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Recent Changes to WEAP

5/29/13, Version 3.43

  • New API functions: Branch.NodeAbove, Branch.NodeBelow, Branch.ReachAbove, Branch.ReachBelow. Get the node or reach above or below the current branch. For example, IF WEAP.Branch("\Supply and Resources\River\Weaping River\Reaches\Below Central Reservoir").NodeAbove.TypeID = 4 THEN ...
  • New API function: Branch.River: Gets the WEAPBranch for the river this node or reach is on.
  • New API function: Branch.RiverOrder: Gets the ordering of this node or reach on the river, starting at the top, where the headflow reach has Order = 0. Returns -1 if the branch is not on a river.
  • Ability to refer to catchment Total Yield results (for simplified coefficient method) in expressions.
  • Ability to refer to catchment Soil Moisture results in expressions: For the soil moisture method (2 bucket model), you can refer to the results from the previous timestep for any catchment branch's soil moisture (%) for either bucket 1 or bucket 2. For example, from the Tutorial chapter on hydrology, you could use the following expression: PrevTSValue(Demand Sites and Catchments\Agriculture Catchment\Irrigated:Relative Soil Moisture 1[%])
  • Improved handling of corrupt data tables: WEAP can detect and offer to repair certain types of data corruption that in some cases was preventing WEAP from starting.
  • Better handle reading from Excel files (using Interp function) that have the same name but are in different folders.
  • Catchments using method "Irrigation Demands only (simplified coefficient method)" no longer require a runoff or infiltration link to surface or groundwater.
  • LossRate variable now used for monthly demand method in addition annual demand method.
  • Fixed bug (from version 3.4101) in Results View: Current Accounts year was not being shown.

4/17/13, Version 3.4101

  • Improved speed of chart creation in the Results View, especially in large models
  • Fixed bug in SoilProfile wizard

4/15/13, Version 3.41

  • Fixed crash during calculations: In a few cases, some people were getting an error during calculations: Table does not exist: Result_38.DB

