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Research partners: Adam Csank: Desert Research Ins�tute Steph McAfee: University of Nevada, Reno Greg Pederson: USGS-‐Bozeman Greg McCabe: USGS-‐Denver Steve Gray: USGS-‐Anchorage Water management partners: Bureau of Reclama�on, Lower Colorado District Colorado River District (State of CO) Denver Water, Colorado NOAA Colorado Basin River Forecast Center Salt River Project, Arizona
Disentangling the Influence of Temperature and Antecedent Soil Moisture on Colorado River Water Resources Project start and dura�on: September 1, 2014, 24 months Funder: U.S. Department of the Interior, Southwest DOI Climate Science Center
Purpose of the workshop: Year 1 assessment and Year 2 direc�ons for this project Plan for the Day (workshop agenda):
Summary of results to date (instrumental data analysis)
Work in progress (tree-‐ring reconstruc�ons) Planning for future climate impacts analysis Feedback, ques�ons, discussion, comments , sugges�ons throughout!
Introduc�ons
Disentangling the Influence of Temperature and Antecedent Soil Moisture on Colorado River Water Resources
PART 1: How have the contribu�ons of antecedent soil moisture, spring/summer temperatures, and total cool season precipita�on varied during the major periods of low flow in the upper Colorado River basin (UCRB)? And more generally, what have been their contribu�ons to water year flow?
Data Gridded climate data from PRISM for total monthly precipita�on, average monthly temperature (4 km resolu�on)
Monthly soil moisture storage from McCabe and Wolock (2011) monthly water balance model
Water year natural flow es�mates for the Colorado River at Lees Ferry and major tributaries
Analysis period: 1906-‐2012
Data have been converted to percen�les in compara�ve analyses
Analysis Variables October-‐April total precipita�on March, March-‐May, March-‐July average temperature October or November soil moisture
correla�ons
Selec�on of temperature, precipita�on, and soil moisture variables for analysis
Monthly mean temperature Monthly total precipita�on
Correla�ons with Colorado R Lees water year flow, 1906-‐2012 (prior July – September)
5 Oct-‐April total precipita�on April, March-‐Apr-‐May, and March-‐July
average temperature
*
correla�ons
Antecedent soil moisture assessment
Correla�ons of Lees Ferry water year flow with soil moisture storage and monthly flows for the common years, 1981-‐2010, prior October to September.
McCabe/Wolock water balance model soil moisture capacity
CBRFC model soil moisture storage
monthly Colorado River at Lees Ferry flows
McCabe/Wolock soil moisture was selected (longer dataset than CBRFC, higher correla�ons with flow than CBRFC and monthly flows) October and November selected, based in large part on our hypothesis of antecedent soil moisture influence
correla�on
Quan�fying the contribu�on of cool season precipita�on, temperature, and antecedent soil moisture in water year flow
Stepwise model with pool of 6 predictors: Oct-‐Apr precipita�on March, March-‐May, Mar-‐Jul temperature Oct , Nov soil moisture
Step Multiple Multiple R-square F - to p-level Variables+in/-out R R-square change entr/rem included
OctAprP 1 0.813312 0.661476 0.661476 205.1700 0.000000 1MarJulT 2 0.859178 0.738188 0.076712 30.4723 0.000000 2novsoil 3 0.870644 0.758021 0.019834 8.4423 0.004488 3
March-‐July temperature accounts for only 8% of the total variance explained, but is it more important in certain years?
