- Dams cause greenhouse gas emissions. According to a study done by the National Institute for Space Research, India’s 4,500 dams (third highest behind the US and China) “emit an amount of methane that is equivalent to 850 million tons of carbon dioxide per year.” It seems both carbon dioxide and methane are “released from the decaying vegetation of spillways, reservoirs and turbines of hydropower dams, but methane is twenty-three times more formidable in trapping heat than carbon dioxide.”
- Dams displace people. As many as 80 million people have been displaced by dams worldwide. This is due to the reservoir created by the dam. In addition, those who live downstream from the dam will no longer have the dynamic river ecosystem that created their environment in the first place. Obviously, these are not humans with wealth and power.
- Dams promote erosion. The folks at International Rivers explain that dams hold back sediments that would naturally replenish downstream ecosystems. “When a river is deprived of its sediment load, it seeks to recapture it by eroding the downstream river bed and banks, undermining bridges and other riverbank structures,” they continue. “Riverbeds downstream of dams are typically eroded by several meters within the decade of first closing a dam; the damage can extend for tens or even hundreds of kilometers below a dam.”
- Dams lead to plant and animal extinctions. As touched on above about salmon, the introduction of such an unnatural structure and concept quite predictably has led to the extinction of many fish and other aquatic species, the disappearance of birds in floodplains, and massive losses of forest, wetland and farmland.
- Dams are temporary solutions. And like many temporary solutions, dams ultimately create more problems than they were supposed to solve. Because they eventually fill up with silt, by definition, they are not a sustainable solution.
– from planetgreen.discovery.com