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iMOD User Manual version 5.2 (html)


7.18Waterbalance

WHY?
The Waterbalance Tool can be used to calculate the sum of budget quantities for different components for specified regions within the model extent and/or the entire model extent. Several budget items can be selected, as well as particular mode layers and/or model output periods, see section 7.18.1. The output can be analysed in the iMOD Water balance Analyser, see section 7.18.2.

WHAT?
The Waterbalance Tool uses specific results from iMODFLOW that start with BDG*.IDF and/or MetaSwap output file starting with MSW*.IDF. Those files are stored in folders with identical names, such as BGGFLF\BDGFLF*.IDF. All these files store the flow quantity in m\({}^{3}\)/day (cubic meters a day). As a rule of thumb the flow quantity is negative whenever it leaves the cell and positive whenever it enters the cell. Flow that leaves the cell from the Right Face (BDGFRF), the Front Face (BDGFFF) and/or the Lower Face (BDGFLF) is negative. However, for flow terms that enter the cell from the Left Face, Back Face and/or Top Face of a model cell, the appropriate flow terms from the adjacent cells need to be multiplied with minus 1, to be consequent. For Internal Boundary Conditions (e.g. rivers, drainage systems, recharge, wells) a similar approach is valid: water that enters the cell is positive, withdrawal of water is negative. Water that flow from a specified water balance region to another region is noted netagive as it leave the corresponding water balance region.

Note: The waterbalance assumes that the dimensions for data that is included are in m\(^3/\)day. Bear in mind that fluxes that are produced by MetaSWAP are in m\(^{3}\)/m\(^{2}\) and represent cumulative values as specified in the TIME_SIM.INP. Those may NOT overlap with the output file from iMODFLOW.

Example of budget terms inside and outside a computational cell for (left) cell-by-cell flow terms and (right) internal boundary conditions:

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The Waterbalance Tool will just add all flow terms within (defined) areas and list them within a summary text files (*.TXT and *.CSV) to be opened with e.g. NotePad, TextPad and/or Excell. Alternatively, it is possible to read in a generated *.CSV file into the waterbalance analyser.

HOW?
To compute a water balance, select the option Toolbox from the main menu, choose Water Balance and then choose Compute Waterbalance to open the Waterbalance window. To analyse the results of a water balance computation, select the option Toolbox from the main menu, choose Water Balance and then choose Analyse Waterbalance to open the Analyse Waterbalance window


7.18.1Compute Waterbalance

Start the Compute Water Balance window by selecting the option Toolbox from the main menu, choose Water Balance and then choose Compute Waterbalance.

Compute Waterbalance window, Result Folder tab; left for results from the Models folders and right from a different folder:

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Browse:

Select this radio button to specify a result folder from a different location.


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Select Folder
Click this button to search for a folder on disk and use that folder to list the existing budget terms. Alternatively, it is possible to enter a folder name into the string field.

Existing folder
with Results ...

Select one of the folders that appear in this list box. These are the folders in the {IMOD_USER} \MODELS folder.

Select Budget Term

iMOD will list all sub folders under the current selected or entered folder. If none are selected the other tabs in this window are unavailable. Also, whenever incorrect folders (folders that doesn’t contain the correct files) are selected this happens. Each time a single, or multiply budget terms are selected, iMOD starts searching for corresponding files. For large models, this can take a while, so it is often better to select the items in one click using Ctrl-Left- Mouse-Button or Shift-Left-Mouse-Button. The name convention is that the folder should start with BDG and/or MSW:

Subfolder

Alias

BDGBND\bdgbnd*

CONSTANT HEAD

BDGFLF\bdgflf*

FLUX LOWER FACE

BDGFRF\bdgfrf*

FLUX RIGHT FACE

BDGFFF\bdgfff*

FLUX FRONT FACE

BDGSTO\bdgsto*

STORAGE

BDGWEL\bdgwel*

WELLS

BDGDRN\bdgdrn*

DRAINAGE

BDGRIV\bdgriv*

RIVERS

BDGEVT\bdgevt*

EVAPOTRANSPIRATION

BDGGHB\bdgghb*

GENERAL HEAD BOUNDARY

BDGOLF\bdgolf*

OVERLAND FLOW

BDGRCH\bdgrch*

RECHARGE

BDGISG\bdgisg*

SEGMENT RIVERS

BDGIBS\bdgibs*

INTERBED STORAGE

BDGCAP\bdgcap*

CAPSIM

BDGDS\bdgds*

DECREASE WATER ST. ROOTZONE

BDGPM\bdgpm*

MEASURED PRECIPITATION

BDGPS\bdgps*

SPRINKLING PRECIPITATION

BDGEVA\bdgeva*

NET EVAPORATION WATER

BDGQRU\bdgqru*

RUNOFF

Modflow

Select this option to select budget terms that are specific for Modflow, automatically.

MetaSwap

Select this option to select budget terms that are specific for MetaSwap, automatically.

Found 34 correct files

Displays the number of files (34) that are correct (i.e. they fulfil the naming convention as described above and contain model layer information (_L*) and a date string (YYYYMMDD and/or YYYYMMDDHHMMSS) or STEADY-STATE keyword, e.g. BDGFLF_STEADY-STATE_L1.IDF or BDGFLF_20111231_L8.IDF or BDGWEL_20120414123015_L3.IDF.

Create CSV …
Create TXT …
Create IPF …

Click this button to save the water balance computation into a CSV, TXT or IPF file, respectively. Use the extent *.TXT to define a “table” layout of the water balance in which all components are listed together. Use the extension *.CSV to define a “time series” layout of the water balance in which all component are listed as time series. This file can be read by the Analyse Water Balance Tool, see section 7.18.2. All default settings from the other tabs (Period and layers and Apply to) will be used. Check these before clicking this button!

Help…

Click this button to start the HELP functionality

Close

Click this button to close the Compute Waterbalance window

Compute Water Balance window, Period and Layers tab (left) for a steady-state configuration and (right) for a transient configuration:

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Steady-State

Click this radio button to use files only that contain the keyword steady-state, e.g. BDGFLF_STEADY-STATE_L1.IDF. This option is only available whenever these files can be found in the result folder selected on the Result Folder tab.

Transient

Click this radio button to use files only that contain date information (YYYYMMDD), e.g. BDGFLF_20111231_L1.IDF. This option is only available whenever these files can be found in the result folder selected on the Result Folder tab.

From:

Specify the start date (day, month and year) from which the water balance needs to be computed. It has been on default filled in with the earliest result file that could be found in the result folder selected in the Result Folder tab.

To:

Specify the end date (day, month and year) to which the water balance need to be computed. It has been on default filled in with the earliest result file that could be found in the result folder selected in the Result Folder tab.

Define Period
here:

Enter the periods for which the water balance need to be computed solely. Each period consist of two dates delimited by a slash, e.g. dd-mm/dd-mm. In-between periods, use the “;” as a delimited. The convention is as follows:
01-01/31-4:
Periods starts on the first of January and ends after the 31\(^st\) of April
01-8/31-12:
Periods starts on the first of August and ends after the 31\(^st\) of December

Select one or
more of the layers

Select one or more of the listed model layers. This content of the list box is based on the BDG*-files that are found in the selected result folder on the Result folder tab. Use the Ctrl+left mouse button to exclude or add individual layers, otherwise drag the mouse cursor to select layers.

Year selection

Select one or more of the listed years. The content of the list box is based on the bdg*-files that are found in the selected result folder on the Result folder tab.

Compute Waterbalance window, Apply To tab for (left) applied to selected shapes only or (right) for all non-NoDataValues within a selected IDF-file:

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Apply to entire
model domain

Select this option to compute all budget terms for the entire model extent. In fact this will be that area and dimension as described by the first BDG*.IDF to be read.

