Mechanisms for Interannual Mechanisms for Interannual Variations in Summer Streamflow Variations in Summer Streamflow from Headwater Catchments in from Headwater Catchments in

Western MexicoWestern Mexico

David J. Gochis, Nat’l Center for Atmos. Res.Luis Brito-Castillo, CIBNOR, Guaymas, Son. MX

Presented: NOAA Climate Diagnostics and Pred. Workshop, Oct. 27, 2005

AcknowledgementsAcknowledgements

• Balaji Rajagopalan and Katrina Grantz (CU-Boulder)

– Grantz, K., B. Rajagopalan, M. Clark, and E. Zagona, Spatio-Temporal Variability of the North American Monsoon (submitted), Journal of Climate, Special issue on the North American Monsoon, 2005.

• http://civil.colorado.edu/~balajir/ publications

• CNA

• NOAA-OGP GEWEX Americas Prediction Project: NA16GP2002

Objectives…Objectives…

• Provide a basic overview of the hydroclimatology of the headwater region in the Sierra Madre Occidental

• Characterize rainfall-runoff relationships governing streamflow on intra-seasonal to inter-annual timescales

• Explore interannual variability of streamflow associated with the North American Monsoon, and the relationship between cool season and warm season flows

Data:Data:

Timeseries of monthly streamflow• 15 headwater catchments• BANDAS dataset, courtesy CNA

NCEP/Climate Prediction Center

1x1 gridded daily precipitation• uniformly disagg. to 0.1 • monthly averaged across basins

Water Management Issues:Gila River

Gila River BasinArizona and New Mexico

Basic Hydroclimatology

The “Monsoon” Water YearThe “Monsoon” Water Year

• Monthly mean cycle dominated by warm season rainfall associated with the N. American Monsoon (NAM)

• Jul-Aug-Sep flow volume accounts for 50-85% of total annual flow

• Minor appearance of secondary max in Dec-Jan in response to synoptic transient systems

• Maximum recorded flows occur during monsoon, late fall or early winter

Previous Findings…Previous Findings…(Dettinger and Diaz, (Dettinger and Diaz, JHMJHM; Gochis et al., 2003, ; Gochis et al., 2003, JHMJHM; Grantz ; Grantz

et al., 2005 (submitted et al., 2005 (submitted J.ClimJ.Clim))

Latitudinal transition to a summer-dominated regime proceeding southward from Mogollon Rim.

Monthly Percent of Mean Annual Flow Volume

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

1 2 3 4 5 6 7 8 9 10 11 12

Month

% o

f Ann

ual F

low

Salt River near Chrysotile, AZ

Verde River, Camp Verde, AZ

Gila River near Clifton, AZ

San Pedro @ Charleston, AZ

Rio Sonoita, Sonora, MX

Rio Mayo, Sonora, MX

Rio Fuerte, Sinaloa, MX

Gila River near RedRock, NM

0

50

100

150

200

250

300

350

400

450

1 2 3 4 5 6 7 8 9 10 11 12

Month

Str

eam

flo

w (

cfs

)

Regionalization of Precipitation and Regionalization of Precipitation and Streamflow Streamflow (Gochis and Brito-Castillo, J. Hydrol. in press)(Gochis and Brito-Castillo, J. Hydrol. in press)

• VARIMAX rotated EOF analysis of seasonal (JAS) streamflow reveals three distinct regions of coherent streamflow variability:

•EOF1 – north•EOF2 – south•EOF3 – east

• Explain ~ 71% of the JAS variance

• Nearly identical EOF analysis of seasonal (JAS) precipitation reveals three very similar regions

• Explain ~ 86% of the JAS variance

Regionalized Rainfall-Runoff Analyses: Regionalized Rainfall-Runoff Analyses: Runoff Coefficient (Qr=Q/P)Runoff Coefficient (Qr=Q/P)

• Seasonal increase in Qr peaking in Oct• Reductions in precipitation in greater proportion than reduction in streamflow result in the marked increase in Oct values• Distinct sub-regional differences in this evolution

