A framework for social impact analysis of large dams: A case study of cascading dams on the Upper-Mekong River, China

Wang, P., J.P. Lassoie, S. Dong, and S.J. Morreale, 2013: “A framework for social impact analysis of large dams: A case study of cascading dams on the Upper-Mekong River, China.” Journal of Environmental Management, v. 117, pp. 131-140, doi: 10.1016/j.jenvman.2012.12.045.

Construction of large dams on the Upper-Mekong River, China, has significant social impacts on local communities. To analyze the social impacts, we identified three classes of wealth for the affected people, material, embodied, and relational, and comprehensively compared the loss and compensation in each type of wealth. Then we examined the effects on gap of wealth at household and community levels. Lastly, an insider–outsider analysis was conducted to understand the differences in the perceptions of wealth loss between local villagers and policy makers, and recommendations for more reasonable compensation policies were provided.

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Uncertainty in climate change projections of discharge for the Mekong River Basin

Kingston, D.G., J.R. Thompson, and G. Kite, 2011: “Uncertainty in climate change projections of discharge for the Mekong River Basin.” Hydrology and Earth System Science, v. 15, pp. 1459-1471, doi: 10.5194/hess-15-1459-2011.

The Mekong River Basin is a key regional resource in Southeast Asia for sectors that include agriculture, fisheries and electricity production. Here we explore the potential impacts of climate change on freshwater resources within the river basin. We quantify uncertainty in these projections associated with GCM structure and climate sensitivity, as well as from hydrological model parameter specification. This is achieved by running pattern-scaled GCM scenarios through a semi-distributed hydrological model (SLURP) of the basin. Pattern-scaling allows investigation of specific thresholds of global climate change including the postulated 2 °C threshold of “dangerous” climate change. Impacts of a 2 °C rise in global mean temperature are investigated using seven different GCMs, providing an implicit analysis of uncertainty associated with GCM structure. Analysis of progressive changes in global mean temperature from 0.5 to 6 °C above the 1961–1990 baseline (using the HadCM3 GCM) reveals a relatively small but non-linear response of annual river discharge to increasing global mean temperature, ranging from a 5.4 % decrease to 4.5 % increase. Changes in mean monthly river discharge are greater (from −16 % to +55 %, with greatest decreases in July and August, greatest increases in May and June) and result from complex and contrasting intra-basin changes in precipitation, evaporation and snow storage/melt. Whilst overall results are highly GCM dependent (in both direction and magnitude), this uncertainty is primarily driven by differences in GCM projections of future precipitation. In contrast, there is strong consistency between GCMs in terms of both increased potential evapotranspiration and a shift to an earlier and less substantial snowmelt season. Indeed, in the upper Mekong (Lancang sub-basin), the temperature-related signal in discharge is strong enough to overwhelm the precipitation-related uncertainty in the direction of change in discharge, with scenarios from all GCMs leading to increased river flow from April–June and decreased flow from July–August.

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Assessment of uncertainty in river flow projections for the Mekong River using multiple GCMs and hydrological models

Thompson, J.R., A.J. Green, D.G. Kingston, and S.N. Gosling, 2013: “Assessment of uncertainty in river flow projections for the Mekong River using multiple GCMs and hydrological models.” Journal of Hydrology, doi: 10.1016/j.jhydrol.2013.01.029.

Hydrological model-related uncertainty is often ignored within climate change hydrological impact assessments. A MIKE SHE model is developed for the Mekong using the same data as an earlier semi-distributed, conceptual model (SLURP). The model is calibrated and validated using discharge at 12 gauging stations. Two sets of climate change scenarios are investigated. The first is based on a 2 °C increase in global mean temperature (the hypothesised threshold of ‘dangerous’ climate change), as simulated by seven GCMs. There are considerable differences in scenario discharge between GCMs, ranging from catchment-wide increases in mean discharge (up to 12.7%; CCCMA CGCM31, NCAR CCSM30), decreases (up to 21.6% in the upper catchments; CSIRO Mk30, IPSL CM4), and spatially varying responses (UKMO HadCM3 and HadGEM1, MPI ECHAM5). Inter-GCM differences are largely driven by differences in precipitation. The second scenario set (HadCM3, increases in global mean temperature of 1–6 °C) shows consistently greater discharge (maximum: 28.7%) in the upper catchment as global temperature increases, primarily due to increasing precipitation. Further downstream, discharge is strongly influenced by increasing PET, which outweighs impacts of elevated upstream precipitation and causes consistent discharge reductions for higher temperatures (maximum: -5.3% for the main Mekong). MIKE SHE results for all scenarios are compared with those from the SLURP catchment model and the Mac-PDM.09 global hydrological model. Although hydrological model-related uncertainty is evident, its magnitude is smaller than that associated with choice of GCM. In most cases, the three hydrological models simulate the same direction of change in mean discharge. Mac-PDM.09 simulates the largest discharge increases when they occur, which is responsible for some differences in direction of change at downstream gauging stations for some scenarios, especially HadCM3. Inter-hydrological model differences are likely attributed to alternative model structures, process representations and PET methods (Linacre for MIKE SHE and SLURP, Penman-Monteith for Mac-PDM.09).