3/22/13, Version 3.4

  • MODFLOW groundwater flow field vectors: The groundwater flow field can be shown both as 3-D vectors and superimposed on the Schematic, one per MODFLOW cell, with the length of the vector reflecting the magnitude of the Darcy velocity. See WebHelp/index.html#MODFLOW_Run.htm for details.
  • Display of MODFLOW cell attributes: When viewing MODFLOW results, there is now an option to display the MODFLOW cell attributes in each cell (W=Well, R=Recharge, D=Drain, V=River, H=Constant Head, F=Flooded, dry=Dry Cells). See WebHelp/index.html#MODFLOW_Run.htm for an example.
  • Pumping from dry cells: A demand site is no longer able to pump from a MODFLOW cell that is or becomes dry, which might result in unmet demand (depending on if all of the linked cells are dry, and it cannot use other supplies).
  • Link Demand Site sub-branches to specific MODFLOW cells: For even more precision in specifying pumping and recharge, you may link WEAP demand site sub-branches to individual MODFLOW cells. In this case, flows to and from these branches will go to only the cells linked to those branches. See WebHelp/index.html#MODFLOW_Link.htm for details.
  • Enhanced display of background maps: Many new options for displaying background layers, including "thematic" shading based on geographic data. See WebHelp/index.html#Map_Layer.htm for more information.
  • A Demand Site's Supply Preference can now vary over time (monthly or yearly) or by scenario.
  • Two buckets for Mabia catchment method: If your model includes any catchments that use the MABIA catchment method, you can now choose whether to use one or two vertically stratified "buckets" (compartments) to compute the water balance. The top bucket is defined by the rooting zone, and includes the surface layer (the layer that is subject to evaporation). The bottom bucket, if the two bucket method is used, is the remainder of the soil below the rooting depth down to the Total Soil Thickness. The size of the two buckets changes with the rooting depth, but the sum remains constant. Infiltration takes place at the top bucket only, groundwater recharge from the bottom bucket only. Flow from bucket one to bucket two, or from bucket two to groundwater, only occurs if the bucket's field capacity is exceeded. If using two buckets, WEAP will calculate the average soil water capacity separately for the top and bottom bucket, based on the horizons that fall within each bucket.
  • Mabia Soil Profile Wizard and Consolidated Rock: Layers below consolidated rock are ignored.
  • Mabia crops can now span a water year boundary.
  • Divide into Clusters (ReadFromFile disaggregation method): Divide the monthly value from the CSV file into a sequence of evenly spaced "events," such as rainstorms, each of which can last several days. The number of events per month is specified by the Disaggregation Method Parameter; the duration of each event is specified by the ClusterLength parameter. Useful for creating a plausible daily timeseries of rainfall from a monthly CSV file. See WebHelp/index.html#Read_From_File.htm for details.
  • Lookup function for expressions: Looks up the value of an independent variable (X), and returns a value for a corresponding dependent variable (Y). The set of N data points -- (X1, Y1), (X2, Y2), ..., (Xn, Yn) -- defines a function: f(X) = Y. Syntax: Lookup( XTitle, YTitle, InterpMethod, X, X1, Y1, X2, Y2, ..., Xn, Yn) InterpMethod is either "Linear" or "Step". E.g., Lookup( Cost[$], Demand[m^3], Linear, \Key\Water Price, 0.10, 2000, 0.50, 1000, 1.0, 100) ; X is water price and Y is water demand. As price goes up, demand goes down.
  • Wizard for Lookup function: Wizard to help constructing a Lookup expression, including pasting an array of numbers from Excel. In the Data View, click the dropdown arrow in the expression box and choose "Lookup Function Wizard."
  • New API function SaveSchematic: Save the Schematic to a jpg, png or Google Earth file. See help for details.
  • New API function ZoomSchematic: Zoom the Schematic out to show the full area boundaries.
  • Refer to groundwater overflow result in expressions: Can now refer to the previous timestep's result for groundwater overflow in an expression, e.g., PrevTSValue(North Aquifer:Overflow)
  • Line charts: The line width on charts can be changed (anywhere from 1 to 4 pixels wide). To make all vectors the same color, change "Number of colors" to 1 on the Legend Colors dialog. (Click the rainbow button on the chart toolbar.) Also, you can change the color palette (rainbow, greyscale, reds, greens, blues). Therefore, to make the lines all black, set to 1 color and gray scale. This can be useful to simplify the display of groundwater flow field results from MODFLOW.
  • Translations: Spanish translation complete; partial translations for Arabic, Chinese, Farsi, French, Greek, Korean, Lithuanian, Portuguese, Russian, Thai and Vietnamese.
  • Added global cities layer to new, blank WEAP areas.
  • Disabled old WEAP license registration codes: Registration codes from before 2008 were not secure, so they have been disabled. If you still qualify for a free license, you may re-apply online: Apply
  • Fixed bug in groundwater "wedge" model: When using the groundwater wedge model (Option: "Model groundwater-surface water interactions" WebHelp/index.html#Purkey_Wedge_Method.htm ), WEAP had been overestimating groundwater-surface water flows by a factor of 365 (both inflows and outflows). In this new version, when WEAP first opens a model that has groundwater wedges, it will warn you about the previous error, and offer to make a correction (decrease Horizontal Distance by 19.1, which is the square root of 365) so that the results will be unchanged.
  • Fixed bug in editing water quality variables: Unable to make changes to variables that represented Temperature.
  • Fixed bug in order of reaches: Newly added reaches were not being added into the correct place in the tree in the Data View.
  • Fixed bug in orphaned user-defined result variables: If a user created a new variable and marked it as a result variable, then deleted it, it was still showing up on the list of results variables in the Results View.
  • Fixed unit conversion bug in initial snow data: WEAP was incorrectly dividing the initial snow data by 1000.
  • Fixed bug in MODFLOW linkage: WEAP was not adding the newly created Recharge package to the new Name file if one didn't exist in the original MODFLOW name file.
  • Fixed bug in user-defined LP constraints: WEAP would crash if a constraint referred to a streamflow variable using a flow unit (e.g., CFS).
  • Fixed bug in Random() function: It was crashing when called with 2 or fewer parameters
  • Fixed bug that prevented WEAP from starting in Windows XP if not running as administrator.
  • Fixed bug in reservoir evaporation: If a reservoir was not active in the current accounts and had data (in the scenario) on maximum hydraulic outflow, WEAP incorrectly calculated evaporation in years before the reservoir became active.
  • Fixed bug in CSV export of daily results (all dates after the 600th day were missing).
  • Fixed bug in maximum hydraulic outflow constraint for local reservoirs.