Jul Oct

Jul-Aug-Sep

Seasonal Evolution of Precipitation, Runoff and Runoff Coefficient

0

0.2

0.4

0.6

0.8

1

1.2

J un J ul Aug Sep Oct

Month

0

50

100

150

200

250

EOF1 Qr

EOF2 Qr

EOF3 Qr

EOF1 P

EOF2 P

EOF3 P

EOF1 Q

EOF2 Q

EOF3 Q

21%

34%

19%

• Relationship between JAS P and Q is non-linear and the runoff fraction (Qr=Q/P) exhibits substantial interannual variability

• Tendency for Qr to trend towards the 1:1 line (increase in value) with higher precipitation values

• This feature is most pronounced in EOF2(south) which receives the most rainfall

• Possible indication that in-basin abstractions are being met so that basins produce runoff with higher efficiency with greater seasonal precipitation

Precipitation-Runoff Precipitation-Runoff Processes: Runoff Processes: Runoff FractionFraction

JAS Regionalized Precip. vs Streamflow

0

50

100

150

200

250

300

350

400

450

500

550

600

650

700

750

0 100 200 300 400 500 600 700

JAS Streamflow (mm)

JA

S P

rec

ipit

ati

on

(m

m)

Q EOF1

Q EOF2

Q EOF3

1:1

Streamflow Diagnostics:Precipitation – Streamflow Relationship

Precipitation – streamflow relationship is non-linearHigh rainfall very little infiltration high streamflowDecaying influence of in-basin abstractions

JAS Regionalized Precip. vs Streamflow

0

50

100

150

200

250

300

350

400

450

500

550

600

650

700

750

0 100 200 300 400 500 600 700

JAS Precipitation (mm)

JA

S S

tre

am

flo

w (

mm

)

Q EOF1

Q EOF2

Q EOF3

1:1

Interannual Relationships

Timeseries of Jan-Apr Flows

y = 0.4562x - 876.62

y = 0.1486x - 268.35

y = 0.0914x - 170.390

50

100

150

200

250

300

1940 1950 1960 1970 1980 1990 2000 2010

Str

ea

mfl

ow

(m

m) EOF1

EOF2

EOF3

Linear (EOF2)

Linear (EOF1)

Linear (EOF3)

Timerseries of Jul-Aug-Sep Flows

y = 0.196x - 297.94

y = -1.0476x + 2258.2

y = -0.6322x + 1326.6

0

50

100

150

200

250

300

350

400

1940 1950 1960 1970 1980 1990 2000 2010

Streamflow (mm)

Zone 1 (North)

Zone 2 (South)

Zone 3 (East)

Linear (Zone 1 (North))

Linear (Zone 2 (South))

Linear (Zone 3 (East))

Linear Trend in Flow Volume

Jan-Apr Jul-Sep

Region (mm/yr) (mm/yr)

EOF1 0.149 0.196

EOF2 0.456 -1.048

EOF3 0.091 -0.632

Streamflow Diagnostics:Volume Analysis (summer)

San Francisco River at Clifton, AZJuly, Aug: decreasing trendSep, Oct: increasing trend

San Francisco River at Clifton, AZ JULY

y = -0.4539x + 976.79

0

50

100

150

200

250

300

1920 1930 1940 1950 1960 1970 1980 1990 2000 2010

Year

Str

eam

flo

w (

cfs)

San Francisco River at Clifton, AZ AUGUST

y = -0.695x + 1558.6

0

200

400

600

800

1000

1200

1400

1600

1920 1930 1940 1950 1960 1970 1980 1990 2000 2010

Year

Str

eam

flo

w (

cfs)

San Francisco River at Clifton, AZ SEPTEMBER

y = 0.1866x - 221.29

0

100

200

300

400

500

600

700

800

900

1920 1930 1940 1950 1960 1970 1980 1990 2000 2010

Year

Str

eam

flo

w (

cfs)

