The Mekong River: Threats to a unique human-ecosystem | South East Asia


The Mekong River is unique among the world’s great rivers in the size of the human population supported by its ecosystem. Approximately 60 million people derive their livelihoods from aquatic life in the river system. Largely unregulated through most of the 20th century, the Mekong River system is undergoing extensive dam construction throughout the basin for hydroelectric generation, with over 140 dams planned, under construction, or built. What will be the cumulative effects of these dams on the geomorphology, ecology, and human populations of the river and its delta? How will these changes interact with other changes such as deforestation in steep uplands, levees and channelization, and accelerated sea level rise?


9 thoughts on “The Mekong River: Threats to a unique human-ecosystem | South East Asia

  1. Until Matt Kondolf’s talk, dams were simply a barrier that impounds water and a place to obtain energy. A system that provides water to households, agriculture, different industries, flooding, and navigation control. A system that when you are on or in the dam for the local tours, puts life into perspective; they can be massive for the most part. I never thought of the impacts dams place on it surroundings and even distant environment(s). From the blocking and killing of fish to now what I never even thought could be a problem the lack of sediment that the dams block. Causing what is called hungry water is a term I have never heard of before Matt’s talk. I thought it was interesting that as the US is in a dam removal stage, the rest of the world is doing the opposite and building more and more dams. I also wonder if with the techniques on how to build dams keeping that issue in mind, if any of the new construction are being built that way. I wonder if the increase in dam construction in other countries could harm us (i.e. the US) in some fashion over time? As we better understand issues of having to feed gravel into certain points to add to the sediment load. Even using the different methods such as sediment pass through, downstream routing, and drawdown flushing. All to help improve the issue. On the other hand we still have this mentality of territories and as if those invisible boundary lines pertain to us and what we own, the environment also abides by. We all share this world and can connected to each other somehow or way.

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  2. Thanks Cocena. I agree with you and would like to add that the gap between the extents of knowledge achieved by river experts seem to be so far from the existing practice especially in the Global South. The developing countries have less tendency to look after their ecological systems because they are busy trying to make economic progress (jobs, tourism, hydro-power,….etc). The intentions to build more dams in many other places is not different from the “Mekong River”, where the decision is driven by multiple forces that does not include the natural habitat and the wellbeing of people relying on the river.


  3. I found the talk fascinating. Again, hungry water was a new concept to me, too, and had no realization of the impact these dams could have. What was worrying was the private ownership of these dams (I think he said 25 years) before they are passed on to the respective governments. What they will find is that there is no such thing as a free lunch, or a free dam in this case. The resevoirs will be filled with sediment by the time they are passed over – incurring large removal cost. However, the real cost may not even be seen in the market like this…it will be in the damage to ecosystems such as the Tonle Sap lake, and to the 17m people who live on a delta and rely on the sediment for their livelihoods.

    A more rigorous extended cost-benefit analysis should be carried out to in some way monetize these non-market impacts. It will be difficult to convince private companies that they should re-do their plans to incorporate sediment routes. Perhaps these governments could front the money to include these plans, but is this realistic for cash-strap governments?

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  4. I found this talk about dams’ effect on their riparian systems by Matt Kondolf to be very interesting. I have been aware that despite a relatively low carbon footprint (perhaps only without all things considered) there are other environmental issues with dams. This talk explicitly spelled these problems out through a discussion of a variety of current case studies around the world. This discussion is particularly relevant as lower carbon emission energy sources become more sought after.
    As Kondolf pointed out, global dam construction is currently growing at an exponential rate. This rapid proliferation no doubt exacerbates other environmental impacts of dams such as blocking nutrient and sediment transportation, which require expensive endeavors to effectively mitigate. On top of this the “quick cash” nature of many of these dam investments means that a short life expectancy before filling up and defaulting to the public.
    The dam construction on the Mekong River Basin could ultimately in theory determine the environmental collapse of the Mekong delta. If this disaster were to occur not only would millions of people be severely affected but I also imagine it would be possible to calculate the vast amount of atmospheric carbon released and sequestration potential lost in the loss of so many productive wetlands. Although maybe not explicitly said a major theme of this talk was the interconnectedness of our physical world; how one change ripples through its’ surroundings for better or worse.

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  5. Matt Kondolf’s lecture was an overall synopsis of LA 227, the River and Stream Restoration course. This semester there have been a couple of “ah-ha” moments. When I think of a river, I perceive the notion of water moving from one place to another along a path. Little did I know that was only one part, since “rivers carry water and sediment.” I had no idea how important the latter was to the function of the water body in terms of channel form. In the absence of this sediment, due to the construction of dams the sediment continuity and transport is interrupted. This causes two problems, reservoirs fill with sediment and the downstream channels are deprived of necessary sediment loads. Ultimately, depriving leads to hungry water that can eroded river beds and banks.

