Using a ResSim model to support real-time release decision making has always been assumed to include the use of release overrides to enable the user to develop a release schedule that best meets the overall requirements of the basin that few (if any) models could do without user interaction.
Unfortunately, the existing ResSim Overrides Editor requires too many "clicks" to define the overrides, compute, review results, and repeat… for the process to be considered "quick". The OSI was designed to streamline the process in a user-customizable way.
We will illustrate how to setup the OSI to perform Release and Elevation overrides using our Hayes Basin watershed:
The Hayes Basin model has two reservoirs, Hayes and Hurst, and two downstream control points, Carmichael and Smithford. The reservoirs are operated as a system to meet minimum and maximum constraints at the control points. Hayes is about 4 times larger than Hurst but its drainage basin is only about twice that of Hurst's drainage basin.
Hayes has substantial controlled release capacity of up to 15000 cfs at the top of conservation with a gated spillway added in near top of flood control. But the channel capacity below the dam is only 5000 cfs. Hurst has a maximum controlled release capacity of only 5000 cfs with a channel capacity of 4000 cfs. In order to pass large events, Hurst has an uncontrolled spillway whose crest is at the top of the flood pool.
An unregulated basin, about half the size of Hurst's, flows into the system between Carmichael and Smithford. Flooding starts at Carmichael at approximately 8000 cfs and at 11000 cfs at Smithford.
Although standard operations rules perform well during low to moderate inflows, they perform poorly during large events over the basin. To give the water management staff more modeling control, we developed an OSI with a tab for developing a release schedule using Release Overrides and a separate tab for using Elevation Target Overrides. How each tab was setup is described in the next two sections.