West Channel Sand Bar Relocation 02-Feb-07

To observe sand bar relocation caused by gate operation, gate #22 and #20 were alternately lowered. Gate #22 was lowered for 1 day (figure 1). Gate #20 was then lowered, while #22 was raised back up (figure 2). The sand bars downstream of gate #20 were subsequently washed away. Each of these configurations were set to maintain the 3 ft water depth upstream of the diversion structure.

Gate #20

Figure 1 [02-Feb-07] gate #22 lowered Figure 2 [02-Feb-07] gate #20 lowered

Figure 3 shows sequential sand bar flushing to downstream of gate #20. Turbulent flow (red color circle) was occurred since increased channel bed shear stress caused by shallow flow on the sand bar. This turbulence degraded and delivered the sand bar downstream.

Gate #20