Recently, many countries around the world have been suffering from heavy rainfall that never stops and landslides. In China, rain hasn’t stopped for more than two months, which has caused 219 casualties and injuries, and flooding with landslides destroyed roads and infrastructures, resulting in 60 million flood victims. As a result, the Chinese government ended up opening several dams in central and southern China, releasing enormous amounts of water. When China’s neighboring countries such as Korea and Japan are also having similar problems, I came up with this question on the effects of releasing freshwater from dams on ecosystems and the environment.

First of all, discharging huge amounts of water creates a very strong water stream, which carries mud, pebbles and stones downstream. This could change the condition and water quality of downstream, which will affect organisms, especially those only living in clear water will be severely affected as water will be very turbid until the release is done. Also, stones carried by strong water flow could also kill river organisms. Additionally, water released from the dam will separate upstream and downstream, obstructing migration of fish to upstream. 

Considering the freshwater released would flow through each river stream and eventually come together to the ocean, discharge of a great amount of water from the dam could also affect the ocean system. If freshwater intrudes the ocean, it will be mixed with the seawater, which could dilute the water and lower salt concentration. This also could change the temperature and pH of the ocean: this increases coral bleaching that is already severe as corals are very sensitive to slight temperature and pH changes. Those changes in the ocean environment will definitely affect various marine life. 

Although damages on the ecosystem is not significantly considered as of now because the floods are directly threatening people and society, we should also be aware of the impacts of our action on the environment and organisms in the river and the ocean.