[LTER-mcm-pi] wait... there IS more variability in streamflow since 2002!

Mon Aug 17 21:00:51 MDT 2015

Need to plot dt/dz for temperature from the CTD data down the water column before and after the flood year. This will give us a quick look at water column stability through time.

JP

From: mcm-pi [mailto:mcm-pi-bounces at lists.lternet.edu] On Behalf Of Peter Doran
Sent: Monday, August 17, 2015 7:10 PM
To: mcm-pi at lists.lternet.edu
Subject: Re: [LTER-mcm-pi] wait... there IS more variability in streamflow since 2002!

It was the conductivity I was remembering. This is a lake level corrected plot for ELB conductivity. Note the variation post flood year. We can try and update this for Boulder as well.

-Peter

Peter Doran, Professor and John Franks Chair

Department of Geology and Geophysics

E235 Howe Russell Geosciences Complex

Louisiana State University

Baton Rouge, Louisiana, USA 70803

Ph: 225-578-3955

Fx: 225-578-2302

http://geology.lsu.edu/People/Faculty/item73533.html

On 8/17/15 6:16 AM, Peter Doran wrote:

I seem to recall a difference in the pre and post flood year variability in upper lake temperatures in the analysis we did a few years ago as well. I will check.

Andrew, we can include any met variability analysis to the group in our presentation of the summaries in Boulder. Mike has now created a slot for met which was missing. I'll talk to Maciek when he's in BR this week

-Peter

On Aug 16, 2015, at 6:58 PM, Andrew Fountain <andrew at pdx.edu><mailto:andrew at pdx.edu> wrote:

Mike,

Is the variance higher because the flow is higher after the flood year?  Did you do a coefficient of variation analysis?

Maciek is working on air temp and soil temp.

Andrew

On Sun, Aug 16, 2015 at 1:55 PM, Michael Gooseff <michael.gooseff at colorado.edu<mailto:michael.gooseff at colorado.edu><mailto:michael.gooseff at colorado.edu><mailto:michael.gooseff at colorado.edu>> wrote:

Hi all,  (greetings from Toolik)

I wanted to follow up on a conversation we had a few months ago about the variability in the MDVs since 2002.  Recall that Chris shared with us a spreadsheet of annual flow volumes from the Fryxell basin streams, and that the analyses suggested that variance had gone down in the 2003-2013 period (compared to 1990-2001).  My recollection is that this sort of took the wind out of our sails on that discussion.

I revisited these analyses in the past week in trying to get some writing and a figure together for the Bioscience paper that Andrew is leading and Chris and I revised the analyses -

 1.  We fixed an error we found in the calculation of % change of variance from pre- to post-flood.

 2.  We took out the 2001-02 flood year (to look at 'before' and 'after', we argue that we shouldn't lump the flood year in either if we postulate that it is a turning point)  -> doing these 2 steps alone resulted in an increase of variance of 185% in the post-flood vs pre-flood period...

 3.  However, we had several seasons in each period of poor or no flow estimates because of technical problems with gauges or controls (3 in the pre-flood period (~4%), 7 in the post-flood period (~7%)).  Chris came up with some nice correlations to fill in these gaps (no relationship has an R2 < 0.70), and the result is an increase in variance of 48% in the post-flood period vs. the pre-flood period.  This is (I think) our best analysis of the flow records and indicates increased variance in the recent decade.  (most updated figure inserted below with snip of text)

So, I'd like to suggest that we revisit the notion that our system is becoming more variable as we emerge from the cooling trend as a potential theme for the renewal.  What are some of the other ecosystem parameters we might evaluate for similar changes?

-> JP showed us UW PAR data last week that looks like it could be more variable, but will be hard to evaluate with the gaps

-> Soil or Air temperature analyses?

-> Soil moisture analyses from a long-term plot?

-> chl-a in lake photic zone?

If we can demonstrate change in ecosystem temporal trends (the synthesis paper mega plot) and increased variance of some drivers, I think we have an easy sell on the motivation for the proposal...

Talk to you all on Thursday.

Cheers

-Mike

Snip of text:  [in the pre-flood period] mean annual streamflow was 0.85 x 106 m3 with a standard deviation of 0.93 x 106 m3 and a variance over this period of 0.86 x 109 m3.  The highest annual flows on record were observed in the 2001-02 flow season (total streamflow over 5 x 106 m3).  Since this 'flood year', mean annual discharge has increased (2003-2013; 1.59 x 106 m3), as has the standard deviation (1.13 x 106 m3) and the variance (1.28 x 109 m3, an increase of 49%).

[cid:A5029176-02CE-4C56-8D60-60E7C7B196AD]

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