Perry Creek Conduit, Sioux City, Iowa. Hydraulic Model Investigation

Perry Creek Conduit is located on Perry Creek in Sioux City, Iowa. Perry Creek has less than 10-year flood frequency protection with its present channel and conduit. A proposed plan of improvement will provide 100-year flood frequency protection along a portion of Perry Creek by making channel and conduit modifications. A model investigation was conducted to evaluate the performance of the proposed improvement plan and to develop modifications, if needed, that would enable the Perry Creek Conduit to safely pass a 16,000-cfs discharge. Model tests revealed that the capacity of the original design flood control channel was only 10,200 cfs and excessive bend losses were occurring. A second improvement plan was designed and tested in the model and found to be satisfactory provided modifications are made to the channel berms and channel invert and a stilling basin is installed at the end of the conduit. Discharge and velocity measurements and water-surface elevations are presented and flow conditions are shown in photographs.