Model Development and Application to Manage Inflow and Deposited Sediment in Paonia Reservoir

A one-dimensional sediment transport model is updated to simulate a sediment sluicing/flushing plan with the proposal of outlet works modifications. Paonia Reservoir is located on Muddy Creek in western Colorado, and nearly 25% of its original capacity of 20,950 acre-feet has been lost to sediment deposition. In the Fall of 2014, Paonia Dam became partially blocked with sediment and debris. Assuming the reservoir outlet works can be modified to pass woody debris and sediment, a proposed sediment sluicing/flushing plan was conceptualized to lower the reservoir pool in the early spring and to sluice and flush sediment with high spring run-off flows through the outlet works before closing the gates to refill the pool for irrigation season. For this reason, the numerical model is modified to include a user-defined set of reservoir operation rules, which is implemented to assess the long-term effects of managing inflow and sediment deposition in Paonia Reservoir. The numerical model is calibrated by the 2015 reservoir survey and incoming and outgoing suspended sediment concentrations from April 2013 to June 2015, and is used to predict the reservoir sedimentation with a long term simulation in the next 20 years.