    In order to counteract the negative effects of dams and get sediment where it needs to go there are a couple options. There is sediment by passing and diverting to off-channel reservoirs, sediment sluicing, and drawdown flushing. Sluicing is downstream routing before deposition while flushing carries sediment downstream after it is deposited. Another shocking fact delivered by Kondolf was the gravel augmentation below dams. To alleviate sediment starvation gravel is added to water bodies. It was unreal seeing the photo of two huge barges dump gravel and sand into the water. To know it is done year round almost every day of the year, 2 barges at 170k m3 capacity, is shocking.

    The Mekong River is vast resource and vital to many Asian countries that make a living from it. The fishing industry for one includes over 60 million people depending on it. It’s annual rise and fall, flooding and draining, brings fine sediment nutrients imperative to fishing productivity. The number of dams under construction or already built totals more than 133. It is interesting the simulations ran on the percentage of sediment load trapped by the construction. For the sake of hydroelectricity ecological functions are being loss. The idea of turning over the power of the dams after a couple decades to the private governments is a bit frightening. It is also interesting that in one country we are going through extensive damn removal as in the Elwha but in another we are building hundreds. Overall, an eye opening lecture in terms of sustainability as related to hydrology and geomorphic processes.

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  6. Professor Matt Kondolf’s talk made it clear that dams can cause major ecological problems. As a result, it seems like good news that the World Bank has been turning away from financing dams. However, as we learned from the talk, the rate of new dams is still increasing around the world. This is because many developing countries are still building dams as power sources.

    This got me thinking. In my own work I study Rwanda, and I remember reading last week that a new dam on the River Nyabarongo in Rwanda has just been completed to add 28 megawatts of power to the national grid. Rwanda is a largely agrarian country that is largely below the poverty line, but its government aims to transform it into a middle-income nation with a service-based economy. The question that this brings to mind for me is: do developing countries have the right to industrialize in the same way that developed countries did? In other words, if today’s industrialized countries have largely gained their affluence through fossil fuel-based development and other unsustainable or ecologically damaging practices, is it fair to expect developing countries to avoid taking the same path for moral reasons? And is sustainable/green development an additional burden on the world’s poorest countries, effectively preventing them from having access to affordable energy?

    But some research on the internet has suggested to me that in fact, some developing countries already are leaders in green energy technologies. The report “Climatescope 2014: Mapping the Global Frontier for Clean Energy Investment” ( found that emerging markets saw a 143% growth in clean energy capacity, compared to 84% for more established economies in the same time period. Additionally, in this week’s talk, Professor Kondolf led me to believe that it is critical for governments to realize that, although they may be looking for short- or medium-term economic gain, there are long-term ramifications to damaging ecosystems. These ramifications can include the destruction of food supplies, livelihoods, and even entire settlements, resulting in devastating economic impacts. Therefore, I am convinced that green development is not a burden on developing countries, but actually very much a strategic benefit to them.

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  7. Matt Kondolf presented me with a new perspective of dams. I believed that dams were beneficial to society in times of drought and alternative methods of energy for society. However, I realized that the long term negative effects of dams may actually outweigh the good. The fact that dams interrupt the sediment flow down the river and build up the sediment in reservoirs allow for an unequal distribution of sediment which erode rivers. Also the disruption of migratory fish, such as salmon, will continue to effect the environment and the villages surrounding the Mekong River.
    I was able to see now how much damage a dam can bring to the natural environment and hurt society as well. This was a good issue to pose to landscape architects because as designers I believe it is important to create designs that can provide some benefits of dams without disrupting the sediment flow and interrupting the migratory path of fish. However, I do not know exactly how a project like this would be achieved, but it interested me in finding more insight on how design could be used to combat and even replace inventions such as dams.

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  8. Matt Kondolf’s lecture on dams was really quite fascinating and actually gave me different perspectives on dams. In China they have been using dams frequently on the Mekong River and it has been having seriously adverse affects on the river and the ecology of the surrounding area.
    The issues with dams lie primarily in their interruption of sediment movement downstream through the river. The removal of sediment is causing bed erosion in the area, which has affected the environment downstream. He highlighted many potential solutions to this issue that his organizations are actively trying to employ on the Mekong. He discussed sediment pass-through, sediment sluicing, drawdown flushing, and gravel augmentation. In many countries these solutions are proving more and more necessary as people’s demand for energy continues to skyrocket. He really presented these solutions well and explained how they could all be implemented by countries to improve their ever-growing issues with dams. I particularly liked his work with the governments in establishing more sustainable dams that will limit the amount of environmental damage that is being done.
    I do wish he could have discussed the benefit that these dams are providing to the countries in greater detail. I felt like it would have been better to have both sides presented equally, since there are both costs and benefits with limiting dam construction. Without dams many of these countries would be facing worse energy crises than they already have. China in particular consumes a great deal of energy and the Mekong River has been a consistent source for power. I would be curious to learn what would happen to the country if these dams were removed.
    I really had not realized the impacts that dams were having and the need for a more sustainable way to build them. I think it is interesting to try and understand what the costs and benefits are with dam construction and whether or not it is actually worth it to build the dams.


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