compensations to damed rivers through engineering, biological and management measures to prevent or alleviate stresses on dams to river ecology system with varying degrees.  

3.1 Environment evaluation of dam projects  

Chinese government attaches great importance to EIA. Environment Impact Assessment Law of the People’s Republic of China (EIAL) comes into effect from Sept. 2003. EIAL states that “Environment impact assessment refers to the methodologies and institutions to conduct analysis, prediction, and evaluation of environment impacts initiated by the construction of planned projects, to put forward countermeasures to prevent or alleviate possible negative environment impacts and to carry through tracking monitoring”, “EIA must objectively, openly, equitably and comprehensively consider all the potential impacts of planned or constructed projects to all kinds of environment factors and their ecological system”. The issue of EIAL and its execution are great promotions towards environment friendly dams. There still existed a few aspects that need to be consummated and improved in present environment assessment in China.  

(1) The scope of environment assessment 

According to the provisions of EIAL, it is divided into two sorts. One is on the development and construction planning of regions, river basins, and coastal areas, including relevant professional planning such as water resources and energy, etc. The other is on projects. For dam projects, either single dam or multi-staged dams, the impact scopes will be on the whole river basin. Therefore, according to EIAL, much attention should be paid in river basin planning on the analytical prediction and evaluation of environment impacts by dam construction. 

In the EIA of dam project, besides the EIA of dam site, reservoir, and downstream areas, it is also required to conduct the EIA of the whole river basin. The reasons exist in that daming will change the hydrological and biological continuity of a river and as a result cause influences on the whole basin. Comprehensive and integrated study should be conducted on the interrelation of eco-factors and biotic factors of the whole basin. 

Temporal scale is also very important. Evolvement of ecosystem caused by dams is a dynamic process. Some project cases have indicated that the impacts of dams on river ecosystem emerge gradually after one to several decades. Because of the limitations of science development level and people’s cognition capacity, it is very difficult to make accurate and comprehensive long-term prediction on this kind of impacts. Therefore, it is necessary to conduct long-term biological and hydrological monitoring in order to get long temporal-scale river ecosystem evolvement data and based on these to carry out tracking evaluation. 

(2) Main topics for EIA of dam projects 

Emphases of EIA of dam projects should be put on the influences of daming on the healthy and sustainability of river ecosystem, including influence analysis, prediction, and evaluation of river ecosystem configurations and functions. River ecosystem is an integrity composed by organism with its physical, chemical and geographical environment. All elements have relations with each other of inter-dependence, interpromoting and restriction or checking, cause and effect.  

In a specific river ecosystem, its ecosystem configuration is formed by the variety and quantity, density, ratio, temporal and spatial distribution and combination of biotic and abiotic components. This configuration forms the functions of the river ecosystem through input and output of material flow, energy flux and information flow. The configuration and functions of an ecosystem determine its quality, productivity, and self-purification ability, etc.  

It should be specially stated that the negative impacts of daming are often expressed as the degradation of biocommunity diversity. Therefore the EIA of dam projects should pay much attention on the change of biodiversity. The essential to maintain the river biocommunity diversity is to maintain an appropriate ecosystem configuration and function.  

Present EIA of a dam is usually conducted according to the requirement of an individual subject or local function, such as to separately study the protection of endangered or special animals and plants in reservoir inundation areas or to study the influences on water quality, etc. This work lacks of systematic analysis and evaluation on the interaction, interrelation, inter-dependency, reciprocal transformation of all the components of the ecosystem. 

(3) To promote interdiscipline collaboration, encourage public involvement, and conduct scientific research 

EIAL ordain that: “the state encourage relevant institutes, experts, and the public to take part in EIA in a proper way.” EIA of dam is a complex work related with multi-specialty, multi-discipline, and multi-department. Interdiscipline collaboration should be advocated to conduct relevant scientific research, explore principles and promote the scientificaalness of evaluation. In addition, active public involvement should be facilitated in many forms such as conference activities, workshops, forum, etc. This will help to drive the process towards scientific and democratic decision-making of major projects. 

3.2 Explore and develop Ecological-Hydraulic Engineering (Eco-Hydraulic Engineering) 

Since 1970’s, in the face of worldwide degradation of ecological environment, Scholars of different countries seek to develop system approaches for solving this kind of problem. Under the drives of modern ecology, as a new interdiscipline, ecological engineering emerges as the times require. In 1962, H. T. Odum put forward that the self-organization function of ecosystem could be used in engineering. For the first time, he brought forward the word of “ecological engineering” in order to promote the combination of ecology with engineering. In the ecological engineering workshop hosted by American Academy in 1993, according to Mitsch’s suggestion, ecological engineering was defined as: “the design of sustainable ecosystems that integrate human society with natural environment for the benefit both.” Ecological engineering has very wide applications in ecological constructions, including rivers, lakes, wetlands, mines, forests, lands and coasts, etc. 

