1. Supply & Demand Approach— CAP:SAM
Ken Seasholes
Manager, Resource Planning & Analysis
Central Arizona Project
EMS Basin Study Supply & Demand Team Meeting #1 January 15, 2019

2. Water Supply & Demand
Some of the major factors that affect water supply, demand and reliability:
Growth
Shortage
Climate Variability
Socio-Economic Changes
Agricultural Trends
Water Storage Preferences
Policy Changes
Behavioral Shifts ….
“Driving Forces”

3. Supply & Demand Challenges
Complex relationships among supply & demand factors
Within demand (e.g., housing development on Ag land)
Within supply (e.g., use of long-term CAP contracts affects Excess CAP)
Between supply & demand (e.g., reductions in interior use affect effluent supplies)
Significant uncertainties across multiple dimensions
The rate of growth
The location of growth
Changes in current and future demand factors
The use of different supply types
The reliability of those supplies

4. CAP Service Area Model (CAP:SAM)
Tool for projecting supply and demand in CAP’s three county service area
135 entities (municipal providers, irrigation districts, Tribes, AWBA, CAGRD, etc.)
16 water supply types
Accounts for complex legal and physical characteristics of users and supplies
Designed to easily generate “what-if” scenarios
Data from ADWR, CAP, Associations of Governments

5. Growth Rates Large Established City Exurban Community
Small Bedroom Community
Medium Established City

6. Growth Patterns 2040 Water Providers Outward Growth Infill
Redevelopment
2040
Water Providers

8. Urbanization of Agricultural Land
The spatial housing unit scenarios can be used to project urbanization of agricultural land
Agricultural Data:
Acreage by Crop Type (NASS, )
Usage by Supply Type (ADWR, )
Crop Consumptive Use (ADWR)
National Agricultural Statistics Service CropScape Data Layer, 2013
Town of
Gilbert
Queen Creek
Chandler Heights

9. Other CAP:SAM Agricultural Factors
Recharge via Groundwater Savings Facility (GSF) partnerships
On-Reservation Tribal agricultural use
Changes in cropping patterns
Substitution of higher water use crops
Changes in evapotranspiration due to climate change
Changes in efficiency/irrigation technology

10. Model Integration Global Circulation Models (GCMs)
Temp,
Precip, etc.
Environmental
impacts
Regional Downscaling (Statistical or Dynamical; VIC; etc.)
Evapotranspiration
& Natural Recharge
Hydrologic “Traces”
Evapo-
transpiration
Colorado River Simulation System (CRSS)
Supply & Demand by Entity
CAP:SAM
Supply
to CAP
Pumping &
Recharge
by Entity
Supply
to AZ
Arizona On-River Uses
Distribution of Streambed & Mnt. Recharge
Distribution of Pumping & Recharge
Growth
Projections
Land Use, Housing & Pop (COGs, Census, Applied Economics) by
Cell by
Cell
Water
Supplies
Groundwater Flow Model (MODFLOW)
Water Supply Portfolios, Use, etc.
(ADWR, CAP)
GW Levels