Piloting Utility Modeling Applications: The San Francisco Public - - PowerPoint PPT Presentation

Piloting Utility Modeling Applications: The San Francisco Public Utilities Commission

PUMA Workshop December 1, 2010 San Francisco

David Behar Climate Program Director Alexis Dufour, P.E. Hydrology and Water Systems Modeling

The San Francisco Public Utilities Commission

• 1. Department of City and County of San

Francisco

• 2. 2.5 million customers
• 3. 28 wholesale customers in four counties,

800,000 retail customers in City of San Francisco

• 4. 2300 employees
• 5. Three Enterprises: Water, Wastewater,

Power

• 6. FY 2011-12 budget: $867 million

SFPUC assessment work to date

• 1. Statistical modeling, simple delta

method, temperature only, to 2025

• 2. Developing hydrological modeling tools

(Dufour)

• 3. Treasure Island development – Assisting

in framing adaptation/ adaptive management approach for SLR

• 4. Co-founder and Chair, Water Utility

Climate Alliance

Audiences for this work

• 1. Utility Staff
• 2. Senior Managers
• 3. Commission
• 4. Board of Supervisors
• 5. Mayor
• 6. RATEPAYERS (wholesale and retail)

Our goals

• 1. Learn
• 2. Stay abreast of the science
• 3. Develop ongoing expert relationships
• 4. Understand and synthesize uncertainty
• 5. Advance impacts analysis step-by-step
• 6. Be the most informed constituency in

San Francisco

• 7. Plan adaptation

SFPUC Water System

85% 10% 5%

Hydrologic models for Sierra Nevada & Bay Area Watersheds Planning Model (HH/ LSM) Decision Making (Decision Support Planning Methods) Infrastructure Planning

Water Supply Vulnerability to Changing Climatic Conditions: Modeling Approach

Climate Modeling & Downscaling Tools Policy Planning

Assess sensitivity of SPUC water entitlement to changing climatic conditions

5,000 10,000 15,000 20,000

Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep

Water Year 2010 Unimpaired Flow at La Grange TI D/ MI D Entitlements (cfs) 100 200 300 400 500 600 700 800 Water Available to the City (1,000 AF)

Unimpaired flow at LG Districts Max Rights City entitlement

Hetch Hetchy Reservoir

Snowline in 2000

Monthly Hetch Hetchy Inflow Exceedences WY 1931 to 2005

50 100 150 200 250 300 350 400 450 Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Monthly Inflow (TAF) 5% 25% 50% 75% 95%

Hydrologic models for Sierra Nevada & Bay Area Watersheds Planning Model (HH/ LSM) Decision Making (Decision Support Planning Methods) Infrastructure Planning

Water Supply Vulnerability to Changing Climatic Conditions: Modeling Approach

Climate Modeling & Downscaling Tools Policy Planning

Water supply planning model: the Hetch Hetchy and Local System Model – HH/ LSM

• mass balance model
• representation of each
• perational objective

and constraint

• Excel VBA platform
• monthly time step
• recurrence of

historical hydrology (1920-2002)

Hydrologic models for Sierra Nevada & Bay Area Watersheds Planning Model (HH/ LSM) Decision Making (Decision Support Planning Methods) Infrastructure Planning Climate Modeling & Downscaling Tools Policy Planning

Water Supply Vulnerability to Changing Climatic Conditions: Modeling Approach

• physically-based conceptual hydrologic

model to simulate: snow accumulation and melt, soil moisture and runoff

• model time step: hourly
• input:

temperature, precipitation, solar radiation, wind movement, and potential evapotranspiration

• output:

snow pack, soil moisture, actual evapotranspiration, streamflow

HFAM Hydrologic Modeling Tool

Land Segments defined by: topography (elevation, aspect, slope), mean precipitation, soils/ rock, vegetation Size: 2 – 6 km 2 (500 – 1,500 acres)

River reaches receive land segment runoff and transport water to reservoirs

HF AM Natur al F low Re ac he s

Legend Rafferty 3005 3000 Tuolumne 3020 reach Dana 3010 3020 3110 reservoir Delaney 3015 3110 reservoir represented as a reach Cathedral 3024 3025 3185 gaged reach 3040 3045 3030 direction of flow 3044 3050 3055 3060 Matterhorn 3054 3059 Register 3064 3065 Piute Cr. 3070 3075 3080 3085 Benson Lake 3079 3084 Rancheria 3090 3124 3125 3094 3095 3135 Falls Creek 3100 3105 3112 Hetch Hetchy 3139 3140 3147 3104 3109 Lake Eleanor Cherry Creek 3155 3165 3152 3117 Cherry Lake 3160 3170 3182 3187 3122 Diversion to Mountain Tunnel 3169 3190 3195 3200 3237 South Fork, Tuolumne 3205 3210 3220 3225 3215 3230 Clavey River 3239 3240 3250 3255 3262 Pine Mountain Lake 3245 3265 3270 Big Creek North Fork, Tuolumne 3275 3280 3285 3302 Turnback 3290 Moccasin 3295 Sullivan 3305 3317 Don Pedro Woods Creek 3310 3317 LaGrange

Weather Stations currently used in HFAM

11 stations Period of interest 1975-2008 1/ 8 deg( ~ 12x12km)

Hydrologic models for Sierra Nevada & Bay Area Watersheds Planning Model (HH/ LSM) Decision Making (Decision Support Planning Methods) Infrastructure Planning Climate Modeling & Downscaling Tools Policy Planning

Water Supply Vulnerability to Changing Climatic Conditions: Modeling Approach

How to use climate data and climate projections?

1) Methodological approach 2) Hydrologic modeling implementation

Methodological approach questions

• 1. What can we expect from climate

models given the uncertainties (forcing, initial conditions, model imperfections)?

• > How to use the projections?
• 2. Should we use ensemble data from the

model with the greatest skill or use multi-model ensemble data?

• 3. Dynamical vs statistical downscaling?
• 4. Top-down vs Bottom-up

Hydrologic modeling questions

• 1. Temporal distribution of temperature

projections on a seasonal and diurnal time scale

• 2. Sensitivity of temperature projections

to elevation

• 3. Trends for precipitation projections
• 4. Projections for other variables: Solar

radiation, wind, relative humidity

Trend in Daily Minimum Temperature at Hetch Hetchy (1930-2005)

QUESTIONS

1 2 3 4 5 6

2040 2070 2100

Temperature Change (deg C)

• 15
• 10
• 5

5 10 Precipitation Change (% of MAP) 1A 2A 2B 2C 3A 3B

Current approach to climate change projections

• SFPUC,
• USGS,
• NRCS Snotel,
• NWS Climate Prediction Center,
• NWS River Forecast Center,
• IRI Seasonal Forecast

Other products from academic institutions Up Count untry

• WSFM
• Base Ops
• MOS

Time scal scale: Monthly to Seasonal Decis isio ions: releases, pipeline rates, treatment plant rates, instream flow, maintenance outages, transfers Data ata: Bay A y Area

• Hydrologic Frequency Analysis
• Qualitative Demand Forecasting
• Local Reservoir System Model

Water Supply Forecast Model