Introduction

A significant challenge exists in assessing the social and ecological impacts of development projects in a holistic and comprehensive manner. Integrated assessments are required to better understand the consequences of large-scale ecosystem modification and the linkages between ecosystem change and human health and well-being. Often significant research is invested in the ecological effects of development projects, as well as on the predicted consequences for human health and well-being. Unfortunately, these efforts often exist largely in disparate spheres and lack the necessary integration required to address the linked problems of ecosystem change and human health.

Our objective is to elucidate the linkages between ecological change and human well-being and its importance in integrated assessment policy for development projects, using the Three Gorges Dam (China) as a case study. Significant investigation has focused on the effects of the Three Gorges Dam, including research describing ecological changes to the aquatic ecosystems of the Yangtze River and the Three Gorges reservoir. Investigations into social dynamics, including impacts on human health and well-being associated with the construction of the dam also have been undertaken. Despite these efforts, very little research has integrated information across disciplines to link ecosystem changes and environmental health impacts associated with the Three Gorges Dam.

Methods

Our intent is to characterize the ecosystem- and landscape-level changes in ecologic processes and condition of the Yangtze riparian system attributed to the dam, and integrate information on social and human health effects for a more holistic view of the effects of the Three Gorges. To do so, we performed a review of grey literature, published scholarly works (English and Chinese journals), and results from other research in the Yangtze River basin to identify linkages between ecosystem change and human well-being, as well as the social–ecological impact (+/−) associated with the Three Gorges. We propose a collaborative and integrative approach to investigating the linkages between human well-being and ecosystem change. We then turn our focus to the need for such an integrated assessment in the evaluation of development projects, and conclude with a call for investigators to engage in collaborative and transdisciplinary partnerships to achieve holistic results that can be applied to policy and decision-making. These results are applicable both to the continuing management of the Three Gorges Dam and to future proposed development projects.

Profile of the Three Gorges Dam

There are more than 35,000 large hydropower dams worldwide and China has built more than any other country (World Commission on Dams, 2000). By 1996, China had constructed 118 large hydropower dams, displacing an estimated 10.2 million people. The Three Gorges is unrivaled globally in terms of scale (Figs. 1, 2), producing a 60,000 ha (232 mi2) reservoir 600 km in length on the Yangtze (Changjiang) River (Delin and Lijun, 2000; Sino-German Center for Research Promotion, 2006) and displacing more than a million people (Sleigh and Jackson, 1998; Stone, 2008).

Figure 1
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The Three Gorges Dam, Sandouping, Yichang, Hubei Province. Photo credit: Kris Coontz, 2008.

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Figure 2
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Considerable diversity exists in the housing afforded to relocates in a newly created township adjacent to the Three Gorges Dam, Sandouping, Yichang, Hubei Province. Photo credit: Kris Coontz, 2008.

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The Three Gorges has a long history in the People’s Republic of China. A dam was first proposed at the Three Gorges site in 1919, has been supported by various Chinese leaders through the early and mid 1900s, and was finally approved in the early 1990s by the Chinese National People’s Congress. It was financed almost completely by the Chinese government, with a total estimated cost of ~$24 billion (USD) (Jackson and Sleigh, 2000). Construction on the Three Gorges commenced in the late 1990s and the final impoundment of water was completed in 2008. Construction included three successive impoundments, raising the water levels to >180 m above sea level (Delin and Lijun, 2000). These impoundments inundated a largely subsistence agrarian landscape and extensively altered the riparian ecosystem of the Yangtze.

The Three Gorges Dam is one of the largest modifications of a riparian ecosystem in human history, with habitat fragmentation and significant land use change occurring both within the reservoir area and downstream (Shen and Xie, 2004; Wu et al., 2004; Miller et al., 2005). The Three Gorges Dam represents a significant threat to biodiversity in a global biodiversity hotspot (Dudgeon, 2000; Myers et al., 2000). Of immediate concern is the likely extinction of the Yangtze River dolphin (Baiji) (Turvey et al., 2007) and potential loss of more than 44 species of endemic fish, the critical habitat for which has undergone radical hydrological changes (Fu et al., 2003; Park et al., 2003; Xie et al., 2003). Other species under threat include a number of endemic plant species (Xie, 2003), various other invertebrate and mammal species, and critical habitat for the threatened golden monkey, giant panda, and red panda.

