UPW - Upstream Weighting Package

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Abbreviation in Name file

UPW

Purpose

The Upstream Weighting package is used to specify properties controlling flow between cells in MODFLOW-NWT

Documentation

•Niswonger, R.G., Panday, Sorab, and Ibaraki, Motomu, 2011, MODFLOW-NWT, A Newton formulation for MODFLOW-2005: U.S. Geological Survey Techniques and Methods 6-A37, 44 p.

•Release.txt for MODFLOW-NWT

•Hanson, R.T., Boyce, S.E., Schmid, Wolfgang, Hughes, J.D., Mehl, S.M., Leake, S.A., Maddock, Thomas, III, and Niswonger, R.G., 2014, One-Water Hydrologic Flow Model (MODFLOW-OWHM): U.S. Geological Survey Techniques and Methods 6–A51, 120 p., http://dx.doi.org/10.3133/tm6A51.

Related Packages

The LPF package has nearly identical input.

The NWT Solver is required in the UPW package is used.

Supported in

•MODFLOW-NWT

•MODFLOW-OWHM

Other Notes

•Every model must  use one and only one of the four packages (BCF6, LPF, HUF2, and UPW) that are used to specify properties controlling flow between cells. UPW is only available in MODFLOW-NWT and MODFLOW-OWHM.

•Input data types and formats described below are nearly identical to those for the LPF Package and described on pages 8-28 through 8-31 of the MODFLOW-2005 manual (Harbaugh, 2005). However, the input variable LAYWET should be set to zero for all layers because all layers that are specified as convertible (that is, LAYTYP>0) are assumed to be wettable in the UPW Package. The model will stop and print an error statement to the main Listing file if LAYWET is non-zero for any layers. Options are not allowed in the UPW Package, as they are in the LPF Package, and the variable IPHDRY is new to the UPW Package.

•The optional variable PHIRAMP in the Well package can be specified in MODFLOW-NWT.

•An option to print property arrays in the LPF and UPW packages to separate files can be activated in the PVAL file in MODFLOW-OWHM.

Cell property data are read from the file that is type “UPW” in the Name File. Free format is used for reading all values.

For Each Simulation

Data Set 0.

[#Text]

Item 0 is optional—“#” must be in column 1. Item 0 can be repeated multiple times.

Text is a character variable (199 characters) that starts in column 2. Any characters can be included in Text. The “#” character must be in column 1. Lines beginning with # are restricted to the first lines of the file. Text is written to the Listing File.

Data Set 1.

IUPWCB HDRY NPUPW IPHDRY Options

IUPWCB is a flag and a unit number.

•If IUPWCB > 0, cell-by-cell flow terms will be written to this unit number when “SAVE BUDGET” or a non-zero value for ICBCFL is specified in Output Control. The terms that are saved are storage, constant-head flow, and flow between adjacent cells.

•If IUPWCB = 0, cell-by-cell flow terms will not be written.

•If IUPWCB < 0, cell-by-cell flow for constant-head cells will be written in the listing file when “SAVE BUDGET” or a non-zero value for ICBCFL is specified in Output Control. Cell-by-cell flow to storage and between adjacent cells will not be written to any file.

The flow terms that will be saved are the flows through the right, front, and lower cell face. Positive values represent flows toward higher column, row, or layer numbers.

HDRY is the head that is assigned to cells that are converted to dry during a simulation. Although this value plays no role in the model calculations, HDRY values are useful as indicators when looking at the resulting heads that are output from the model. HDRY is thus similar to HNOFLO in the Basic Package, which is the value assigned to cells that are no-flow cells at the start of a model simulation.

NPUPW is the number of UPW parameters.

IPHDRY is a flag that indicates whether groundwater head will be set to HDRY when the groundwater head is less than 1×10-4 above the cell bottom (units defined by LENUNI).

•If IPHDRY=0, then head will not be set to HDRY.

•If IPHDRY>0, then head will be set to HDRY.

If the head solution from one simulation will be used as starting heads for a subsequent simulation, or if the Observation Process is used (Harbaugh and others, 2000), then HDRY should not be printed to the output file for dry cells (that is, the UPW Package input variable should be set as IPHDRY=0).

Options—are optional key words that activate options:

•NOPARCHECK turns off the checking that a value is defined for all cells when parameters are used to define layer data.

Data Set 2.

LAYTYP contains a flag for each layer that specifies the layer type.

•0 – confined

•>0 – convertible

•<0 – confined

Data Set 3.

LAYAVG contains a flag for each layer that defines the method of calculating interblock transmissivity.

•0—harmonic mean

•1—logarithmic mean

•2—arithmetic mean of saturated thickness and logarithmic-mean hydraulic conductivity.

Data Set 4.

CHANI contains a value for each layer that is a flag or the horizontal anisotropy. If CHANI is less than or equal to 0, then variable HANI defines horizontal anisotropy. If CHANI is greater than 0, then CHANI is the horizontal anisotropy for the entire layer, and HANI is not read. If any HANI parameters are used, CHANI for all layers must be less than or equal to 0.

Data Set 5.

LAYVKA contains a flag for each layer that indicates whether variable VKA is vertical hydraulic conductivity or the ratio of horizontal to vertical hydraulic conductivity.

•0—indicates VKA is vertical hydraulic conductivity

•not 0—indicates VKA is the ratio of horizontal to vertical hydraulic conductivity, where the horizontal hydraulic conductivity is specified as HK in item 9.

