Impacts of Mainstream Hydropower Dams on Fisheries and Agriculture in Lower Mekong Basin

Abstract

The riverine ecosystems of the Mekong River Basin possess the world’s most productive inland fishery and provide highly productive food crops for millions of people annually. The development of hydropower potential in the Mekong River has long been of interest to governments in the region. Among the existing 64 dams, 46 dams have been built in the Lower Mekong Basin (LMB) to produce up to 8650 MW of electricity. Additionally, of the 123 proposed built hydropower dams, eleven hydropower plants have been nominated for the river mainstream and are expected to install a total of 13,000 MW in the LMB countries. However, serious concerns have intensified over the potential negative economic consequences, especially on fisheries and agriculture in Cambodia and Vietnam. To date, most of the concerns have concentrated on the impacts on hydrology, environment, livelihood, and diversity in the LMB attributed to hydropower development. This paper, however, discusses the fishery and agricultural sectors of the LMB and focuses on the downstream floodplains of Cambodia and Vietnam. The dam construction has caused greater losses of biodiversity and fisheries than climate change in the LMB. The reduction of 276,847 and 178,169 t of fish, 3.7% and 2.3% of rice, 21.0% and 10.0% of maize will contribute to a decrease of 3.7% and 0.3% of the GDP of Cambodia and Vietnam, respectively. Lao PDR may benefit the most revenue from electricity generation than the other country in the LMB, as most of the proposed dams are projected in the country. Cambodia burdens 3/4 of the reduction of total capture fishery destruction, whilst Lao PDR, Thailand, and Vietnam endure the remaining 1/3 losses. The tradeoff analyses reveal that losses of capture fisheries, sediment or nutrients, and social mitigation costs are greater than the benefits from electricity generation, improved irrigation, and flood control of the LMB region. The socioeconomic and environmental damage caused by hydropower dams in developing countries, including the Mekong, is greater than the early costs in North America and Europe. It is proposed that dam construction for hydropower in the Mekong River, as well as other rivers in developing countries, should be gradually removed and shifted toward solar, wind, and other renewable resources.

Development of a SWAT Hydropower Operation Routine and Its Application to Assessing Hydrological Alterations in the Mekong

“…Overall, we found that the cumulative impacts of reservoir operations and climate change are more sensitive to the magnitude and duration of extreme flow conditions for the 3S basin. In addition, our study confirms that reservoir operations appear to have a considerably stronger impact on the flow regime than climate change [72][73][74]. Furthermore, land use change plays a major role in hydrological alterations [75], but in this study we have limited the analysis of impacts to reservoir operations and climate change.…”

“…The abundant biodiversity in the basin depends on the natural flood pulse; therefore, changes in the flood pulse may be one of the factors to compromise high biodiversity. Hence, hydrological alterations due to reservoir operations may cause great losses of biodiversity and fisheries in the 3S basin [27,74].…”

A Current Update on the Distribution, Morphological Features, and Genetic Identity of the Southeast Asian Mahseers, Tor Species

“…This has accelerated the exploitation of wild fish both as broodstock for aquaculture and a premium supply for the ornamental fish market [ 63 ]. Moreover, habitat alteration (e.g., damming or deforestation) and deterioration have been additional threats to these valuable species [ 64 ]. Therefore, it is urgent to gather information on species distribution and diversity to enable proper conservation plans before some species are lost.…”

Assessment of Hydrology and Sediment Yield in the Mekong River Basin Using SWAT Model

“…The operation of dams in the UMB will be either seasonal or yearly, but all those 11 proposed dams in the LMB are intended for daily operation. However, recently the Upper Mekong River in China is governed by a number of dams and reservoirs, all of which have laid dramatic changes in navigation patterns, the flow of water as well as sediment to the Mekong Delta [40].…”