Estimation of areal recharge Estimation of areal recharge for the Spokane Valley-for the Spokane Valley-

Rathdrum Prairie AquiferRathdrum Prairie Aquifer

J.R. BartolinoJ.R. BartolinoU.S. Geological SurveyU.S. Geological Survey

Idaho Water Science CenterIdaho Water Science CenterSVRP Aquifer SummitSVRP Aquifer Summit

May 8, 2007—Spokane, WAMay 8, 2007—Spokane, WA

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Magnitude of areal recharge

► Areal recharge is Areal recharge is second-largest single second-largest single inflow componentinflow component 233 ft233 ft33/s: 16% of total/s: 16% of total

► Includes permeable Includes permeable and impermeable and impermeable surfacessurfaces Permeable surface

assumes no overland runoff

Impermeable surface excludes impervious cover that drains directly to the Spokane River or other water body

1,471ft3/sinflow

1,468ft3/s outflow

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Four methods identifiedFour methods identifiedRunoff based: assumes

Runoff = Recharge► Langbein (1961): Raft Langbein (1961): Raft

River, IDRiver, ID Annual onlyAnnual only Precipitation and PETPrecipitation and PET

► ESPAM (Contor, 2004) ESPAM (Contor, 2004) Based on Rich (1951, Based on Rich (1951,

1952) and calibrated to 1952) and calibrated to previous GW flow model. previous GW flow model.

Three soil types: thin Three soil types: thin and thick soils, lava rockand thick soils, lava rock

PrecipitationPrecipitation

ET based: assumes Precipitation - ETc = Recharge

► USDA (1970)USDA (1970) Effective rainfall calculatedEffective rainfall calculated Precipitation, PET, and Precipitation, PET, and

temperaturetemperature

► FAO Penman-Monteith FAO Penman-Monteith (Allen and others,1998)(Allen and others,1998)

Reference ET (ETReference ET (EToo) ) calculated—requires many calculated—requires many meteorological data; most meteorological data; most can be approximatedcan be approximated

Single coefficient approach: Single coefficient approach:

ETc = Kc ETo

re = 0.70917 rt0.82416-0.11556(10)0.02426u(f)

Pa / La vs Ra / La curve

Precipitation vs Runoff curve

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Active NWS stations within 20 Active NWS stations within 20 milesmiles► Bayview Model Basin

► Coeur D’Alene 1E ► Newport► Sandpoint Exp.

Station► Priest River Exp.

Station► Spokane WSO Airport

► Mean annual precipitation 16.1 in—Spokane 32.0 in—Sandpoint

► Mean annual temperature 50.3°F—Bayview 53.4°F—Coeur

d’Alene ► Closest AgriMet station is Seven Bays Marina, Washington, (SBMW) 50 mi west of Spokane

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Mean monthly rechargeMean monthly recharge

► Langbein: Langbein: Annual onlyAnnual only

► ESPAM:ESPAM: Recharge 1-57% of Recharge 1-57% of

monthly precipitationmonthly precipitation Lava rock > Thin > ThickLava rock > Thin > Thick

► USDA: USDA: Recharge 53-73% of Recharge 53-73% of

monthly precipitationmonthly precipitation

► FAO Penman-FAO Penman-Monteith single Monteith single coefficient (Spokane coefficient (Spokane only): only): Recharge 0-93% of Recharge 0-93% of

monthly precipitationmonthly precipitationMean monthly precipitation

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Mean annual rechargeMean annual recharge► Langbein: Langbein:

Recharge 0-11% of annual Recharge 0-11% of annual precipitationprecipitation

► ESPAM:ESPAM: Recharge 2-52% of annual Recharge 2-52% of annual

precipitationprecipitation Lava rock > Thin > ThickLava rock > Thin > Thick

► USDA: USDA: Recharge 64-69% of annual Recharge 64-69% of annual

precipitationprecipitation

► FAO Penman-Monteith single FAO Penman-Monteith single coefficient (Spokane only): coefficient (Spokane only): Recharge 30% of annual Recharge 30% of annual

precipitationprecipitation

All problematic All problematic conceptually or in water conceptually or in water budgetbudget

0

5

10

15

20

25

30

35

BayviewModelBasin

Coeur D'Alene 1E

Newport Priest Riv.Exp. Stat.

