Download City of San Diego Water Demand Forecast

Presentation to Scripps Institute of Oceanography City of San Diego Water Demand Forecast
Public Utilities Department
Engineering Program Management Division
Feryal Moshavegh, Associate Engineer
Michael Voss, Assistant Engineer May 25, 2010 City of San Diego
Population 1.3 million
• Service Area covers 403 square miles
•
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San Diego’s Water Treatment Plants
The Water System Includes:
• 28 Potable Water Reservoirs
• 47 Potable Water Pump Stations
• 505 Miles of Transmission Pipelines
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Miramar Water
Treatment Plant
5
15
805
805
67
52
• 3,000 Miles of Distribution Pipelines
• 134 Pressure Zones
8
163
94
125
54
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5
805
805
905
Potable Water Model
The detailed Water
Model analyzes the
entire water distribution
system:
• 6,000 major valves
• 280,000 customer meter connections
• 667 pressure regulators
• Interface with GIS, CIS and SCADA systems
• On going calibration, updates from SCADA every 15 minutes
North City & South Bay Recycled Water System
The Recycle Water Model
consists of:
• 2 Reclamation Plants
• 94 miles of pipelines
• 404 customer meter connections
• 6 Pump Stations
• 5 Reservoirs
• 8 Pressure zones
• Interface with GIS, CIS & SCADA
Raw Water Model
The Raw Water Model
consists of:
San Vicente Reservoir
CWA 1st Aqueduct connection
• 40 miles of Pipelines
• 2 Pump Stations (Lakeside & El Monte)
• 3 Reservoirs (Murray, El Capitan, and San Vicente)
El Capitan Reservoir
Lakeside PS
Lake Murray
The Year 2030 Master Plan Model
Model is based on latest water demand projection report. It includes: • Future growth (latest SANDAG release population & land use
• Water & Sewer Rate
• Conservation parameters
• Global Warming effects
How are the models used?
• Master Planning
• Operation support, system optimization, shutdown & backup studies
• New development, cast iron replacement group job studies
• Pressure zone studies & fire flow analysis
• Water quality analysis • Water source contribution (tracer studies)
• Emergency planning and water security analysis
• Quality control check of GIS, CIS and SCADA data
Development of Water Demand Forecasts
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Demand Forecast Report Objectives
Demand Forecasts are used to:
• Plan for expansion of system capacity (sources of supply, transmission, treatment). • Evaluate the effectiveness (or water savings) of alternative conservation measures
• Prepare contingency plans for water shortages caused by drought or source contamination
• Guide development (Urban Water Management Plan)
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Data Used for Water Demand Forecast
•
SANDAG 2050 Update, Series 12
– Employment (totals & NAICS)
– SF and MF occupied households
– SF and MF housing density (computed from acreage)
– Median household income
•
Marginal price of water & sewer
•
Weather data
– historical observed
– Climate change scenarios
•
Historical Water use data
– Customer billing information, premise code, and month
– Wholesale water use
– Percent NRW from annual report
•
Conservation savings and future programs
Model Weather Variables
• Weather variables:
– Average maximum daily temperature
– Monthly total precipitation
– Number of rainy days in month
– One and two month lag effects for precipitation variables (varies by sector)
• Measured as departure from normal (average) weather
Global Climate Change Data
• Models provided by Scripps
• Two global climate models selected:
– Geophysical Fluid Dynamics Laboratory (GFDLCM2)
– National Center for Atmospheric Research Parallel Coupled Model (NCARPCM)
• Data used:
– Monthly average maximum daily temperature
– Monthly total precipitation
– Number of days in each month with precipitation greater than 0.01 inches
Scripps Data Processed
• Data provided for a 200 x 200 km grid
• Grids selected that overlay with weather station data used to develop demand forecast model
• CDM calculated moving average of data to capture trends – forecast model estimates demand in 5‐year increments and single‐year climate change data not representative of trend
• Data then transformed to departure from historical average
Climate Grids for City of San Diego Service Area
Modeled Demand with Climate Change
• Calculated climate change departures in weather input into forecast model for future years
• Estimates a per unit use under the given scenario
• 2030 demands under GFDLCM2 conditions can increase by 4.5% from the average weather scenario
Comparison of Historical Average and Scripps Climate Change Models
NCARPCM
GFDLCM2
Historical Average
7
6
No. Rainy Days
5
4
3
2
1
0
1 2 3 4 5 6 7 8 9 101112 1 2 3 4 5 6 7 8 9 101112 1 2 3 4 5 6 7 8 9 101112 1 2 3 4 5 6 7 8 9 101112 1 2 3 4 5 6 7 8 9101112
2010
2015
2020
2025
Number of Rainy Days in Month
2030
Comparison of Historical Average and Scripps Climate Change Models
NCARPCM
GFDLCM2
Historical Average
2.5
Precipitation
2.0
1.5
1.0
0.5
0.0
-0.5
1 2 3 4 5 6 7 8 91011121 2 3 4 5 6 7 8 91011121 2 3 4 5 6 7 8 91011121 2 3 4 5 6 7 8 91011121 2 3 4 5 6 7 8 9101112
2010
2015
2020
Monthly Precipitation
2025
2030
Comparison of Historical Average and Scripps Climate Change Models
NCARPCM
GFDLCM2
Historical Average
85
80
Temperature
75
70
65
60
55
50
1 2 3 4 5 6 7 8 9 101112 1 2 3 4 5 6 7 8 9 101112 1 2 3 4 5 6 7 8 9 101112 1 2 3 4 5 6 7 8 9 101112 1 2 3 4 5 6 7 8 9 101112
2010
2015
2020
Temperature
2025
2030
Historical Population and Water Demand
Comparison of Demand under Climate Change Scenarios (MGD)
Questions and Comments?
Contact Information:
Feryal Moshavegh
(858) 654‐4241
[email protected]
Michael Voss
(858) 654‐4246
[email protected] 23