9/12/12, Version 3.3001

  • Handle MODFLOW models without recharge packages
  • Fixed bugs in Copy and Rename functions of the Scenario Manager

9/3/12, Version 3.3

  • Major new version of WEAP released: highlights include:
  • Model the Water-Energy Nexus: Dynamic linkage to SEI's Long-range Energy Alternatives Planning (LEAP) system
  • Wizard for modeling environmental flow requirements
  • Wizard for exploring and importing time series data files (CSV)
  • Calculations are faster and more robust
  • Numerous other improvements, optimizations and bug fixes
  • Model the Water-Energy Nexus: Dynamic linkage to SEI's Long-range Energy Alternatives Planning (LEAP) system. Create dynamic, bidirectional links between a WEAP water planning model and a LEAP energy planning model. Users can now explore how individual water or energy management choices ripple through both the water and energy systems, understanding tradeoffs that might not be apparent when looking at either system alone. They can then evaluate outcomes against their policy goals and priorities: to supply enough water for all, to reduce GHG emissions, etc. If one approach leads to unacceptable results, they can then explore alternative policies and measures.
  • Modeling environmental flow requirements: There is a new function and wizard to help with specifying environmental flow requirements. Starting with streamflow gauge record, either historical or artificial (e.g., from a climate projection), WEAP can shift this "flow duration curve" by a variable amount to approximate different Environmental Management Classes (EMC). The syntax is: FDCShift( ReadFromFile(CSVFileName, other ReadFromFile parameters...), Environmental Management Class), where Environmental Management Class is a letter from A-F that indicates how far to shift the original time series. There is a FDCShift Wizard to help build this expression. See WebHelp/index.html#Read_From_File_Wizard.htm for more info.
  • ReadFromFile Wizard for exploring and importing time series data files (CSV): Use the wizard to quickly explore, compare and select individual time series from one or more CSV text files. See WebHelp/index.html#Read_From_File_Wizard.htm for more info.
  • Added FirstYear and LastYear parameters to ReadFromFile: The optional 8th and 9th parameters to ReadFromFile can be used to restrict the first and last years of data to use from a CSV file. If not specified, they will default to the first and last years of data in the file. See WebHelp/index.html#Read_From_File.htm for more info.
  • Added "Cycle" parameter to ReadFromFile: The optional 10th parameter to ReadFromFile is either "Cycle" or "No Cycle" (without the quotes). If "Cycle" is specified, WEAP will wraparound from the end of the file back to the beginning. For example, if the WEAP area time horizon is 2000-2050 and a CSV file has data from 1960-1969, WEAP would use data from 1960-1969 for years 2000-2009, then wraparound so that 2010-2019 would also use 1960-1969, and the same for all subsequent years. If the cycle parameter is not specified, it will default to "No Cycle."
  • Changed how missing values are filled in ReadFromFile: If you are aggregating daily data into monthly values, or monthly data into annual values, WEAP will now fill missing data using the Missing Value Method before aggregating. For example, if you have daily temperature data that you need to aggregate to monthly averages, you might use the Interpolate Missing Value Method to fill in gaps in the daily data, all of which will all be averaged to get the monthly average temperature.
  • Calculations:
  • Faster: Numerous optimizations to speed up calculations and display in both the Data View and Results View.
  • More robust: Make structural changes to the LP model formulated by WEAP that result in speed and stability improvements. In rare cases, typically with very complex models, WEAP's internal linear program (LP) solver had be unable to solve the allocation and flows in a few timesteps. Several changes to the LP formulation have improved its reliability. In extremely rare circumstances where it still cannot find a solution, WEAP will use the open source GLPK solver
  • Improved handling of reservoir maximum hydraulic outflow (MHO): In some cases, typically where the flow into the reservoir was much larger than the total storage capacity of the reservoir, it caused an LP failure. Now, any MHO constraints that cause an LP failure will be temporarily disabled (for that timestep only). WEAP will report which MHOs were temporarily disabled.
  • Improved allocation algorithm: WEAP now does a better job at equalizing coverage among demand sites with the same supply priority and preference. NOTE: this change may cause results from previous versions of WEAP to differ slightly from results in this new version.
  • Minimize unused outflow from diversions: WEAP will try to reduce the amount diverted into a diversion, so as to minimize how much water flows out the end of the diversion (and is lost from the system).
  • You can speed up calculations by turning off selected result variables: The more result variables you calculate, the longer calculations will take and the more disk space will be used, but the more detail you can see in the Results View. Some variables must be saved because they are used internally during calculations. Also, if you reference any result variables in Data View expressions (with the PrevTSValue function), you must also save these. On the menu, go to Edit, Result Variable, Select Variables to Calculate.
  • Warning message in calculations if you have an extremely large data value (larger than 100 billion), because very large numbers can cause problems for the LP solver.
  • Warning message in calculations if you run low of disk space during calculations (less than 50 MB free).
  • Warning message in calculations if any estimated surface water flows to groundwater (when using the "Model GW-SW Flows" method) had to be reduced (because they exceeded available river flow).
  • Disallowed using a transmission link to move water from one river or diversion to another river or diversion. Use a diversion instead.
  • Change in Interp: When using the Interp function for scenario expressions, now you can override the Base Year value with a different value. If so, WEAP will interpolate using the new Base Year value instead of the actual Base Year value from Current Accounts.
