Reservoir Sedimentation -Some Aspects of Reservoir Asset Management

Reservoirs and lakes accumulate gravels and sands particularly in flood flows, forming extensive deltas, and reduce the live storage which is one of the economic barometers of a reservoir for water supply, irrigation or hydro generation. Effects will vary depending on reservoir size, the nature of sediment and the reservoir operation characteristics. Finer particles may be deposited' continuously even at low inflows with environmental effects in addition to depleting storage. If not settled out in the reservoir or excluded at an intake, particles can be carried through conduits and turbines or pumps inducing wear and hence reducing the value of a downstream asset. Sedimentation of reservoirs is active in NZ because of its varied geology and the paper will give examples from a variety of sedimentation conditions and outline ways in which adverse effects can be mitigated.