Omaha Districts Inflow Forecast Regression Analysis
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Omaha Districts Inflow Forecast Regression Analysis. Carrie Vuyovich and Steven Daly ERDC-CRREL Cold Regions Res. and Engr. Lab. (CRREL) U.S. Army Corps of Engineers January 2011. Overview. Background Multiple linear regression analysis to forecast spring inflows to reservoirs
Omaha Districts Inflow Forecast Regression Analysis
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Omaha Districts Inflow Forecast Regression Analysis Carrie Vuyovich and Steven DalyERDC-CRREL Cold Regions Res. and Engr. Lab. (CRREL)U.S. Army Corps of Engineers January 2011
Overview Background • Multiple linear regression analysis to forecast spring inflows to reservoirs • 6 snow-dominated watersheds • Monthly forecasts beginning in January Goals • Update regressions with recent data, improve accuracy • Develop better estimate of SWE • Work towards a more automated process • Identify possible climate trends
Parameters • Q (106 ac-ft) = Forecasted total volume inflow to reservoir (+ Holdouts) • SWE (in) = Average station SWE on first of month • ANTQ (106 ac-ft) = Total antecedent inflow from Oct – Nov of previous year (+ Holdouts) • ANTPREC (in) = Total annual precipitation in previous year • P (in) = Total precipitation since beginning of year Holdout Calculation:
Canyon Ferry Area = 15,886 mi2 Average Apr-Jul total volume inflow = 1.9 M ac-ft (2 M ac-ft Natural) Average Oct-Nov total volume inflow = 0.56 M ac-ft (0.56 M ac-ft Natural) Average monthly total precipitation (in)
Clark Canyon Area = 2,315 mi2 Average Apr-Jul total volume inflow = 0.08 M ac-ft (0.09 M ac-ft Natural) Average Oct-Nov total volume inflow = 0.04 M ac-ft (0.05 M ac-ft Natural) Average monthly total precipitation (in)
Tiber Area = 4,724 mi2 Average Apr-Jul total volume inflow = 0.43 M ac-ft Average Oct-Nov total volume inflow = 0.04 M ac-ft Average monthly total precipitation (in)
Yellowtail Area = 19,693 mi2 Average Apr-Jul total volume inflow = 1.0 M ac-ft (1.4 M ac-ft Natural) Average Oct-Nov total volume inflow = 0.30 M ac-ft (0.32 M ac-ft Natural) Average monthly total precipitation (in)
Boysen Area = 7,750 mi2 Average Apr-Jul total volume inflow = 0.56 M ac-ft (0.6 M ac-ft Natural) Average Oct-Nov total volume inflow = 0.11 M ac-ft (0.11 M ac-ft Natural) Average monthly total precipitation (in)
Glendo Area = 15,562 mi2 Average Apr-Jul total volume inflow = 0.60 M ac-ft (0.88 M ac-ft Natural) 0.14 M ac-ft below Alcova Average Oct-Nov total volume inflow = 0.13 M ac-ft (0.09 M ac-ft Natural) 0.03 M ac-ft below Alcova Average monthly total precipitation (in)
Percent Error *2011 Yellowtail forecast of Actual reservoir inflow for Apr – Jul (USACE and BoR) USACE Forecast for May-Jul, includes holdouts from Boysen, Buffalo Bill and Bull Lake
Automation • Goals: • Link regression equations, data and statistics to final forecast sheet • Links to data sources (semi-automated) • Limit data entry and calculation errors • Easily transfer regression coefficients each year • Easily transfer annual data to regression analysis workbook
2011 Issues • Late snowfall in April • Switched from 1 Apr SWE to Max(1 Apr, 1 May) • Real-time precipitation data • Difficult to automate • Canyon Ferry results • Not capturing complete water balance by the end of the season
Proposed Improvements to Inflow Forecasting • Daily estimates of forecasted inflow for monitoring • Need to automate regression analysis and data stream • Climate change impacts to regression analysis • Temperature appears to be increasing, Precipitation neither increasing or decreasing • Changes in climate will reduce the accuracy of regressions over time • Limit data used in analysis to recent years rather than entire period of record
Proposed Improvements to Inflow Forecasting • Further investigation of better SWE estimation • Test in different basins • Field measurements to better understand distribution of snow Canyon Ferry
Proposed Improvements to Inflow Forecasting • Passive Microwave Satellite Observations of SWE in the Great Plains • Algorithms developed in Great Plains region of Canada. • Shown promising results in Red River of the North Basins • Independent estimate of SWE, available real-time • Long period of record (1987 – present) • Evaluate by comparison to NOHRSC, ground and flight observations, hydrologic analysis
Proposed Improvements to Inflow Forecasting • Passive Microwave detection of snowmelt and runoff • Affected by presence of wet snow • Research into detection of “ripe” snow and rain-on-snow events • May provide information on timing of melt and flood forecasting • Hydrologic Analysis of Plains snowpack • Correlation between timing and volume to SWE in Plains to discharge • Terrain-state modeling • Statistical analysis/rank-order