San Francisco River at Clifton, AZ OCTOBER

y = 3.8691x - 7403.9

0

500

1000

1500

2000

2500

3000

3500

4000

4500

1920 1930 1940 1950 1960 1970 1980 1990 2000 2010

Year

Str

eam

flo

w (

cfs)

Date of Center of Mass (DOY)

0

50

100

150

200

250

300

350

1930 1940 1950 1960 1970 1980 1990 2000 2010

Year

DO

Y

SEXT

RAMO

BATO

MAYO

CHIN

URIQ

HUMA

PIAX

PRES

BALU

ACAP

CHOI

BADI

TAMA

Date of Center of Mass (DOY)

0

50

100

150

200

250

300

350

1930 1940 1950 1960 1970 1980 1990 2000 2010

Year

DO

Y

EOF1

EOF2

EOF3

Annual Streamflow Annual Streamflow Center of VolumeCenter of Volume

(Procedure by Stewart et al., 2004)

All Basins

EOF Comp.

• No consistent long-term trend in CoV date though EOF2 has had more frequent early peaks since mid 1990s

• Marked increase in CoV date variability since 1976-1977 climate shift most evident in individual basins

• Effect is to increase the occurrence of early season peaks prior to DOY 200 (7/19)

• Only EOF 1 (North) exhibits a weakly sig. correl. w/ ENSO

• Shift due possibly to shift in onset, decreased summer flows or increased cool season flows

Correlation Scores Between SOI and EOF Zone Averaged Runoff

-0.50

-0.40

-0.30

-0.20

-0.10

0.00

0.10

0.20

0.30

0.40

0.50

SOI (Oct-Mar) SOI (Jan-Jun) SOI (Apr-Sep) SOI (Jun-Sep)

Lag

Co

rrel

atio

n

Zone 1

Zone 2

Zone 3

Jul-Aug-Sep

n SOI (Oct-Mar) SOI (Jan-Jun) SOI (Apr-Sep) SOI (Jun-Sep)

39 Zone 1 -0.06 0.05 0.18 0.20

55 Zone 2 -0.18 0.03 0.40 0.42

33 Zone 3 -0.04 0.09 0.15 0.15

JAS Total Q JAS Total Q Correlation to ENSO: Correlation to ENSO: SOISOI

• Clear evolution towards stronger correlations at ‘decreasing’ lags

• Peak correlation occurs with EOF2 and concurrent SOI (sig. @ 95% level)

• Sign of correl. indicates that higher flows occur during La Nina (high SOI) and low flows occur during El Nino (low SOI)

SS

S – Significant @ 95%

JAS Total Q Correlation JAS Total Q Correlation to ENSO: TNI & Nino to ENSO: TNI & Nino 3.43.4

• Character of correlation is markedly different with respect to regions

• EOFs 1(North) and 3(East) exhibit modest negative correlations with TNI and N3.4 at all nearly all

• EOF2(South) exhibits no long term correl. with TNI or N3.4

TNI – ‘Trans-Nino Index’ of Trenberth and Stepaniak, 2001, J. Clim

Correlation Scores Between TNI and EOF Zone Averaged Runoff

-0.50

-0.40

-0.30

-0.20

-0.10

0.00

0.10

0.20

0.30

0.40

0.50

TNI (Oct-Mar) TNI (Jan-Jun) TNI (Apr-Sep) TNI (Jun-Sep)

Lag

Co

rre

lati

on

Zone 1

Zone 2

Zone 3

S SSS

SS

S

Correlation Scores Between Nino3.4 and EOF Zone Averaged Runoff

-0.50

-0.40

-0.30

-0.20

-0.10

0.00

0.10

0.20

0.30

0.40

0.50

Nino 3.4 (Oct-Mar) Nino 3.4 (Jan-Jun)

Nino 3.4 (Apr-Sep)

Nino 3.4(Jun-Sep)