  • Allow changing value of "Model WQ?" variable for diversions not active in Current Accounts.
  • WEAP will now check for and prohibit Catchment Land Area from being less than zero.
  • New Result Reports:
  • Wastewater Treatment Plant Total Inflow. Total volume of wastewater that flows into a wastewater treatment plant (without regard to the plant's capacity). Could be useful in calculating treatment costs or energy use on a per unit basis.
  • Unconstrained and Constrained Flow from Surface Water to Groundwater: If you are using the "Model GW-SW Flows" method, in some cases it can estimate flows from surface water to groundwater that exceed available flow in the river. When this happens, the estimated flow to groundwater must be reduced. These two Supply and Resources\River reports show the original, unreduced estimated flow ("Unconstrained") and the actual amount simulated by WEAP AFTER any required reductions are made ("Constrained"). Note: The Groundwater Inflows and Outflows report shows the Constrained flows.
  • Link Water Quality: Concentrations of water quality constituents in transmission links, return flow links and infiltration/runoff links.
  • Wastewater Treatment Plant Capacity Utilization: The fraction of a Wastewater Treatment Plant's capacity that is used. (Capacity is an optional data variable--if left blank, there will be no capacity restriction.)
  • Water quality reports renamed for clarity: "Surface Water Quality" is now "River Water Quality"; "Source Water Quality (by Source)" is now "Outflow Water Quality (by Source)" (the concentration of outflows from non-river nodes); and "Source Water Quality (by Mixed)" is now "Inflow Water Quality (Mixed)" (the concentration of the mixed transmission link inflows to a demand sites).
  • API:
  • Get or set Branch.StartupYear: View or change an object's Startup Year in the active scenario using the API Branch.StartupYear property, e.g., WEAP.Branch("\Supply and Resources\River\Weaping River\Reservoirs\North Reservoir").StartupYear = 2014. Make sure the active scenario is correct first, e.g., WEAP.ActiveScenario = "Supply Measures"
  • Get or set WEAP.DiscountRate: View or change the area-wide discount rate (percent). E.g., To set the discount rate to 3%, WEAP.DiscountRate = 3 Can also be set in WEAP from the Main Menu: General, Units, Monetary.
  • GIS coordinates via Branch API: New properties (IsNode, IsLine, X, Y, X2, Y2) added to the Branch API class that exposes the GIS coordinates of any node or line from the WEAP Schematic. For example, in Weaping River Basin, WEAP.Branch("Demand Sites\South City").X will get the longitude for South City. See the help topic "WEAPBranch and WEAPBranches Classes" for details and more examples.
  • Get if WEAP is registered (licensed): WEAP.Registered
  • Bugs Fixed:
  • Expression references to variables of an object that was not active in the Base Year and only became active after the first scenario year incorrectly evaluated to 0.
  • Water quality constituents were not being calculated in flows in transmission link from supplies into reservoir or river nodes.
  • Catchment results were not correct in daily models that included leap days on March 1 in non-leap years.
  • Water was prevented from flowing from Other Local Supplies that were directly connected to a river or diversion.
  • In some cases, when viewing Data Variables in the Results View, some data variables were not being recalculated.
  • WEAP occasionally froze while the user was drawing a new river on the Schematic.
  • Deleting a river left behind orphan branches on the tree in the Data View.
  • In some cases where the maximum catchment ponding depth decreased at the same time of heavy precipitation, there was negative irrigation demands for ponding (with the Soil Moisture method).
  • Fixed discrepancy with reported groundwater outflow to river: In some cases, there was a discrepancy between results on the "Groundwater Outflow to River" report and the "Groundwater Inflows and Outflows" report.
  • Working directory management:
  • Option to automatically delete all files in the working directory when WEAP exits: Put the following line in the WEAP.ini file, which is located in the WEAP Areas folder (not the WEAP Program folder): DeleteWorkDirFilesOnExit=1 It is completely safe to do this--WEAP will copy them back to the working directory when it next starts. Note: To edit WEAP.ini, make sure WEAP is not running at the time.
  • WEAP will now automatically create a custom working directory location that is specified in WEAP.ini (using the line: WorkDir=), no matter how many directories it contains, e.g., WorkDir=B:\WEAP Files\Jack\Temp Note: to speed up WEAP's calculations, you can create a RAMDisk and place WEAP's working directory on it. See index.asp?action=9&read=1352&fID=30 for more information.
  • You can use the Windows user name to set the customized working directory using %UserName% in the WEAP.ini WorkDir line, e.g., WorkDir = B:\WEAPFiles\%UserName%
  • Miscellaneous:
  • Saving and restoring large datasets is now twice as fast
  • Ranges for variables displayed in Data view: If a data variable has a required range (e.g., Consumption must be between 0 and 100%), it will be listed below the description of that variable.
  • Set variables read only: The Edit Variable screen has a setting to make a variable (both user-defined and built-in) read only. If a variable is read only, the user cannot override the default value or expression.
  • Hide cost variables: Cost data variables (e.g., Capital Costs, Operating Costs) can be selectively hidden for different object types. For example, you could hide the cost variables for demand sites and groundwater nodes, but not for transmission links or wastewater treatment plants. (Previously, if you hid Capital Costs for Demand Sites, it would also be hidden for all other objects.)
  • Ability to rename "Other Assumptions" branch name: right click on the branch and choose Rename.
  • Remember schematic setting for priority display: When opening an area, WEAP will remember the previous setting for the display of priorities and preferences on the Schematic. (From the menu: Schematic, Change priority view)
  • Export to Excel: Export Expressions to Excel will now export the Startup Year variable
  • The "FAO Crop Requirements Method" has been renamed the "Simplified Coefficient Method."

