Transcript Slide 1
Modeling the Boise Reservoir System with Climate Change Leslie Stillwater, Pacific NW Region Reclamation’s Boise Project The Boise Project provides water to lands in southwestern Idaho and eastern Oregon Boise Basin Project Reservoirs, active capacities: Anderson Ranch, 413 kAF Arrowrock, 272 kAF LuckyPeak (COE facility), 264 kAF Lake Lowell, 159 kAF Irrigated Lands: 224,000 acres primary supply 173,000 acres supplemental supply Climate Change Is Likely to Bring… • Warmer Temperatures • Less Snowpack • More Precipitation (some say) • Greater variability in flows • Earlier runoff • Higher winter flows; lower summer flows Preliminary Assessment Questions • will Reclamation meet it’s current contractual obligations for water storage and delivery? • will Reclamation meet it’s environmental obligations? • will current flood risk management practices be adequate? Intergovernmental Panel on Climate Change (IPCC) The IPCC is a scientific intergovernmental body set up by the World Meteorological Organization (WMO) and by the United Nations Environment Programme (UNEP). The IPCC provides an objective and neutral source of information about climate change. The IPCC does not conduct research nor does it monitor climate related data or parameters. Selected IPCC Model Output Three projection scenarios for the year 2040 were selected from among the suite of IPCC models. Each applies an aggressive emissions scenario, assuming increasing emissions based on population growth and current technological and economic trends. ECHAM • developed by the Max Planck Institute for Meteorology, Germany • Echam simulations produce moderate temperature and precipitation trends when compared to other IPCC models. IPSL • developed by the IPSL Institut Pierre Simon Laplace, France. • IPSL simulations produce the greatest warming and increased precipitation trends. GISS • developed by NASA / Goddard Institute for Space Studies, USA • GISS simulations produce the lowest warming trends and a small decrease in precipitation. Selected IPCC Model Output Modeled Predictions for the Year 2040 6 Scenarios were developed from 3 Climate Change Projections for Year 2040 Echam - Temp Adjustments Only Echam - Temp and Precip Adjustments GISS - Temp Adjustments Only GISS - Temp and Precip Adjustments IPSL - Temp Adjustments Only IPSL - Temp and Precip Adjustments Climate Impacts Group (CIG) The projected precipitation and temperature changes were downscaled to the Pacific Northwest by the Joint Institute for the Study of Atmosphere and Oceans Climate Impacts Group (CIG) at the University of Washington. How Climate Affected Naturalized Streamflows were Developed • T and P Adjustments were obtained from the Climate Impacts Group for each Climate Scenario • T and P Adjustments were applied to the National Weather Service River Forecast System model (NWSRFS) to produce daily local naturalized streamflows (WY1949-1996) NWSRFS Model Forecasts streamflow Collection of hydrologic/hydraulic models calibrated to observed snow, soil moisture, river, and reservoir conditions and historical meteorological data Model input (for this study): T and P Model components: • Sacramento Soil Moisture Accounting Model • SNOW-17 NWSRFS Concepts http://meteora.ucsd.edu/~knowles/html/land/mod_descr.html NWSRFS Concepts Average Unregulated Daily Flows LuckyPeak Peak Dam Daily Naturalized Flows atatLucky for Scenarios with for 2040 using Temperature Predictions (NWSRFSAdjustments model results) Only Temperature 10,000 9,000 8,000 7,000 No Adjustment echam T giss T ipsl T 5,000 4,000 3,000 2,000 1,000 1-Sep 1-Aug 1-Jul 1-Jun 1-May 1-Apr 1-Mar 1-Feb 1-Jan 1-Dec 1-Nov 0 1-Oct cfs 6,000 Average Unregulated Daily Flows LuckyPeak Peak Dam Daily Naturalized Flows atatLucky with using Temperaturefor andScenarios Precipitation Predictions for 2040 (NWSRFS model results) Temperature and Precipitation Adjustments 10,000 9,000 8,000 7,000 No Adjustment echam TP giss TP ipsl TP 5,000 4,000 3,000 2,000 1,000 1-Sep 1-Aug 1-Jul 1-Jun 1-May 1-Apr 1-Mar 1-Feb 1-Jan 1-Dec 1-Nov 0 1-Oct cfs 6,000 How Climate Affected Streamflows were applied in the Planning and