extreme events, water hazards and water supply
Post on 23-Feb-2016
35 Views
Preview:
DESCRIPTION
TRANSCRIPT
Extreme events, water hazards and water supply
Speaker: Marty Ralph (NOAA) Co-authors: Michael Hanemann (UC Berkeley, Arizona State U)
Ben Brooks (U. of Hawaii) Mike Dettinger (USGS and Scripps/UCSD)
Dan Cayan (UCSD/Scripps and USGS)Konstantine Georgakakos (HRC)
Jay Lund (UCD)Jay Famiglietti (UCI)
Michael Anderson (DWR)Jeanine Jones (DWR)
Presented at “Vulnerability and Adaptation to Extreme Events in California in the Context of a Changing Climate: New Scientific Findings”
Scripps Institution of Oceanography, La Jolla, California13 December 2011
Decreasing California Snowpack
Important Energy Facilities in the Delta Would Also Be At Risk
• The Sacramento - San Joaquin Delta is protected by levees.
• Delta islands are below sea level
• Energy Facilities:– Underground natural gas
reservoirs– Transmission lines– Power plants on the west
side of the Delta
Source: PPIC 2007
Sources: CO Climate Report, 2008; Christensen and Lettenmeier, 2007
Projections: Upper Colorado River Basin
2025 2055 2085 2025 2055 2085 2025 2055 2085
• Temperature increases• Precipitation variable• Runoff is earlier in the season and totals decrease by 6–20%
California Water Supply Includes the Colorado River
5
Heavy Precipitation and Flooding
Flooding on the Russian River, Guerneville, CA
California averaged $370 M/year in flood damages
3rd highest in the nation
Total Damage in Period 1983-1999(1995 $ equivalent)
LARGEST 3-DAY PRECIPITATION TOTALS, 1950-2008
Ralph, F.M., and Dettinger, M.D., in press, Historical and national perspectives on extreme west-coast precipitation associated with atmospheric rivers during December 2010: Bulletin of the American Meteorological Society, (in press, Nov 2011)
CALIFORNIA’S STORMS ARE AS BIG AS ANY IN THE COUNTRY!
Atmospheric Rivers in IPCC-AR4 climate-change projections by 7 modern GCMs
Dettinger, M.D., 2011, Climate change, atmospheric rivers and floods in California—A multimodel analysis of storm frequency and magnitude changes: Journal of American Water Resources Association, 47, 514-523.
Water Vapor & Low-Level Winds
Obs case
By end of 21st Century, most GCMs yield: •More atmospheric vapor content, but weakening westerlies
Net increase in “intensity” of extreme AR storms
• Warmer ARs (+1.8 C) snowline raised by ~ 1000 feet on average
• Lengthening of AR seasons (maybe?)
8
Adaptation
• Central Valley Flood Protection Plan• Scenario development
– Drought Scenario: (Harou etal. 2010, Water Resources Research)
– Storm/flood scenario: “ARkStorm” (Dettinger et al. 2011, Natural Hazards)
• Forecast-Based reservoir Operations (see Willis et al. 2011, San Francisco Estuary and watershed Science)
• Better storm and runoff predictions are a potential adaptive strategy
Central Valley Flood Management Planning Program, 2011, Climate Change Analysis: Attachment 11, 2012 Central Valley Flood Protection Plan, 76 p. (Courtesy of Mike Anderson, CA-DWR)
Central Valley Flood Protection Plan “Thresholds Approach”
Assess Vulnerability & Consequences
Identify Causal Conditions
Assess Likelihoods
Assess Vulnerability & Consequences
Identify Causal Meteorological and Hydrological Conditions
Assess Vulnerability & Consequences
Identify Causal Conditions
Assess Likelihood of Exceedence
Assess Human, Infrastructure and Economic Vulnerabilities
ARkStorm Severe Storm Scenario
Dettinger, M.D., and co-authors, 2011, “Design and quantification of a severe winter storm scenario for emergency preparedness and planning exercises in California.” Natural Hazards, in press, 27 p.
A USGS-led emergency preparedness scenario- Dozens of scientists and
engineers contributed- Shaped by real past
events incl. 1986, 1969, and 1861/62
- Economic impacts estimated to be >$500 B
- Methods and results were peer reviewed
Atmospheric Rivers, Floods and the Water Resources of Californiaby Mike Dettinger, Marty Ralph, , Tapash Das, Paul Neiman, Dan Cayan
Water, 2011 (June)
25-35% of annual precipitation in the
Pacific Northwest fell in association with
atmospheric river events
35-45% of annual precipitation in California
fell in association with atmospheric river events
An average AR transports the
equivalent of 7.5 times the average discharge of the
Mississippi River, or ~10 M acre feet/day
12
Conclusions• California has significant vulnerabilities to shifts in extreme
precipitation and runoff• Reduced snow pack is a key risk to water supply, as are
reductions in Colorado River flow and inundation of the Delta
• Changes in the strength of atmospheric rivers and in snow level are key to future flood risks
• Improving monitoring and prediction of critical hydrometeorological conditions can enable adaptation to a changing climate such as by modernizing reservoir operations methods
top related