Water: Course Preview

A Challenged River

This discussion was selected from Week 2 of the AMNH online course Water, part of Seminars on Science, a program of online graduate-level professional development courses for K-12 educators. This is an excerpt from an actual course discussion, but learner names have been changed. Explore more sample resources...


Discuss how humans have altered the Mekong River ecosystem. Describe the ecosystem services provided by the river. How does human activity impact these services?


Jennifer 16 Jul 09 5:02 AM

Humans have altered almost every thing about the Mekong River ecosystem. They have altered the water quality from fertilizer, pesticide, and urban waste pollution. They have affected the biodiversity by over fishing and fishing by explosives. In addition, humans have affected biodiversity because they have destroyed habitats by deforestation, for example the mangroves, and by blocking or destroying spawning grounds. They have altered the path of the river by building dams and blasting canals to open trade routes. This stops the flow of sediments and nutrients that are vital for soil replenishment. Humans have introduced invasive species like hyacinth and mimosa that quickly take over the wetlands and crowd out native plants. Every aspect of the river has been affected by humans.

The river ecosystem provides many services to humans. It provides sustenance in the form of water, fish, and soil to grow rice and other crops. Rivers provides habitat for the greatest concentration of life on the planet (Biodiversity article) and the Mekong is the third most bio-diverse inland waterway in the world (The Mekong article). The river ecosystem provides wood for fuel and shelter, and power in the form of hydroelectricity. The river is the basic underpinning of the entire economy of the region.

Human activity threatens the economy of the region. As the fish population declines, it affects the fishing industry as well as all the support industries. As the soil becomes less suitable for rice and other crops, the agriculture industry declines. Food becomes scarce. The affect of species extinction is hard to predict. Then the fact that the river provides hydroelectricity becomes irrelevant because the people are starving.

Scientist: Cathy 16 Jul 09 1:35 PM

Certainly, there are several major costs and disadvantages associated with the damming (and the proposed damming) of the Mekong, and you reviewed them very well. However, energy production will have to increase in the coming years to sustain the growing global population, but especially to provide utility services to the millions of people currently without access. Energy production and consumption are major issues in the world today. With respect to the Mekong, are there other opportunities that the relevant governments could explore that could raise utility standards of those without service now and for the growing population later while alleviating the pressure on the natural ecosystem?

Jennifer 17 Jul 09 3:16 PM

There seem to be problems with every energy source. I think I might have chosen nuclear power over hydroelectric. The main problem is getting rid of the nuclear wastes - transporting them and storing them until they decay. But it seems to be a much more efficient energy source.

Instructor: Cheryl 18 Jul 09 6:13 AM

There has been a lot of industry, including nuclear power cropping up along the waterways and the result is that these industries use a fair amount of water. If you weigh the two options would you still choose nuclear power?

Jennifer 20 Jul 09 1:35 PM

Yes, and as I understand it, the water when it is returned to the environment from the nuclear power plants is warmer than normal, so thermal pollution is another problem. It seems that maybe the way we are implementing hydroelectric power with the gigantic dams is maybe too aggressive. Maybe many small dams would have less affect than one big dam. I think I would still choose nuclear at least for the short term until the scientists can get solar to work more efficiently or make fusion practical.

Brian 26 Jul 09 3:25 PM

There are at least three water use issues with thermoelectric power plants (coal, oil, gas, nuclear):

1) The amount of water consumed which varies with the technology used (closed loop, open loop, wet cooling or evaporative cooling) which seems to vary from 1-5% of total water use - or from 95-99 % non-consumptive use.
2) The total amount of water used. Example - "The Harris reactor near Raleigh, N.C., draws 33 million gallons of water a day, with 17 million gallons lost to evaporation in the cooling towers." (Evaporative cooling withdraws far less water but most is used consumptively.) http://planetsave.com/blog/2008/01/23/water-shortage-could-dry-up-nuclear-power-plants-in-southeast/
3) The thermal pollution created by water returned to the water sources.

In some areas the water being used is groundwater and the power company has purchased land/water rights to the water. http://www.kctribune.com/article.cfm?articleID=18748

An issue from the standpoint of the power company & its customers: Power plants have come close to reducing output or closing because insufficient cooling water is available. http://www.istockanalyst.com/article/viewiStockNews/articleid/3234023
http://www.msnbc.msn.com/id/22804065/

Another interesting resource: ENERGY DEMANDS ON WATER RESOURCES
http://www.sandia.gov/energy-water/docs/121-RptToCongress-EWwEIAcomments-FINAL.pdf

Gloria 17 Jul 09 9:14 PM

Population is the number one reason that many of our ecosystems are in decline, including the Mekong and Colorado River systems.

Solar, solar, solar is still the answer, a mirror powered electricity production facility, or flex panels on every rooftop. In some areas wind could work pumps or turn turbines. Will it cost more than a dam? Only if you don't consider all of the damage we have all been discussing this last week. The displacement of the people behind the dam, the loss of fish that the people rely on for one of their main food sources, the loss of fertility of the soil, and the loss of countless species that we don't even know yet.

The Mekong has a great opportunity to start out this century by starting with the newest ways of improving the lives of their people, and not by relying of last century's methods.

Jose 17 Jul 09 6:29 AM

I had been thinking about what the these river basins would be like if humans did not exist. Then noticed reference in the text that without human interference, life would be sustained indefinitely in a "steady state" or "balance of nature" and, "without human disturbance, the net storage of chemical elements within an ecosystem will remain constant over time". [Environmental Science - Earth as a Living Planet, Botkin & Keller, John Wiley & Sons, 2009. Page 91]. Makes you wonder if we can restore the balance that we disrupt.