PowerPoint

Drought, restoration, and evapotranspiration in the Middle
Rio Grande riparian corridor, New Mexico
James Cleverly, Michael Slusher, James Thibault, Jennifer Schuetz,
and Clifford Dahm
*UNM Hydrogeoecology, http://sevilleta.unm.edu
sevilleta.unm.edu/~cleverly

Populus deltoides ssp. wislizenii
(Rio Grande Cottonwood)
Native
Exotic
Elæagnus angustifolia (Russian Olive)
Tamarix chinensis (Tamarisk)

Evapotranspiration
Atmosphere
Sensors
Phreatophytes
Shallow Aquifer
Floodwater and soil water evaporation (exposed & shaded, sand & clay)

Video: P Sprott
3-D Eddy Covariance
R n : Net Radiation (incoming energy flux)
λET: Latent Heat Flux (evapotranspiration energy flux)
H: Sensible Heat Flux (temperature gradient flux)
G: Ground Heat Flux (soil heat flux)
R n - λET -H -G = closure*

Tower-equipped
Sites
Flooding Russian-olive
Nonflooding Tamarisk
Flooding
Cottonwood
Nonflooding
Cottonwood
Flooding Tamarisk

Seasonal Drought
Year
Winter/Spring Summer
2000 normal-dry very dry
2001 normal-wet normal
2002 dry very dry
2003 very dry very dry
2004 normal-dry normal-dry
2005 record wet very dry

Annual ET
ET
150
130
110
90
70
50
2000 2001 2002 2003 2004 2005
Cottonwood/Saltcedar/Russian Olive
Cottonwood/Willow/(Alfalfa)
Russian Olive/Willow
Monospecific Tamarisk
Tamarisk/Saltgrass
Year
• Drought is associated with ET decline in all but invaded cottonwood forest
• ET increased before cessation of drought at two sites
• Following drought, ET at all mesic riparian sites were equivalent

Wait a minute, isn’t Tamarisk
supposed to be drought tolerant
ET
150
130
110
90
70
50
2000 2001 2002 2003 2004 2005
Year
ET
(mm/day)
6.2
5.7
5.2
4.7
4.2
3.7
3.2
2000 2001 2002 2003 2004 2005
Dense Tamarisk
Tamarisk/Saltgrass
Season length (days):
Year
2000 2001 2002 2003 2004 2005
T 211 198 181 209 192 209
T+SG 202 193 181 196 206 198

Why did ET remain stable at the
invaded cottonwood site
ET
150
130
110
90
70
50
-2
Leaf Chlorophyll Content (mg m )
P. deltoides
T. chinensis
E. angustifolia
Depth to Groundwater (cm)
700
600
500
400
300
200
100
0
125
150
175
200
225
250
275
300
325
350
375
a
ad
cd
bc
bc
b
b b
e
Albuquerque Belen Bosque del Apache
2000 2001 2002 2003 2004 2005
Year

Understory Restoration
150
130
ET
110
90
70
50
2000 2001 2002 2003 2004 2005
Year

Restoration water salvage
♦ Understory Russian olive and
saltcedar removed from South
Valley Albuquerque cottonwood
forest between 2003 and 2004
growing seasons
♦ First year reduction in ET of 9%
while other sites increasing by 12%
(total = -21% or -26 cm/yr)
♦ Second year increase matched
increase at other sites: 0 cm/yr
140
120
Albuquerque's South Valley: cottonwood
La Joya: Russian olive/coyote willow
San Acacia: saltcedar/saltgrass
Bosque del Apache: monospecific saltcedar thicket
Non-native native understory cleared
ET (cm/yr)
100
80
60
2003 2004 2005
Year

Increased Tamarisk ET during
150
drought
130
ET
110
90
70
12
Depth to Groundwater (cm)
BDAS 2003
ET (mm/day)
50
2000 2001 2002 2003 2004 2005
Year
30
10
-50
0
25
8
50
PPT (mm/day)
ET
20
6
15
4
100
150
200
GW
10
250
2
300
5
0
350
50 100 150 200 250 300 350
Day of Year

Tamarisk and Groundwater
♦ Depth to groundwater does not limit
transpiration:
♦ when the water table is 10-m below the surface
(Horton et al 2001)
♦ when the water table is 25-m below the
surface (Gries et al 2003)
♦ Tamarisk found in sites with seasonally
variable depth to groundwater
(Lite & Stromberg 2005)

Groundwater recession
1 Draining begins, soil too
saturated for taproot
elongation, uptake continues
at original capillary fringe
Falling
2
1
Rising
-7.5 -5 -2.5 0 2.5 5
dWT/dt (9-day average, cm/day)
3
9
8
7
6
5
4
ET (9-day average, mm/day)
3 Uptake continues at
deeper water table, uptake
at original water table
curtailed by soil drying
2 Taproot growth exploits
deeper water table, uptake
continues at or near original
capillary fringe
(Cleverly et al 2006)

Conclusions
120
ET (cm/yr)
100
80
Cottonwood,
Tamarisk, &
Russian olive
CW
Monospecific
Tamarisk
RO
Tamarisk
&
Saltgrass

Acknowledgements
♦
NASA award NAG5-6999
♦ Bosque Initiative/Bosque
Improvement Grant
♦ Interstate Stream Commission
♦ US Bureau of
Reclamation/Endangered
Species Workgroup
♦ US Army Corps of Engineers
♦ US Fish and Wildlife
Service/Bosque del Apache
NWR
♦ NM House Bill 2
♦ NSF/EPSCoR RII-2
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
UNM Hydrogeoecology
UNM Sevilleta LTER
NM ET Workgroup
NM Bosque Hydrology Group
City of Albuquerque Open
Spaces Division
Middle Rio Grande Conservancy
District
NM State Land Office
Bosque del Apache NWR
Sevilleta NWR
Rio Grande Nature Center