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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