This article was originally posted to the Institute of Water Resources Planning (IWRP) website of the Ministry of Agriculture and Rural Development in Vietnam. Read the original article.
As the largest river in Southeast Asia and the sixth largest in the world, the Mekong, originating from the Tibetan Plateau, travels more than 4300 kilometers southeast and ends in the South China Sea, with a total annual runoff of 475 km3. This is also the river bounding up six countries, namely China, Myanmar, Laos, Cambodia, Thailand and Viet Nam, not only geographicaly but also culturaly and economicaly.
Currently, more than seventy million people (equivalent to one third of the total population of the four countries – Thailand, Viet Nam, Laos and Cambodia) are living in the Mekong River basin which covers an area of 795,000 km2. Eighty percent of the population living in the basin is dependent on agriculture and the river’s resources. The river is essential for people’s economic survival and it secures their livelihoods throughout the whole basin.
However, in recent decades as a result of both natural and man-made impacts the river has been facing major challenges that have severely hampered the future sustainable development of the region.
Challenges arising from climate change and natural disasters
The Mekong Basin and especially the lower part in the delta, is vulnerable to the effects of climate change.
Climate change causes extreme phenomena such as more prolonged droughts during the dry season and more severe floods in the rainy season, these being the discernable effects of El Nino and La Nina. This trend has been changing the natural water cycle, which has therefore induced significant impacts on water resources. Changes in river flow regimes and tides will directly affect the extent of salinity intrusion in the downstream deltas, particularly in the dry years.
The phenomenon of the rise in sea level and salt intrusion is also increasing. The Mekong delta is considered to be one of the three major deltas most severely affected by the rise in sea level and saline intrusion. According to climate change scenarios in 2016, if there is a further 100 cm rise in the sea level without any remedial response it will mean that 38.9% of the Mekong Delta in Vietnam will be in danger of being submerged.
The challenges resulting from socio-economic development
In addition to the natural challenges, human actions also have a major influence on the health of the Mekong.
1. The construction of water reservoirs and hydropower stations on the Mekong mainstream, especially in the upper section, has not only attracted the attention of the region but also of experts around the world.
According to the results of remote sensing analysis by the Ministry of Natural Resources and Environment (Viet Nam, 2014), there are 176 hydropower reservoirs either in operation or under construction within the entire basin. There are eight dams on the main stream, including seven in Yunnan-China and one in Laos.
Hydropower: China plans to build 14 hydropower dams with a combined capacity of 22,590 MW on the Lancang River. Currently, China has already built six out of seven dams in the middle and lower reaches of the Lancang River (Phase I) with a total capacity of over 16,000 MW. At the same time, there has been the construction of six hydroelectric dams in the upstream section of the Lan Thuong River (Phase II). Furthermore 11 mainstream hydropower projects have been proposed in the middle section in Laos, Thailand and Cambodia. In particular, Laos is expected to build nine hydropower plants (including two of which have officially started, and another which is preparing to start construction). Cambodia is also planning to build two hydropower plants on the Mekong mainstream, namely in Sambor and Stungtreng.
The discharge of the reservoirs in the upper Mekong in China at the beginning of the flood season and the accumulation of water at the beginning of the dry season has lead to an increase in flow trends in the first months of the flood season and a decrease in first months of the dry season. Due to the weather changes resulting from El Nino, the entire Mekong basin had to endure a very severe dry season in 2015-2016 with the Mekong Delta having experienced particularly serious impacts of the drought. The river flow rates into the Mekong River Delta were at a historical low in the last 100 years.
The large reservoirs on the upper Mekong mainstream retain substantial amounts of silt and sediment which would otherwise be deposited on the lower plains. It has been estimated that the total amount of silt and sediment could be reduced by as much as 65 percent. If the sediment is held back by the upstream hydropower projects in China, only about 15 million tons sedimentation, less than 10% of natural conditions could reach the Mekong Delta.
The impacts of the mainstream hydropower cascade could lead to a 50% reduction in total fish catches for both Viet Nam and Cambodia. Dams on the tributaries will also increase the loss of fish catches in the area. This will adversely affect the food security, livelihoods, social and economic welfare of most of the people living in the floodplains of Cambodia and the Mekong Delta of Viet Nam who are dependent, directly or indirectly, on fisheries and other related occupations.
Biodiversity in the area has also been affected, including the risk of the reduction in the number of fish species and even the extinction of some (by about 10% in the total number of species). Further adverse effects have been a reduction in the number of migratory fish; a loss of freshwater dolphins in Ira-oa River; a diminishing number of freshwater mollusk species; and a reduction in the mobility of molluscs.
In addition to these hydropower projects, Thailand has recently studied a number of large-scale water diversion projects in the North and Northeast of Thailand in the Mekong Basin which would firstly divert 6.2 billion m3 water out of the watershed each year. Secondly about 9 billion m3 of water per year would be transferred from the mainstream into tributaries. Particularly in the context of climate change and extreme events, if there is a lack of coordination regarding benefit sharing between rivers, the operation of upstream water facilities will be a great concern for downstream countries.
2. The pressure of population growth and socio-economic development have also been a considerable challenge. The basin’s population is projected to rise from about 70 million at this point of time to about 83 million in 2060, and industrialization and urbanization will continue to expand. This will reduce the agricultural land area and increase the demand for clean water while at the same time generating more waste water. This will place an enourmous pressure on the Mekong’s water resources, especially the supply of fresh water given an increase in water pollution. The demand for food and fresh water is also increasing, and this has has led to the problems of reduced water quality as well as water pollution. Conflicts arising from the freshwater needs of the economic and social sectors have taken place in many locations. Rapid population growth and the development of agriculture and aquaculture have in the past decades significantly reduced the natural value of the Mekong River Basin. Many wetlands, such as mangroves, ponds, lakes, lagoons and wet grasslands, have been disappearing to make room for irrigation, forestation, salt production, industrial development and shrimp farming. In addition, the over-exploitation of natural resources has become a major threat to the ecosystem. The area of mangroves has decreased, making coastal erosion and salinity intrusion even more serious.
People’s lives are being severely impacted by environmental degradation and the loss of natural resources. This situation is being further exacerbated by the increase in the demand for water and energy as well as the change in the river’s natural flow due to the development of river infrastructure. Increased pressure on degraded water resources has led to an increase in conflicts between upstream and downstream users. Resolving the challenges faced by the Mekong River is no longer the responsibility of a single country but it requires the united cooperation of the concerned countries with the support of the international community.
In 2017 Great Mekong Forum on Water, Food and Energy held in Yangon, Myanmar, the Institute of Water Resources Planning – Vietnam with partners from the Institute of Natural Heritage – the United States (NHI), the Network for Sustainable Hydropower Development in the Mekong Region (NSHD – M), the German Development Cooperation (GIZ), the Deltares Institute (Netherlands) and the Centre for Sustainable Water Resources Development and Climate Change Adaptation – Vietnam (CEWAREC) will co-chair the technical workshop, “Towards more effective river basin management in the Mekong Basin – Challenges and Opportunities” that will focus on the challenges in the management and use of the Mekong’s water resources. National and international experts will also share their practical experience in managing water resources from other international rivers. Through the round table discussions, regional and international experts will also exchange opportunities and solutions for countries in the river basin to share water resources, so as to bring about the sustainable development of the Mekong community.