Texture, spatial distribution, and rate of reservoir sedimentation within a highly erosive, cultivated watershed: Grenada Lake, Mississippi

While more than 75,000 dams nationwide have served a multitude of purposes over the past 50 years, current emphasis is being placed on decommissioning those aged infrastructures considered environmentally harmful. Grenada Lake, a relatively large flood control reservoir in Mississippi, is located in a highly erodible region of the United States and is fed by historically unstable stream channels. Through a variety of stratigraphic analyses, postimpoundment sediments are identified in the reservoir, showing that the lake has lost a nominal 3% of its flood storage capacity since its inception in 1954. A simple sediment budget constructed for the Yalobusha River's contribution of channel-derived sediments shows that about 76% of this sediment remains stored upstream, about 16% is stored in the reservoir, and about 8% has exited the lake. Sediment delivery ratios, known to be low for relatively large watersheds, appear to be unaffected by upstream channel instabilities and aggressive channelization projects.