Overview of CAP:SAM

Lower Santa Cruz River Basin Study Meeting

April 27, 2016

1

• Tool for projecting supply and demand in

CAP’s three county service area

• Accounts for complex legal and physical

characteristics of users and supplies

• Can simulate a wide range variations of

“driving forces”

• Designed to generate “what if” scenarios

CAP Service Area Model (CAP:SAM)

CAP Service Area Model (CAP:SAM)

• All Major Water Using Entities• 80 Municipal Providers

• 23 Irrigation Districts

• 12 Tribes and Districts

• 20+ other user categories (CAGRD,

AWBA, Industrial users, etc.)

• 16 Water Supply Types

• Includes Surface Water, Effluent, CAP, LTSC, Groundwater, Recovered Water, etc.

• Incorporates shortage scenarios from Colorado River Simulation model (CRSS)

Model IntegrationGlobal Circulation

Models (GCMs)

Colorado River

Simulation System

(CRSS) CAP:SAM

Regional Downscaling (Statistical or Dynamical;

VIC; etc.)

Distribution of

Pumping & Recharge

Arizona On-River

Uses

Groundwater Flow

Model (MODFLOW)

Distribution of

Streambed & Mnt.

Recharge

Pumping &

Recharge

by Entity

Land Use, Housing &

Pop (COGs, Census,

Applied Economics)

Supply &

Demand

by Entity

GW

LevelsWater Supply

Portfolios, Use, etc.(ADWR, CAP)

Supply, Demand & Uncertainty

Some of the major factors that affect water supply, demand and reliability:

• Growth

• Shortage

• Climate

• Socioeconomics

• Sector Trends

• Policy Changes

• Behavioral Shifts

• ….

“Driving Forces”

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

Muni Growth

Rate of Ag

Urbanization

Ag Demand

Use of CAP

Water by Ag

Excess CAP

for CAGRD

GSF Capacity

Sector Example

Interdependencies

Interdependencies

SRP Cutback

Use of CAP

Subcontracts

Geographic Example

Excess CAP

for AWBA

Recharge @

SAVSARP

Growth

Both the rate of growth and the location of growth are critical

• Rate

• Affects total use of supplies

• Location

– Different water use characteristics for each utility

– Different water supply portfolios

– Different regulatory and institutional requirements

-

15,000

30,000

45,000

60,000

75,000Housing Scenarios

Growth Rate

• Annual housing unit growth can be adjusted to account for the effects of the recession, and longer-term trends

Growth Location: BaselineLegend

HU_Change / Area

Low Growth

High Growth

2040

Water Provider Overlay

10,000

15,000

20,000

25,000

30,000

2010 2015 2020 2025 2030 2035

Hypothetical Housing Unit Projection

Original

New

Year: 2015

Units: 13,521

Year: 2011.8

Units: 13,521

Reconcile Growth Rate & Location

Alternate Growth Scenarios

• Socioeconomic Allocation Model

– Developed by Applied Economics

• Land use analysis with linear regression techniques

• 46 study areas in CAP Service Area

• Reallocated to neighborhood level, then to water provider

– Allocation Factors

• Historical growth patterns

• Major residential development projects

• Employment centers

• Transportation infrastructure

• Land value

Change From

Baseline Scenario

Outward Growth

2040

Slower Growth

- 75,000 HUs

Faster Growth

+ 75,000 HUs

• Commute time less important

Infill

2040

Slower Growth

- 75,000 HUs

Faster Growth

+ 75,000 HUs

Change From

Baseline Scenario

• Planned residential development projects less important• Commute time more important

Slower Growth

- 75,000 HUs

Faster Growth

+ 75,000 HUs

Urban Redevelopment

2040

Change From

Baseline Scenario

• Planned residential development projects less important• Additional capacity for redevelopment

0

200,000

400,000

600,000

800,000

1,000,000

1,200,000

2010 2015 2020 2025 2030 2035 2040 2045 2050

Housin

g U

nits

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

2010 2015 2020 2025 2030 2035 2040 2045 2050

Housin

g U

nits

Growth Scenarios

Large Urban Provider Growing Rural Provider

Conversion to Water Demand

• Existing Approach– Housing units are multiplied by a provider-specific value of

Gallons Per Housing Unit per Day (GPHUD)

– Can adjust rate of change, maximum change and minimum floor

– Separate calculations for new and existing housing units

• Enhancements– Interior versus exterior demand

– Commercial, industrial, and irrigation

– Socioeconomic & housing characteristics

– Changes in demographics

– Heat Island effects

Supply Utilization

• The model contains each water provider’s unique portfolio of supplies (i.e., entitlements)

– Annual supplies (e.g., CAP, surface water, effluent)

– Volumetric supplies (e.g., LTSCs, GW allowances)

– Accrual (and debiting) of long-term storage credits is modeled, as is incidental recharge and Pinal renewable GW allowances

– Leases, exchanges, transfers and reallocations through time can also be modeled

Supply Utilization

An Established City, with Moderate Growth, and

a Diverse Renewable Supply Portfolio

CAP

Surface Water

Effluent

A Medium-Sized Provider, with Moderate Growth,

and a Large Renewable Supply Portfolio

CAP

Effluent

Supply Utilization

A Small Member Land Provider, With Low

Growth, and No Renewable Supplies

Non-Replenished Groundwater

Excess Groundwater

Other GW

Supply Utilization

A Medium-Sized Provider, with Rapid Growth,

and No Renewable Supplies

Non-Replenished Groundwater

Excess Groundwater

Other GW

Supply Utilization

0

200,000

400,000

600,000

800,000

1,000,000

1,200,000

1,400,000

1,600,000

Projected Actual

Effluent

Surface Water

CAP

Non-Replenished GW

Other GW

Excess GW

Supply Utilization: Total

Urbanization of Agricultural Land

National Agricultural Statistics Service CropScape Data Layer, 2013

• The spatial housing unit scenarios can be used to project urbanization of agricultural land

• Agricultural Data:

– Acreage by Crop Type (NASS, 2008-2014)

– Usage by Supply Type (ADWR, 1985-2013)

– Crop Consumptive Use (ADWR)

Queen Creek

Chandler

Heights

Town of

Gilbert

Example Projection of Irrigation District

Supply Utilization

Projection Actual

Service Area Analysis ExampleCAP Water Use by Destination

Crops

Treatment

Plants

Recharge

Basins

Other

Total

Recharge

(GSF+USF)

Projection Actual

Total

Recharge

(GSF+USF)Crops

Treatment

Plants

Recharge

Basins

Other

Projection

Shortage

Service Area Analysis ExampleCAP Water Use by Destination with Shortage

Actual

Validation Steps

• Base data validation

– Maps of projected service areas

– Review of supply portfolios

– Base case model run validation

• Anticipated supply utilization

• Incorporation of known events

Scenario Generation

• Review and confirmation of driving

forces (including climate)– Sensitivity analysis can be used to help identify

• Selection of internally consistent

ensembles of factors– e.g. in a “Hot & Dry” scenario, crop Et and

residential exterior demand adjusted upwards

• Review of results

Options & Strategies Runs

• Selection of “control case”

• Selection of potential adaptation/

mitigation strategies• e.g., new regional infrastructure, increased

supply leasing, policy changes, etc.

• Comparison of Strategy versus

Control Case• Effect on GW levels, etc.