The Three Gorges Dam is the largest of more than 60+ hydrological modifications on the Yangtze and was preceded by the massive Gezhouba Dam. The construction of the dam was predicated on the overarching goal of economic development and energy production and also was touted for other social benefits including decreased downstream flooding risk, increased water conservancy, tourism, and fisheries. Concurrent with the construction of the Three Gorges, the People’s Republic of China has experienced perhaps the highest rate of economic growth the world has ever witnessed. The intensified urbanization of China’s population, and the shifts in resource demands, including energy, has altered significantly the social and ecological landscape of the world’s most populous nation (Karasov, 2000, 2002; Schmidt, 2002). Changes associated with increased urbanization and development include increased interconnectivity with global financial markets, large cultural and technological changes, shifts away from primary care in China’s health sector, a demographic and epidemiologic transition, a growing demand for energy, and tentative steps toward a national environmental movement.

The Three Gorges Dam has significantly affected the linkages between human societies and the ecosystem (the linked social–ecological system) of the Yangtze River basin. There is a critical need to consider holistically the ecosystem changes and attendant impacts on human health associated with the Three Gorges to more fully understand the impacts and weigh the costs versus the benefits of large-scale development projects (Edmonds, 1992; Sleigh and Jackson, 1998; Jackson and Sleigh, 2000; Gohlke et al., 2008).

Results

Ecosystem Change and Human Well-Being: Social–Ecological Interactions and the Three Gorges Dam

Discerning the linkages between human well-being and ecosystem change is difficult because of the complexity of interactions between ecological and social systems, or linked social–ecological systems. The complex dynamics of social–ecological systems have been described as nonlinear and cross-scale, exhibiting multiple stable states between which abrupt and potentially irreversible changes can occur (Gunderson and Holling, 2002; Berkes et al., 2003; Liu et al., 2007). Elucidating the direct and indirect links between environmental change and human well-being requires consideration of the presence of multiple modifying forces, which can be destructive, constructive, or synergistic (Millennium Ecosystem Assessment and World Resources Institute, 2005).

The most comprehensive framework to date for evaluating the linkages between ecosystems and human well-being has been presented in the Millennium Ecosystem Assessment (MA) (Millennium Ecosystem Assessment, 2003; Levy et al., 2005; Millennium Ecosystem Assessment and World Resources Institute, 2005). The MA framework has defined human well-being as consisting of five principal dimensions: access to basic materials, freedom and choice, health, social relations and social capital, and security (Millennium Ecosystem Assessment, 2003; Levy et al., 2005; Table 1).

Table 1 Five Principal Dimensions of Human Well-Being, as Defined by the Millennium Ecosystem Assessment (Millennium Ecosystem Assessment, 2003; Levy et al., 2005)
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The MA definition of human well-being was used to evaluate studies with respect to their direct (or proximate), impact, and potential future impacts on the linked social–ecological system of the Three Gorges Dam. In evaluating studies, the multiple pathways and mediating processes through which ecological change can affect human well-being were considered. Individual studies were qualitatively classified as to their impact on the dimensions of human well-being. Using the MA definition as a general framework, we found the evidence of direct social and ecological impacts of the Three Gorges Dam could be grouped into four primary categories, which are specific to the Three Gorges social–ecological system: (1) toxicological impacts; (2) shifting infectious disease dynamics; (3) natural hazards; and (4) social health. Social–ecological relationships were altered in complex ways by the Three Gorges Dam, with both direct and indirect effects, positive and negative interactions, and chronic and acute impacts on human well-being (Table 2). Each category is affected by both social and ecological drivers that affect the linkage between human well-being and ecosystem change for the Three Gorges Dam (Table 3). Below, the four primary and direct linkages between human well-being and ecosystem change in the Three Gorges region are summarized.

