Conservation and flood control reservoirs are subject to similar processes of sediment
accumulation, which over time reduce storage capacity. This decline in storage eventually
eliminates the intended capacity for flow regulation, water supply and flood control needs,
and reduces hydropower, navigation, recreation and environmental benefits that are
dependent on reservoir storage. Though difficult to quantify on a worldwide basis,
Mahmood [1987] estimates that reservoirs globally may be losing storage capacity as rapidly
as one percent per year and that the associated annual cost of sediment accumulation has
approached $6 billion.