t/Ag/EnSc/EnSt 404/504 - Global Change) t/Ag/EnSc/EnSt 404/504 - Global Change) Water Resources (from IPCC WG-2, Chapter Water Resources (from IPCC WG-2, Chapter Water Resources Water Resources Primary Source: Primary Source: IPCC WG-2 Chapter 3 – Freshwater Resources and Their Management IPCC WG-2 Chapter 3 – Freshwater Resources and Their Management
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(Mt/Ag/EnSc/EnSt 404/504 - Global Change) Water Resources (from IPCC WG-2, Chapter 3) Water Resources Primary Source: IPCC WG-2 Chapter 3 – Freshwater.
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(Mt/Ag/EnSc/EnSt 404/504 - Global Change)(Mt/Ag/EnSc/EnSt 404/504 - Global Change) Water Resources (from IPCC WG-2, Chapter 3)Water Resources (from IPCC WG-2, Chapter 3)
Water ResourcesWater Resources
Primary Source: Primary Source:
IPCC WG-2 Chapter 3 – Freshwater Resources and Their ManagementIPCC WG-2 Chapter 3 – Freshwater Resources and Their Management
(Mt/Ag/EnSc/EnSt 404/504 - Global Change)(Mt/Ag/EnSc/EnSt 404/504 - Global Change) Water Resources (from IPCC WG-2, Chapter 3)Water Resources (from IPCC WG-2, Chapter 3)
Human Activities Affecting Water ResourcesHuman Activities Affecting Water Resources
(modified after Oki, 2005)
clear land
irrigate?
drain?
less ET?
less precip?
(Mt/Ag/EnSc/EnSt 404/504 - Global Change)(Mt/Ag/EnSc/EnSt 404/504 - Global Change) Water Resources (from IPCC WG-2, Chapter 3)Water Resources (from IPCC WG-2, Chapter 3)
Human Activities Affecting Water ResourcesHuman Activities Affecting Water Resources
(modified after Oki, 2005)
veg. change?
soil moisture?
more ET?
more precip ?
(Mt/Ag/EnSc/EnSt 404/504 - Global Change)(Mt/Ag/EnSc/EnSt 404/504 - Global Change) Water Resources (from IPCC WG-2, Chapter 3)Water Resources (from IPCC WG-2, Chapter 3)
Drivers of Water Consumption?Drivers of Water Consumption?
• PopulationPopulation
• Food consumptionFood consumption
• Economic policy (including water pricing)Economic policy (including water pricing)
(Mt/Ag/EnSc/EnSt 404/504 - Global Change)(Mt/Ag/EnSc/EnSt 404/504 - Global Change) Water Resources (from IPCC WG-2, Chapter 3)Water Resources (from IPCC WG-2, Chapter 3)
Runoff Runoff ChangeChange
SRES A2SRES A2
2050s vs.2050s vs.1961-19901961-1990
Seasonality?Seasonality?
(Mt/Ag/EnSc/EnSt 404/504 - Global Change)(Mt/Ag/EnSc/EnSt 404/504 - Global Change) Water Resources (from IPCC WG-2, Chapter 3)Water Resources (from IPCC WG-2, Chapter 3)
Groundwater RechargeGroundwater Recharge Using a global hydrological model - WGHM Using a global hydrological model - WGHM
(Mt/Ag/EnSc/EnSt 404/504 - Global Change)(Mt/Ag/EnSc/EnSt 404/504 - Global Change) Water Resources (from IPCC WG-2, Chapter 3)Water Resources (from IPCC WG-2, Chapter 3)
What is drought?
• One definition:One definition:
• Elements of the definition:Elements of the definition:• deficiency of precipitationdeficiency of precipitation• extended period (how long is "extended"?)extended period (how long is "extended"?)• water shortage for some user ("group or water shortage for some user ("group or
activity") activity")
A deficiency of precipitation over an A deficiency of precipitation over an extended period that causes water extended period that causes water
shortage for some group or activity.shortage for some group or activity.
(Mt/Ag/EnSc/EnSt 404/504 - Global Change)(Mt/Ag/EnSc/EnSt 404/504 - Global Change) Water Resources (from IPCC WG-2, Chapter 3)Water Resources (from IPCC WG-2, Chapter 3)
Drought depends on the user
• Crops rely on stored soil water. Soil water can be rapidly depleted, so that monthly droughts may affect crops.
(Mt/Ag/EnSc/EnSt 404/504 - Global Change)(Mt/Ag/EnSc/EnSt 404/504 - Global Change) Water Resources (from IPCC WG-2, Chapter 3)Water Resources (from IPCC WG-2, Chapter 3)
Drought depends on the user
• Rivers and streams may dry out during seasonal droughts.
(Mt/Ag/EnSc/EnSt 404/504 - Global Change)(Mt/Ag/EnSc/EnSt 404/504 - Global Change) Water Resources (from IPCC WG-2, Chapter 3)Water Resources (from IPCC WG-2, Chapter 3)
Drought depends on the user
• Multi-year droughts Multi-year droughts may deplete ground water that may deplete ground water that supports communities.supports communities.
(Mt/Ag/EnSc/EnSt 404/504 - Global Change)(Mt/Ag/EnSc/EnSt 404/504 - Global Change) Water Resources (from IPCC WG-2, Chapter 3)Water Resources (from IPCC WG-2, Chapter 3)
Drought, more precisely
• Must define Must define the time period the time period over which precipitation is over which precipitation is below normal.below normal.