Colorado River at Lees Ferry, natural flows, 1906-‐2012
Major Droughts*
*using defini�on from Drought Catalog for Reclama�on -‐ below average flows broken by no more than 1 year of above average flow
Average values for each hydroclima�c variable across all years in a given drought period, color coded by drought
9
Individual years with in major droughts: percen�le values of WY flow, and variables that influence flow
1930s
1950s
2000s
Individual years with in major droughts: percen�le values of WY flow, and variables that influence flow
1930s
1950s
2000s
Lees Ferry flow and October-‐April total precipita�on, in percen�les
Lees Ferry flow and October-‐April total precipita�on, in percen�les
Gray bar = 1 standard devia�on from the mean; these are years when Lees WY flow is markedly greater or less than Oct-‐Apr total precipita�on (ver�cal bars are individual years)
flow greater rela�ve to precip
flow less rela�ve to precip
Trend in March-‐July average temperature, 1906-‐2012
A closer look: 4 flavors of years
Colorado River flow
A closer look: 4 flavors of years
Colorado River flow
Water year flow and cool season precipita�on, averaged for each set of years
Years with flow < precipita�on above median flow yrs below median flows yrs
Years with flow > precipita�on above median flow yrs below median flows yrs
N = 4 N = 9 N = 10 N = 7
Expe
cted
flow
giv
en P
PT
GRE
ATER
Observed streamflow
MEDIAN > MEDIAN < High-‐flow + Low-‐flow +
Above or below median flow years
Flow > rela�ve to precipita�on Below median temperatures Soil moisture corresponds to
moisture anomalies
Water year flow, cool season precip, March-‐July temperature, and November soil moisture averaged for each set
Expe
cted
flow
giv
en P
PT
GRE
ATER
LE
SS Observed streamflow
MEDIAN > MEDIAN < High-‐flow +
Low-‐flow -‐
Low-‐flow +
Below median flow years Flow < rela�ve to precipita�on Above median temperatures. Soil moisture corresponds more
closely to precipita�on
Above or below median flow years
Flow > rela�ve to precipita�on Below median temperatures Soil moisture corresponds to
moisture anomalies
Water year flow, cool season precip, March-‐July temperature, and November soil moisture averaged for each set
Expe
cted
flow
giv
en P
PT
GRE
ATER
LE
SS Observed streamflow
MEDIAN > MEDIAN <
High-‐flow -‐
High-‐flow +
Low-‐flow -‐
Low-‐flow +
Below median flow years Flow < rela�ve to precipita�on Above median temperatures. Soil moisture corresponds more
closely to precipita�on
Above or below median flow years
Flow > rela�ve to precipita�on Below median temperatures Soil moisture corresponds to
moisture anomalies
Above median flow years Flow < rela�ve to precipita�on Temperatures are not warmer
but nearly average…..
These 7 years coincide with some of the we�est ranking winters. How do they compare with 7 we�est winters with correspondingly high flows?
WETTEST COOL SEASONSWY Oct-‐Apr, percentile1973 0.9912005 0.9811941 0.9721952 0.9631979 0.9541993 0.9441980 0.9351997 0.9261942 0.9171920 0.9071909 0.8981995 0.8892011 0.8801907 0.8701986 0.8611906 0.8521985 0.8431978 0.8331917 0.8241984 0.8151929 0.8061958 0.7961999 0.7871932 0.7781914 0.7691911 0.7591916 0.750
Above median flow years with flow < ppt
We�est winters with similarly high flows
Total cool season precipita�on, in percen�le, averaged for 2 sets of years, by month
Differences in Distribu�on of Precipita�on over the Cool Season?
Oct-‐Apr cool season precipita�on we�est winters – high-‐flow<precip yrs
Seasonal pa�erns vary, but in general, the we�est winters with correspondingly high flows show greater precipita�on in headwaters regions, par�cularly for the Yampa, main stem, and Gunnison.
Mean temperature, in percen�le, averaged for 2 sets of years, by month
Differences in Average Monthly Temperatures, March-‐July?
March mean temperature we�est winters – high-‐ flow <precip yrs
March mean temperature we�est winters – high-‐ flow <precip yrs
In the in contrast to the years with flow < precipita�on, in the we�est winters , March temperatures are cooler, especially in the upper por�on of the Upper Basin. In July, temperatures are slightly cooler in these years, except in the southwestern part of the basin.
July mean temperature we�est winters – high-‐flow<precip yrs
One more thing: If we just use these 30 years – when the difference between flow and cool season precipita�on is greater than 1 standard devia�on – what variables best es�mate water year flow?
As before, stepwise model with pool of 6 predictors: Oct-‐Apr precipita�on March, March-‐May, Mar-‐Jul temperature Oct , Nov soil moisture
But n = 30 years
Lees Ferry flow, years difference between flow and cool season precipita�on > 1 standard devia�on: Regression model
Step Multiple Multiple R-‐square F -‐ to p-‐level+in/-‐out R R-‐square change entr/rem
Mar-‐Jul T 1 0.647 0.419 0.419 20.190 0.000Oct-‐Apr P 2 0.781 0.611 0.192 13.281 0.001Oct soil 3 0.831 0.691 0.081 6.802 0.015
Summary
Spring/summer temperatures do not explain a large part of the total variance in water year flow, but….
In years when the difference between cool season precipita�on and flow is greatest, temperatures may be especially influen�al (in high flow years, with even we�er winters, this rela�onship is a bit less straigh�orward).
Some related follow-‐up ques�ons from Denver Water and Colorado River District visits this summer: 1. In the regression model using climate variables to es�mate Lees Ferry water year flow, a) do models for more recent years look different? And b) does adding water year precipita�on or summer precipita�on to the predictor pool change anything? 2. Analysis for sub-‐basins – any differences, especially between San Juan Dolores and Green/Yampa?