10/31/11, Version 3.22

  • Fixed PEST problem: Fixed a problem that was preventing the PEST Calibration Wizard from working correctly.

10/21/11, Version 3.21

  • Instream water quality calculations: Fixed a problem that caused incorrect calculations for instream water quality calculations in cases where the unit for river flow and river width was not CMS and meters, respectively.
  • Groundwater nodes not active in Current Accounts: Fixed a problem that ignored the initial storage for groundwater nodes that were not active in Current Accounts.

10/13/11, Version 3.2

  • User-defined result variables: Some data variables may actually represent calculated results, especially if you provide a default expression. In this case, you might want to highlight the result by having it appear in the Results View among the built-in result variables, instead of with all the other data variables under the results category "Input Data." To do this, right click on the data variable tab and choose Edit, then check "Result Variable" and choose the results category under which it should appear (e.g., Demand, Reservoir, Groundwater).
  • New report: Reservoir Storage Volume and Zones. For a single reservoir, see how the simulated storage compares with the reservoir zones (Conservation, Buffer, Inactive). See Downloads/ReservoirZones.gif
  • Automated error reporting: In the unlikely event of a crash in WEAP, you now have the option to email the error report to The error report will contain details of the crash, the full errorlog file (WEAP_Errors.txt), and the option to attach the current area (zipped) and/or a screen capture at the moment of impact.
  • Password-protect areas: Option to add a password to an area that would then be required to either open or save changes to the area. Add a password when creating an area. Add or change the password from the Manage Areas screen.
  • Add notes when creating an area: At the moment you create an area you can give a description of the new area. This should make it easier and therefore more likely for you to add this crucial piece of documentation to your data.
  • Semicolon (;) is now allowed as List Separator character: Previously, because ";" (semicolon) was reserved as the comment character for expressions, WEAP did not allow the Windows List Separator character to be ";"
  • Access to Net Cost and Net Present Value result values from expressions (sums across cost types) and API: For example, PrevTSValue(Supply and Resources\Transmission Links:Net Cost[$]) is the sum of the capital costs, operating costs and benefits (net cost) in all transmission links.
  • Calculations faster: Made several optimizations in the calculation code to speed up calculations. Some models will see greater speed up than others, depending on the details of the models.
  • Dynamic loading of background GIS layers: Previously, WEAP was always loading or attempting to load background layers on the Schematic map, even if they were not marked as being shown (unchecked in the list on the left). With this change, WEAP will only load a layer onto the map if it is set as visible (checked). This results in a substantial speedup in opening WEAP areas that referenced GIS layers on inaccessible network drives (e.g., 40 seconds, because WEAP had to wait for Windows to time out its network search).
  • Complete list of background GIS layers: Previously, if a GIS layer was not available (for example, if the area had come from another user who had referenced a layer in a folder outside the WEAP area folder, and therefore did not exist on the new user's computer), WEAP would not list it in the list of background layers. With this change, WEAP will list all the layers in the list on the left, even those that are not accessible, so that the user can see which ones are missing, and have the option to find the GIS files or remove the layer from the map. If a layer had been checked but is currently unavailable, it will be unchecked.
  • Hydropower result unit: Hydropower can now be reported in Power (e.g., megawatt) as well as Energy (e.g., megawatt-hour) units.
  • Improved selection of nodes on Schematic: You can now click anywhere on a node (e.g., Demand Site, Reservoir, Groundwater node) to select it, not just near the center of the node.
  • Fixed bug with wastewater routing: Previously, if wastewater was routed to a wastewater treatment plant that had not started, the pollution disappeared. With this fix, the pollution will not disappear, and a calculation message will warn that wastewater was routed to an inactive wastewater treatment plant.
  • Fixed error caused by diversions flowing out of local reservoirs.

