By Joseph J. Bailey, University of Nottingham, UK.

Rivers are the arteries of the world, carrying life-giving water to the organs that are the natural habitats and human settlements. An increase or decrease in flow can have disastrous consequences through droughts and flooding, thus ensuring a sustainable water supply is seen as a priority by many states worldwide. Despite the vast number of environmental problems dams can (and do) cause, they allow people to not only control water flow to the population in times of low or high supply/demand, but also produce energy through hydroelectric technologies. Whether or not to build a dam, and when to remove a dam, is, or at least should be, decided by comparing the environmental impact with the benefits of energy and water provision. The accumulated impact of building multiple dams within a watershed should also be considered, because this can result in lower…