Ground-Water Hydrology of the Upper Deschutes Basin, Oregon

Kenneth E. Lite Jr., Oregon Water Resources Department

Study Area

UpperDeschutes Basin

Study Area

Oregon

Major Parts of a Regional Ground-Water Study

• Geologic framework– Geologic controls on

ground-water flow

• Hydrologic budget– Recharge– Discharge

• Flow-system– Flow directions– Water-level and

discharge fluctuations

• Computer Modeling

Hydrogeologic Units

• Quaternary Sediment

• Cascade Range and Newberry Volcano Deposits• Deschutes Formation

Inactive Margin Deposits Ancestral Deschutes River Deposits Arc Adjacent Plain Deposits Proximal Volcanic Deposits

• Pre-Deschutes Formation Deposits

Recharge

Estimate

Average Annual Recharge,

1993-1995

Hydraulic Head

Distribution

GeneralizedWater-Table Map

of theUpper Deschutes Basin

To Streams

> 500 cfs gain100 to 500 cfs gain50 to 100 cfs gain10 to 50 cfs gain0 to 10 cfs gain0 to 10 cfs loss10 to 20 cfs loss20 to 50 cfs loss50 to 100 cfs lossMeasurement endpoint

Estimated Stream Gains and Losses

Precipitation and SW trends

Climate-Driven Fluctuations in Ground-Water DischargeAt Fall River

0

50

100

150

200

250

1930 1940 1950 1960 1970 1980 1990 2000

Dis

char

ge

(Cu

bic

Fee

t p

er S

eco

nd

)

-25

25

75

125

175

225

Cu

mu

lati

ve D

epar

ture

(In

ches

)

Discharge of Fall River

Cumulative Departure from AveragePrecipitation at Crater Lake

SW and GW trends

Climate-Driven Fluctuations in Ground-Water Dischargeand Water Levels in Wells

Fall

Riv

er

Dis

charg

e (

CFS

)

Depth

to W

ate

r in

Well

(Feet)

0

50

100

150

200

250

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

40

60

80

100

120

140

Monthly mean discharge, Fall River

Depth to water, Well 15S/10E-8ACD

Natural recharge occurs primarily in the Cascade Range. It takes time for the recharge pulses to propagate across the basin.

Responses of Wells at Varying Distances from the Cascades

1/93 1/94 1/95 1/96 1/97 1/98 1/99

Time

Wat

e-L

evel

Ch

ang

e (2

ft

per

mar

k)

14S/9E-8aba

15S/10E-8acd

15S/10E-36aad2

15S/10E-2cda

14S/12E-9acb

15S/13E-4cab2

15S/13E-18add

1993 1994 1995 1996 1997 1998 1999

The response to recharge pulses is delayed and attenuated with increasing distance from the Cascade Range.

Wat

er-L

evel

(2

feet

per

mar

k)

Summary• Our present understanding of the ground-water hydrology is

based on years of careful data collection and analysis.

• The unique hydrologic character is due to highly permeable volcanic deposits juxtaposed against older low-permeability deposits, and the incision of the Deschutes River down to these older deposits.

• The ground-water system of the upper Deschutes Basin helps maintain relatively even stream flow, however ground-water levels and streamflow vary markedly in response to climate cycles.

• Ground-water pumped from wells and used consumptively will mostly be reflected in reductions in ground-water storage and diminished ground-water discharge to streams.

Simulation of Regional Ground-Water Flow in the Upper Deschutes Basin, Oregon, by Marshall W. Gannett and Kenneth E. Lite Jr., WRIR 03-4195.

Ground-Water Hydrology of the Upper Deschutes Basin, Oregon, by Marshall W. Gannett, Kenneth E. Lite, David S. Morgan and Charles A. Collins, WRIR 00-4162.

Geologic Framework of the Regional Ground-Water Flow System in the Upper Deschutes Basin, Oregon, by Kenneth E. Lite Jr. and Marshall W. Gannett, WRIR 02-4015.

Chemical Study of Regional Ground-Water Flow and Ground-Water/Surface-Water Interaction in the Upper Deschutes Basin, by Rodney R. Caldwell, WRIR 97-423.

Ground-Water and Water-Chemistry Data for the Upper Deschutes Basin, Oregon, by Rodney R. Caldwell and Margot Truini, WRIR 97-197.

http://or.water.usgs.gov/projs_dir/deschutes_gw/index.html