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Projecting Climate Change Impacts on Water Resources in Regions of Complex Topography: A Case Study of the Western United States and Southern California
The document examines the impact of climate change on water resources in the western United States, particularly Southern California, highlighting the critical role of snowfall and water supply systems like the Colorado River and local aqueducts. Projections indicate significant alterations in the hydrologic cycle, with increased temperatures, shifting precipitation patterns, and rising water demands due to population growth, leading to heightened risks of water shortages and flooding. Recommendations include improving local water supply strategies, enhancing stormwater capture, and promoting recycled water usage to adapt to these changes.
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Projecting Climate Change Impacts on Water Resources in Regions of Complex Topography: A Case Study of the Western United States and Southern California
- 1. Projecting Climate Change Impacts on Water Resources in Regions of Complex Topography: A Case Study of the Western United States and Southern California Brianna Pagán1, Moetasim Ashfaq2, Deeksha Rastogi2, Donald R. Kendall1, Shih-Chieh Kao2, Bibi S. Naz2, RuiMei2 Jeremy S Pal1 <jpal@lmu.edu> 1. Loyola Marymount University, Dept of Civil Engineering and Environmental Science 2. Oak Ridge National Laboratory, Climate Change Science Institute
- 2. Western US Water Hydrologic Cycle Schematic Precipitation (when it falls) Demand (whenwe need it)Runoff (when we get it) Reservoirs store surplus water in the spring for the summer when demands are highest. Large reservoirs store water during periods of surplus to get us through multi-year droughts. 75% of annual streamflow in California is snowmelt. In California, water in many reservoirs is released in wintertime for flood control purposes. Climate change impacts on western US hydrology is critical to our understanding of future Southern Californian water resources.
- 3. Where does Southern California get its water? Local Supplies Groundwater Recycled Water Conservation Colorado River Aqueduct Colorado River Basin LA Aqueduct Mono Lake /Owens Valley CA Aqueduct Sacramento River Basin San Joaquin River / Tulare Lake Basins California hosts world'slargest, most productive, and most controversial water system à 49 km3/yr, 30 million people, 2.3 million ha of irrigation.
- 4. Los Angeles Aqueduct (~7%) Mono Lake and Owens Valley: 0.50 km3/yr (16 m3/s), 674 km, Gravity Owned by the Los Angeles Department of Water and Power. Owens Lake Mitigation – Dust Control • Dry lake bed •Largest source of dust pollution (PM- 10) in US. • Human health risks • Reduced 0.05 km3/yr (1.6 m3/s) Mono Lake Decision (1982) • Migrating and nesting birds • Reduced 0.14 km3/yr (4.5 m3/s)
- 5. Colorado River Aqueduct (~25%) California allocation • 5.4 km3/yr (172 m3/s) •Irrigation districts • Metropolitan Water District of Southern California (MWD): 55 m3/s, 389 km, 5 pumping stations, 492 m lift. Modern Issues • Over allocated by ~4.7 km3/yr (~150 m3/s) • Rising populations in other states Colorado River • 19.7 km3/yr (625 m3/s) – ~2.7 Adige Rivers • Serves 30 million people across seven states – ~1/2 Italy
- 6. State Water Project (~30%) Basins support 25 million people and $36 billion agriculture industry Modern Issues – Delta Smelt • Indicator speciesfor the overall health of the Delta's ecosystem • Endangered Species Act • Delta Smelt Pumping restrictions Originates from SRB and SJR-TLB in San Francisco Bay Delta Metropolitan Water District of Southern California: 2.4 km3/yr (75 m3/s), 489 km, 6 pumping plants, 988 m lift Hypomesus transpacificus / U.S. Fish and Wildlife Service http://www.water.ca.gov
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- 9. Greenhouse Gas Concentrations (0 - 2014) IPCC 2007 500 750 1000 1250 1500 1750 2000 250 275 300 325 350 375 400 0 200400 600 800 1000 1200 1400 1600 1800 2000 CH4(ppb) CO2(ppm)N2O (ppb) Year Data Source: NOAA Carbon Dioxide (CO2) – 43% increase Nitrous Oxide (N2O) – 21% increase Methane (CH4) – 140% increase
- 10. -0.50 -0.25 0.00 0.25 0.50 0.75 1.00 1880 1890 19001910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 Differnece from 1951-1980 (°C) Global Surface Temperature Differences from 1951-1980 Warmer than Normal Colder than Normal 2015 Data Sources: NASA (T) & NOAA (ENSO) 2016 Most of the warming has occurred in the past 50 years or so, as have most of the anthropogenic greenhouse gas emissions. • The 17 warmest years have occurred in the past 19 years. • 1976 was the last cooler than normal year.
