Appendix C-8: Alternative 312 - Spring Flood Targets

Alternative Description & Objective The goal of Alternative 312 was to evaluate whether or not increasing the maximum allowable flow at Sherwood and Minot reduces the magnitude and/or duration of flooding from the spring snowmelt. [...] 2.1 Changes to the State Variable Script The only changes made to the model’s code were within the state variable “a_fld_MASTER_gc_gd” in line 29, (if applicable), and line 30 within the “Initialization” tab of the “State Variable Editor”. [...] An example of changes to the state variable needed to run Alternative 312 2.2 Removing the Estevan Flow Constraint for the “SM100_Xest” Iteration The only change made to the reservoir operating rules within Alternative 312 was made in iteration “SM100_Xest”; here the Estevan flow constraint rule was removed from Rafferty Reservoirs’ rule tree. [...] 4.3 SM100_Xest Again, after observing essentially the same operations as the baseline model at Rafferty Reservoir in all of the previous iterations, another simulation was run removing the flow constraint at Estevan and increasing max flows at Sherwood and Minot by 100%. [...] The lack of change to the Bankfull Exceedences PI in nearly all reaches suggests increasing the Sherwood and Minot target flows alone does not significantly reduce the duration of flooding over the entire period of record.