How Hydropeaking Can Decrease Population Sizes In River Ecosystems

Hydropeaking is fluctuation in the flow/water levels of a river or stream, in this case caused by the sudden release of water from hydroelectric dams and hydropower stations. The river volume is controlled day by day, or even hour by hour in order to meet electricity demands. These sudden disturbances to the rivers water levels can disrupt egg laying patterns of some insect and fish species living in the river as normally (without hydropeaking) the river’s water levels do not change so quickly. Because the water level can fall so suddenly, any eggs laid near the shore, just below the river’s surface (e.g. by caddis flies, mayflies and stoneflies) will dry out and any hatched larvae will be stranded and die.

This is a huge concern as some of these insect species are a vital food source for other wildlife within the river ecosystem. This means that by getting rid of a primary consumer, larger species of secondary consumers will have to compete for other food sources or won’t have any food source at all. This then leads to a decrease in population size of the consumers relying on the insects as a food source.

The sudden drop in water level can also cause sediment to cover fish eggs, so they then cannot hatch, further decreasing the fish population size.

Dams also have other adverse effects on river ecosystems such as altering the flow and temperature of the river and blocking migratory paths.

Around 800000 dams exist globally and hydropower provides 19% of the world’s electricity supply. Hydropower is a renewable resource, so means the more we use it, the less we have to rely on fossil fuel, therefore, until a better alternative is invented, we need hydropower. However, we could decrease the adverse effects of hydropeaking by leaving the rivers water levels stable for a few days at a time, instead of suddenly changing the water levels, so that the insects could lay their eggs and let them hatch with success. Of course this doesn’t completely solve the problem, but it is a step towards solving it.

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