6/4/11, Version 3.11

  • Fixed bug in Remainder: Version 3.1 had a bug in the calculation of Remainder that could cause incorrect results in some cases.
  • SaveVersion API: WEAP.SaveVersion API method has a new, optional parameter to include result in the version. SaveVersion(Comment, IncludeResults): Create a new version of the active area with the given comment. If optional IncludeResults is TRUE, include the results in the version.
  • DeleteResults API: WEAP.DeleteResults: Delete all results files for the active area. This might speed up calculations, if the results file contain previously calculated results from many scenarios, but you only want to look at results for one or a few scenarios.

5/24/11, Version 3.1

  • Export results to Google Earth: WEAP can export the area schematic and results in Google Earth format (.kmz). This provides a powerful and convenient way to package the results from a WEAP analysis to share with others--everything is saved in one file that can be sent via email or posted on a web site for others to download and open in Google Earth. See WebHelp/index.html#Google_Earth.htm for details. See a video demonstration:
  • Maximum reservoir outflow: Option to constrain reservoir release due to a maximum hydraulic flow. If there is a hydraulic constraint, specify it on the new reservoir variable "Maximum Hydraulic Outflow" (Category: Physical). Typically this will be function of reservoir elevation at beginning of timestep, which you can access with PrevTSValue(Storage Elevation). Optional--no constraint if blank. Also, no constraint in timesteps when reservoir is completely full--water will overtop reservoir at unlimited rate. See WebHelp/index.html#Reservoir_Max_Outflow.htm
  • New LP solver: Updated to latest version (5.52) of linear program (LP) solver, which should be faster and more numerically robust. LP Solver version number now listed in Help, About.
  • Area names with international characters: Fixed bug that prevented WEAP from recognizing WEAP areas with international characters in the name.
  • Faster zooming on map: Hold down the control key while moving the mouse wheel over any map to speed up zooming in and out
  • API methods to add and delete scenarios: WEAP.Scenarios.Add("New scenario name", "Parent Scenario") will create a new scenario as a child of the named parent scenario, e.g., WEAP.Scenarios.Add("Larger reservoir", "Supply Measures"). WEAP.Scenario("Scenario name").Delete will delete the scenario, e.g., WEAP.Scenario("Larger reservoir").Delete. If it has children, you must use the optional DeleteChildren parameter set to true, e.g., WEAP.Scenario("Reference").Delete(True)
  • Trig functions: Version 3 of WEAP had inadvertantly redefined the trigonometry function (cos, sin, tan, arccos, arcsin and arctan) to use radians instead of degrees. With this version, they will use degrees again.
  • Better handling of key assumptions values in Data View: In cases where different key assumptions have the same unit but different scales (e.g., AF and TAF), WEAP now displays the values correctly in Data View charts and tables. (WEAP had always been using the correctly scaled values for calculations.)
  • Different LP scaling factors: Changed LP scaling factors to fix rare instances of LP infeasibilities.
  • Fixed bug with daily models with leap days: A bug was preventing WEAP from opening areas that had a daily timestep and leap years turned on.
  • Turn off catchments: To facilitate catchment calibration, you can temporarily turn off individual catchments to speed up calculations (e.g., turn off all but the few catchments being calibrated). Just set them not active in the Current Accounts with no startup year, and they will not be calculated. The easiest way to turn them on or off: In the Schematic View, go to the menu: Schematic, Set "Active in Current Accounts?" If you want to only activate a few at a time, click "Set All NOT Active" then individually turn on the few that are active.