River restoration is a branch of ecological engineering. ASCE defines river restoration as “an activity to environmentally protect and restore a river system to a more natural condition with sustainable features that enhance ecosystem values and biodiversity” ^[5,6].Under the concept of “River restoration”, there are perhaps five distinct terms that states different restoration goals^[7]:

 “Full restoration” is defined as “the complete structural and functional return to a pre-disturbance state”.

 “Rehabilitation” is defined as “partial return to a pre-disturbance configuration or function”.

“Enhancement”” is defined as “any improvement in environmental quality”.

“Creation” is defined as “development of a resources that did not previously exist at the site.”

 “Naturalization” emphasizes that human utilization of natural resources is a component of the current ‘natural’ environment and this factor must be considered explicitly in efforts to protect or improve the quality of existing natural resources.  

Scholars with “full restoration” preserve an ideal opinion that is rarely practiced. They define their objectives of river restoration to be the pre-disturbance geomorphological state by human being, which lead to the oppositions to dam and decommissioning of all dams. Many scholars have different opinions. They believe that it is impossible to achieve complete restoration for a river to get back to its presettlement conditions because that a new ecosystem has been formed through natural processes and the influences of human activities. Practical methodologies are to realize the necessity for human to reasonably utilize natural resources and to adopt multi-approaches to promote the healthy evolution of river ecosystem.  

In the aspect concerning river training, emphases have been put on ecological restoration in developed countries. China is in a quite different situation that in the next 10 years hydraulic and hydroelectric projects will be developed at a high speed. Therefore we should not only attach great importance to the ecological restoration of damed rivers, but also pay much attention on ecological compensation problems of newly developed dams in order to avoid the unsuccessful experiences of developed countries. For traditional hydraulic engineering, the goals of water resources exploitation are achieved by constructing project infrastructures, controlling rivers and controlling water flow. This is based on the disciplines of hydrology and engineering mechanics. Traditional hydraulic engineering overlooks the facts that rivers are in an integrated ecosystem, and then separately deals with the hydrological problems of water quantity, water quality and hydropower etc. in water resources, as well as the problems of life system of animals, plants, and microbes in a river system. As a result, they cause stresses of varying degrees to river ecosystem while they bring major social and economical benefits for mankind. Therefore it is required to improve and consummate present project planning methods, to absorb the theories and techniques of ecology, to explore and develop Ecological-Hydraulic Engineering (Eco-Hydraulic Engineering). Eco-Hydraulic Engineering is a branch of hydraulic engineering science. It is an engineering science to study the principles and technical methodologies for hydraulic engineering to meet the needs of mankind and at the same time to take account of the health and sustainability requirements of aquatic ecosystem^[8].   

There are three tasks for the rehabilitation of river ecosystem. The first is the improvement of hydrological conditions. The second is the improvement of river geomorphological characteristics. The third is the restoration of special or endangered species. The total target is to improve river ecosystem configurations and functions. Its indicators are the increases of bio-community diversity ^[9] . 

Improvement of hydrological conditions means the improvements of water quantity and water quality, as well as the simulation of natural hydrological cycles. It includes the following aspects:

l          To maintain the minimum water quantity.

l          To control sewage discharge through waste water treatment, and improve river water quality by promoting clean production.

l          To simulate natural hydrological cycles in reservoir operation whilst meet the social and economical requirements.  

The improvement of river geomorphological characteristics includes the restoration of continuity in longitudinal direction and connectivity in cross direction, maintaining the configuration varieties in both directions and preventing the use of harden riverbed materials. 

4. Value assessment of river ecosystem services and ecological compensation policies 

The basis of sustainable development is to maintain the sustainability of biosphere and that of ecosystem services. The services provided by river ecosystem maintain the living surroundings that human rely on, and offer various welfares for the communities. These include the maintenance of biodiversity; the supply of food, medicine and materials; the purification of freshwater; water conservation and the alleviation of draught and waterlogging; the stabilization of local climate; the detoxifcation and decomposition of rubbish; the spread of seed and the recycle of nutrient; the satisfaction of human aesthetics demand, etc. One aspect of the services exerts as ecological products in the form of material objects, such as food, medicine and material. Their economic values can be embodied in the market circulation. The other exerts as non-material objects, including the diversity of biological community, environment, climate, water quality, human culture, etc. These functions have profound and significant influences on social economy though they are often indirect.    

For a long time, people consider that river ecosystem services are free bestows of the nature and could be gained without refunds. People think they are the cosset of the earth and feel no regret while accept them. Especially in commercial society, the tangible ecological products can be considered, while the large amounts of non-material values of ecological service are often ignored. When large-scale river training works bring huge and direct economic benefit for mankind, some services of rivers are lost. Its influences may be indirect, however the consequences are severe. It has been a hot topic in the field of sustainable development that how to assess the values of these functions. International society has realized that it is required to study the benefit of ecosystem services deeply and quantify their values, as well as to integrate them into the national accounting system in order to disclose the huge contributions of ecosystem for mankind. In 1992 “Agenda 21” passed by United Nations’ Conference on Environment and Development ((UNCED) clearly state that it is necessary to conduct studies on the evaluation of ecological values and natural capital. In 1994, “China’s Agenda 21” puts forward that “In order to incorporate the capacity for sustainability into economic decision-making, it is necessary, first and foremost, to measure the crucial role the environment plays as a source of natural capitals and as a carrying body for the by-products generated by human activities. Traditional economy indicators, GNP or GNP, neither reflect ecological damage, environmental degradation and the loss of resources caused by economic growth, nor calculate the values of non-commercial labor services,××××××. Therefore, it is necessary to establish an integrated accounting system, which considers resources and the environment as well as the economy, so as to monitor the performance of the entire national economy.” 