SandpointExp. Stat.

SpokaneWSO

Airport

An

nu

al m

ean

pre

cip

itat

ion

an

d r

ech

arg

e, in

ches

Precipitation USDAESPAM (lava rock) ESPAM (thin soil)Langbein ESPAM (thick soil)FAO Penman-Monteith single coeff

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What’s wrong with these What’s wrong with these estimates?estimates?

► Single coefficient FAO: no recharge for summer months—unlikely

► Monthly time steps assume that there is always sufficient soil moisture to satisfy ET, but: Daily soil moisture will

occasionally be insufficient to meet ETc demand, thus actual ET will be less than the calculated ETc

► For recharge to occur soil moisture has to be replenished: Depends on the amount and

timing of individual precipitation events

► The FAO Penman-Monteith dual-coefficient approach with daily time steps addresses this temporal variation

► Mass-balance to determine soil drainage/deep percolation/recharge

► Spreadsheet based► Used wind speed from

Spokane WSO Airport for all stations

ETcd = (Kcb + Ke) ETo

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Recharge with 1990-2005 daily Recharge with 1990-2005 daily valuesvalues

► Daily calculations show timing of precipitation can be Daily calculations show timing of precipitation can be more important than the amountmore important than the amount

► Is this important? It depends on the model and Is this important? It depends on the model and purpose…purpose…

PrecipitationSPOKANE WSO AIRPORT

Soil drainage

0

JAN

MAY

SEP

T

JAN

MAY

SEP

T10

20

30

40

50

60

DEE

P P

ERCOLA

TION

AN

D P

REC

IPIT

ATI

ON

, IN

MIL

LIM

ETER

S

1990 1991 1992 1993 1994 1995

JAN

MAY

SEP

T

JAN

MAY

SEP

T

JAN

MAY

SEP

T

JAN

MAY

SEP

T

PrecipitationSPOKANE WSD AIRPORT

Soil drainage

0

JAN

MAY

SEPT

JAN

MAY

SEPT

10

20

30

40

50

60

DEE

P PE

RCOLA

TION

AN

D P

RECI

PITA

TION

, IN

MIL

LIM

ETER

S1990 1991 1992 1993 1994 1995

A.

JAN

MAY

SEPT

JAN

MAY

SEPT

JAN

MAY

SEPT

JAN

MAY

SEPT

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Comparison and applicationComparison and application

► Realistic and defensibleRealistic and defensible► Calculations are for Calculations are for

points:points: Triangular network-linear Triangular network-linear

interpolationinterpolation

!

!

!

#

#

#

#

#

#

Newport, WA

Coeur D' Alene 1E, ID

Bayview Model Basin, ID

Spokane WSO Airport, WA

Sandpoint Exp. Station, ID

Priest River Exp. Station, ID

0 10 205 Miles

EXPLANATION

# weather station

! auxiliary vertex

expanded triangular network

extent of SVRP aquifer model

Fr

0

5

10

15

20

25

30

35

BayviewModelBasin

Coeur D'Alene 1E

Newport Priest Riv.Exp. Stat.

SandpointExp. Stat.

SpokaneWSO

Airport

An

nu

al m

ean

pre

cip

itat

ion

an

d r

ech

arg

e, in

ches

Precipitation USDAESPAM (lava rock) FAO Penman-Monteith dual coeffESPAM (thin soil) LangbeinESPAM (thick soil) FAO Penman-Monteith single coeff

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Recharge from impermeable Recharge from impermeable surfacessurfaces

► Precipitation on an impermeable surface that runs off to: a recharge well an infiltration basin adjacent permeable surfaces

► Assumed that 85% recharges and 15% lost to ET

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Reports and linksReports and links► Report available from Report available from

the USGS the USGS Publications Publications Warehouse at URL:Warehouse at URL:http://pubs.usgs.gov/sir/2007/ http://pubs.usgs.gov/sir/2007/ 5038/5038/

► Rick Allen’s site:Rick Allen’s site: Includes spreadsheets Includes spreadsheets

and links to the FAO and links to the FAO reportreport

http://www.kimberly.uidaho.ehttp://www.kimberly.uidaho.edu/ water/fao56/index.htmldu/ water/fao56/index.html