Apply within
(Selected) Polygons (*.GEN)

Select this option to specify regions of interests by polygons. By default all polygons will be used for the water balance, however, if the option Selected is selected, only those polygons will be used that are currently selected, in the example above, this is polygon SHAPE2.


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Click these buttons to draw, open, save, delete or rename a shape. More detailed information can be found in section 4.2 (Create a GEN-file).

Apply for non-
NODATA values
within IDF

Select this option to use an IDF-file that describes the area of interest by its non-NoDataValue. For those locations of the first BDG*.IDF or MSW*.IDF read, the value within this IDF-file will be read and evaluated. A non existing IDF file name will outgrey the Create CSV …, Create TXT … and Create IPF … button.


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Open IDF-file
Click this button to open an IDF-file. The selected file will be displayed, however, an IDF-file can be entered in the string field alternatively. If the IDF-file does not exists, the Apply button will grey out.

Save Interconnected fluxed between zones

Select this option to generate interconnected flux between the zones. This option is only valid whenever the flux terms BDGFRF and BDGFFF are active.

Note: After a computation for a water balance, iMOD will save an IDF-file at the location where you’ve saved the output file via Create CSV; Create TXT; Create IPF. This IDF files contains the location of the raster cells for each zone. Inspection of this file can lead to adjustment of the polygons used, and/or reuse this particular IDF file for different model scenarios. Remember that in case of overlap in polygons, the value of the zone in the IDF-file becomes negative, so zone 1 might appear as -1. This doesn’t affect the computation of the water balance volumes but has a purpose for finding overlap only.

Example of “table” layout of the water balance:

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Example of a “time serie” layout of the water balance:

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7.18.2Analyse Waterbalance

To analyse the results of a water balance computation, select the option Toolbox from the main menu, choose Water Balance and then choose Analyse Waterbalance to open the Analyse Waterbalance window. The key thought is that a CSV file is read in first and after that several selection can be made by the different tab on the window. Finally an output can be defined, this can be a schematic representation of the water balance, a time series, a table and/or spatial patterns of water balance term saved in IDF files.

Analyse Waterbalance window, CSV-file tab:

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Open Predefined
Configuration
from INI file:

Select this radio button to select an INI file that contains a particular set of configuration parameters.


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Select INI file
Click this button to select an INI file from a folder. iMOD will read the configuration and read the CSV file defined in te INI file.

Open CSV-file
with Budget terms:

Select this radio button to select a CSV that contains the budget terms for a particular set, default configuration parameters will be applied.


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Select CSV file
Click this button to select a CSV-file from a folder on disk. iMOD will read the CSV completely and stores the content in memory to perform adequate and efficient selection as defined by the other tabs. The content of the CSV file will be listed as:
  • Name of the CSV file: This is the name of the read CSV file;

  • Number of records: This is the number of entry records, it is a multiplication of the number of periods, zones and layers;

  • Number of Budget Terms: This is the number of budget terms, this can include the interconnected flow as separate entries;

  • Number of Periods: This the number of periods, time series can be constructed whenever this is large than 1;

  • Number of Layers: This is the number of model layers that exists in the CSV file;

  • Number of Zones: This is the number of zones

All the above mentioned separate quantities can be selected, aggregated and displayed by setting the appropriate selection criteria in the following tabs.

List in iMOD Manager

Click this button to export the zones as defined in the CSV file into an IDF file ({IMOD_USER} \TMP \WATERBALANCE.IDF) and listed in the iMOD Manager for viewing options, this is the only way to get the zones stored in the CSV out to re-use them and/or select the appropriate zones once the original GEN- or IDF file has been deleted.

Save Current Configuration:

Click this button to save the current configuration (the name of the CSV and the corresponding selection and settings, including changed colours to a INI file. This INI file can be loaded by the Open Predefined Configuration from INI file: and/or used in the iMOD Batch function WBALANCE, see section 8.11.2.

Help…

Click this button to start the HELP functionality

Close

Click this button to close the Analyse Waterbalance window

Analyse Waterbalance window, Budget Terms tab:

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Select All

Click this button to select all budget items in the table (first column) and/or select all the available periods in the list of Timesteps.