Operations Models • Naturalized streamflows from each NWSRFS Climate Scenario were compared to the unadjusted NWSRFS Scenario (calibrated to historic streamflows) to produce daily local naturalized streamflow adjustments • The daily streamflow adjustments were applied to the Monthly Planning Model (Snake River Revised MODSIM Model) • The daily streamflow adjustments were also applied to the Daily Boise Operations Model (MODSIM) Model Purposes and Assumptions • The monthly planning model addresses storage, Reclamation contract obligations, water rights, irrigation deliveries and minimum streamflows – Modeled irrigation deliveries are based on present level delivery requirements – Environmental obligations are based on current practices • The daily operations model addresses flood risk management and refill Results (page1) • The ability to refill Project reservoirs may not be significantly impacted by Climate Change, but refill is dependent on the successful response to changing flood risks • Project deliveries are likely to not be significantly affected by Climate Change (natural flow diversions decline, Project storage deliveries increase) • Environmental obligations for storage and streamflows are likely to not be significantly affected by Climate Change Planning Study: Modeled Diversions Temperature Adjustments Only Planning Study: Modeled Diversions Temperature and Precipitation Adjustments Planning Study: Modeled Refill Temperature Adjustments Only 1000000 900000 700000 NoAdjust echam T giss T ipsl T 600000 500000 400000 0.95 0.89 0.82 0.75 0.68 0.61 0.55 0.48 0.41 0.34 0.27 0.20 0.14 0.07 300000 0.00 active capacity (acre feet) 800000 Planning Study: Modeled Refill Temperature and Precipitation Adjustments 1000000 900000 700000 NoAdjust echam TP giss TP ipsl TP 600000 500000 400000 0.95 0.89 0.82 0.75 0.68 0.61 0.55 0.48 0.41 0.34 0.27 0.20 0.14 0.07 300000 0.00 active capacity (acre feet) 800000 Results (page2) • However, winter and spring flooding and flood control operations are more likely with Climate Change and will be the major issue in the Treasure Valley • Flood risk management and reservoir refill go hand-in-hand Observations on Flood Risk Management and Reservoir Refill (page1) • Current COE regulations, guidelines and space requirements are outdated, having been developed using data from 1895 through 1980. • Starting about 1980, the guidelines under-predict inflows prior to April 1 and over-predict inflows after April 1 • With Climate Change, the under- and over- predictions are even larger Observations on Flood Risk Management and Reservoir Refill (page2) • Accurate forecasts will become more difficult develop to due to the influences of precipitation on the basin and increased flow variability Historic (same as No Adjust Scenario) Difference between Observed Inflows and Projected Inflows for April 1 - July 31 Inflow Volumes Projected Inflows are calculated using COE Water Control Manual Projection Equation grey area shows the range of the anticipated standard error 150,000 -50,000 -450,000 Projection Equation developed using data prior to 1980 -650,000 -850,000 -1,050,000 1901 1903 1905 1907 1909 1911 1913 1915 1917 1919 1921 1923 1925 1927 1929 1931 1933 1935 1937 1939 1941 1943 1945 1947 1949 1951 1953 1955 1957 1959 1961 1963 1965 1967 1969 1971 1973 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 acre feet -250,000 echamT Scenario Difference between Modeled Inflows and Projected Inflows for April 1 - July 31 Inflow Volumes Projected Inflows are calculated using COE Water Control Manual Projection Equation grey area shows the range of the anticipated standard error 150,000 -50,000 -450,000 -650,000 -850,000 -1,050,000 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 acre feet -250,000 echamTP Scenario Difference between Observed Inflows and Projected Inflows for April 1 - July 31 Inflow Volumes Projected Inflows are calculated using COE Water Control Manual Projection Equation grey area shows the range of the anticipated standard error 150,000 -50,000 -450,000 -650,000 -850,000 -1,050,000 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 acre feet -250,000 