UCODE

The new capabilities include support of parameters that are required for predictions but that had not been considered previously in model development.

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contributed at 2019-06-28

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epoeter@mines.edu;mchill@ku.edu
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Earth System SubjectEarth Surface SystemHydrosphere

Detailed Description

 

The new capabilities include support of parameters that are required for predictions but that had not been considered previously in model development. Examples of situations with such parameters are storage parameters when calibration conditions are steady-state and prediction conditions are transient, and transport parameters when calibration conditions involve only a flow field and prediction conditions include advective, advective-dispersive, or advective-dispersive-reactive transport. Second, weighting based on user-supplied coefficients of variation are supported more thoroughly in UCODE_2014 than in previous versions of UCODE and, we believe, any other available software package. Third, the use of singular value decomposition (SVD) for parameter estimation has been integrated into UCODE_2014 and the transparency offered to SVD users by sensitivity analysis is stressed. The implementation of SVD in UCODE_2014 is useful for estimating parameters in some circumstances, and guidance is provided for migrating to PEST when its unique capabilities are of interest. Inclusion of Markov-chain Monte Carlo (MCMC) uncertainty measures means that UCODE_2014 has three methods of uncertainty evaluation that proceed from (i) linear uncertainty intervals that are very computationally frugal (commonly 10s to 100s of parallelizable model runs) and depend on the model not being too nonlinear and errors being approximately Gaussian, to (ii) nonlinear uncertainty intervals with moderate computational demands (commonly 1,000s of model runs) and depend on model smoothness and Gaussian errors, to (iii) MCMC uncertainty intervals that are computationally demanding (commonly 10,000s of model runs and more) and few restrictive assumptions. Having this range of methods in one program encourages application and exploration of the entire range of methods.

 

Auxiliary programs introduced since UCODE_2005 are described briefly. This includes three auxiliary programs: MMA for multi-model analysis, OPR-PPR for value of information measures, and Sim-Adjust for when simulated equivalents to observations cannot be calculated. Three graphical interfaces are also described: ModelMate for constructing and running applications of UCODE_2014, GW_Chart for evaluating model fit, sensitivity analysis results, and uncertainty measures, including support for the new capabilities, and enhancements to Model Viewer for plotting objective-function surfaces using the UCODE _sos data-exchange files.