Author(s): Weiming Wu
Linked Author(s): Weiming Wu
Keywords: Levee breach, simplified physically-based model, piping, flood, Sutter Bypass Channel
Abstract: A series of storms caused record flows throughout the California Central Valley in early January 1997. High flows on the Sacramento River activated overflow weirs, diverting water into the Sutter Bypass Channel. The southwest levee of Sutter Bypass failed due to piping or seepage, shortly after the peak flow passed on January 4, 1997. The final breach was about 274 m wide, and approximately 130 km2 of the Meridian Basin that was inundated. A simplified physically-based dam and levee breach model, DLBreach, is used in this study to simulate the Sutter Bypass levee breaching process. The time series of water levels in the Sutter Bypass Channel at the breach location calculated using HEC-RAS are imposed as the headwater condition for the present breach modeling. The volume-elevation curve of the Meridian Basin is obtained by using the 1-foot contour lines generated from a Lidar data collection in 2008. In order to account for the effect of the roads, the basin volume-elevation curve is modified by considering that the flood water filled in the zone below the breach first and then overtopped the roads and entered the remaining zones. The representative soil in the levee body was silty sand (SM) or clayey sand (SC), and the soil erodibility kd is estimated at 14. 5 cm3/N�s. The model reproduces well the levee breach widening process. The calculated final breach width is 270. 4 m and it compared well with the measured value
Year: 2017