Lag

Co

rre

lati

on

Zone 1

Zone 2

Zone 3

S SS S

SS S

1. S

an P

edro

del C

onchos

2. C

hin

ipas

3. M

ayo

4. U

rique

5. B

ato

pila

s

6. C

hoix

7. S

extin

8. H

um

aya

9. B

adiraguato

10. T

am

azula

11. R

am

os

12. P

iaxtla

13. P

resid

io

14. B

alu

art

e

15. A

caponeta

All Years

La Nina (Hi SOI)

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

Fraction of Annual Average

Basins

Composite

Composite JJAS Average Fraction of Total Annual Streamflow - SOI Based

All Years

El Nino (Lo SOI)

La Nina (Hi SOI)

Influence of ENSO on NAM Influence of ENSO on NAM Water ResourcesWater Resources

• Using composite El Niño/La Niña years from SOI:

• Spatially, it is seen that La Niña’s influence is enhanced in EOF2(south)

• Reason for large influence of La Niña is combined factor of more summer precip. and reduced winter precip. especially in southern basins during La Niñayears:

Effect of ENSO on Annual Flow Partitioning - JJAS Season Flows

0

200000

400000

600000

800000

1000000

1200000

1400000

1600000

1800000

Basins

Tota

l Str

eam

flow

Vol

ume

All Year JJAS

El Nino JJAS

La Nina JJAS

El Niño: Pct Change in JJAS Flow La Niña: Pct Change in JJAS Flow

EOF1 decreases During El Nino

Large sensitivityin EOF2

• Compositing EOF Qr values by strongest correlate (SOI-EOF2, TNI-EOF1 and 3) it is shown that higher JAS runoff fractions tend to occur with La Nina than with El Nino

• Difference in composite means significant @ 90% level in EOFs 1 and 2

• ENSO composite averages bound the all year averages

Interannual Variability Interannual Variability of the Runoff Fraction of the Runoff Fraction (Qr):(Qr):

Qr EOF1(TNI)

Qr EOF2(SOI)

Qr EOF3(TNI)

All Years

El Nino

La Nina0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

JAS Runoff Fraction for EOF Regions Separated by ENSO Phase

All Years

El Nino

La Nina

JJAS Composite JJAS Composite Difference MapsDifference MapsNCEP/NCAR Rean.:NCEP/NCAR Rean.:

• Subtracting SOI-based El-Nino from La-Nina years yields:

• Enhanced Pacific-North American continent SLP gradient

• Weaker E. Pac. Trade winds south of Mexico occur during La Nina compared to El Nino along with increased meridional component…

• Increased meridional winds into Mexico during La Nina present up to mid-levels (though more confined to the coast)

Flux into Mx. increased

Flux out of Mx. decreased

• Modestly enhanced PW field over entire NAM region (except E. Chih) w/ enhanced differences in southern region

JJAS Composite JJAS Composite Difference MapsDifference MapsNCEP/NCAR Rean.:NCEP/NCAR Rean.:

JAS Total Q ENSO JAS Total Q ENSO Correlation Modulated Correlation Modulated by PDO:by PDO:

• Brito-Castillo et al showed that correlations between ENSO and streamflow are significantly modulated by PDO (~ 76-77 shift)

• Correls. between concurrent SOI and Q increase in EOFs 2 and 3 during low PDO phase (79-99) compared to full record and compared to PDO high phase (45-76)

• Correl. between concurrent TNI and Q are significantly negative in EOFs 1(North) and 2(south) in high PDO phase (45-76)

• Low PDO phase exhibits weaker correl in EOF1, no correl in EOF2 but stronger correl in EOF3(East)

Correlation Scores Between SOI and EOF Zone Averaged Runoff for High and Low PDO Phases

-0.50

-0.40

-0.30

-0.20

-0.10

0.00

0.10

0.20

0.30

0.40

0.50

SOI-PDO High (1945-1976:Jun-Sep) SOI-PDO Low (1976-1999:Jun-Sep)