gissT Scenario Difference between Observed Inflows and Projected Inflows for April 1 - July 31 Inflow Volumes Projected Inflows are calculated using COE Water Control Manual Projection Equation grey area shows the range of the anticipated standard error 150,000 -50,000 -450,000 -650,000 -850,000 -1,050,000 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 acre feet -250,000 gissTP Scenario Difference between Observed Inflows and Projected Inflows for April 1 - July 31 Inflow Volumes Projected Inflows are calculated using COE Water Control Manual Projection Equation grey area shows the range of the anticipated standard error 150,000 -50,000 -450,000 -650,000 -850,000 -1,050,000 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 acre feet -250,000 ipslT Scenario Difference between Observed Inflowsand Projected Inflows for April 1 - July 31 Inflow Volumes Projected Inflows are calculated using COE Water Control Manual Projection Equation grey area shows the range of the anticipated standard error 150,000 -50,000 -450,000 -650,000 -850,000 -1,050,000 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 acre feet -250,000 ipslTP Scenario Difference between Observed Inflows and Projected Inflows for April 1 - July 31 Inflow Volumes Projected Inflows are calculated using COE Water Control Manual Projection Equation grey area shows the range of the anticipated standard error 150,000 -50,000 -450,000 -650,000 -850,000 -1,050,000 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 acre feet -250,000 Boise Project Flood Operations • Starting on January 1, a volume forecast from ‘now’ until the end of July is developed • Part of that forecast will arrive April – July producing the April 1 space requirements (rule curves) • The remainder of that forecast will arrive ‘now’ – March determining the rate of release to get down to the April 1 space requirements • Measure of success is discharge < 7,000 cfs at Glenwood Bridge No Adjustment 1970/1971 Apr 1 Space (AF) required = 950,150 achieved = 885,780 Echam T 1970/1971 Apr 1 Space (AF) required = 664,530 achieved = 663,780 Giss T 1970/1971 Apr 1 Space (AF) required = 822,790 achieved = 820,390 Ipsl T 1970/1971 Apr 1 Space (AF) required = 588,970 achieved = 582,100 Echam TP 1970/1971 Apr 1 Space (AF) required = 784,410 achieved = 613,210 Giss TP 1970/1971 Apr 1 Space (AF) required = 834,650 achieved = 831,930 Ipsl TP 1970/1971 Apr 1 Space (AF) required = 852,310 achieved = 244,280 No Adjustment 1970/1971 Apr 1 Space (AF) required = 950,150 achieved = 885,780 Impacts to Reservoir Refill • Refill capabilities go hand-in-hand with flood control operations • When modeled, perfect forecasts (!) and revised operating rules produce excellent refill capability in all Climate Change Scenarios studied So, will Reservoirs fill? • Streamflow forecasts will need to be early – that seems unlikely • Greater streamflow variability produces greater uncertainties in streamflow forecasts • Operators will be hesitant to draw down early and start an early fill So, will there be flooding in Boise? • Most likely* *given our current assumptions Comments on the Daily Operations Studies • Assumptions drive the study results – A2 IPCC scenarios (aggressive emissions) – T and P results are scalable to PN Region and to the Boise Basin – Starting storage conditions of Nov 2001 (historic median) – Perfect forecasts • We addressed uncertainties by employing results from a range of IPCC models Daily Operations Study Results • • • • • Reliable forecasts will be even more critical Early forecasts (prior to Jan 1) will be required Drawdown needs to start before Jan 1 Space requirements need to start earlier than Apr 1 Maintaining 55% space in Lucky Peak and Arrowrock may not be possible • Glenwood Bridge discharge Jan – Apr will be higher • Glenwood Bridge discharge > 7,000 cfs can be anticipated if the wettest scenario is realized Web sites • Hydromet teacup diagrams: – http://www.usbr.gov/pn/hydromet • Intergovernmental Panel on Climate Change – http://www.ipcc.ch/ • NWS models – http://www.nws.noaa.gov/ • Climate Impacts Group, U of Washington – www.cses.washington.edu/cig/