Table 2 The Range of Impacts to Human Well-Being of Four Primary Categories of Social–Ecological Interactions Affected by the Three Gorges Dam
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Table 3 Four Primary Categories of Social–Ecological Interactions Affected by the Three Gorges Dam
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Toxicological Impacts and Environmental Health Effects

The construction of the Three Gorges Dam constituted a major alteration of the riparian ecosystem of the Yangtze River basin (Wu et al., 2004). Significant changes in the aquatic ecology of the Three Gorges Reservoir area and the Yangtze riparian system are evidenced by shifts in nutrient levels and hydrography (Fang et al., 2006; Feng et al., 2008), plankton and microbial community structure (Sekiguchi et al., 2002; Hu and Cai, 2006; Kuang et al., 2007), and benthic communities (Shao et al., 2006). Increased eutrophication of the Three Gorges Reservoir has resulted from increased retention of nutrients in the reservoir area from agricultural practices, industrialization along the Yangtze River and in its watersheds, and increasing urbanization (Liu and Qu, 2002; Liu et al., 2004a; Zheng et al., 2008). Shifts in planktonic community composition and structure are associated with alterations in natural biogeochemical cycles, hydrographic processes, and alteration of watersheds associated with the Three Gorges Dam (Kuang et al., 2005; Hu et al., 2006; Hu and Cai, 2006; Kuang et al., 2007). Notable among these shifts are the increased prevalence of cyanobacterial algal blooms due to nutrient loading (Mei et al., 2003; Tang et al., 2006; Ye et al., 2007), which affect the environmental quality of the reservoir area (Stone, 2008). Algal blooms may include species known to produce deleterious toxins (Carmichael, 1994; Shen et al., 2003).

The construction of the Three Gorges Dam resulted in increased retention of industrial, agricultural, and natural toxicants both in the Three Gorges Reservoir and downstream of the dam due to significantly reduced water flow rate. Accumulation of toxicants has resulted in increased human exposure, particularly in subsistence populations that rely on the Yangtze for food, water, and other basic materials. Increased exposure is due to the bioaccumulation of heavy metals and pesticides in the waters and sediment of the Yangtze River and Three Gorges Reservoir (Gu et al., 1988; Xu et al., 1999a; Yuan, 2002; Xing and Bao, 2004; Gao et al., 2006; Zhang et al., 2007), as well as fish species (Xu et al., 1999a), including those species that may targeted for consumption by local residents (Jiang et al., 2007; Zhang et al., 2007). Analysis of dietary patterns and food items suggest that heavy metals represent a significant hazard for households in the Three Gorges Reservoir area (Jiang et al., 2007). Heavy metals also are entering the Yangtze River system through geologic sources, as mountain rocks that have become inundated leach metal ions in the reservoir (Li and Wu, 1999; Yuan, 2002). Additionally, elevation of subsoil water may cause increases in agricultural soil toxins, increasing the burden of already prevalent dietary diseases, such as fluorosis in the Three Gorges area (World Health Organization, 1999; Delin and Lijun, 2000).

The Three Gorges also has altered sedimentation and natural flow patterns, including seasonal flooding patterns (Dudgeon, 2000; Dong, 2005). Natural sedimentation rates have been historically altered due to human land use practices, and analyses suggest that forced relocation will likely exacerbate sediment delivery to the Three Gorges Reservoir area (Lu and Higgitt, 2001). Downstream effects on fisheries, including alteration of biogeochemical processes, have resulted in decreased productivity in downstream portions of the Yangtze River and in neritic ecosystems of the E. China Sea (Chen, 2002; Jiao et al., 2007). Fisheries resources in the Three Gorges Reservoir also have been impacted by alteration of nutrient cycles, as well as overfishing (Dudgeon, 2000; Duan et al., 2002).

Shifting Infectious Disease Dynamics

Changes in infectious disease dynamics can result from alteration of ecological processes as well as social dynamics. From an ecological perspective, land use change, loss of biodiversity, changes in habitat, and alteration of processes, such as nutrient cycling and pathogen dispersion, can significantly alter the dynamics of disease (Patz et al., 2004). From a social perspective, alteration in lifestyle and livelihoods can reduce or enhance exposure to disease vectors and pathogens. Human well-being impacts associated with shifting disease dynamics are primarily attributed to an increase in social or behavioral risk factors, the vulnerability of affected populations, and the ecological dynamics of habitat and vector species that affect the pathogen (Wilcox and Colwell, 2005; Confalonieri et al., 2007).

