Engineering solutions can reduce the burden on producers, and therefore the
conflict between environmental and economic performance, by adding operational
flexibility. For example, Richter and Thomas (2006) suggest the use of a water storage
facility downstream of a power house to re-regulate the release pattern. Such an alternative typically exists in cascade hydropower systems, where the most downstream
reservoir can serve this purpose. In some systems, afterbays have been created for this
purpose. When temperature management in the reservoir and releases is relevant, a
temperature control device (TCD) can be introduced. The most practical and widely
adopted method for the case of a stratified reservoir is selective withdrawal, which
consists of strategically located outlets to allow releases from different zones of the
reservoir