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- 16. 100 200 300 400 100 200 300 400 0100000200000300000400000500000600000700000800000 CO2 (ppm) Years Before Present 100 200 300 400 500 600 700 800 900 1000 100 200 300 400 500 600 700 800 900 1000 0100000200000300000400000500000600000700000800000 CO2 (ppm) Years Before Present CO2 Concentrations from the Past 800,000 years (ice cores) Pre-Industrial AnthropogenicFuture Current Level CO2 in 2100 (business as usual) 2°C COP21 Minimum Hoped For ”Paris” Pledge 3.5°C COP21 Current ”Paris” Commitment
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- 19. Human Health Agriculture Water Resources Ecosystems StormSurges Regional Climate Model for Impacts Studies Regional Climate Models (RCMs) can be “nested” within an AOGCM in order to increase the resolution (10s km) of a climate simulation. Boundary conditions are obtained from the AOGCM. Intended to enhance the AOGCM simulation.
- 20. Climate Change Projection Simulations 10 AOGCMs 1 High-ResRCM 1 Hydro Model Impacts on Water Resources ACCESS BCC-CSM CCSM4 CMCC-CM FGOALS IPSL-CM5A-LR MIROC5 MPI-ESM-MR MRI-CGCM3 Nor-ESM1-M RegCM4 16-km VIC 4-km Simulations performed on ORNL’s Titan – The fastest supercomputer in the US. To date, the most comprehensive and highest resolution assessment. Greenhouse Gas Concentrations: Historical (1976-2005) RCP 8.5 Future Scenario (2021-2050)
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- 22. -25 -15-75 -65-55 -45 -35 -25 -15 -51.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 Temperature (o C) a Snow Depth (%) b E Precipitation (mm/yr) Evapotranspiration (mm/yr) Runoff (m Albedo ( c Projected Changes (2021-2050 minus 1976-2005 Temperature and Snow Changes: 2021-2050 minus 1976-2005 Temperatures projected to increase an additional 1.0 to 2.0°C by 2050. • Higher than the global average. The largest increases at projected at higher elevations due to snow related changes in surface albedo (reflectivity). °C -25-75 -65 -55 -45 -35 -25 -15 -51.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 Temperature (o C) a Snow Depth (%) b Precipitation (mm/yr) Evapotranspiration (mm/yr) Run Albe c Projected Changes (2021-2050 minus 1976-2 % Up to 75% decrease1.0 to 2.0°C increase
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- 24. Precipitation Seasonality Changes: 2021-2050 minus 1976-2005 0.008 -0.004 00.004 0.008 Precipitation Seasonality Changes (2021-2050 minus 1976-2005) dimensionless Elevation Contours from 1500m to 2000m by 500Methodology from Feng, Porporato and Rodriguez-Iturbe, 2013 Additional precipitation occurs in the winter, which is the wettest part of the year.