1/6/11, Version 3.0

  • Major new version of WEAP released: highlights include:
  • Scenario Explorer
  • Internal scripting
  • User-defined variables
  • FAO 56, dual Kc, daily catchment hydrology (MABIA)
  • Allocate water for hydropower demands
  • Calibration Wizard (PEST)
  • Groundwater particle tracking (MODPATH)
  • Safe Yield Wizard
  • Chart improvements
  • Windows 7 and 64-bit Windows compatibility
  • Many other improvements
  • Scenario Explorer: The Overviews View has been renamed the Scenario Explorer View, and it now comes with a section to create "sliders" for data variables. Move the slider to change the value of the associated data variable, and then recalculate to see the impact on results. Scenarios can be created and managed directly from the Scenario Explorer. Right click on various items for context menus, or choose the Explorer menu. See WebHelp/index.html#Scenario_Explorer.htm
  • Scripting: Build scripts (using WEAP's script editor) in VBScript, JavaScript, Python, Perl, Ruby or any other ActiveScript-enabled scripting langauge to create more powerful expressions and functions for a WEAP model (e.g., create a script to calculate reservoir water quality). Call these scripts from data variables expressions using the CALL function, or from certain stages in the calculations (Events). On the menu, go to Advanced, Scripting. These scripts can use any WEAP API function. See WebHelp/index.html#Script_Editor.htm
  • User-defined variables: You can create user-defined variables under the sections for Demand Sites, Supply and Resources, and Water Quality, which you can reference in expressions elsewhere in WEAP. The definition can include default expressions for Current Accounts and Scenarios, allowing for the creation of a calculated variable (vs. a data variable). This is a very powerful feature, as it allows you to easily create your own models within WEAP. Right-click on a Data View variable tab and choose Add New Variable, or from the Edit menu choose Add New Variable. See WebHelp/index.html#User_Defined_Variables.htm
  • Edit built-in data variables: In addition to user-defined variables, built-in data variables (e.g., Demand Site Consumption) can now be edited. In particular, the default expression for Current Account and Scenarios can be changed. Right click on the variable tab and choose Edit Variable.
  • Hide data variables: Built-in data variables (e.g., Demand Site Consumption) can be hidden. Right click on tab and choose "Hide," or go to Edit, Data Variables menu. To unhide, select "Show" from these menus and select the variable to unhide.
  • Data variable report: Get a report of all available data variables, along with their definitions (including unit, default expressions, min and max values). Variables for non-existent objects, e.g., catchments variables if the area has no catchments, are not shown. To view report, go to the menu Edit, Data Variables, Report. The report can be exported to a CSV, ASCII, Excel, Word, HTML or XML file, or to the Windows clipboard.
  • Customize Result Variables: You may customize WEAP's result variables (e.g., Unmet Demand or Inflows to Area) to some extent. You are allowed to edit the title of a variable or hide it entirely. In the Result View, right click on the result variable selection box at the top and choose Edit Name or Hide. (Or from the Main Menu: Edit: Result Variable) If you have changed the name of a variable and want to reset it to its original value, right click and choose Reset Name to Default. To unhide previously hidden variables, right click and choose Unhide, and then choose the variable to show, or All Variables to unhide all previously hidden variables. Hiding unused variables can be a useful way to simplify a model's appearance, perhaps for display to stakeholders. Note: result variables can still be used in calculations even when hidden (via the PrevTSValue function).
  • MABIA: New method for catchment hydrology: the MABIA method is a daily simulation of transpiration, evaporation, irrigation requirements and scheduling, crop growth and yields, and includes modules for estimating reference evapotranspiration and soil water capacity. The MABIA Method uses the "dual" Kc method, as described in FAO Irrigation and Drainage Paper No. 56, whereby the Kc value is divided into a "basal" crop coefficient, Kcb, and a separate component, Ke, representing evaporation from the soil surface. The basal crop coefficient represents actual ET conditions when the soil surface is dry but sufficient root zone moisture is present to support full transpiration. In this way, MABIA is an improvement over CROPWAT, which use a single Kc method, and hence, does not separate evaporation and transpiration. It was derived from the MABIA suite of software tools, developed at the Institut National Agronomique de Tunisie by Dr. Ali Sahli and Mohamed Jabloun. For more information about MABIA and to download standalone versions of the software, visit For more information about MABIA in WEAP, see WebHelp/index.html#Overview_of_Catchment_Calculation_Methods.htm