1. For the model of Lees WY flow, what happens if we look at different periods of �me? Lees Ferry modeling with different �me periods (1960-‐2012, 1973-‐2012, 1983-‐2012): Using same pool, Oct-‐Apr precip, Apr T, Mar-‐May T, Mar-‐Jul T, Oct soil m, Nov soil m Li�le difference in models for the 3 sub-‐periods: All had Oct-‐Apr precip as 1st step, explaining about 70% of the variance (> than for the full period)
All had a temperature variable as 2nd (Mar-‐Jul, except 1972-‐2012 was April instead), ~6% variance explained.
All had Nov soil as 3rd (3%, 2%, 4% added variance explained)
2. What happens if we add water year precipita�on as a poten�al predictor? Full period: the same model resulted, but WY precipita�on entered as 4th variable, explaining 2% of the variance.
Similar result for 1960-‐2012, but WY precip is not significant as a predictor (4th variable, 1% explained)
For the 30-‐ and 40-‐yr sub periods (1973-‐2012, 1983-‐2012), WY precip replaced Oct-‐Apr precip as 1st predictor)*
*Some of this could be due to climate data issues?.
3. What if spring/summer precipita�on is added to the pool as a poten�al predictor? May, June, July, May-‐June-‐July (MJJ) and May-‐Aug (MJJA) precipita�on were added to the pool For the full period, a�er Oct-‐Apr P and Mar-‐Jul T, July P entered as the 3rd variable (3%), then Nov soil (2%) then MJJA precip (1%)
In the 3 sub-‐periods, July P or Aug P entered a�er Oct-‐Apr or WY precip (2nd or 3rd predictor)
Years when flow and cool season precip differences are > 1 standard devia�on
Sub-‐basin results: Ex
pect
ed fl
ow g
iven
PPT
GRE
ATER
LE
SS
Observed streamflow:Green/Yampa
MEDIAN > MEDIAN <
High-‐flow + Low-‐flow +
High-‐flow -‐ Low-‐flow -‐
MEDIAN > MEDIAN <
Observed streamflow
MEDIAN > MEDIAN <
High-‐flow -‐
High-‐flow +
Low-‐flow -‐
Low-‐flow +
Expe
cted
flow
giv
en P
PT
GRE
ATER
LE
SS
High-‐flow + Low-‐flow +
High-‐flow -‐ Low-‐flow -‐
Green/Yampa San Juan/Dolores*
13
3
11 4
12 5 14
6
Years when flow and cool season differences are > 1 standard devia�on
Sub-‐basin results
*San Juan/Dolores regression model selected Oct instead of Nov soil moisture; the only difference in the sub-‐basin models
Observed streamflow
High-‐flow -‐
High-‐flow +
Low-‐flow -‐
Low-‐flow + 10
9 7
4
MEDIAN > MEDIAN <
Green/Yampa San Juan/Dolores
MEDIAN > MEDIAN < MEDIAN > MEDIAN <
UCRB
13 6
5 14 12
11 4
3
Years when flow and cool season differences are > 1 standard devia�on
UCRB and sub-‐basin comparison <
Exp
ecte
d flo
w g
iven
PPT
>
Distribu�on of years with flow/cool season precipita�on differences > 1 standard devia�on
Expe
cted
flow
g
iven
PPT
>
<
Observed streamflow
MEDIAN > MEDIAN < High-‐flow + Low-‐flow +
High-‐flow -‐ Low-‐flow -‐
Discussion
Resource management feedback, needs, challenges for using these results, sugges�ons for addi�onal work
Research challenges -‐ Climate data uncertain�es: Steph McAfee, Greg Pederson, Greg McCabe -‐ Measuring antecedent moisture; sources, op�ons and alterna�ves? Baseflows?
Climate data uncertain�es Steph McAfee, Greg Pederson, Greg McCabe
Baseflows have been suggested as a be�er metric for antecedent moisture condi�ons
Colorado River at Cameo, es�mated base flow and water year streamflow, 1983-‐2012
baseflow
streamflow
Lunch!
PART 2. Using tree-‐ring reconstruc�ons of antecedent soil moisture, temperature, and precipita�on for past centuries, are contribu�ons of these three factors to low flows over past centuries similar to those of the 20th and 21st century? Are there differences in these contribu�ons between cooler and warmer �me periods? Have contribu�ons changed over �me? What are common or unusual sets of clima�c and spa�al factors that have led to low flows in the past?