In the Three Gorges, the primary focus has been on schistosomiasis, a vector-borne, zoonotic disease that results in internal organ damage in adults and impairs cognitive development in children. Impoundment and hydrological alterations are expected to increase the range of Oncomelania snails, the host vector for Asian schistosomiasis, and the disease transmission rates (Maszle et al., 1998; Xu et al., 1999b, 2000; Li et al., 2000; Li et al., 2007; Zheng et al., 2002). The increase in vector habitat, however, may be less of a threat than the increased exposure related to the relocation of thousands of people and their ruminant livestock (Jackson and Sleigh, 2000; Li et al., 2007). Relocation effects include increased human habitation and population density in marginal agrarian environments where people access vector habitats for subsistence activities (fishing, farming, etc.) and livestock practices. Also important is a lack of basic health services and sanitary excreta facilities in rural agrarian areas, further contributing to disease prevalence (Li et al., 2007).

Relocation of populations to crowded urban areas and water contamination in the reservoir may increase transmission of diseases, such as hepatitis, pneumonia, diarrheal diseases, and Hantavirus (Sleigh and Jackson, 1998; Jackson and Sleigh, 2000; Sleigh et al., 2006; Long et al., 2007). Malaria is not endemic to the Three Gorges area, but similar projects elsewhere have been found to increase malaria transmission (Keiser et al., 2005). There has been a minor but consistent resurgence of malaria in China between 1998 and 2003, and there was an outbreak at the dam site in 1996 (Jackson and Sleigh, 2000; Xiaonong, 2004). Whereas specific diseases, such as schistosomiasis and malaria, represent direct impact on disease incidence, the loss of biodiversity constitutes a more indirect and insidious affect on disease dynamics. Biological diversity is hypothesized to control pathogen emergence in ecosystems by down-regulating host-parasite dynamics, and thus functions as an ecological buffer for pathogens in natural systems. The loss of biodiversity due to the Three Gorges may remove ecosystem functions that down-regulate pathogen intensity (Ostfeld and LoGiudice, 2003).

Natural Hazards

The construction of the Three Gorges Dam will have complex upstream and downstream effects on natural hazards, such as flooding, historically a major problem in the Yangtze River basin, and landslides. The net effect on catastrophic flooding will likely be beneficial, with downstream risks of floods decreased from a 10-year to 100-year frequency (Chinese Academy of Sciences, 1993; Jackson and Sleigh, 2000). Altered sedimentation and siltation patterns may cause increased flooding events in some areas from increased erosion. There is concern that people will relocate into risky areas downstream that were previously classified as floodplains (World Commission on Dams, 2000).

There was an increase in human-caused landslides during the 1990s in the Three Gorges area, and approximately 5% of the 5,900 km of reservoir shoreline was classified as high risk for “destructive” or “disastrous” landslides in 2001 (Wu et al., 2001). Although some dangerous areas were submerged, the combination of deforestation, relocation of people to high-risk shoreline areas, and increased development in landslide risk zones are of great concern (Liu et al., 2004b). Because they can create large waves, landslides in reservoirs need not be proximate to human populations to cause harm. Other natural hazard threats include catastrophic dam failure and earthquakes due to dam-associated seismicity (World Commission on Dams, 2000; McCully, 2001; Gupta, 2002).

Social Health

Social health effects are related to population relocation as well as socioeconomic, cultural, and demographic changes associated with the dam. Health concerns center around livelihood and food security, physical and mental illness in forced migrants, and erosion of social and cultural support systems. Before the construction of the dam, the population of the Three Gorges region was poor, densely but patchily populated, and primarily agricultural. Literacy rates and health care system workforce capacity were lower than China’s national average (Delin and Lijun, 2000). Some relocates have been moved into newly constructed townships (Fig. 2), but many have been displaced into growing urban centers such as Chongqing. Estimates for population displacement from the Three Gorges Dam vary widely, but at least 1 million people have already been relocated (Cernea, 2003; Sleigh, 2006; Li et al., 2007). Recently the Chinese government has suggested that perhaps as many as 4 million will ultimately be relocated, which constitutes a quarter of the population living in the reservoir area (Stone, 2008). Forced resettlement has resulted in population issues that could portend social unrest and resentment against political institutions (Jackson and Sleigh, 2000; Heming et al., 2001).

