Projected Elevation

Overview

The objective of this section is to verify and validate the HEC-ResSim operations feature: Projected Elevations. This is accomplished by creating a simple ResSim model and several operation sets with and without Projected Elevations to compare results. This document covers Projected Elevations used in: Rules, Zone Definitions, IF Blocks and Diversions. Additional model set up is required to verify and validate Projected Elevations used in State Variables and Scripted Rules.

Model Setup

A simple ResSim model was set up to be used for all the Projected Elevation simulations, consisting of a single stream and one reservoir. The reservoir has a controlled and an uncontrolled outlet. Figure 1 displays the model schematic and the physical attributes of the reservoir.

Projected Elevation in Rules

Model Setup

To test Projected Elevations in Rules, two Operation Sets were created with the same zones and almost identical rules. One Operation Set served as a baseline (without projected elevation) where the main release rule was a function of the Reservoir Elevation previous value. The second Operation Set's main release rule was a function of the Reservoir Projected Elevation's previous value with a 4-hour Projection Time Window. Alternatives were created for each operation set and run for the same time window. Figure 2 displays the Operation Set that has releases as a function of the Reservoir's Projected Elevation. The Elevation-Release table for the non-Projected operation set is exactly the same.

Results and Discussion

The results from the alternative using projected elevation were compared to the baseline and the resulting tabular data can be viewed in Figure 3 and the plot can be viewed in Figure 4. The release rule for both operation sets has a release of 300 cfs at and elevation of 70 ft and a release of 500 cfs at 80 ft. Those transitions have been highlighted in Figure 3. On 08May2099, the baseline alternative increases releases to 300 cfs at 09:00 when the previous value is 70.07 ft. The alternative using projected elevations increases to 300 cfs at 07:00 when the previous projected elevation is 70.03 ft and the actual elevation is 69.83 ft. The actual elevation does not exceed 70.07 until after 11:00, 4 hours later. This test verifies that the projected elevations are causing the releases to increase sooner and that they are based on projected elevations rather than actual.

Projected Elevation in Diversions

Model Setup

To test Projected Elevations in Diversions, the same Operation Sets and Alternatives that were set up to test use of Projected Elevations in Rules were used. Since diversions are specific to the Network, the diversion was initially set as a function of date and were updated in the Simulation Network. For the baseline (without projected elevation) Alternative, the release rule is a function of the Reservoir Elevation previous value. For the Alternative with Projected Elevations, the release rule is a function of the Reservoir Projected Elevation's previous value. Figure 5 displays the Diversion Editor that has releases as a function of the Reservoir's Projected Elevation. The table within this figure is the release schedule for both alternatives with the only difference being the Function of.

Results and Discussion

The diversion releases from the alternative using projected elevation were compared to the baseline and the resulting tabular data can be viewed in Figure 6 and the plot can be viewed in Figure 7. Referencing the table within Figure 5 while reviewing the outputs in Figure 6, this test verifies that the projected elevations are causing the releases to increase sooner and based on projected elevations rather than actual. On 08May2099, the baseline alternative increases releases to 50 cfs at 09:00 when the previous value is 70.07 ft. The alternative using projected elevations increases to 50 cfs at 07:00 when the previous projected elevation is 70.03 ft and the actual elevation is 69.83 ft. The actual elevation does not exceed 70.07 until after 11:00, 4 hours later. This behavior repeats for the other flow increases displayed as well.

Projected Elevation in IF BLOCKS

Model Setup

To test Projected Elevations in IF BLOCKS, two Operation Sets were created with the same zones and almost identical rules. One Operation Set served as a baseline (without projected elevation) where the IF BLOCK's conditional expression looked to see if the reservoir's pool elevation exceeded 80 ft while the second Operation Set's IF BLOCK looked to see if the Reservoir Projected Elevation exceeded 80 ft. The Projected Elevation Time Window is set to 4-hours. Alternatives were created for each operation set and run for the same time window. Figure 8 displays the Operation Set where the IF BLOCK is using the Reservoir's Projected Elevation. The Flood Rule has a specified release of 1,000 cfs and the WaterCon Rule has a specified release of 200 cfs.

Results and Discussion

The results from the alternative using projected elevation in IF BLOCKS were compared to the baseline and the resulting tabular data can be viewed in Figure 9 and the plot can be viewed in Figure 10. Results shows in Figure 9 shows that the IF BLOCK Alternative without projected elevation starts to increase releases from 200 cfs to 1,000 cfs on 09 May 2099 at 10:00 as the first elevation that exceeded 80 ft occurred at 09:00. Releases are then ramped up by 100 cfs/hour according to the Increasing Rate of Change Rule. The results of the IF BLOCK Alternative with projected elevation start to increase releases from 200 cfs to 1,000 cfs on 09 May 2099 at 07:00. At 07:00, the actual elevation is 79.26 ft while the projected elevation is 80.6 ft. This test verifies that the projected elevations are causing the releases to increase sooner and that they are based on projected elevations rather than actual.

Projected Elevation in Zones

Model Setup

To test Projected Elevations in Zones, a new operation set was created where the Conservation Zone was set up to be a function of the Reservoir Projected Elevation. The Conservation Pool Elevations were set to remain above the Projected Elevations. The Projected Elevation Time Window is set to 4-hours. The Flood Max rule has a specified release of 6,000 cfs and the Conservation Rule has a specified release of 100 cfs. For a baseline, the Operation Set with no projected elevations that was used for testing rules and diversions was used. While the operational rules are different, this test's focus is on the Conversation Zone boundary line so the rules within were not important. An alternative was created for the Zone Boundary Projected Elevation test and compared to the baseline. Figure 11 displays the Operation Set where the Conservation Zone is using the Reservoir's Projected Elevation.

Results and Discussion

The results from the alternative using projected elevation for a Zone were compared to the baseline and the resulting tabular data can be viewed in Figure 12 and the plot can be viewed in Figure 13. Results shows in Figure 13 shows that the Conservation Zone that is a function of the Projected Elevation is increasing and that when the projected elevation is at 70 ft and 80 ft, the Conservation Zone is at 75 ft and 90 ft, respectively as it is dictated in the elevation-zone table in Figure 11. Additionally, in Figure 13 the Conservation Zones for the with and without projected elevation alternatives can be seen in blue. For the baseline, the conservation zone is set at 70 ft and the releases increase and enter the flood control pool. For the alternative with the conservation zone using projected elevation, the zone continues to increase ahead of the elevation until it reaches the flood control zone. The releases are also held to 100 cfs (Conservation) as the elevation remains within the Conservation Zone. This test verifies that the projected elevations are causing the releases to increase sooner and that they are based on projected elevations rather than actual.