It has great significance to evaluate and quantify the values of river ecosystem services, and integrate this into the national economic accounting system by laws. First, the short-term activities for obtaining direct economic benefits can be avoided through comparing its direct social economy benefits with the losses of ecosystem services when make decisions for big hydraulic projects. Secondly, it will help to urge project owners to take ecological compensation measures to alleviate stress to river ecosystem and as a result reduce the total value losses of ecosystem services. Finally, this kind of evaluation can also quantify the amounts of compensation capitals that should be offered by project owners.  

In the field of environment protection, the principle of “who pollute, who pay” has gotten widespread approval of international societies. Refer to this principle, it is suggested to clarify the principle of “who damage, who pay” in dam construction policies that the dam owner is the main body responsible for ecological compensations. The determinations of compensation standard shouldn’t only consider the capital need for protecting endangered and rare animals and plants or restoring the vegetation in reservoir area. It seems to be applicable to determine the standard based on the total value loss of river ecosystem services. Compensation scope should not limit to reservoir and its downstream areas. It should be extended to the whole river basin. The compensation period should be accord with dam’s life span, which means that the compensation should be carried out after dam construction. Besides bioengineering measures, the compensation mode should also include law establishment in order to implement reservoir operation modes in favor of river biology growth and multiplication. The induced power loss can also be taken as a kind of compensation mode.   

For a long time, riverine and riparian animals and plants are often obliged to migrate or go into exile after damming. Migratory fishes have to stop at the dam and some special plants are inundated. Because of strong human activities, biology has to endure and can say nothing. Whom can they say to and who will say something for them? Under the concept of sustainable development, governments, especially water administration agencies, should undertake the tasks to protect rivers. If a mechanism of restriction and coordination between river development and ecology protection can be established, our country’s hydropower development and dam construction will get on a much healthier development approach than before. 

5. Conclusions 

1) It is physically existed that dam will cause stresses of varying degrees to river ecosystem. We should treat this with a scientific attitude and advocate to pursue profits and avoid disadvantages. It is not receivable to “give up eating for fear of choking.” 

2) It is required to comprehensively evaluate the pros and cons of dam construction in the compound ecosystem of nature, society and economy to seek optimized strategies that will help to satisfy the demands of human society and to avoid or alleviate the damages to ecosystem.

3) It is possible to implement ecological compensations to damaged river. Stresses to river ecosystem can be alleviated by taking bioengineering methods as well as structural, biological and management measures. Interdiscipline research and demonstration project construction should be conducted to develop ecology friendly hydraulic and hydroelectric engineering. 

4) It is suggested to legislate in order to conduct value evaluation of ecosystem services of natural rivers and integrate it into the national economic accounting system. The evaluation results can be the basis for decision-making of major hydraulic and hydroelectric engineering. Legislations on ecological compensations are also proposed.    

Brief introduction on author: Dong Zheren,  Chairman of China technical advisory committee of Global Water Partnership (GWP), Professor of China Institute of Water Resources and hydropower Research (IWHR), Director of Chinese Society of Hydraulic Engineering, Visiting Professor of Tsinghua University, Dalian University of Technology, Sichuan University, Hohai University. 

References 

[1] Jia Jinsheng, et al, Introduction on world dams in 2003, China Water, No. 13, 2004, pp25-32.

[2] Dong Zheren, Diversity of river morphology and diversity of bio-communities, Journal of Hydraulic Engineering, No.11, 2003.

[3] Vannote, R. L. et al, The river continuum concept, Can. J. Fish. Aqua. Sci., 37:130-137, 1980.

[4]Mitsch W. J. & Jorgensen S E.，Ecological Engineering and Ecosystem Restoration [M].  PP 134-137, Published by John Wiley & Sons, Inc., Hoboken, New Jersey, 2004

[5]ASCE River Restoration Subcommittee on Urban Stream Restoration，Urban stream Restoration，Journal of Hydraulic Engineering,  ASCE , July 2003, pp 491-493

[6]Brookes,A., Shields JR,F.D., River Channel Restoration, John Wiley & Sons, UK, 2001

[7]Dong Zheren, Objectives of river restoration, China Water, No.10, 2004.

[8] Dong Zheren, Theoretical framework of Eco-hydraulic Engineering, Journal of Hydraulic Engineering, No.1, 2003.

[9] Dong Zheren, Design principles for ecological hydraulic engineering, Journal of Hydraulic Engineering, No. 10, 2004

[10]Costanza R, d’Arge R, Rudolf de Groot, et al. The value of the world’s ecosystem services and natural capital. Nature,1997,387: 253-260