CalSim-II Hydrological Data Extension of Recent Historical Period California Water and Environmental Modeling Forum Asilomar Conference Center, California March 1-3, 2005 Messele Ejeta California Department of Water Resources
Objective Extend historical hydrological data through water year 2003 to simulate 82 years of hydrological variability CalSim-II studies CalSim-III development (CalSim-II Peer Review)
Background Hydrological data used to determine available water supply to meet projected demand Planning purposes Input to CalSim Assumptions Historical hydrology used as indicator of expected future hydrology Hydrologic variability of the past several decades will repeat in the near future (planning horizon) Limitation: effect of climate change not considered Impact of climate change study underway Separate investigation
Existing Hydrological Data Existing CalSim-II benchmark studies Released to the public on September 30, 2002 2001 and 2020 level of developments Hydrological data for benchmark studies: 1922 1994 (water year)
Extension Effort Extension period: 1995 2003 (water year) Sacramento Valley extension effort by DWR San Joaquin Valley extension effort by Reclamation/consultants Tentative projected level of developments 2005 for current 2020 for future Other consideration Rice straw decomposition water demand
Central Valley Depletion Study Areas
Required Data Two major sets of data groups Diversion requirement at projected level of development Local water supplies at projected level of development Other data groups Precipitation data Inflows from upstream areas including Yuba, Upper American and Bear River systems Reservoir evaporation Eastside streams ( Cosumnes, Mokelumne and Calaveras river systems)
Diversion Diversion requirement Total applied water necessary to meet demand Associated non-recoverable loss, return flow and deep percolation Diversion requirement based on land use Land use data from Bulletin 160-98 Consumptive use computer program used to calculate amount
Local Water Supply Factors in projected local water supply (LWS) Historical local water supply Additional runoff due to land use change at projected level Additional rice drainage at projected level Calculation procedure Start with mass balance on historical data to get historical local water supply Unimpair historical local water supply to obtain predevelopment level local water supply Use unimpaired data and additional runoff at a projected level of development to get projected local water supply
Conceptual Model for Calculating LWS Simplified DSA HDL NV HCU NV PCU NV Historical LWS = Outflow + Hist. Depletion of Applied Water- Inflow Unimpaired LWS = Historical LWS + Cons. use of precip by developed land - Cons. use of precip by replaced native vegetation Projected LWS = Unimpaired LWS + Additional runoff due to change in land use
Data Sources California Data Exchange Center (CDEC) DWR districts (Northern District, Central District) Reclamation s report of operations United States Geological Survey (USGS) Local Agencies East Bay Municipal Utility District (EBMUD) Nevada Irrigation District (NID) South Sutter Water District (SSWD) Solano Irrigation District
Status Completed development of future water demand Historical land use data obtained from DPLA 1995 1998, 2000 and 2001 land use data available 1999, 2002 and 2003 data assumed using same water year types 1999 same as 1998 (Wet) 2002 same as 2001 (Dry) 2003 same as 2000 (Above Normal) Estimated historical outflows for certain DSAs To be completed Missing historical data Implementation of rice straw decomposition
Sample Preliminary Result 2500 Sacramento Valley Annual Average Diversion Requirement Comparison for Different Periods (2020 Level of Development) Average Annual Diversion in TAF 2000 1500 1000 500 1922-1994 1995-2003 1987-1992 2001-2002 Dry and Critical Year Frequency (%) Existing Period (73 years) 38.4% Extension Period (9 years) 22.2% Extended Period (82 years) 36.6% 0 DSA 10 DSA 12 DSA 15 DSA 58 DSA 65 DSA 69 DSA 70
Next Steps Complete preparing projected local water supply Complete implementation of rice straw decomposition water demand for the extension period Make any other necessary refinements Run CalSim-II with the extended data for current and future level of developments
Questions?