Deselect All

Click this button to deselect all budget items in the table (first column) and/or deselect all the available periods in the list of Timesteps.

Modflow

Click this button to select all specific iMODFLOW budget terms.

MetaSwap

Click this button to select all specific MetaSwap budget terms.

BDG*
2010*

Enter a search string to select or deselect budget terms (second column in the table FluxTerm) and/or select Timesteps. The search string is case sensitive and contain wildcards such as * and question marks to notate a fixed number of character, such as 2010??01.


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Increase Selection
Click this button to increase the current selection for budget terms in the table with Available Budget Terms and/or periods in the list of available Timesteps.


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Decrease Selection
Click this button to decrease the current selection for budget terms in the table with Available Budget Terms and/or periods in the list of available Timesteps.

Units

Select one of the options to define the units in the water balance. If the option m3day is selected no conversion is applied, whenever the option mmday is chosen, the budget volumes will be divided by the area of the corresponding zone and multiplied with 1000.

Available Budget Terms

The table gives all existing budget terms in the current read CSV file. The following columns are defined:
  • Select: This column activates and deactivates a individual budget to more included or excluded in the presentation of a water balance;

  • FluxTerm: This is a non-editable column with predefined labels for the budget terms. This is used by iMOD to be able to assign the appropriate budget terms to specific entries for the graphical representation that can be chosen on tab4;

  • Colour: The colour for each row in the table is used to colour the bar in the time series graph. To change the colour, select the appropriate cell and the standard colour picking window appears in which it is possible to select a colour, see section 2.8;

  • LabelName: Enter a name for each budget term that will be used in the output of the waterbalance, it will be used as a legend name in the time series and as a name in the graphical representation of the water balance. iMOD fills in a default for each distinguished budget term;

  • Group: This column is filled in with a group number. By default the groups are unique numbers starting from 1 to the number of budget terms in the CSV file. The use of this group number is twofold:

    • – The group number is used to group budget terms into a single entry for the time series. So whenever two budget term receive an similar, unique group number that appear as a single budget term in the output. The name for the legend of that group will be formed by the first entry of a budget term that belongs to that group. Any number can be entered as a group number, zero is sustained as a group number as well. In the example on the figure above, the budget terms BDGFLF and BDGFTF are grouped together as group number 2;

    • – The value of the group number defines the order in which budget terms are plotted in the time series. The appearance of the time series might change significantly by changing the group numbers. In the example on the figure above the budget term BDGDRN_SYS1 is plotted at last since its group number is 88 and the highest value compared to the others.

Analyse Waterbalance window, Aggregation tab:

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Aggregation

Select one of the following options to aggrate the water balance for the period as selected on tab 2:
  • All Time steps: a single value for all entries

  • Year: a single value per year

  • Months: a single value per month, starting at the first month in the series

  • Hydrological Seasons: two seasons are used, 1) April - September and 2) October - March

  • Decade: a single value per 10 days and the remaining days in that month

  • Hydrological Year: four seasons are used 1) December - February 2) March - May 3) June - August 4) September - November

  • Quarters: a single value per 3 months, starting in January

  • None: all entries remain unchanged.

Net fluxes

Select this option to compute net fluxes. In that case iMOD will compute a total net flux for all selected budget terms, each budget terms receives in that particular case a single net (sum of the in- and outflow) entry in the water balance

Select All

Click this button to select all model layers in the list of available Model layers and/or select all the available zones in the list of Zones.

Deselect All

Click this button to deselect all model layers in the list of available Model layers and/or select all the available zones in the list of Zones.

10*
1?

Enter a search string to select or deselect budget terms (second column in the table FluxTerm) and/or select Timesteps. The search string is case sensitive and contain wildcards such as * and question marks to notate a fixed number of character, such as 1?.


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Increase Selection
Click this button to increase the current selection for model layers in the list of available Model Layers and/or zones in the list of available Zones.


