CSUB: Skeletal Storage, Compaction, and Susidence Package Pane

The CSUB: Skeletal Storage, Compaction, and Susidence package pane is on the MODFLOW Features tab of the Object Properties dialog box.

Two types of data can be specified for the CSUB package: data for individual interbed systems and transient stress offset values. At least one of these types of data must be defined in the CSUB package input file but either one can be skipped if the other is defined.

Interbed systems

For each interbed system defined in the CSUB package in the MODFLOW Packages and Programs dialog box, the user can specify the properties of an interbed system.

•Interbed is the name of the interbed system as defined in the CSUB package in the MODFLOW Packages and Programs dialog box.

•Used determines whether or not the object defines the properties of the interbed.

•pcs0—is the initial offset from the calculated initial effective stress or initial preconsolidation stress in the interbed, in units of height of a column of water. PCS0 is the initial preconsolidation stress if SPECIFIED INITIAL INTERBED STATE or SPECIFIED INITIAL PRECONSOLIDATION STRESS are specified in the CSUB package in the MODFLOW Packages and Programs dialog box. If HEAD BASED is specified in the CSUB package in the MODFLOW Packages and Programs dialog box, PCS0 is the initial offset from the calculated initial head or initial preconsolidation head in the CSUB interbed and the initial preconsolidation stress is calculated from the calculated initial effective stress or calculated initial geostatic stress, respectively.

•thick frac—is the interbed thickness or cell fraction of the interbed. Interbed thickness is specified as a fraction of the cell thickness if CELL FRACTION is specified in the CSUB package in the MODFLOW Packages and Programs dialog box.

•rnb—is the interbed material factor equivalent number of interbeds in the interbed system represented by the interbed. RNB must be greater than or equal to 1 if the interbed system is a DELAY system. Otherwise, RNB can be any value.

•ssv_cc—is the initial inelastic specific storage or compression index of the interbed. The compression index is specified if COMPRESSION INDICES is specified in the OPTIONS block. Specified or calculated interbed inelastic specific storage values are not adjusted from initial values if HEAD BASED is specified in the CSUB package in the MODFLOW Packages and Programs dialog box.

•sse_cr—is the initial elastic coarse-grained material specific storage or recompression index of the interbed. The recompression index is specified if COMPRESSION INDICES is specified in the OPTIONS block. Specified or calculated interbed elastic specific storage values are not adjusted from initial values if HEAD BASED is specified in the CSUB package in the MODFLOW Packages and Programs dialog box.

•theta—is the initial porosity of the interbed.

•kv—is the vertical hydraulic conductivity of the delay interbed. KV must be greater than 0 if the interbed system is a DELAY system. Otherwise, KV can be any value.

•h0—is the initial offset from the head in cell cellid or the initial head in the delay interbed. H0 is the initial head in the delay bed if SPECIFIED INITIAL INTERBED STATE or SPECIFIED INITIAL DELAY HEAD are specified in the CSUB package in the MODFLOW Packages and Programs dialog box. H0 can be any value if the interbed system is a NODELAY system.

Transient

The only transient data defined in the CSUB package is the stress offset (sig0).

•sig0—is the stress offset for the cell. SIG0 is added to the calculated geostatic stress for the cell.