Using the analysis results from RiverCAD HEC-RAS, you would have to manually compute the sediment transport and sediment trap efficiency.
The USGS recently published a report on sediment trap efficiency for small reservoirs:
http://pubs.usgs.gov/sir/2007/5008/index.html
And, performing a google search, you can find other references to how to compute sediment trap efficiency:
http://ppg.sagepub.com/cgi/content/abstract/24/2/219
http://books.google.com/books?id=Wm6...oMTT4EfI&hl=en
Sincerely,
Chris Maeder, M.S., P.E.
Senior Technical Engineer
chris.maeder@bossintl.com