Berryessa Creek Channel Junctions, Santa Clara County, California. Hydraulic Model Investigation

Tests were conducted on a 116-scale and two 120-scale models of the Berryessa Creek and three of its major tributaries to evaluate the performance of the proposed designs and develop desirable modifications, if needed, to safely pass the 100-year-frequency discharges through the three channel junctions. Specifically, the Sierra Creek, Los Coches Creek, and Piedmont Creek junctions with Berryessa Creek were investigated. The BerryessaSierra junction model 116 scale reproduced approximately 500 ft of the Berryessa channel and 200 ft of the Sierra channel. The model was constructed so that the slopes of the channels could be adjusted to reproduce energy gradients equivalent to those resulting from prototype Mannings n values of 0.012 and 0.014. Initial tests, conducted with the invert slopes adjusted to reproduce an energy gradient resulting from a Mannings n value of 0.014, indicated that the original design would effectively convey the design flow 2,680 cfs, and with minor modifications, flow conditions could be improved at the Morrill Avenue box culvert. Tests indicated that flow conditions at the Morrill Avenue box culvert could be improved with the addition of a triangular pier extension.... Hydraulic models, Sierra Creek, Channel improvement, Los Coches creek, Channel junctions, Piedmont creek, Berryessa creek.