The Teton Dam on the Teton River in Idaho failed in 1976. The reservoir container 250,000...

The Teton Dam on the Teton River in Idaho failed in 1976. The reservoir container 250,000 ac-ft (309 million m3) of water when the 300-ft (91.5-m) high earthfill dam failed in approximately 2 hrs (BTDR = 2.0), resulting in a peak discharge rate of 2,300,000 cfs (65,200 cms) downstream of the dam and a peak discharge rate of 1,060,000 cfs (30,000 cms) in the channel approximately 50,000 ft (15,200 m) downstream of the dam. The initial water surface elevation in the reservoir (WSELD) was 5,300 ft (1,615 8 m). The breach had a bottom width (BWDF) of 50 ft (15.2 m) and a bottom elevation (BELF) of 5,050 ft (1,539.6 m), with breach side slopes (SSB) of 1.5. The reservoir and downstream channel are located in a deep, narrow canyon. Model the dam break as three channels in series (NOC = 3) with the dam located at the downstream end of channel 2 (IBSEG = 2). Use the following cross-section for all three channel segments. Length of each segment is 70,000 ft (21,340 m).

Model the dam break for 24 hrs (NOH = 24) with no lateral inflow (LI = 0 an NOL = 0). The invert elevation of the upstream end of channel 1 (ELEV) is 5,2101 (1,588.4 m). At the start of the break (BTST = 0), the width of the breach (BWDI) i 10.0 ft (3.05 m). Use the explicit routing procedure with 30 computational segment in each channel (MMOS = 30) and TFT = 0.7. An inflow hydrograph file will be required (INFLOWHY.DAT). Use 24 values of 1,000 cfs (28.3 cms) for the inflow hydrograph. Modify the cross-section for the downstream channel three by lowering the end elevations (Pts 1 and 8) to 5,150 ft (1,570.1 m).