Estimating the effects of large development projects on social health is difficult due to the complexity of effects. Effects are positive and negative, as well as direct and indirect/diffuse. Large development projects typically result in improvements in aggregate health indicators coupled with increasing inequalities, which in turn are paradoxically associated with poorer health (Li and Zhu, 2006). Given the relationship between economic development and improving aggregate health indicators, it is plausible to predict direct and indirect benefits of the Three Gorges on health through poverty reduction, new employment opportunities, increased energy production and availability (Haines et al., 2007), and economic stimulation and changes in resource availability. For example, the South-to-North Water Transfer Project will help increase agricultural productivity, quality of life and sanitation, to the water-parched north. Nonetheless, large development projects exacerbate existing local disparities, with the greatest burden of ill effects falling disproportionately on the poor and vulnerable (World Commission on Dams, 2000; Tilt et al., 2009). The difficulty in understanding the true costs and benefits are in estimating whether aggregate benefits offset the effects of population relocation, including depriving millions of people of their homes, ancestral lands, and traditional livelihoods.

The impoundments will result in the flooding of more than 30,000 ha of agricultural land (Jackson and Sleigh, 2000). A policy of “de-farming” to reduce environmental costs may increase psychosocial hardship and food pressures in an already dense population (Jim and Yang, 2006). Additionally, the higher elevation areas where resettlement occurs are less suitable for agriculture and would likely require much greater quantities of land for equal productivity. Notably, only 60% of farmers will be resettled to areas where farming is possible (Jackson and Sleigh, 2000). Malnutrition in this area is a serious concern and is affected not only by productivity of agricultural lands, but also by rising water tables and salinization of agricultural land (Jackson and Sleigh, 2000).

The Three Gorges Project Construction Committee’s official policy of local resettlement will further increase population density in some areas (Jing, 2000) but may also cushion the psychological sequelae of forced re-livelihood (Figs. 1, 2). Rural inhabitants have borne much of the impact of the forced resettlement, stressing at-risk populations and altering the labor pool by forcing relocates to pursue migrant work (Shaoquan et al., 2004; Jim and Yang, 2006). Increased population density could lead to conditions ripe for water-borne illnesses and other diseases related to sanitation in addition to increased spread of communicable diseases, such as tuberculosis and pneumonia. Even in the presence of reasonably effective resettlement programs, forced migrants rarely fare well (Cernea, 2003). Psychosocial sequelae are associated with forced relocation, including traumatic stress, stigmatization, depression and violence (World Health Organization, 1999). A prospective study in the Three Gorges area found that forced migration resulted in increases in depression both directly and through disintegrating social support networks, with greater depression in rural migrants (Hwang et al., 2007). Other causes of psychosocial problems include the erosion and loss of cultural capital and the associated social support systems, as well as forced transition away from traditional livelihoods (Hwang et al., 2007).

The health care system capacity of the Three Gorges area and the receiving areas for relocates will be important in determining health outcomes. HIV/AIDS and other communicable diseases in resettlement areas or areas where migrants temporarily work may cause changes in disease geography and transmission (World Commission on Dams, 2000:119). Temporary migration to the dam area by workers and increases in commercial sex work also may bring new diseases to the Three Gorges area. Additionally, forced migrants relocated to urban areas may experience decreased activity and changes in diet that may lead to increases in chronic diseases (Millennium Ecosystem Assessment, 2005).

It is important to consider who are the winners and who are the losers from large development projects, because it often is the case that the winners benefit at the expense of the losers, and it is generally vulnerable local populations who bear the greatest share of the cost (World Health Organization, 1999; World Commission on Dams, 2000; Millennium Ecosystem Assessment, 2005). The principle of equity demands that the populations that bear the cost of large dam projects should share in the benefits (World Commission on Dams, 2000). Management agencies should consent to independent tracking and analysis of the outcomes of those forced to move by the project. Although it is too late to debate the merits of relocating so many, it may not be too late to minimize harm caused and to learn valuable lessons for future development projects.