• Must define what is Must define what is a water shortage a water shortage that affects a that affects a particular activity.particular activity.
(Mt/Ag/EnSc/EnSt 404/504 - Global Change)(Mt/Ag/EnSc/EnSt 404/504 - Global Change) Water Resources (from IPCC WG-2, Chapter 3)Water Resources (from IPCC WG-2, Chapter 3)
Iowa corn yields
1988 drought1993 flood
(Mt/Ag/EnSc/EnSt 404/504 - Global Change)(Mt/Ag/EnSc/EnSt 404/504 - Global Change) Water Resources (from IPCC WG-2, Chapter 3)Water Resources (from IPCC WG-2, Chapter 3)
Recurrence of 100-yr DroughtsRecurrence of 100-yr Droughts
• IS92a IS92a emissionsemissions
• Business-as-Business-as-usual water usual water scenario scenario
(Mt/Ag/EnSc/EnSt 404/504 - Global Change)(Mt/Ag/EnSc/EnSt 404/504 - Global Change) Water Resources (from IPCC WG-2, Chapter 3)Water Resources (from IPCC WG-2, Chapter 3)
Increased Water StressIncreased Water Stress
(Mt/Ag/EnSc/EnSt 404/504 - Global Change)(Mt/Ag/EnSc/EnSt 404/504 - Global Change) Water Resources (from IPCC WG-2, Chapter 3)Water Resources (from IPCC WG-2, Chapter 3)
Runoff Changes - Two AnalysesRunoff Changes - Two Analyses
A1B ScenarioA1B Scenario
Agree on sign of Agree on sign of change?change?
white: < 66%white: < 66%
stippled: > 90%stippled: > 90%
(derived from Milly et al. 2005)(derived from Milly et al. 2005)
(derived from Nohara et al. 2006)(derived from Nohara et al. 2006)
(2081-2100) minus (1981-2000)
Lake MeadLake Mead
(Mt/Ag/EnSc/EnSt 404/504 - Global Change)(Mt/Ag/EnSc/EnSt 404/504 - Global Change) Water Resources (from IPCC WG-2, Chapter 3)Water Resources (from IPCC WG-2, Chapter 3)
Lake Mead Facts• Lake Mead was formed in Black Canyon when the
Hoover Dam was finished in 1935.• Water source for over 22 million people. • Lake Mead supplies water to:
• Las Vegas• 90% of the supply comes from Lake Mead
• Los Angeles• San Diego• Southern California Agriculture
• Extends 110 miles behind the dam• Capacity is 28.5 million acre-feet
• Saylorville = 641,000 acre-feet
(Mt/Ag/EnSc/EnSt 404/504 - Global Change)(Mt/Ag/EnSc/EnSt 404/504 - Global Change) Water Resources (from IPCC WG-2, Chapter 3)Water Resources (from IPCC WG-2, Chapter 3)
Lake Running Dry? The CausesLake Running Dry? The Causes
• Colorado River system is seeing a deficit of Colorado River system is seeing a deficit of
1 million acre-feet of water per year1 million acre-feet of water per year• This amount can supply 8 million people for 1 year.This amount can supply 8 million people for 1 year.
• The water supply is not being replenishedThe water supply is not being replenished• 8 years of continued drought in the region8 years of continued drought in the region• Below average snowfall within the Colorado River Below average snowfall within the Colorado River
watershedwatershed
• Human factorsHuman factors• Human demand has increased as populations in the Human demand has increased as populations in the
southwest have exploded.southwest have exploded.• Increased evaporation off the lakeIncreased evaporation off the lake• Human induced climate changeHuman induced climate change
(Mt/Ag/EnSc/EnSt 404/504 - Global Change)(Mt/Ag/EnSc/EnSt 404/504 - Global Change) Water Resources (from IPCC WG-2, Chapter 3)Water Resources (from IPCC WG-2, Chapter 3)
A ComparisonA Comparison
Lake Mead has dropped over 100 feet in the last 10 years Lake Mead has dropped over 100 feet in the last 10 years to its lowest level since the 1960s.to its lowest level since the 1960s.
September 1998 June 2008September 1998 June 2008
(Mt/Ag/EnSc/EnSt 404/504 - Global Change)(Mt/Ag/EnSc/EnSt 404/504 - Global Change) Water Resources (from IPCC WG-2, Chapter 3)Water Resources (from IPCC WG-2, Chapter 3)
Personal Experience (R. C.-G.)Personal Experience (R. C.-G.)A photo I took of the The same view behindA photo I took of the The same view behind
1998 flood at the dam - the dam in June 2008.1998 flood at the dam - the dam in June 2008.water topped the water topped the 8 years of drought and over-use of water8 years of drought and over-use of water
spillways for 4 days.spillways for 4 days.May 1998 Las Vegas flood and above average snowfallMay 1998 Las Vegas flood and above average snowfall
(Mt/Ag/EnSc/EnSt 404/504 - Global Change)(Mt/Ag/EnSc/EnSt 404/504 - Global Change) Water Resources (from IPCC WG-2, Chapter 3)Water Resources (from IPCC WG-2, Chapter 3)
Update: Update: New Record New Record
LowLow
(Source: Climate.gov)(Source: Climate.gov)
(Mt/Ag/EnSc/EnSt 404/504 - Global Change)(Mt/Ag/EnSc/EnSt 404/504 - Global Change) Water Resources (from IPCC WG-2, Chapter 3)Water Resources (from IPCC WG-2, Chapter 3)