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- 26. Projected Runoff Changes: 2021-2050 minus 1976-2005 -25 -15 -55 15 25 Elevation Contours from 1500m to 2000m by 500 f Runoff (mm/yr) -150 -90 -30 30 90 150 c Basin Ensemble Average Ensemble Range Colorado River +9% -3 to 50% Owens Valley – Mono Lake +9% -13 to 35% Sacramento River +2% -30 to 22% San Joaquin – Tulare Lake -1% -27 to 30% -1 to 9% change ensemble average at basin level, but with a large range of uncertainty. mm/yr
- 27. Runoff Timing Changes (2021-2050 minus 1976-2005) -8 -4 04 8 a Center of Mass Day (days) Changes (2021-2050 minus 1976-2005) Mid-Flow Date (days) More precipitation falls as Rainfall and snow melts earlier. • Less natural storage à Artificial storage and flood Issues Streamflow arrives up to 10 days earlier. Winter water levels in many reservoirs are kept low for flood control purposes. • In conflict with storage needs! Mann-Kendall Trend Test (Red bars = significant at 5%)
- 28. Projected Changes (2021-2050w.r.t. 1976-2005) in 50 year Return Period c Annual Cumulative Min Runoff a return period Projected Changes (2021-2050 w.r.t. 1976-2005) in 50 year Return Volume Annual Cumulative Min RunoffAnnual Cumulative Max Runoff 0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 60 70 80 90 100 Annual Cumulative Min RunoffAnnual Cumulative Max Runoff Projected Changes (2021-2050 w.r.t. 1976-2005) in 50 year Return Period c Annual Cumulative Min Runoff a return period Projected Changes (2021-2050 w.r.t. 1976-2005) in 50 year Return Volume Annual Cumulative Min RunoffAnnual Cumulative Max Runoff 0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 60 70 80 90 100 Annual Cumulative Min RunoffAnnual Cumulative Max Runoff 50-year Cumulative Annual Runoff Changes: 2021-2050 minus 1976-2005 Basin Wet Periods Colorado River +20% (14 yr) Owens Valley – Mono Lake +10% (26 yr) Sacramento River +3% (42 yr) San Joaquin – Tulare Lake +6% (38 yr) Increase in both abnormally wet and dry years (except OV-ML) • Less normal years • Less reliability Projected Changes (2021-2050 w.r.t. 1976-2005) in 50 year Return Period c Annual Cumulative Min Runoff a return period Projected Changes (2021-2050 w.r.t. 1976-2005) in 50 year Return Volume d Annual Cumulative Min Runoff b Annual Cumulative Max Runoff 0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 60 70 80 90 100 Annual Cumulative Min RunoffAnnual Cumulative Max Runoff Projected Changes (2021-2050 w.r.t. 1976-2005) in 50 year Return Period c Annual Cumulative Min Runoff a return period Projected Changes (2021-2050 w.r.t. 1976-2005) in 50 year Return Volume d Annual Cumulative Min Runoff b Annual Cumulative Max Runoff 0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 60 70 80 90 100 Annual Cumulative Min RunoffAnnual Cumulative Max Runoff Dry Periods +3% (38 yr) -4% (69 yr) +13% (29 yr) +10% (36 yr) GEV Distribution; Hatchings for KS GOF test at 5%
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- 34. Outdoor Irrigation Turf rebate programs are effective. Rain barrels, but rains occur when irriagtion requirements are lowest. In current Southern Californian climate, grass lawns require ~1.3 m/yr of water. •Increasing temperature will likely increase this demand. • This may be offset slightly by increasing precipitation, but problem of timing (rains in winter). Urban and agricultural irrigation demands are expected to increase with climate change and rising population. Widescale efficient irrigation is needed.
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- 38. Infrastructure Existing Infrastructure: • Raise in-stream storage structures. • Reduce conveyance channel and pipe leakage and cover aqueducts. New Infrastructure: •Stormwater Capture • Delta 2 Tunnels – Perhaps https://ww2.kqed.org/science/2016/07/25/about-that- 17-billion-water-project-delta-tunnels-101/
- 39. Management http://cw3e.ucsd.edu/FIRO/ - December 2013 Lake Mendocino Example Agriculture to urban water transfers. Reservoir Rule Curve Reservoir Storage Cumulative Rainfall Forecast Informed Reservoir Operations (FIRO). •Reservoirs water levels are often lowered in the winter for flood control purposes. • Weather forecasts are little used for reservoir management.
- 40. Does Near TermClimate Change Risk Represent a ‘Yard Sale' for the US Ski Industry? Daniel Scott1, Brianna R. Pagán2,3, Robert Steiger4, Moetasim Ashfaq5, Deeksha Rastogi5, Jeremy S. Pal2 Lake Louise, Canada 321 4 5