In progress:
Preliminary results for Reconstruc�ons
Reconstruc�ng Antecedent Soil Moisture Using Tree Rings: Becky Brice
Can a mul�-‐proxy approach to tree-‐ring data be used to reconstruct temperature? Adam Csank
Comparing reconstruc�ons of precipita�on and streamflow: Connie Woodhouse
Reconstruc�ng Antecedent Soil Moisture Using Tree Rings
Becky Brice
Can a mul�-‐proxy approach to tree ring data be used to reconstruct temperature? Adam Csank
Comparing reconstruc�ons of UCRB cool season precipita�on and water year streamflow
Connie Woodhouse
4 predictor chronologies in the model 70% of the variance explained
Observed and reconstructed UCRB October-‐April Precipita�on, 1906-‐1999
Reconstructed Lees Ferry flow and October-‐April total precipita�on, in percen�les, 1906-‐1997
flow greater rela�ve to precip
flow less rela�ve to precip
Gray bar = 1 standard devia�on from the mean; these are years when Lees WY flow is markedly greater or less than Oct-‐Apr total precipita�on (ver�cal bars are individual years)
Reconstructed Lees Ferry flow and October-‐April total precipita�on, 1906-‐1997
Reconstructed (top) and observed (bo�om) Lees Ferry flow and October-‐April total precipita�on, 1906-‐1997/2012
Ver�cal bars are years when Lees WY flow is > 1 SD greater (blue) or less (orange) than Oct-‐Apr total precipita�on percen�le values.
Correla�on comparison: Observed WY Lees flow & Oct-‐Apr precip, r = 0.820 Reconstructed WY Lees flow & Oct-‐Apr precip, r = 0.836
Reconstructed and observed differences between Lees Ferry flow and October-‐April total precipita�on, 1906-‐1997
Reconstructed Lees Ferry flow minus October-‐April total precipita�on 1569-‐1997
Reconstructed Lees Ferry flow minus October-‐April total precipita�on 1569-‐1997
Period with flow o�en less than expected given Oct-‐Apr precipita�on…..Warmer??? Drier antecedent condi�ons???
Ques�ons, comments, sugges�ons?
PART 3. What is the sensi�vity of UCRB low flows to different scenarios of changes in antecedent soil moisture, winter precipita�on, and winter/spring temperatures projected by CMIP5 models? Do “no-‐analog” sets of seasonal condi�ons exist (a warm, winter wet) and what is the impact on flow? How common are the set(s) of climate condi�ons causing past low-‐flow events in the ensembles and under what circumstances they occur (e.g., emissions scenario, �me period, model)? We Need Feedback on this part especially!
Op�ons for exploring future climate impacts on the UCRB
Steph McAfee
Discussion Are we heading in the right direc�on on the research ques�ons?
What kinds of informa�on, data, and products would be useful to you?
Wrap up Plans for the next (and final) year of the project
Advice on the final project workshop (for broader resource management audience; whom to invite?)
OTHER SLIDES
CBF-‐WBM WBM-‐Lees monthly flows
CBF -‐Lees monthly flows
oct nov dec jan feb mar apr may jun jul aug sep
0.80 0.81 0.81 0.81 0.75 0.66 0.58 0.40 0.77 0.95 0.93 0.92
0.83 0.83 0.78 0.71 0.74 0.74 0.58 0.60 0.87 0.87 0.91 0.89
0.82 0.80 0.86 0.53 0.75 0.74 0.75 0.93 0.95 0.93 0.94 0.81
Correla�ons between soil moisture capacity from the CBRFC model (CBF), soil moisture storage from the McCabe/Wolack water balance model (WBM), and monthly Colorado River at Lees Ferry flows (Lees monthly flows), for the common years, 1981-‐2010.
All values are significant at p < 0.05
Addendum on regression models explained Lees Ferry water year flow, with cool season precipita�on, March-‐July temperatures, and November soil moisture (model on slide 7). The following graphics highlight what flow years are most improved with, first, the addi�on of temperature in the regression model (along with precipita�on), then with both temperature and November soil moisture.
Colorado river flow values (in percen�le) for the 10 years with the most improved fit when temperature is added to the precipita�on-‐only model
Colorado river flow values for the 10 years with the most improved fit when soil moisture is added to the precipita�on + temperature model
Summary With respect to the regression model: While cool season precipita�on explains most of the variance in water year flow, temperatures may contribute in low flow years, while soil moisture may influence flows in the very we�est years
The Role of Temperature (and soil moisture) in Media�ng Rela�onships between Cool Season Precipita�on and Water Year Streamflow in the UCRB
Connie Woodhouse, University of Arizona With Adam Csank (Desert Research Ins�tute), Steph McAfee (Univ. of Nevada, Reno), Greg Pederson (USGS-‐Bozeman), Greg McCabe (USGS-‐Denver), and Steve Gray (USGS-‐Anchorage)
This work is being funded by a DOI Southwest Climate Science Center grant.
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