Hydropower in the Mekong River Basin
[4] These developments in the Mekong River Basin have resulted in substantial environmental and social impacts, which are summarised below.
Large amounts of Yunnan's hydropower is exported eastwards to energy intensive load centres, such as Guangxi and Guangdong.
[13] Power production (from all sources, including hydropower) contributed 12.8% to national GDP in 2022, while electricity exports comprised almost 29% of total export values in the same year,[14] and investments in electricity production represented 79% of total foreign direct investment in 2021.
Cambodia also exports electricity directly from the Don Sahong HPP, a southern Lao dam located on the Mekong mainstream.
[20] In Thailand, little technically exploitable hydropower potential remains in its parts of the Mekong River Basin.
Most of its HPPs were developed in the 1980s and 1990s, and accompanied by large-scale irrigation infrastructure development as part of the massive Kong-Chi-Mun Project,[21] more recently rearticulated as the Khong-Loei-Chi-Mun Project [22][23] Large-scale energy infrastructure in Thailand has been met with strong resistance - for example, the Assembly of the Poor's opposition to the Pak Mun HPP, the last dam to be commissioned in Thailand.
This has forced Thailand to export the social and environmental externalities of hydropower construction and operation to neighbouring states.
[24][25] While there are multiple HPPs planned for Myanmar parts of the Mekong River Basin,[26] years of political instability have generally impended hydropower development.
Vietnam's hydropower investments in this area includes sizeable dams on two key Mekong tributaries, the Sesan and the Srepok rivers.
[40] In another study by the Mekong River Commission, fisheries assessments conducted in 2020 suggested that the annual finfish yield from the lower Mekong (i.e. those parts of the basin that fall within Cambodia, Laos, Thailand and Vietnam)) was between 1.51 to 1.71 million tonnes, while the harvest of other aquatic animals (OAAs) was approximately 443,000 tons.
The 1,570 MW Manwan HPP on the Mekong mainstream in China, for example, lost 21.5–22.8% of the total storage capacity to sediments in its first 11 years of operation.
[50] Over 2006/07, the Lao national timber quota was temporarily raised by 400,000 m3 to allow for logging specifically related to the development of the Nam Theun 2 HPP.
[51] It has been argued that logging represents an additional motivation to hydropower development, and is frequently linked to corrupt actors[clarification needed].
[52] River connectivity: 'connectivity' refers to the degree to which matter and organisms can move among spatially defined units in a natural system.
[56] Young reservoirs tend to release larger amounts of GHGs than older ones due to the availability of decomposing vegetation and other organic matter soon after initial inundation; tropical reservoirs tend to release more than temperate ones due to higher rates of net primary production.
[58] Hydropower reservoirs that also provided irrigation water (22) had generally higher emissions reaching over 22,000 kg of CO2 per MWh.
[58] These results, the study authors caution, are tentative and they suggest that hydropower in the Mekong Region cannot be considered categorically as low-emission energy.
Most immediately are those displaced by an HPP (i.e. resettled due to the presence of the dam itself, its reservoir, and/or ancillary buildings and infrastructure).
