forecast operations study · flood management paradigm shift • new – harness forecasting...

FOLSOM JOINT FEDERAL PROJECTFORECAST OPERATIONS STUDY

Photo courtesy of USACE-SPK

Brett Whitin – California Nevada River Forecast CenterRandi Field – U.S. Bureau of Reclamation

FOLSOM LAKE

Storage Capacity: 976,000 acre feet(1.204x109 m3)

Watershed: 1,861 square miles (4,820 km2)

Multi-Objective Reservoir

High Refill Potential

Upstream of Urban Area - Sacramento

AMERICAN RIVER HYDROLOGIC MODEL

AMERICAN RIVER HYDROLOGIC MODEL

Hindcast:- Ensemble forecast performed for historical time period

using current forecasting methodology (1985-2010)- Meteorological Ensemble Forecast Preprocessor (MEFP)

using GEFSv10 precip and temp- Run the forcings through our hydrologic models

Value of Hindcasts:Provide a large and consistent sample for verification

Bottom Line: demonstrate forecast quality/reliability

Hindcasting

He

ENSEMBLE RIVER FORECASTS

Timeline

Mod

el R

un T

ime

Observed Weather

Streamflow

Model States

Short Term Weather Models(GEFS)

Days 1-15

Hourly ensemble inflow forecasts to Folsom

- 61 traces per day• Daily forecasts for 1985-2010

HINDCAST FINAL PRODUCTS

HINDCAST VERIFICATION OF RESULTS

FOLSOM 3-DAY AVERAGE FLOW

(MEAN ENSEMBLE FORECAST VS. OBSERVED)

FOLSOM 3-DAY 25% EXCEEDENCE FLOW

(MEAN ENSEMBLE FORECAST VS. OBSERVED)

FOLSOM 1986 3-DAY INFLOW VOLUME

Feb

12th

Feb

13th

Feb

14th

Feb

15th

Feb

16th

Feb

17th

FOLSOM FEB18-20 (3-DAY) VOLUME FORECAST PROGRESSION

FLOOD MANAGEMENT PARADIGM SHIFT

• Old – Upstream Storage Credit– Conservative from a flood protection perspective– Precipitation measurements already “on the ground” – Leverage existing flood reserve space

FLOOD MANAGEMENT PARADIGM SHIFT• New

– Harness forecasting technology– Increase flood preparation “Advanced-release” – Increase water supply use efficiency

MANAGEMENT GOALS

1. Use advanced release to improve flood risk2. Reduce Safety of Dams and high release risks3. Increase water supply use efficiency

FORECAST INFORMED DESIGN STRUCTURE

1. Advance Release “Blue Sky Action”2. Evacuate storage prior to a storm event3. Communication Opportunities4. Forecast Dynamics

FORECAST INFORMED DECISION MAKING PROCESS

Ensemble

Model Runs

FORECAST INFORMED DECISION MAKING PROCESS

392

417

442

467

492

517

542

567

592

617

642325

350

375

400

425

450

475

500

525

550

575

0 10020030040050060070080090010001100120013001400150016001700 Floo

d Co

ntro

l Res

erva

tion

(FCR

) (10

00 a

c-ft

)

Top

of C

onse

rvat

ion

(TO

C) S

tora

ge (1

000

ac-

ft)

Forecasted Inflow Volume (1,000 ac-ft)

Variable Top of Conservation

24-hr

48-hr

72-hr

120-hr

TOC

25% Exceedance Probability

Cumulative Volume for Day 1, 2, 3, and 5

Test if Cumulative Volume > 300,000 acre feet

Yes

No

Increase Release based on Confidence and Risk

Maintain current Release

FORECAST INFORMED DECISION MAKING

NEW WATER CONTROL MANUAL SIGNED(JUNE 12TH 2019)