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Science to Sustain At-Risk Terminal Lakes
Walker River Basin Project
In Cooperation with the Bureau of Reclamation
Legislative Committee on Public Lands
March 24, 2006
Presentation Overview
•Problem•Objectives•Status of activities•Plans for upcoming year
Location of Walker
River Basin
West Walker R. West Walker R. near Hudsonnear Hudson
Walker R. near Walker R. near WabuskaWabuska
East Walker R. East Walker R. above above Strosnider Strosnider Ditch near Ditch near MasonMason
Walker R. at Walker R. at Lateral 2-A Lateral 2-A near Schurznear Schurz
Walker Lake Salinity
Walker River Streamflow
Objectives
• Quantify streamflow in the Walker Basin
• Estimate evapotranspiration from the lake and vegetation
• Develop an improved water budget for Walker Lake
• Develop the capability to predict how changes in upstream irrigation practices would affect flows to Walker Lake
Activities
• Surface-Water (SW) network• Ground-Water (GW) network• Evapotranspiration (ET) network• Mapping vegetation, elevation,
bathymetry• Preliminary streamflow analysis• Web Site
SW Network –new and upgraded
gages
New Stream Gages
Green Ck near Bridgeport Virginia Ck near Bridgeport
Real-Time Data on Walker Lake Gage
GW Network
• GW sites
Ground-Water/Surface-Water Sites
• Willows ET (above Weber)• Cow Camp Gage• Lateral 2-A Gage• Powerline Road• Walker River
at Mouth
GW/SW Site Locations
WillowsWillows
Above WeberAbove Weber
Lateral 2-ALateral 2-A
Powerline RoadPowerline Road
Walker River MouthWalker River Mouth
ET Networ
k
Results – ET from Walker Lake
Measured ET on Walker Lake
Water year 2005
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct
ET
(m
m)
0
2
4
6
8
10
12
14
Net
Rad
iati
on
(W
/m^
2)
-50
0
50
100
150
200
250
300
ET Net Radiation
Provisional-—Subject to revision
ET compared with RAWS Radiation
Water year 2005
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct
ET
(m
m)
0
2
4
6
8
10
12
14
So
lar
Rad
iati
on
(kW
-hr/
m2)
0
2
4
6
8
10
12
ET RAWS Solar Radiation
Provisional-—Subject to revision
ET vs RAWS radiation
y = 0.0548x2 + 0.5356x
R2 = 0.6533
0
2
4
6
8
10
12
14
0 2 4 6 8 10 12
Daily Solar Radiation (KW-hr/m^2)
Dai
ly E
T (
mm
)Provisional—Subject to revision
Total ET for 2005 Water Year
Water year 2005
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct
ET
(m
m)
0
2
4
6
8
10
12
14
ET Estimated ET
Total 2005 Water Year ET = 1814 mm or 6.0 ft*
Provisional—Subject to revision
Results – ET from Walker Lake
• ET for WY2005 was 6.0 ft*, up from previous estimates of 4.1 ft.
• Area of Walker Lake in June 2005 was 32,000 acres.
• Volume evaporated from Walker Lake in 2005 was 192,000 acre-ft*.
• ~ 50% increase over previous estimates.• If relation between Lake ET and RAWS
solar radiation holds, may be able to estimate annual ET from 1999-2004.
* Provisional—Subject to revision
Salt Cedar site• Site underwent substantial defoliation due to
introduction of a biologic control agent: Salt Cedar Leaf Beetle (Diorhabda elongata)
• Changed characteristics and ET rate for large stand of Salt Cedar
Reduction of ET using Salt Grass
Date 2005
Mar May Jul Sep Nov
ET
(m
m)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Leaf
Cov
er (
%)
0
20
40
60
80
100
Salt CedarNormalized Salt GrassSalt Cedar Leaf Cover
203 mm*
57 mm*
This is a 22% reduction in ET*
Provisional—Subject to revision
Results – ET Summary
ET Station
Wal
ker
Lake
Will
ow
Alfa
lfa B
11
Alfa
lfa B
01
Sal
t Gra
ss
Sal
t Ced
ar
Rab
bit B
rush
Gre
asew
ood
ET
(in
ches
)
0
20
40
60
806.0 ft
3.5 ft 3.3 ft2.8 ft
0.7 ft 0.7 ft0.4 ft 0.4 ft
Provisional—Subject to revision
Mapping:
• Satellite imagery
• New imagery• Lidar• Bathymetry• Side-scan
sonar
Bathymetry
Imagery (infrared)
Scaling up of ET
• Create map of ET units
• Extrapolate ET data to ET units to estimate total ET in basin
Bathymetry
Provisional—Subject to revision
Maximum depth Maximum depth Spring 2005 was Spring 2005 was 82.8 ft82.8 ft
Tufa Mounds in
Walker Lake?
• Side-scan sonar• More GW
inflow?
Effect of ET on Streamflow
Streamflow—Wabuska vs Schurz
Web Site
http://nevada.usgs.gov/walker/
Click on Data link for interactive map page
Plans for This Year
• Continue to collect data – Data network is essentially in full operation
• Report on bathymetry of Walker Lake• Classify and map vegetation• Geophysics near Double Springs, river
mouth, and south end of lake• Install additional observation wells to
refine hydrologic understanding of GW system
Recommended