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Modelling the Mekong: Hydrological simulation for environmental impact studies

Kite, G., 2001: “Modelling the Mekong: Hydrological simulation for environmental impact studies.” Journal of Hydrology, v. 253, pp. 1-13, doi: 10.1016/S0022-1694(01)00396-1.

The Mekong, with a basin area of almost 800,000 km2 and a length of 4500 km, is one of the most important rivers of the world. The many lakes and wetlands along the river, including Cambodia’s Tonle Sap (Grand Lac), are major sources of fish for the riparian peoples and form an important part of the regional economy. This resource may be affected by proposed developments in the basin. Using climatic, topographic and land cover data from the Internet, the semi-distributed land-use runoff process (SLURP) hydrological model was used to simulate the complete hydrological cycle of the Mekong and its tributaries. Information on dam locations and reservoir characteristics were obtained from local sources. The model was verified by comparing simulated flows with recorded daily flows for the Mekong River and by comparing simulated levels of the Tonle Sap lake with recorded daily levels. The daily computed levels of the Tonle Sap lake were then converted into flooded areas for each land cover around the lake which were then used in a fish production model to evaluate the possible impacts of basin development on the fisheries. Model outputs may also be used to investigate issues such as water allocations and the effects of land use change or climate change on water resources and the aquatic and riparian environments.

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'Water war' in the Mekong Basin?

Pearse-Smith, S.W.D., 2012: “‘Water war’ in the Mekong Basin?” Asia Pacific Viewpoint, v. 53, pp. 147–162, doi: 10.1111/j.1467-8373.2012.01484.x.

The Mekong River system provides a crucial source of natural resources for riparian nations. However, the increasingly rapid pace of hydro-development in the Mekong Basin is threatening the integrity of the river system, posing a real concern for Lower Basin states, which are particularly dependent on the basin. This scenario has led to warnings of armed conflict, or even ‘water war,’ between riparian states. Certainly, the expanding scale of hydro-development can be expected to continue increasing interstate tensions in the Mekong region; but are these tensions really likely to escalate to armed conflict? This paper explores this question by drawing on the water and conflict theory of Aaron Wolf. Ultimately, this paper concludes that interstate tensions over Mekong hydro-development are unlikely to generate armed conflict. This is in part due to the strategic impracticality of such a conflict as well as the presence of a river basin management institution. Most compellingly, though, armed conflict is unlikely because the economic imperative shared by Mekong states is better served by cooperation – or at least non-interference – than conflict, over regional hydro-development. In closing, the paper urges that the study of water and conflict in the Mekong Basin be refocused at the intrastate level.

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Adaptation in a transboundary river basin: Linking stressors and adaptive capacity within the Mekong River Commission

Heikkila, T., A.K. Gerlak, A.R. Bell, and S. Schmeier, 2013: “Adaptation in a transboundary river basin: Linking stressors and adaptive capacity within the Mekong River Commission.” Environmental Science and Policy, v. 25, pp. 73-82, doi: 10.1016/j.envsci.2012.09.013.

River basin organizations serve as potential forums to promote adaptation to environmental change in transboundary river basins. Yet how these organizations adapt is an understudied area of the literature. We explore and compare four examples of adaptation within the Mekong River Commission (MRC), focusing on how the nature of stressors shapes adaptation responses. We measure adaptation responses in terms of adaptive capacity, which includes technical, institutional, social and financial capacity. We find that the uncertainty of the impact of stressors plays a role in shaping the extent of adaptive capacity. We also find that the adaptive response may depend on a river basin organization’s pre-existing capacity to address the stressor. Finally, our research suggests that investments in new capacity can create a feedback mechanism that helps reduce uncertainty and foster further adaptation.