Data Set 6.

LAYWET(NLAY)

(Item 6 should always be set to zero in the UPW Package because all layers with LAYTYP(NLAY)>0 are assumed to be wettable)

LAYWET contains a flag for each layer that indicates whether wetting is active. LAYWET should always be zero for the UPW Package because all cells initially active are wettable.

Repeat Items 7-8 for each parameter to be defined (that is, NPUPW times).

Data Set 7.

[PARNAM PARTYP Parval NCLU]

PARNAM is the name of a parameter to be defined. This name can consist of 1 to 10 characters and is not case sensitive. That is, any combination of the same characters with different case will be equivalent.

PARTYP is the type of parameter to be defined. For the UPW Package, the allowed parameter types are:

•HK—defines variable HK, horizontal hydraulic conductivity

•HANI—defines variable HANI, horizontal anisotropy

•VK—defines variable VKA for layers for which VKArepresents vertical hydraulic conductivity (LAYVKA=0)

•VANI—defines variable VKA for layers for which VKA represents vertical anisotropy (LAYVKA≠0)

•SS—defines variable Ss, the specific storage

•SY—defines variable Sy, the specific yield

•VKCB—defines variable VKCB, the vertical hydraulic conductivity of a Quasi-3D confining layer.

Parval is the parameter value. This parameter value may be overridden by a value in the Parameter Value File.

NCLU is the number of clusters required to define the parameter. Each repetition of Item 8 is a cluster (variables Layer, Mltarr, Zonarr, and IZ). Each layer that is associated with a parameter usually has only one cluster. For example, parameters which apply to cells in a single layer generally will be defined by just one cluster. However, having more than one cluster for the same layer is acceptable.

Each repetition of Item 8 is called a parameter cluster. Repeat Item 8 NCLU times.

Data Set 8.

[Layer Mltarr Zonarr IZ]

Layer is the layer number to which a cluster definition applies.

Mltarr is the name of the multiplier array to be used to define variable values that are associated with a parameter. The name “NONE” means that there is no multiplier array, and the variable values will be set equal to Parval.

Zonarr is the name of the zone array to be used to define the cells that are associated with a parameter. The name “ALL” means that there is no zone array, and all cells in the specified layer are part of the parameter.

IZ is up to 10 zone numbers (separated by spaces) that define the cells that are associated with a parameter. These values are not used if ZONARR is specified as “ALL”. Values can be positive or negative, but 0 is not allowed. The end of the line, a zero value, or a non-numeric entry terminates the list of values.

A subset of the following two-dimensional variables is used to describe each layer. All variables that apply to layer 1 are read first, followed by layer 2, followed by layer 3, and so forth. A variable not required due to simulation options (for example, Ss and Sy for a completely steady-state simulation) must be omitted from the input file.

These variables are either read by the array-reading utility subroutine, U2DREL, or they are defined through parameters. If a variable is defined through parameters, then the variable itself is not read; however, a single line containing a print code is read in place of the control line. The print code determines the format for printing the values of the variable as defined by parameters. The print codes are the same as those used in a control line. If any parameters of a given type are used, parameters must be used to define the corresponding variable for all layers in the model.

Data Set 9.

HK(NCOL,NROW) - U2DREL

If any HK parameters are included, read only a print code.

HK is the hydraulic conductivity along rows. HK is multiplied by horizontal anisotropy (see CHANI and HANI) to obtain hydraulic conductivity along columns.

Data Set 10.

[HANI(NCOL,NROW)] - U2DREL

Include item 10 only if CHANI is less than or equal to 0. If any HANI parameters are included, read only a print code.

HANI is the ratio of hydraulic conductivity along columns to hydraulic conductivity along rows, where HK of item 9 specifies the hydraulic conductivity along rows. Thus, the hydraulic conductivity along columns is the product of the values in HK and HANI. Read only if CHANI ≠ 0.

Data Set 11.

VKA(NCOL,NROW) - U2DREL

If any VK or VANI parameters are included, read only a print code.

VKA is either vertical hydraulic conductivity or the ratio of horizontal to vertical hydraulic conductivity depending on the value of LAYVKA. If LAYVKA is 0, VKA is vertical hydraulic conductivity. If LAYVKA is not 0, VKA is the ratio of horizontal to vertical hydraulic conductivity. In this case, HK is divided by VKA to obtain vertical hydraulic conductivity, and values of VKA typically are greater than or equal to 1.0.

Data Set 12.

[Ss(NCOL,NROW)] - U2DREL

Include item 12 only if at least one stress period is transient. If there are any SS parameters, read only a print code.

Ss is specific storage. Read only for a transient simulation (at least one transient stress period).

Data Set 13.

[Sy(NCOL,NROW)] - U2DREL

Include item 13 only if at least one stress period is transient and LAYTYP >0. If any SY parameters are included, read only a print code.

Sy is specific yield. Read only for a transient simulation (at least one transient stress period) and if the layer is convertible (LAYTYP >0).

Data Set 14.

[VKCB(NCOL,NROW)] - U2DREL

Include item 14 only if LAYCBD (in the Discretization File) is not 0. If any VKCB parameters are included, read only a print code.

VKCB is the vertical hydraulic conductivity of a quasi-three-dimensional confining bed below a layer. Read only if there is a confining bed. Because the bottom layer cannot have a confining bed, VKCB cannot be specified for the bottom layer.