Functional Flow Analysis
EFF.RmdIncorperating Effective Functional Flows into R2R
The Reorienting to Recovery Structured Decision Making group proposed a effective functional flow (EFF) scenario. To this date, there is no available CalSIM EFF run so we cannot model full EFF on the entire system. This document outlines our approach to piloting a EFF on the Sacramento River.
Pilot EFF Approach on the Sacramento River
The R2R technical team is working collaboratively with a flow sub group to develop a EFF hydrograph for the Sacramento River. We are building off of the Nature Conservancy’s Natural Flows Database to develop a wet and dry year monthly EFF hydrographs. We will compile these wet and dry year EFF into a 20 year synthetic timeserries based on the historical water year types between 1980 and 2000, the current R2R model timeframe.
Planned Improvements and Next Steps
The technical team is working to review existing literature on pulse flows and expand pulse flow routing logic in the model. This will increase the granularity of flow related model effects despite the monthly timestep of our CalSim flow input data and the model.
The technical team is also working with MBK to incoperate EFF logic into a CalSIM Run that we can use directly in the model.
What is an EFF
California’s EFF include 5 distinct components of a natural flow regime: fall pulse flows, wet season peak flows, wet season base flows, spring recession flows, and dry season baseflows.
For more information on EFF please refer to additional sources:
How can we tailor EFF to our system
EFF are hypothesized to be the best flows for salmon in our historical system. However, our system is highly managed so we may need to alter EFF slightly from their historical values to maximize benefit to salmon.
The R2R techncial team developed proposed EFF monthly flows by combining the Natural Flows Database values with critical flow to survival migratory thresholds on the Sacramento River (from Michel 2021). This original attempt did not maximize habitat so the technical team revised their approach to maximize modeled habitat and survival using the following principles:
- Optimize spawning habitat during full spawning timeframe (October, November, and December)
- Fix dry season base flow at a low value to maximize water for Juveniles, use Natural Flows Database as a guide (August, September)
- Optimize outmigration survival in last 3 model outmigration months (May, June, July). If water volume allows set migratory survival above 50%. If volume of water limited, set migratory survival above 20% (based on migratory survival flow survival thresholds on the Sacramento River (from Michel 2021).
- Utilize additional flows for maximizing FP habitat in (January, February, March & April)
Proposed Model EFF
Wet Year EFF
The table below shows monthly flow CFS for a wet year model EFF on the Sacramento River. This table was constructed using the Natural Flows database and model survival thresholds.
| month | flow_cfs | description |
|---|---|---|
| Jan | 40000 | Utalize remaining water for FP habitat |
| Feb | 40000 | Utalize remaining water for FP habitat |
| Mar | 40000 | Utalize remaining water for FP habitat |
| Apr | 40000 | Utalize remaining water for FP habitat |
| May | 10700 | Optimize for migratory survival (10,700 for mig surv ~50%) |
| Jun | 10700 | Optimize for migratory survival (10,700 for mig surv ~50%) |
| Jul | 10700 | Optimize for migratory survival (10,700 for mig surv ~50%) |
| Aug | 1000 | Set at 1000 to incrase acerage for avaliable for Juv flows |
| Sep | 1000 | Set at 1000 to incrase acerage for avaliable for Juv flows |
| Oct | 4750 | Optimize for spawning habitat based on flow area WUA |
| Nov | 4750 | Optimize for spawning habitat based on flow area WUA |
| Dec | 4750 | Optimize for spawning habitat based on flow area WUA |
The plot below shows the CalSIM modeled flows for the Sacramento River of an existing representative wet year: 1996. 1996 has the median water year index as provided by DWR out of all the “Wet” and “Above Normal” years within our model time frame.
The table below shows the annual total volume of water needed for each flow scenario. The wet year EFF uses more water than the Natural Flows database EFF and then the representative CalSIM year.
| Scenario | Annual Acre Ft Water |
|---|---|
| Natural flows Database flows | 16380382 |
| Proposed Model EFF | 12578235 |
| calsim | 12625023 |
Dry Year EFF
The table below shows monthly flow CFS for a dry year model EFF on the Sacramento River. This table was constructed using the Natural Flows database and model survival thresholds.
| month | flow_cfs | description |
|---|---|---|
| Jan | 18500 | Utalize remaining water for FP habitat |
| Feb | 18500 | Utalize remaining water for FP habitat |
| Mar | 18500 | Utalize remaining water for FP habitat |
| Apr | 18500 | Utalize remaining water for FP habitat |
| May | 4500 | Keep high for migratory survival (4,350 for mig surv ~20%) |
| Jun | 4500 | Keep high for migratory survival (4,350 for mig surv ~20%) |
| Jul | 4500 | Keep high for migratory survival (4,350 for mig surv ~20%) |
| Aug | 500 | Set summer base flow to 550 based on Natural flows tool and to incrase acerage for avaliable for Juv flows |
| Sep | 500 | Set summer base flow to 550 based on Natural flows tool and to incrase acerage for avaliable for Juv flows |
| Oct | 4750 | Optimize for spawning habitat based on flow area WUA |
| Nov | 4750 | Optimize for spawning habitat based on flow area WUA |
| Dec | 4750 | Optimize for spawning habitat based on flow area WUA |
The plot below shows the CalSIM modeled flows for the Sacramento River of an existing representative dry year: 1987 1987 has the median water year index as provided by DWR out of all the “Critical”, “Dry”, and “Below Normal” years within our model time frame.
The table below shows the annual total volume of water needed for each flow scenario. The dry year EFF uses less water than the Natural Flows database EFF and then the representative CalSIM year.
| Scenario | Annual Acre Ft Water |
|---|---|
| Natural flows Database flows | 4967965 |
| Proposed Model EFF | 6203089 |
| calsim | 6208945 |
Creating a synthetic flow timeserries
In order to incorporate these EFF into the model data inputs we combined wet and dry years to make a synthetic timeserries over the full 20 year period. We started by classifying years as “Dry” or “Wet” based on DWR water year type classifications. All “Dry”, “Critical”, or “Below Normal” years fall into the “Dry” category and all “Wet” or “Above Normal” years fall into the “Wet” category.
The plot below shows this synthetic timeserries for the Sacramento River over the 20 year simmulation period.