Lag

Co

rre

lati

on

Zone 1

Zone 2

Zone 3

Correlation Scores Between TNI and EOF Zone Averaged Runoff for High and Low PDO Phases

-0.60

-0.50

-0.40

-0.30

-0.20

-0.10

0.00

0.10

0.20

0.30

0.40

0.50

TNI-PDO High (1945-1976:Jun-Sep) TNI-PDO Low (1976-1999:Jun-Sep)

Lag

Co

rre

lati

on

Zone 1

Zone 2

Zone 3

S

S

S

SS

S

S

ConclusionsConclusions

• The North American Monsoon System exerts significant influence on regional streamflow both in the U.S. and in Mexico with effects being much more pronounced in Mexico

• Headwater systems in the Sierra Madre obtain, on average 50-85% of their annual flow from July-Oct in response to monsoon rains, compare to ~25% for Gila R.

• 3 coherent regions capture a significant majority of the spatial coherence in seasonal precipitation and streamflow (North, South and East)

• Monthly and seasonal rainfall runoff correlations and runoff fraction exhibit sub-regional behavior that is reasonably well encapsulated by the EOF composites; southern basins appear to achieve a ‘conditioned state’

ConclusionsConclusions• SOI impact on EOF2 (south) streamflow seems quite clear

• Significant positive correl.• La Nina (+ SOI) occurs with increased JJAS flow while El Nino (- SOI) occurs with decreased

JJAS flow• Reduced cool season flows also occur during La Nina results in JJAS having possessing large

fraction of annual flow• Mechanisms for increased streamflow seems to be that SOI favors the northward transport of

tropical moisture into southern MX resulting in higher PW values

• Impact of SOI on northern regions is not as well resolved • ENSO as defined by TNI or Nino3.4 indices exhibits neg. correl. with

EOF1 streamflow (and less so with EOF3, perhaps Atlantic influenced?)• Relationship mostly expressed through reduced JJAS flow during El Nino events and NOT as

substantial increase of JJAS flow during La Nina as with SOI• Broadly consistent with findings of Grantz and Rajagopalan

• PDO effects:• SOI:Q correlation in EOF2 increases during low PDO phase (1977-1999) compared full record

while TNI:Q correlation in EOF1 is greater during high PDO phase (1945-1976).• Nearly all basins exhibit higher JJAS fractions of total annual flow prior to 1977 than after 1977

though differences are on the order of 5-10%.• Change in JAS fraction of annual flow is explained by all basins exhibiting greater than or equal

cool season flows post 1977 compared to pre 1977. Increase in cool season flows result in shift in ‘center of volume’ of annual streamflow since 1977.

• Changes in JJAS flows across 1976-77 climate shift are regional dependent with EOF1 possessing increases in JJAS flow post 1977, EOF2 flows generally decreasing since 1977 and EOF3 flows showing mixed signals

NAME research is funded bythe NOAA-OGP with contributions from NSF, NASA and the Mexican Government

Publications:

–Gochis, D.J., L. Brito-Castillo, W.J. Shuttleworth, 2005: Hydroclimatology of the North American Monsoon region in northwest Mexico. J. Hydrol, In press.

–Grantz, K., B. Rajagopalan, M. Clark, and E. Zagona, Spatio-Temporal Variability of the North American Monsoon (submitted), Journal of Climate, Special issue on the North American Monsoon, 2005.

PDO Effect on JJAS StreamflowPDO Effect on JJAS Streamflow

JJAS Average Streamflow Pre- & Post-1977

0.0

50.0

100.0

150.0

200.0

250.0

300.0

350.0

SPDCSEXT

RAMO

BATO

MAYO

CHINURIQ

HUMA

PIAX

PRESBALU

ACAPCHO

I

BADI

TAMA

Basins

Str

ea

mfl

ow

(m

m)

Pre 1977

Post 1977

East North South Low Elev.

JAS Standardized Streamflow Anomalies - High - Low

East Northwest South Low Elev.

(Graphical Assist. by Todd Lane - NCAR)

1976-77 Climate Shift