Uncertainty Analysis Case: E25-NE75   File: test_data.xls 06/15/02
Estimates uncertainty in output variables.  Assumes that sensitivity analysis has already been performed.  Factors include: (1) uncertainty in p cycling parameters (from calibration); (2) uncertainty in other model inputs (user-specified); (3) inherent model error (from calibration); & (4) sensitivity of model output to each input value. Results are for combined outflows.
Reference: Walker, "A Sensitivity & Error Analysis Framework for Lake Eutrophication Modeling", Wtr Res Bul, Feb 1982
               
Select Output Variable: Total FWM Outflow Conc (ppb)   Error CV's = Standard Error / Mean
 
50th Percentile Est. = 28   Total =   12%
  10th Percentile Est. = 24   Model Error = 10%
  90th Percentile Est = 32   Parameter Error = 5%
          Input Data Error = 3%
Show Results
Sensitivity Analysis
 
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Sensitivity Coefficients   % Change in Output Variable  / % Change in Input Variable
Enter assumed error CV (standard error, as percent of mean) in col. B (blue cells) to reflect uncertainty in each input value
Input Variable Error CV Value Case Description: Filename: sta2_data.xls
Design Case Name   E25-NE75 25% Emerg - > 75% NonEmerg
Starting Date for Simulation              
Ending Date for Simulation              
Starting Date for Output              
Steps Per Day       Output Variable   Units Value
Number of Iterations       Water Balance Error   % 0.0%
Output Averaging Interval       Mass Balance Error   % 0.0%
Reservoir H2O Residence Time       Flow-Wtd Conc - With Bypass ppb 27.8
Max Inflow / Mean Inflow       Flow-Wtd Conc - Without Bypass ppb 27.8
Max Reservoir Storage       Geometric Mean Conc ppb 15.4
Reservoir P Decay Rate       95th Percentile Conc   ppb 42.4
Rainfall P Conc 30% 0.010   Freq Cell Outflow > 10 ppb % 68%
Atmospheric P Load (Dry) 30% 0.000   Bypass Load   % 0.0%
Cell Number -->   1 2 3 4 5 6
Cell Label   EM75 NE75        
Vegetation Type   EMERG NEWS        
Inflow Fraction 0% 0.472          
Downstream Cell Number              
Surface Area   -0.092 -0.445        
Mean Width of Flow Path   0.012 0.047        
Number of Tanks in Series 30% -0.005 -0.082        
Outflow Control Depth   0.026 -0.044        
Outflow Coefficient - Exponent              
Outflow Coefficient - Intercept 20% 0.012 0.047        
Bypass Depth   0.000 0.000        
Maximum Inflow              
Maximum Outflow              
Inflow Seepage Rate              
Inflow Seepage Control Elev              
Inflow Seepage Conc   0.000 0.000        
Outflow Seepage Rate 20% 0.004 0.020        
Outflow Seepage Control Elev              
Max Outflow Seepage Conc   0.001 0.001        
Seepage Recycle Fraction   -0.010 -0.021        
Seepage Discharge Fraction              
Initial Water Column Conc              
Initial P Storage Per Unit Area              
Initial Water Column Depth              
C0 =  WC Conc at  0 g/m2 P Storage retrieved from model calibration table 0.032 0.652        
C1 = WC Conc at 1 g/m2 P storage 0.000 -0.090        
K = Net Settling Rate at Steady State -0.078 -0.164        
Zx = Depth Scale Factor -0.026 0.076        
C0 - Periphyton   0.156        
C1 - Periphyton   -0.039        
K  -  Periphyton   -0.115        
Zx - Periphyton            
Sm = Transition Storage Midpoint   -0.095        
Sb = Transition Storage Bandwidth   -0.001