Water Supply ModelingWater Supply Modeling

Analyzing the Effect of Water Analyzing the Effect of Water Supply Activities on Aquatic Life Supply Activities on Aquatic Life and Long-Term Water Availabilityand Long-Term Water Availability

Why Do We Model Water Why Do We Model Water Supply Activities?Supply Activities?

Water is a renewable, but temporally finite Water is a renewable, but temporally finite resourceresource• It gets more scarce when we need it most!It gets more scarce when we need it most!

Water withdrawals (and discharges) effect Water withdrawals (and discharges) effect aquatic lifeaquatic life

Some folks refer to the Eastern US as Some folks refer to the Eastern US as “water rich” … but recent droughts have “water rich” … but recent droughts have seen well failures, emergency water seen well failures, emergency water trestrictions and locatlities “trucking water trestrictions and locatlities “trucking water in”in”

Facts, Figures, Acronymns & Facts, Figures, Acronymns & ConversionsConversions

Facts:Facts:• Water supply modeling is a mass balance equation:Water supply modeling is a mass balance equation:• Qout = Qin + P + R – WD + PSQout = Qin + P + R – WD + PS

Figures:Figures:• Virginians currently use ~10% of annual stream flowVirginians currently use ~10% of annual stream flow• Virginians use > 50% of drought flows in some streamsVirginians use > 50% of drought flows in some streams• Harmful effects of WD may be seen as soon as 20%Harmful effects of WD may be seen as soon as 20%

Acronyms:Acronyms:• Flow: cfs – Cubic Feet Per SecondFlow: cfs – Cubic Feet Per Second• Withdrawal: MGD – Million Gallons per Day Withdrawal: MGD – Million Gallons per Day • Storage: acft - acre-feet (foot of water on acre of land)Storage: acft - acre-feet (foot of water on acre of land)

Conversions:Conversions:• 1 MGD = 1.547 cfs1 MGD = 1.547 cfs

How Do We Model Water How Do We Model Water SupplySupply

Do Cumulative Impact AnalysisDo Cumulative Impact Analysis• WithdrawalsWithdrawals• DischargesDischarges• ImpoundmentsImpoundments

Consider Ecology:Consider Ecology:• IFIMIFIM• Flow-Ecology statistical modelingFlow-Ecology statistical modeling

Looking towards the futureLooking towards the future• Water Supply Planning reg requires localities to prepare Water Supply Planning reg requires localities to prepare

30-50 year water use projections30-50 year water use projections• We have built a modeling system to look at all of itWe have built a modeling system to look at all of it

Our “Meta-Modeling” SystemOur “Meta-Modeling” System

Integrates multiple sub-models• HSPF• GWLF• CBP Model (hspf based)

Remote data sources• USGS gages• NOAA rainfall

Online – web interface Multi-user – collaborative

What is a Cumulative What is a Cumulative Impact Analysis?Impact Analysis?

Local Withdrawals

Month MGD

1 6.31

2 6.45

3 5.92

4 5.95

5 6.02

6 6.26

7 5.99

8 6.11

9 6.14

10 5.56

11 5.61

12 6.73

Cumulative Withdrawals

Month MGD

1 25.33

2 26.03

3 33.60

4 33.45

5 28.29

6 26.38

7 24.67

8 21.37

9 22.92

10 22.58

11 22.19

12 25.10

All withdrawalsAll Dischargers

All Operational RulesAll the way down the stream

Tools We Will UseTools We Will Use

VWUDS DatabasesVWUDS Databases VPDES DatabaseVPDES Database Water Supply PlansWater Supply Plans VWP PermitsVWP Permits Web-Based Web-Based

Modeling SystemModeling System Integrated into a Integrated into a

“Conflict Signal “Conflict Signal Tool”Tool”

0

20

40

60

80

100

120

140

160

1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008

Mean Flow-by Min Flow-by Max Flow-by

What Kind of Comparisons do What Kind of Comparisons do the Models Allow?the Models Allow?

““Pinch Points” or areas of potential conflictPinch Points” or areas of potential conflict Changes to overall the Flow RegimeChanges to overall the Flow Regime Changes in TimingChanges in Timing

North Anna: Avoid Supply North Anna: Avoid Supply Impact / Maintain HabitatImpact / Maintain Habitat

Critical Year Release Days Avg. Release Without Release With Release2002 35 32 (+12) 27 37

Rappahannock: Balancing Rappahannock: Balancing WithdrawalsWithdrawals

Model with Flow-By and Storage Demonstrated Tight, but sustainable water budget

Water Supply Plan info and permit info suggested serious conflict

Pinch Points: How Will We Pinch Points: How Will We Manage?Manage?

• Without new flow-by Rules, we definitely have adverse impact to off & on stream resources• Storage will probably be required to protect instream resources

Now Full Build-Out

Why Do We Need You??Why Do We Need You??

Data Sharing is Quality AssuranceData Sharing is Quality Assurance• More eyes is better for debugging!More eyes is better for debugging!

Flow EcologyFlow Ecology Data visualization inspiration is neededData visualization inspiration is needed

• We need sharp minds & alternative ideasWe need sharp minds & alternative ideas Exploring alternativesExploring alternatives The Eastern US is a Water Supply Analysis The Eastern US is a Water Supply Analysis

DesertDesert• Train people to meet challenges of an uncertain Train people to meet challenges of an uncertain

futurefuture