underscore.txt This file documents modifications and additions to the set of files generated when OUTNAM of the OBS input file (USGS Open-File Report 00-184, page 27) is not NONE. These files are identified by the underscore ("_") character as the first character of the filename extension. -------------------------------------------------------------------------- Version 1.1 of Modflow-2000 added support for generation of an output file with the extension _pc when OUTNAM is not 'NONE', the Parameter-Estimation Process is active, and parameter estimation converges. This file contains a record for each estimated parameter, listing: parameter name, LN, optimized parameter value, BL, BU, lower 95-percent confidence limit on the parameter value, and upper 95-percent confidence limit on the parameter value. -------------------------------------------------------------------------- Version 1.12 of Modflow-2000 includes a modification to the _os file. A fifth column has been added to the _os output file, which was originally described in table 5 on page 28 of USGS Open-File Report 00-184. The fifth column lists the observation time, in model time units, from the beginning of the simulation. For prior information, -1.0 is written. The code modification for ADV assumes that all ADV observations are in the first stress period. -------------------------------------------------------------------------- Version 1.12 also added support for a new optional setting in the OBS Process input file is available. If "ALLFILES" is specified following the ISCALS value, and if the value specified for OUTNAM is not "NONE", up to three additional output files ("_wt", "_su", and "_mc") are generated with the filename base defined by OUTNAM: (1) OUTNAM._wt: When OUTNAM in the OBS input file is not "NONE", and "ALLFILES" is specified after ISCALS, a new file is generated, identified by the extension "_wt". This file contains observation weights, or the full weight matrix if any of the observation types is entered with a variance-covariance matrix (WTQ in the Observation Process input instructions of USGS Open-File Report 00-184). The first line of this file indicates whether the rest of the file contains a vector of weights or a correlated-weight matrix. In either case, the ordering of weights is such that weights on all head observations are listed first, followed by weights on observations of the Drain, River, General Head Boundary, and Streamflow Routing (STR) Packages; observations of constant-head flow (Basic Package); and observations of the Drain-Return and Advective-Transport Packages. If no package has observations for which a variance-covariance matrix has been entered, the first line contains the word "VECTOR", the second line contains ND (the number of observations), and the following ND lines contain the weight calculated for each observation, with one weight (one observation) per line. If any package has observations for which a variance-covariance matrix has been entered, the matrix is written to the _wt file in the compressed format described in the file "compressedmatrix.txt" in the doc directory. The first line contains the word "COMPRESSEDMATRIX". The second line contains NNZ (the number of non-zero entries in the full weight matrix for all observations) and the two dimensions of the full weight matrix (always ND and ND, since it is a square matrix). The following lines contain the position and value of the NNZ non-zero values of the ND-by-ND correlated-weight matrix. The position is an integer indicating the element number where each non-zero entry belongs in the full matrix, assuming a column-major storage scheme. Example: assume a simulation uses 3 head observations, 4 (correlated) observations using the Drain Package, and 2 (correlated) observations of the River Package. This order is the same order in which observations are printed in other "_" output files. The full weight matrix (noting that the matrix is symmetrical) would be a 9-by-9 matrix and might look like this: 11.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 22.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 33.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 44.0 0.54 0.64 0.74 0.0 0.0 0.0 0.0 0.0 0.54 55.0 0.65 0.75 0.0 0.0 0.0 0.0 0.0 0.64 0.65 66.0 0.76 0.0 0.0 0.0 0.0 0.0 0.74 0.75 0.76 77.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 88.0 0.98 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.98 99.0 For this simulation, the _wt file would look like this: COMPRESSEDMATRIX 23 9 9 1 11.00000 11 22.00000 21 33.00000 31 44.00000 32 0.540000 33 0.640000 34 0.740000 40 0.540000 41 55.00000 42 0.650000 43 0.750000 49 0.640000 50 0.650000 51 66.00000 52 0.760000 58 0.740000 59 0.750000 60 0.760000 61 77.00000 71 88.00000 72 0.980000 80 0.980000 81 99.00000 (2) OUTNAM._su: When the OBS and SEN Processes are active, OUTNAM in the OBS input file is not "NONE", and "ALLFILES" is specified after ISCALS, a new file is generated, identified by the extension "_su". This file contains the sensitivity of the simulated equivalent of each observation to each parameter. The first line of the file contains column names, where the first two columns, named "OBSERVATION" and "SYMBOL", hold the user-supplied observation names and plot symbols, respectively. The remaining column names identify the parameters for which ISENS > 0 in the SEN input file. Following the line of column names is a line for each observation, containing the observation name, plot symbol, and simulated-equivalent sensitivity for that observation relative to each parameter for which ISENS > 0. (3) OUTNAM._mc: When the PES Process is active, OUTNAM in the OBS input file is not "NONE", and "ALLFILES" is specified after ISCALS, a new file is generated, identified by the extension "_mc". This file contains the matrix of parameter correlations. The first line of this file lists the names of all parameters for which ISENS > 0 in the SEN input file. -------------------------------------------------------------------------- Richard Yager of USGS in Ithaca, NY, kindly supplied the following information related to the _rc and _rb files produced by RESAN-2000: The "_rc" file lists Cook's D, a measure of the influence of the observation on the set of estimated parameter values, along with the observation name and plot symbol. The "_rb" file lists the name and plot symbol of each observation along with the set of DFBETAS, a measure of the influence of the observation on each parameter value. The derivation of Cook's D is given in Cook and Weisburg (1982) and the derivation of DFBETAS is given in Belsley and others (1980). The application of both influence statistics to nonlinear regression of ground-water flow modeling is discussed by Yager (1998). Belsley, D.A., Kuh, E., and Welsch, R.E., 1980, Regression diagnostics: identifying influential data and sources of colinearity, John Wiley, New York. Cook, R.D., and Weisburg, S., 1982, Residuals and influence in regression, Monographs on Statistics and Applied Probability, v. 128, Chapman and Hall, New York. Yager, R.M., 1998, Detecting influential observations in nonlinear regression modeling of groundwater flow: Water Resources Research, v. 34, no. 7, p. 1623-1633.