Development of a Storm Runoff Simulator. 2. Water Output Control Device
Franti, T.G. | Shelton, D.P. | Cermak, J.D.
Few studies have evaluated conservation buffers at field to buffer area ratios of 30:1 or greater. A storm runoff simulator is needed to better evaluate flow hydraulics, sediment trapping, and water quality benefits of field-scale conservation buffers. Based on an engineering analysis using MUSLE and the SCS Curve Number Method, it was determined that a simulator could be developed for a 1- x 9-m buffer plot, with input constraints of 7580-L stored water and 0.71 metric tons of soil. The objective of this study was to design, build, and test a prototype runoff simulator water output control device operating under gravity flow conditions. The control device regulates flow using a gear motor mounted on a rotary gate valve, and a feedback control system between a flow meter and the rotary valve. A time-compressed 10-yr, 2-h SCS design hydrograph with a 7.3-L s-1 peak flow rate was used to calibrate the flow control device for optimal performance with large changes in flow rate, and for repeatability with a variety of hydrograph shapes. When reproducing the compressed SCS hydrograph, the control device maintained comparable efficiencies among repetitions; with a 2% error between root mean square error and the total flow range. Hydrographs with step changes in flow rate, flow rate plateaus, multiple peaks, and flow rates up to 9.8 L s-1 could be simulated with comparable efficiencies and 4% to 6% error.Show more [+] Less [-]