# Presentation: 284676

## California-NevadaRiver Forecast Center Forecast Operations andthe American River 

## American River, Folsom Dam

- Graphics by Pete Fickenscher
- CNRFC hydrologist

## American River Basin

## Three Phases of RFC Operations

- Calibration of Hydro Model, SAC SMA
- Operational...The Observed Periods
- Operational...The Forecast or Future Periods

## Calibration of the Model

- Long term precipitation gage data, ~20-40 years
- Hourly and daily -> 6 hour time step MAP, Mean Areal Precip
- Long term temperature gage data
- Max/min -> 6 hour time step MAT, Mean Areal Temp
- Melt level derived from MAT
- Long term river flow data,  mean daily
- Usually divide basin into upper and lower sub-basins at “normal” snow line, 5000 ft in American

## Calibration

- Assume precip evenly distributed over the sub-basin, in time and space
- Subdivision of basin dependent on availability of  river gages for calibration

## A GENERALIZED

- TENSION   WATER   STORAGE

- FREE WATER STORAGE

- PRIMARY
- FREE
- WATER
- STORAGE

- TENSION
- WATER
- STORAGE

- TENSION
- WATER
- STORAGE

- SUPPLEMENTARY
- FREE WATER
- STORAGE

_**A GENERALIZED**_
_**HYDROLOGIC MODEL**_

**LOWER ZONE**

**UPPER ZONE**

- DIRECT
- RUNOFF

- INTERFLOW

- SURFACE
- RUNOFF

- BASEFLOW

- SUBSURFACE
- OUTFLOW

## Previous American Watershed Model

## New American Watershed Model

## Approx 60% below 5000 ftApprox 40% above 5000 ft

## Operational ForecastingThe Observed Periods

- Inputs
- 6 hour MAP computed from raingage data
- 6 hour MAT computed from temperature gage data
- Melt level derived from MAT
-  very limited observed melt level data, MFR, OAK, VBG, RNO
- HMT melt level obs will be immediately useful here
- Observed river flow data
- MAP and MAT -> Snow Model -> Rain plus melt
- Rain plus melt -> SAC SMA
- Correct inputs are critical to maintaining soil moisture accounting, precip typing, and snow accumulation/melt in the model

## Precipitation Gages

## Gages with annual normal precip PRISM background

## Operational ForecastingThe Future Periods

- Forecast Precip, QPF
- 72 hours from HPC, days 4 and 5 Rhea orographic
- HPC -> CNRFC HAS -> hydro model sub-basins
- Forecast temp,  WFO fcst and MOS
- Freezing level,  HPC -> HAS -> hydro model
- Based on model forecast of freezing level
- -1500 ft to get melt level
- 6 hour time-steps

## Partners and Customers

- CNRFC, COE, USBR project to permit Folsom pre-release based on CNRFC inflow forecasts
- The first attempt to permit operation of a reservoir in our area based on forecast inflows... it is very important that we provide accurate forecasts, along with an indication of uncertainty
- COE spending $250M for low level outlets for pre-release
- Considering 7’ raise of dam
- COE spent many $ on American levee slurry walls
- Levee breach could affect more than 450K people
- CNRFC, COE, California DWR, YCWA  Forecast coordinated operations, Feather R and Yuba R
- Partners/customers...NWS, CADWR, COE, USBR, SAFCA, Amer R Flood Cntrl, Friends of the River

## Science Challenges

- Current modeling is limited by
- availability of river gaging
- Long term record needed for calibration
- Solid real time river data needed as well, this is a real problem
- Sparse raingage network
- Current network will not support finer scale simulation
- Better all-weather gages would be useful in rain/snow areas
- Finer scale multi-sensor precip estimation would support advanced hydro modeling
- Uncertainty in observed and forecast melt level
- Snow level derived from HMT sensors will be immediately useful

## Science Challenges

- QPF
- 1-5 day probabilistic QPF to support short term probabalistic hydro forecasts
- Quality...can HMT investigation provide the knowledge or tools to improve QPF?
- Mesoscale modeling
- Import HMT data set into RUC model to provide HAS with better short term wx model guidance
- Distributed hydro modeling
- Gridded multi-sensor precipitation inputs necessary
- Gridded QPF and temp, smaller temporal and spatial scale necessary

## So What?

- We need to provide our users with hydro forecasts which are
- Timely
- Accurate
- Include uncertainty
- Short term,  hours
- Long term, months
- Where?
- Reservoir inflow forecasts?
- Small streams?

## Short-term Ensemble Prototype

- Smith River

- Salmon River

- Navarro River

- American River
- (11 basins)

- Van Duzen River

## Short-term Ensemble Prototype

- Appropriately integrate the uncertainty introduced from model, data, and human sources.

**MODEL PARMS**
- snow
- soil moisture
- basin routing

**MODEL STATES**
- snow
- soil moisture
- basin routing

**FORECASTS**
- precipitation
- air temperature
- regulation

**MODELLING SYSTEM**
- simplifications
- temporal issues
- scale issues

**HUMAN INPUT**
- education
- training
- experience
- mental state

- ???

## Short-term Ensemble Prototype NF American (upper subarea)5-day Temperature Ensembles

## Short-term Ensemble Prototype NF American (upper subarea)5-day Precipitation Ensembles

- QPF = 1.5 inches in two successive 6-hr periods, otherwise zero

## Short-term Ensemble Prototype NF American 5-day Streamflow Ensembles

## Short-term Ensemble Prototype NF American5-day Streamflow Distribution

## Short-term Ensemble Prototype Next Steps

- Gain experience from more active (coastal) watersheds
- Validate outcomes
- Are the distributions reasonable (accurate)?
- More experience.
- Retrospective (historical) analysis needed.
- Begin addressing other sources of uncertainty and operational systemization
- Begin addressing the need for education and training
- Internal and external
- Interpretation of probabilistic information