Small Hydro Projects in China Have Big Impacts

Small hydro, big impacts

Researchers compared 31 small dams (defined as less than 50 MW) with four large dams. When they estimated the area of riparian and terrestrial habitat lost to produce one megawatt of power, they found that small hydropower projects were 100 times more detrimental to habitat diversity than large dams. The small projects were also more likely to disrupt network connectivity, lower water quality, and impact hydrology at the sub-basin scale.

The study found that small projects did offer some advantages: they inundated less land, caused less disruption to sediment transport, and did not create as much seismic instability as big dams. However, the degree of ecological disruption, sometimes several orders of magnitude higher than that associated with large hydro, questions the assumption that these projects are sustainable.