geog5839.21, the colorado river
TRANSCRIPT
November 20
Drought and dendrohydrology
WHAT ISDROUGHT?
A drought refers to an extended period of time when a region receives substantially less moisture than it does in most years.
Source: Chazz Layne
METEOROLOGICAL DROUGHT
Source: David Sauchyn
HYDROLOGICAL DROUGHT
Source: library_chic
AGRICULTURAL DROUGHT
This past summer, the central and western US experienced the worst drought in two decades.
Corn stalk destroyed by severe drought near Round Rock, Texas.Jay Janner
bushels of corn per acre
Despite the increase in productivity, you still can’t grow corn without water.
198019881983
1993(flood year)
2002
Source: USDA
The Monticello Nuclear Generating Plant in Monticello, Minnesotashekleton
The mighty Mississippi in 1988
In the 1940s, Tucson was a small city with less than 40,000 residents.
Nearly 1 million people now live in the Greater Tucson Metropolitan Area.
Photograph: Nevada Tourism Media Relations
The Central Arizona Project is a 336-mile canal that diverts water from the Colorado River into central and southern Arizona.
Source: Chazz Lane
Water transfers in the American southwest
Courtesy Glen MacDonald
Photograph: Ben Amstutz
Photograph: Ben Amstutz
Photograph: Michael Koukoullis
COLORADO RIVER COMPACTTHEdivides water from the Colorado River
among seven western states.
Observed discharge, Colorado River
Compact allocation (16.5 MAF)
Low reservoir
Photograph: Glen MacDonald
We’ve never had to worry about our water resources. Our children will not enjoy that luxury.“ ”Patricia Mulroy
Southern Nevada Water Authority
Observed discharge, Colorado River
Compact allocation (16.5 MAF)
READINGDavid Meko and Connie Woodhouse (2010), Application of streamflow reconstruction to water resources management. M.K. Hughes et al. (eds.), Dendroclimatology, Developments in Paleoenvironmental Research.
1How have tree rings been used to understand the hydrology of the Colorado River?
2More generally, what do tree rings have to say about drought across North America?
TRACING THE COLORADO
The history of precipitation and runo! in the Colorado Basin as indicated by tree-rings
Edmund ShulmanPh.D. Thesis Harvard University1944
“The growth of trees is undoubtably controlled more by the movement of water than by the movement of any other single substance.”
Hal Fri!sTree Rings and Climate
water stress
reduced cell division
less cell expansion
reduced photosynthesisnarrow ring
INDIRECTRELATION
READINGDavid Meko and Connie Woodhouse (2010), Application of streamflow reconstruction to water resources management. M.K. Hughes et al. (eds.), Dendroclimatology, Developments in Paleoenvironmental Research.
Connie Woodhouse University of Arizona
Source: Woodhouse et al., 2006
stream gauge
tree-ring estimate
Source: Woodhouse et al., 2006
Source: Woodhouse et al., 2006
Average reconstructed annual flow for the period 1844–1848 was lower than the observed flow for 1999–2004.
“ ”Connie Woodhouse et al.
Water Resources Research, 2006
The long-term perspective provided by tree ring reconstructions points to looming conflict between water demand and supply in the upper Colorado River basin.
“ ”Connie Woodhouse et al.
Water Resources Research, 2006
M E G A D R O U G H Tintensity at least equivalent to modern multiyear droughts
duration longer than the several years to decade thereof
Seager et al., Journal of Climate, 2008
Dave Meko University of Arizona
Relic tree, circa 323 BC Harmon Canyon, Utah
1,200 years of Colorado River discharge Meko et al., GRL, 2007
COLORADO RIVER COMPACTTHEdivides water from the Colorado River
among seven western states.
Tree rings provided the central evidence that caused municipal water agencies to
“RETHINK OLD ASSUMPTIONS”
about worst-case scenarios for reservoir operations and re-evaluate the potential duration and geographic scope of severe drought.
GLOBAL DROUGHT FROM TREES
Terry Hash planted 800 acres of co!on, corn, wheat and sorghum. Almost all of it was destroyed by the 2011 Texas drought.Jay Janner
Palmer Drought Severity IndexThe PDSI incorporates historical records of precipitation and temperature into a water-balance model to estimate
the amount of water available in the soil relative to average conditions and is typically produced once a month.
+4 extreme wet
-4 extreme drought
(compared to ‘average’ for that place)
How much water is in this soil?
One hundred years of drought history around Minneapolis-St. Paul
Source: North American Drought Atlas
Ed Cook Lamont-Doherty Earth Observatory
Drought grid (blue dots) Cook et al., JQS, 2010
Average PDSI, AD 1580 to 1600
HOW DO WE KNOW
THIS WORKS?
Dalhart, TX, 1938
Tree ring
Source: David Stahle
June 1833All-time record flooding on the Arkansas, Canadian, and Verdigris Rivers in Oklahoma. 950 displaced Creek and Seminole drown on floodplain farmsteads.
Source: David Stahle
Source: David Stahle
How has the extent of severe drought changed through time?
Observed (blue) and tree-ring (red) PDSI in ‘The West’
A 1,000 years of drought in the West Cook et al., Science, 2004
Can the Drought Atlas help us place historical events within a context of long-term environmental change?
Square Tower HouseMesa Verde, Colorado
Great Pueblo DroughtA.E. Douglass (1929)
Source: David Stahle
North American Drought Atlas h!p://www.ncdc.noaa.gov/cgi-bin/paleo/pd08plot.pl
Much of the world’s population lives in monsoon Asia and depends on monsoon rainfall for water and agricultural fertility.
“ ”Wahl and Morrill
Science, 2010
E R Wahl, C Morrill Science 2010;328:437-438
Average spatial pa!erns of precipitation and wind during summer
MONSOON ASIA DROUGHT ATLAS
h!p://www.ncdc.noaa.gov/paleo/pubs/cook2010/cook2010.html
E R Cook et al. Science 2010;328:486-489
Tree rings show extent of ‘Great Drought’, 1876-1878
The tree-ring record shows that droughts lasting decades have routinely gripped western North America.
“Jonathan Overpeck and Bradley Udall
”
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