Task 2: Real-Time Operations with HEC-ResSim

Review the Results

1. First add the Future Rain forecast run to the forecast tree. 

2. Compute the Future Rain forecast alternative.

3. Display it in the map panel or place a checkmark in its box in the forecast run tree.

   HINTS...

   To add a forecast run to your forecast, select Run Selector from the Forecast menu. Model Linking for the Future Rain scenario may need to be reviewed.

   To display a forecast run in the map panel, right click on the run in the forecast run tree and select Display in Map.

4. Before Water Managers begin determining reservoir releases, inflows to the reservoirs should be first evaluated through the inspection of the HMS results. In the Map Display, zoom in to the northern portion of the basin and find the HEC-HMS junctions that receive the Lake Mendocino, Ukiah Loc, and Hopland Loc subbasin flows. View results (graphs) at these three junctions. 
5. How well calibrated is the HEC-HMS model for this event?

   1. At Coyote Lake Inflow?

      Answer

      Very good. Good timing and good shape, computed peaks are a bit higher than observed. Nash-Sutcliffe 0.953 and Percent Bias  -5.38%.

   2. At Ukiah Gage?

      Answer

      Ukiah's simulated peaks in the hydrographs match well with the observed flows for timing.  At Percent Bias of 1.03% and Nash-Sutcliffe of 0.897 it is well calibrated.

   3. At Hopland Gage?

      Answer

      Computed volume is less than the observed, although the peak and general shape of the hydrograph match well with observed. While the Nash-Sutcliffe value is good at 0.890 the Percent Bias of -24.60% indicates additional calibration is needed.

6. Check the box in front of each forecast run. This will cause the HEC-ResSim plots and summary reports to include results for all checked alternatives (if there were more than one).

   1. Where was the Coyote pool at time-of-forecast? Is this the same for both Forecast Runs?

      Answer

      744.13 ft, encroached in the flood pool. This was the same for both the Future Rain and No Future Rain Forecasts.

   2. What was the Coyote pool elevation at the end of the forecast for each forecast run?

      Answer

      Both forecasts returned to guide curve elevation of 737.5 ft. The No Future Rain Forecast on Jan 12 and the Future Rain Forecast on Jan 15

   3. What was the highest elevation the Coyote pool reached for each forecast?

      Answer

      745.29 ft for the No Future Rain Forecast, and 750.32 ft for the Future Rain Forecast.

   4. What output option(s) did you use to obtain these elevations?

      Answer

      Release Decision report and Reservoir Summary report.

   5. How did the release differ between the two Forecasts?

      Answer

      While both forecasts released a maximum of 4,000 cfs, the timing of the releases varied. The No Future Rain forecast was able to begin ramping releases to 4,000 cfs on Jan 10th, and then reduced on Jan 12th. The Future Rain forecast kept the gates closed for a longer period, and did not begin ramping up to 4,000 cfs until late on Jan 11th. Releases were maintained until Jan 15th. 

Problem 1 - Debris Dam 

You just got a call from the Emergency Operations Center (EOC) informing you that a debris dam has built up in the river at a major highway bridge near Hopland. They want to start debris removal as soon as possible, but need the flood wave to recede below 3,000 cfs at the Hopland gage. They estimate they need the region as "dewatered as possible" for at least 48 hours. Assume that no rain is forecasted for the next 3 to 4 days.

Operation Support Interface Overrides

Use the Operation Support Interface (OSI) to develop a release schedule to meet the EOC's request for the Hopland bridge. The OSI is a feature in ResSim that allows users to create a customized editor for developing a release schedule (perform overrides). A configured OSI has been provided for you.

1. Click on the HEC-ResSim alternative (RT-Normal) under the No Future Rain forecast run in the Forecasts tree.
2. From the Actions tab, select Operation Support…
3. Select the Reservoir Outflows tab in the OSI and click in the Mendocino Outflow column. Study the current situation. Then, specify a release schedule for Coyote Dam (Mendocino Outflow) to meet the EOC's 48hr dewatering request for Hopland.

How did you accomplish this task?

Great job! You saved the bridge at Hopland!!!

Problem 2 - Deviation for Dam Safety Concerns

At 0600 on 09 Jan you just got a call from the dam safety inspectors who are visiting Coyote Dam. The wet period that Lake Mendocino has been experiencing this year after a long drought has stressed the dam structure. Leakage has increased significantly to the point that the dam safety inspectors have requested Coyote Lake's winter pool be drawn down an additional 10 feet, and that the dam be regulated to keep the pool below 745 feet. They also want operations revised to empty stored flood waters as quickly as possible.

You must make the necessary adjustment to the reservoir's operations, revise the alternative, and verify that your changes meet the requirements.

NOTE – this is a different scenario than Problem 1 so you need to clear out the overrides from the previous problem.

1. Right-click the Future Rain forecast run and select Display in Map to display it in the existing map window. 
2. Right-click on Coyote reservoir in the map and select Edit Properties. (Make sure to select Edit Properties from the Reservoir Menu). This will open the HEC-ResSim Reservoir Editor>RT-Normal-Coyote.
3. Click on the Operations tab.
4. Make a copy of  the Normal Operations operation set and call it Deviation. To do so, select Duplicate… from the Operations menu.
5. Adjust the guide curve in your new operation set to meet the requirements described above.
   

   What changes did you make to the guide curve?

   Answer

   Adjusted the Conservation Zone:

   Set conservation pool to 727.5 instead of 737.5 year round (i.e. no summer pool).

   Since this is a dam safety issue, protecting the integrity of the dam takes precedence over the need for summer pool.

   Are there any other changes you should make to the operation set to reflect the deviation operations called for by the inspectors? What are they?

   Answer

   Set Flood Pool (Flood Control Zone) to 743.0 (want to give a buffer to the dam safety threshold)

   Change Max Release-FC Schedule rule by lowering all of the elevation thresholds by 10 feet (proportional to lowering conservation pool by 10 feet) - Note that changing this rule in one zone will automatically update the rule in other zones where it is used.

   Other modifications could include:

   Remove the rate of change constraints (IF-Block).

   Change the Emergency Release Schedule rule by lowering all of the elevation thresholds by 10 feet to match lowering Conservation Pool and Max Release by 10 feet.

6. If you identified other changes, make them, then click OK to apply your changes and close the reservoir editor.
7. Click on the RT-Normal ResSim alternative under the Future Rain forecast run in the forecast run tree. Then, click on the Edit Alternatives button in the Actions tab below.
8. Click on the Operations Tab in the Alternative Editor, and change the Operation Set for Coyote Reservoir to Deviation and click Save.
9. Compute the forecast and review the results.

Did your changes meet the objective?

How did your changes affect the Coyote reservoir releases for this forecast run?

Great job, you saved the dam!!!