Decision SupportDecision Support Simulation for a Water

Basin

Purpose of DSSp

Based on systems modelingBased on systems modelingIncorporates all major processes within a

tsystemDemonstrates effects of seemingly isolated d i i th ti tdecisions on the entire systemMay show surprising or unanticipated results f t tiof management options

DSS in Education

Gives students a hands on tool to learn aboutGives students a hands-on tool to learn about water resourcesT h h i d i t l t dTeaches comprehensive and inter-related concepts while keeping complicated modeling hiddenmodeling hiddenAllows students to identify effective management strategies and developmanagement strategies and develop compromise plans

Typical DSS Elementsyp

Reservoir/LevelFlow Rate

Auxiliary VariableConstant Variable

ConnectorThis is the data that can bethat can be altered on user interfaces

Example of User InterfaceExample of User Interface

Water Basin DSS

Regional System approximately size of TucsonRegional System approximately size of TucsonLimited water supplyMultiple demand sectorsMultiple demand sectorsPopulation growth over 25 year simulationPresents various ways to make supply meetPresents various ways to make supply meet demandAllows observation of multiple options in a short timep pProvides opportunity for cost-benefit analysis

SupplyGroundwater

18.5 million acre-ft Imported Water

aquiferRenewable supply

Surface WaterAverage streamflow of 200 cfs

Tribal WaterMay be purchased

www.cap-az.com

200 cfsMinimum downstream flow

Reclaimed WaterCan only be used for certain demand

Reservoircertain demand

www.wwm.pima.gov

Demand

Residential TurfResidentialIndoor and Outdoor

Private golf coursesPublic golf courses and parks

AgricultureAlfalfa, Lettuce, Cotton,

parksSchools

Wheat

E i l

Industrial

EnvironmentalIn-stream flow requirementsrequirements

General Water System

INDUSTRIAL

RESERVOIR

Wastewater

INDUSTRIAL

Import/Tribal WATER

SUPPLYAGRICULTURE/

TURFtreatment plantSUPPLY

GWRESIDENTIAL

ENVIRONMENTAL/RECREATIONAL AREA

RIVER

Supply SubmodelsSupply Submodels

Residential SubmodelsResidential Submodels

front loader gal peruse% households w

frontloader

last year

h t Showerclotheswasher use

Households

use per day

current year

new houses topurchase

frontloaders

Shower per Day

Potential ShowerSavings

Shower

reg gallons per use

Shower Pre 89

p y

persons-house

Clotheswasher

Shower Low Flow

Shower Time

Shower Use

Households 1989

Households

Submodel Interface

Goals and Objectivesj

Today: Understand ConceptsToday: Understand ConceptsDemand by sectorConsumptive useConsumptive useReclaimed waterSurface Groundwater InteractionsSurface – Groundwater InteractionsEffects of population growthConservation optionsConservation optionsEnvironmental effects

Goals and Objectivesj

Next time: The Big PictureNext time: The Big PictureDifferent management alternatives and their effects on the systemeffects on the systemCombine and negotiate options to create the best possible outcomepEnhanced supply and treatment options

Big Pictureg

Day 1&2 – Explore basic model options:

Introductory Questions:

Day 3 – Try to simulate your city

D 4 C fli tQuestions:- Turf- Residential- PopulationA i lt

CustomizationChallenges

Day 4 – Conflict resolution exercise –role play with major water user stakeholders

- Agriculture- Water Budget

Control Case

Control case studies – Water supply- Climate variability

FarmerDeveloperCity Manager

Studies – if timeCity ManagerConservationist

Goal: Satisfy everyone's y ywater needs

Important Conceptsp p

Consumptive Use:Consumptive Use:Water that is not returned to the system through recharge or the WWTPrecharge or the WWTP=Total Demand – Recharge – Return to WWTPGenerally indoor use is non-consumptive andGenerally indoor use is non consumptive and outdoor use (irrigation) is highly consumptive.

Conservation Options:Conservation Options:Fixture retrofits, frontloaders, drip irrigation, rainwater harvesting

Streamflow ProcessesUpstream and Downstream Reach refer to location Upstream is streamflow before it gets to the city Downstream is streamflowstreamflow before it gets to the city. Downstream is streamflow in the river after the city has taken water from it and released effluent to it.Losing and Gaining Reach refer to relationship with the aquifer. os g a d Ga g eac e e to e at o s p t t e aqu eLosing streams are above the water table, so they lose water to the aquifer (instream recharge). Gaining streams are below the water table, so they gain water from the aquifer.

Losing ReachGaining Reach

Model Terms

Initial year means before pushing play andInitial year means before pushing play and final year means after pushing play.Default values are those present when theDefault values are those present when the simulation is reset, or before you change anything.New water is any water that is not reclaimed water.Safe Yield: net Extraction < net RechargeThis is the goal of Arizona’s AMA’s

Introduction to Powersim

InstructionsTo navigate, use the arrows, Home button, or hyperlinkshyperlinks. You can change inputs by using the slider bars or typing values in the boxes below the bars. On the

t l i l li k th di b ttcontrol pages, you simply click the radio buttons or enter inputs.You may find it useful to change variables without y grunning the simulation to see direct initial year differences between the results from default values and from the changed values.and from the changed values. The play button runs the simulation, the play/pause button progresses one year with each click, and the rewind button resets the simulation to the initial yearrewind button resets the simulation to the initial year. Each time you reset the simulation, the values return to default.

Inputs and Outputsp p

Basic input pages include Agriculture TurfBasic input pages include Agriculture, Turf, Residential, and Population. Outputs are found on each input page as wellOutputs are found on each input page as well as the main result page, the Water Budget.Advanced input pages are found within theAdvanced input pages are found within the Controls.Additional results can be found on Supply pp yCosts, Riparian Area, Environmental Economics.

Interpreting Resultsp g

This model displays results both numerically andThis model displays results both numerically and graphically. One way to see results is to look at a numerical value with the default inputs and compare it to the value with your inputs.However sometimes the most important results areHowever, sometimes the most important results are best explained through graphs.Each input page has two graphs on it; Streamflow and Aquifer Volume. There are also a few other graphs throughout the model. The following page shows you how to read some of these graphs.y g p

Reading GraphsDownstream flow will generally be lower than upstream flow, because the region removes water from the stream for use, and only a portion is returned from the WWTP and some water also recharges to the aquifer. If upstream Reading Graphsflow falls below downstream flow, this means that the reach has become ‘losing.’ A good goal is to maintain a healthy downstream flow.

The aquifer volume will decline throughout thethroughout the simulation in response to overdraft (extraction that exceeds totalexceeds total recharge). A good goal is to try to keep it level.

Trends

This graph shows demand trends influenced primarily p yby the population growth rate. Observe the slope of these trends, and compare it to th l f ll ithe slopes following a change in the growth rate. Generally the higher the growth rate the steeperrate, the steeper the trend, and thus the greater demand.

Safe Yield

An example of a region meeting g gsafe yield. Extraction does not exceed total recharge, also known as

blrenewable groundwater. The Aquifer Volume graph in this case would actually beactually be slowly rising.