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Effects of cascade hydropower dams on the structure and distribution of riparian and upland vegetation along the middle-lower Lancang-Mekong River

Li, J., S. Dong, Z. Yang, M. Peng, S. Liu, X. Li, 2012: “Effects of cascade hydropower dams on the structure and distribution of riparian and upland vegetation along the middle-lower Lancang-Mekong River.” Forest Ecology and Management, v. 284, pp. 251-259, doi: 10.1016/j.foreco.2012.07.050.

The extensive number of hydropower dams being planned in southwest China has attracted much attention in recent years. Eight cascading dams along the middle and lower reaches of the Lancang-Mekong River basin were selected to assess the riparian and upland vegetation. A total of 24 transects and 126 quadrats perpendicular to the river channel were surveyed from upstream to downstream. By using two-way indicator species analysis (TWINSPAN), the vegetation types in this region were classified into 21 vegetation classes. The ecological gradient analysis was completed using canonical correspondence analysis (CCA) and demonstrated that the dominant environmental factors impacting vegetation distribution were the variations in latitude and altitude. The vegetation impact index (VII) was developed as a quantitative index to assess the impact of dam inundation and operation on the upland and riparian vegetation. The values of VII showed that the most endangered vegetation communities were the shrub and herb communities in riparian habitats along this river. The effects of cascading hydropower dams on riparian and upland vegetation distribution were more complex than those of single dams. Cascading hydropower dams can enhance habitat fragmentation, reduce the distribution ranges (latitude and altitude) of primary vegetation and reduce the complexity of the vegetation types along the river as well as induce the loss of primary vegetation in the whole watershed.

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Dams on the Mekong River: Lost fish protein and the implications for land and water resources

Orr, S., J. Pittock, A. Chapagain, and D. Dumaresq, 2012: “Dams on the Mekong River: Lost fish protein and the implications for land and water resources.” Global Environmental Change, doi: 10.1016/j.gloenvcha.2012.06.002.

Proposed dam construction in the Lower Mekong Basin will considerably reduce fish catch and place heightened demands on the resources necessary to replace lost protein and calories. Additional land and water required to replace lost fish protein with livestock products are modelled using land and water footprint methods. Two main scenarios cover projections of these increased demands and enable the specific impact from the main stem dam proposals to be considered in the context of basin-wide hydropower development. Scenario 1 models 11 main stem dams and estimates a 4–7% increase overall in water use for food production, with much higher estimations for countries entirely within the Basin: Cambodia (29–64%) and Laos (12–24%). Land increases run to a 13–27% increase. In scenario 2, covering another 77 dams planned in the Basin by 2030 and reservoir fisheries, projections are much higher: 6–17% for water, and 19–63% for land. These are first estimates of impacts of dam development on fisheries and will be strongly mediated by cultural and economic factors. The results suggest that basic food security is potentially at a high risk of disruption and therefore basin stakeholders should be fully engaged in strategies to offset these impacts.

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Social impacts of large dam projects: A comparison of international case studies and implications for best practice

Tilt, B., Y. Braun, D. He, 2009: “Social impacts of large dam projects: A comparison of international case studies and implications for best practice.” Journal of Environmental Management, v. 90, pp. S249-S257, doi: 10.1016/j.jenvman.2008.07.030.

This paper applies the tool of social impact assessment (SIA) to understand the effects of large dam projects on human communities. We draw upon data from two recent SIA projects: the Lesotho Highlands Water Project in Southern Africa, and the Manwan Dam, located on the upper Mekong River in southwestern China. These two cases allow us to examine the social impacts of large dam projects through time and across various geographical scales. We focus on a range of social impacts common to many large-scale dam projects, including: the migration and resettlement of people near the dam sites; changes in the rural economy and employment structure; effects on infrastructure and housing; impacts on non-material or cultural aspects of life; and impacts on community health and gender relations. By identifying potential impacts in advance of a large dam project, agencies and policymakers can make better decisions about which interventions should be undertaken, and how. We conclude our analysis with an overview of lessons learned from the case studies and suggestions for best practice in assessing the social impacts of large dams. Conducting proper social impact assessments can help to promote development strategies that address the most important concerns for local populations, enhancing the long-term sustainability of dam projects.

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