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Decrease Selection
Click this button to deecrease the current selection for model layers in the list of available Model Layers and/or zones in the list of available Zones.

Layer aggregation

Select one of the following options:
  • One Balance per Layer: Select this option to treat budget terms as separate items in the selected form for output;

  • Sum Selected Layers: Select this option to aggregate budget terms for selected model layers.

Zone aggregation

Select one of the following options:
  • One Balance per Zone: Select this option to treat budget terms as separate items in the selected form for output;

  • Sum Selected Zones: Select this option to aggregate budget terms for selected zones.

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Figure 7.2: Analyse Waterbalance window, Graphics Output tab


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Select Folder
Click this button to select a folder that iMOD will uses to save images if needed. It depends on the choice of the Output Type whether this is applicable. By default iMOD will save the images in the TMP folder of the {IMOD_USER} folder.

Output Type

Select one of the following output options:
  • Time Series: Select this option to display the selected water balance items in a graph. Below is an example of the time series.

Example of the water balance time series

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Copy
Click this icon to copy the entire content of the graphical area onto the Clipboard of Windows.


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ZoomIn
Click this icon to zoom IN on the centre of the current graphical dimensions.


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ZoomOut
Click this icon to zoom OUT on the centre of the current graphical dimensions.


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ZoomRectangle
Click this icon to zoom in for a rectangle to be drawn. Use your left-mouse button to determine the lower-left corner of the rectangle, click again for the upper-right corner (or vice-versa).


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ZoomFull
Click this icon to zoom in on the entire extent of the time series.


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Move
Click this icon to move the current display. Click the left-mouse button on that location where you want to move from, repeat this after the display has been refreshed (automatically). Use the right mouse button to stop the moving process.

Layer 2; Zone 2

This dropdown menu displays all possible combination in between selected model layers and selected zone, in case no aggregation is selected for both of those entries. If a single model layer and a single zone is selected, or they are both aggregated, the dropdown menu will not appear.

  • Graphical Representation: Select this option to present the water balance items in a illustrative image. Below is an example of the time series.

Example of the water balance as an illustrative image

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  • Preview Table: Select this option to display each value for the water balance items in a table, see the explanation given at the following section;

  • Export to CSV: select this option to export all water balance items into an CSV file;

  • IDF per Layer: Select this option to export all water balance items into separate IDF files. This yields a single IDF per budget term, per model layer and per period as selected. Any aggregation will decrease the number of output combinations. The name of each IDF file is constructed automatically and includes the budget term, the period, model layer.

Zoom to Selected Polygon(s)

Select this option to create an overview image on the graphical representation graph whereby the area is zoomed in on the selected polygon(s).

Apply percentages for Volumes

Select this option to compute percentages for each waterbalance entry in the graphical representation graph.

Title

Specify the title of the graphical representation graph. The title will automatically wrap over two line of the number of characters excceds the number for a single line. The maximum of characters is 256.

Generate Preview
Generate Table

Click this button to generate a preview of the selected Output Type. Not all of the output types support a preview, this button will be out greyed for those situations. Whenever the Generate Table is active, the tab Table Output becomes accessible and display a table form of the results of the water balance.

Generate Graphics
Export CSV File
Export IDF File

Click this button to generate an image to be saved on disc. In this case the output folder as specified by Output Folder is applied. Not all of the output types support a preview, this button will be out greyed for those situations.

Analyse Waterbalance window, Table Output tab:

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Select Available Waterbalance Group

Select from the dropdown the appropriate combination of selected model layers and/or zones. This dropdown menu displays all possible combination in between selected model layers and selected zone, in case no aggregation is selected for both of those entries. If a single model layer and a single zone is selected, or they are both aggregated, the drop down menu will not appear.

Table

The entries in the table are the results of any configuration settings applied in the previous tabs. Each row is a period and depend on the Aggregation type as selected on tab3. It is possible to copy the content of the entire table to the clipboard by the using the option Crtl-C.