Discussion

Holistic Evaluation of the Three Gorges Dam: Toward a Social–Ecological Assessment

Estimating the quantitative costs and benefits of a project the size of Three Gorges is extremely difficult because of the scale, complexity, and unpredicted surprises that characterize ecosystem change (Holling, 1996). Accurate, quantitative, cost-benefit analysis is further complicated by the complexity of human–environment interactions, the inherent problems in valuation of nature, and difficulty in accurately forecasting indirect and dynamics effects of a given project. A holistic evaluation considers the entirety of a social–ecological system rather than individual constituent parts, and the linkages between human and environmental systems. By definition, this requires consideration of the full range of costs and benefits associated with a large-scale development project. In the absence of quantitative assessments, integrated qualitative indicators of the type reported here can provide critical information for decision-making processes. For the Three Gorges, a retrospective qualitative cost-benefit analysis can provide a template for the appropriate ecological and social considerations that may be utilized in future assessments.

The benefits of the Three Gorges are more tractable and include the primary benefit of production of 18,600–22,800 MW of hydroelectric power, constituting approximately 10% of China’s energy production. Another major benefit has been the amelioration of flooding risks (Li et al., 2007). The Yangtze’s nickname is the “sorrow of China,” which is attributed to the sporadic flooding that has claimed innumerable lives since antiquity. In modern times, at least 200 major floods have been recorded, with catastrophic floods in the 1930s and 1950s that killed more than 320,000; as recently as 1998, flooding claimed the lives of more than 3,000 people. Benefits also include economic development of the Yangtze River basin, including a functional connection of major industrial and manufacturing centers in Chongqing to the East China Sea through large-scale shipping transport on the Yangtze (Sino-German Center for Research Promotion, 2006). Tourism also has been beneficial to the Chongqing municipality. Foreign visitors in Chongqing in 1997 reached a quarter million, and exceeded 4 million in conjunction with the 2008 Olympics (Chongqing Statistical Bureau, 1998; China Hospitality News, 2008).

The costs of the Three Gorges are more difficult to calculate than benefits because costs are more diffuse, present estimation problems in terms of economic impact, and are difficult to predict. The primary costs are associated with the displacement of an estimated 2 to 4 million from the reservoir area upstream of the dam (Jackson and Sleigh, 2000). Those directly displaced, however, pale in comparison the total population affected by the dam, which includes approximately 20 million upstream and 200 million downstream of the dam, including a significant proportion of the estimated 900 million subsistence farmers in China. Modification of the Yangtze River basin from the Three Gorges has resulted in loss or alteration of agricultural lands. More than 140 villages and 1,400 factories, and countless cultural heritage sites of incalculable value, were inundated in the impoundment (Childs-Johnson and Shen, 2000). The “hidden costs” associated with social impacts, including health costs, may be difficult to estimate quantitatively but are not likely to be easily subsumed by direct benefits of hydropower, development, and flood risk. More research is needed in this area.

An international consensus on sustainable development and the environment now recognizes the principal objective of placing human health and social needs above all else (United Nations Conference on Environment and Development, 1992; World Summit on Sustainable Development, 2002). In developing countries, the challenges of providing sustainable energy production require consideration of energy efficiency, conservation, and increased use of renewable energy sources (Weidou and Johansson, 2004). However, often the “hidden costs” to human health and well-being of well-intentioned development projects are left out of the cost-benefit analyses. Long-term or irreversible ecological consequences can be similarly diminished in light of the overarching goals of energy production and economic development.

