GEOS
595e: Journal Club
Spring 2007
Reading Focus Questions
Week1:
Streamflow
reconstruction: Classic to current methods and results (Jan 24th)
submitted by Erika W.
Introduction:
The
three papers for this week all deal with reconstructions of
streamflow in the Colorado River Basin. The studies were completed
with different objectives in mind. Each study uses increasingly
"sophisticated" analytical methods and produces somewhat
different reconstructions. Many results are similar between studies,
though, particularly the strongest drought and pluvial time periods.
Reading:
S45: Schulman, E. 1945. Tree-ring hydrology of the Colorado River Basin. University of Arizona Laboratory of Tree-Ring Research Bulletin No.2 XVI (4): 51p.
SJ76: Stockton, C. W. and G. C. Jacoby. 1976. Long-term surface water supply and streamflow levels in the Upper Colorado River Basin. Lake Powell Research Project Bulletin No.18: 70p.
WGM06: Woodhouse, C. A., S. T. Gray and D. M. Meko. 2006. Updated streamflow reconstructions for the Upper Colorado River Basin. Water Resources Research 42 (W05414): 16.
Reading questions:
Why were these three studies undertaken? What is the fundamental problem that each set of authors attempts to solve? How did the objective alter the analyses completed? Have the studies become more or less ambitious in their stated objectives through time?
What are some of the differences in sampling strategies between the studies?
How do the authors of each study deal with the perpetual problems of standardization and autocorrelation?
SJ76 state that they used more "modern dendrohydrology" methods than S45. In what ways are the methods more “modern,” and is there also an increase in sophistication between the SJ76 and WGM06 studies? Have the analyses gotten "better" through time?
What does each study suggest about spatial variability in the sub-basins?
Calibration against "naturalized" (a.k.a. "virgin") flows appears to be an issue in all of these studies. Have the strategies for obtaining naturalized flows changed? Is there a way to avoid this problem?
Trees tend to reconstruct low-flow years better than high-flow years. How might this have changed the results of these studies? How well do each set of authors address this issue?
WGM06 have several hypotheses as to why their reconstruction differs from SJ76. How could they have tested these hypotheses?
WGM06 briefly mention that there has been greater tree growth than expected from streamflow in recent decades, an issue raised in several dendroclimatic studies. What effect would this have on the resulting reconstructions?