A NEW SEDIMENT TRAP EFFICIENCY CURVE FOR SMALL RESERVOIRS1

ABSTRACT The reservoir sediment, trap efficiency value is the most informative single description of a reservoir. This value is the proportion of the incoming sediment that is deposited or trapped in the reservoir, usually expressed in percent. It conveys information on what happens to most of the sediment coming into the reservoir and is indicative of the reservoir's useful life. Since Brune's (1953) report very little research progress has been made on this important reservoir design factor in the last 25 years. This is primarily because of the lack of adequate reservoir sediment, trap efficiency data. Worthwhile data for analysis exists on only 20 ponded reservoirs in the U.S., in the size category usually built by agricultural interests. By analyzing available information on these 20 reservoirs, a new trap efficiency curve, which is slightly different from the one used for the last 25 years, was developed. Use of this new trap efficiency curve could mean a reduction in some reservoirs of 4–10 percent in the volume allocated to sediment storage.