The evaluation of energy production and development projects requires integrated assessments, including a holistic cost-benefit analysis, of both human and environmental consequences (World Commission on Dams, 2000; Gohlke et al., 2008). This includes promotion of a health dimension to social, economic, and development policy (World Health Organization, 1999; Butler and Friel, 2006), as well as consideration of the ecological effects and effects on ecosystem services of engineering and development projects. As a response, a number of countries have implemented a health assessment policy for development projects. Although environmental impact assessment and health impact assessment processes often occur in disparate spheres, a holistic consideration of the social and ecological effects requires conjoint assessment processes (World Health Organization, 1999). As illustrated by the Three Gorges, the linkages between ecosystem change and human well-being require a holistic assessment process that considers the complexity and multiscale dynamics of social–ecological relationships. Further integration of health impact assessments with the environmental impact assessment process can provide more meaningful cost-benefit analysis and better decision making for sustainable futures (McCarthy et al., 2002; Krieger et al., 2003; Bhatia and Wernham, 2008; Gohlke et al., 2008).

Transdisciplinary Approaches to Understanding Ecosystem Change and Human Well-Being

A holistic, multilevel systems approach to the processes that govern complex human-environment systems requires the transdisciplinary integration of various fields of knowledge. A transdisciplinary approach recognizes the value of transcending disciplinary paradigms (integration), designing research approaches and projects in a participatory way (participatory research), and orienting the research effort towards the proper scale of the problem addressed (problem-orientation) (Pohl and Hirsch Hadorn, 2007; Hirsch Hadorn et al., 2008; Wilcox and Kueffer, 2008).

Disciplinary integration should include experts on the ecologic processes and effects of ecosystem change on disease and health in order to enhance understanding of the public health challenges associated with development projects. Conversely, the addition of a human health component to ecological inquiry adds a critical element to understanding the human impact associated with ecosystem change. Social–ecological research also requires a participatory approach, which integrates disciplinary principles, considerations, arguments, and design choices, throughout the research process (van Asselt Marjolein and Rijkens-Klomp, 2002; Zierhofer and Burger, 2007). Transdisciplinary, collaborative approaches are differentiated from inter- or multidisciplinary efforts in the recognition and advancement of an integrative approach to all phases of the research project, from the design phase and investigation to the final authorship of outputs. Resultant research initiatives should ideally involve multiple investigators working collaboratively, stimulating the development of integrative theory, novel forms of knowledge, and a holistic approach to human-environment problems. Collaborative research initiatives can be facilitated through the use of existing conceptual frameworks on human-environment systems, for example social–ecologic and coupled human-natural systems theory (Gunderson and Holling, 2002; Berkes et al., 2003) or biocomplexity theory (Wilcox and Colwell, 2005).

With some notable exceptions (e.g., Jobin, 1999; Sleigh et al., 2006; Li et al., 2007), research programs and efforts on the Three Gorges Dam and human health exist in disparate spheres, resulting in a fragmented approach to what is essentially a linked human-environment system. Although reductionist approaches are necessary, there also is a need for integrative science to more appropriately inform policy. From a policy perspective, a holistic view of the effects of the dam requires a collaborative and integrative approach, undertaken by independent research scientists, institutions, and agencies involved in the monitoring and assessment of the Three Gorges and Yangtze river (e.g., Institute of Hydroecology, Institute of Hydrobiology, and Hubei Institute of Schistosomiasis) in consultation with stakeholders and decision-makers in the political process.

Conclusions

The relationship between the ecological changes attributed to the Three Gorges Dam, and the cascading effects on social and human health present a complex set of human-environment problems. It is clear that the health and well-being of the 200+ million Chinese in the Yangtze River basin are inextricably linked to the Three Gorges Dam. The management of the dam thus requires a holistic and systemic view of these linkages to ameliorate effectively the consequences of social–ecological change associated with the Three Gorges Dam (Edmonds, 1992; Guo et al., 2007; Tilt et al., 2009). Our synthesis supports a comprehensive evaluation of development projects via integrated assessments of human and environmental consequences. This includes promotion of a health dimension to social, economic, and development policy and is probably best achieved through an integrated social–ecological health impact assessment, which can ensure a holistic and comprehensive analysis of expected costs and benefits. The role of research is to elucidate the linkages between ecosystems and human health to better inform the assessment process. A synthesis of the existing information on the Three Gorges suggests that this is best achieved through institutional collaboration and transdisciplinary integration of expertise.