  • Hydropower priority: Hydropower energy demands can be assigned supply priorities, either for individual reservoirs and run of river hydropower, or for the system as a whole. With a priority and energy demand set, WEAP will try to release water from reservoirs in order to meet the energy demands. Many new Result View charts: see Supply and Resources \ Reservoir. See WebHelp/index.html#Reservoir_Hydropower.htm
  • Hydropower: Hydropower now calculated based on elevation at beginning of month, rather than average of begin and end of month (required for hydropower priority enhancement).
  • Removed minimum turbine flow variable
  • PEST Calibration Wizard: Can use PEST (Parameter ESTimation tool) to help calibrate one or more WEAP variables (e.g., parameters for the soil moisture hydrology method), using historical data to calibrate to (e.g., streamflow gauges, reservoir storage records, snowpack data). Go to Advanced, PEST Calibration. See WebHelp/index.html#PEST_Calibration.htm
  • Reservoir storage data: Enter observed data on reservoir storage for use in calibrating to simulated values for reservoir storage. Enter data under reservoir physical data, variable named "Observed Volume."
  • Snowpack gauge data: Enter observed data on snow accumulation for use in calibrating to simulated values for snowpack. Enter data, in melt water equivalent, for the catchment on: Climate, Snow Accumulation Gauge.
  • MODPATH Linkage: WEAP models that are linked to a MODFLOW groundwater model require only additional data on groundwater cell porosity in order to link to the USGS MODPATH groundwater particle tracking model. WEAP can display particle pathlines as 3-dimension vectors. See WebHelp/index.html#Linking_to_MODPATH.htm
  • Safe Yield Wizard: Optimize and evaluate tradeoffs among human and environmental water supply needs by finding the maximum safe yield for a given WEAP model. For example, you could explore different policies for reservoir release, instream flow requirements and demand management to see what impact they had on the maximum safe yield from the reservoir and on instream flow. See WebHelp/index.html#Yield_Wizard.htm
  • Chart improvements: see WebHelp/index.html#Chart_Toolbar.htm
  • New chart types: Step, Area with no lines
  • Pie charts: Pie charts now can be displayed in many more cases than before, including showing multiple pie charts at once (one for each item on the X-axis, such as each year or month)
  • Chart marks: Individual chart points or bars can optionally be labelled with their value or percent. Click the yellow rectangle in the chart toolbar (on the right side).
  • Line symbols: Symbols for every data point can be shown on line charts, greatly enhancing legibility for grayscale charts.
  • Line patterns: Lines on line charts can have patterns (e.g., solid, dots, dashes), to better distinguish them from each other.
  • Bar and area patterns improved: The appearance of these patterns has been improved.
  • Advanced chart options: A detailed dialog box will give access to EVERY detail of chart appearance. See the last icon (bottom) on the chart toolbar.
  • Save chart to file: Export charts to graphic format files (JPG, BMP, PNG, SVP, PDF, GIF, VML/html, EMF, PCX)
  • Manual scaling: Next to the unit dropdown box (next to chart title), the scale can be set manually. This setting can be saved in a favorite.
  • Rotate X-Axis labels: X-Axis labels can be displayed horizontally, vertically and diagonally.
  • Scrolling legend: if the chart legend is too long to fit, a scrollbar will appear
  • Scale overview charts: Click the "Axis Scale" button (to the right of the overview charts) to use the same scale for every chart's Y-axis. This makes it easy to compare values across charts, e.g., how demand compares to reservoir storage. For MODPATH particle pathline charts, this will also scale the X and Y (or Row and Column) axes.
  • Transpose tables: Transpose rows and columns in Results View tables (table toolbar icon: circular arrow).
  • API:
  • Setting and AreaSetting API functions: Set or get a text value associated with a key (text). Value is stored in file weap.ini in main WEAP directory (Setting), or in area.ini in the area subdirectory (AreaSetting). These files can be a convenient place for the user to store settings (WEAP-wide or area-specific). See WebHelp/index.html#WEAPApplication.htm
  • New API properties: The following properties have been added for WEAPBranch: ActiveInCurrentAccounts, ID, Parent, ParentID, TypeID, Order. ActiveInCurrentAccounts is read/write; the others are read only. See WebHelp/index.html#WEAPBranch.htm
  • New API properties: CalledByBranch, CalledByScenario, CalledByTimeStep, CalledByVariable, and CalledByYear. If the script containing these properties are called from an expression using the Call function, they will return, respectively: the WEAPBranch object for the branch that made the call, the WEAPScenario object for the scenario that made the call, the timestep number (from 1 to NumTimeSteps) for the timestep that made the call, the WEAPVariable object for the variable that made the call, and the year number (between BaseYear and EndYear) for the year that made the call. Read only. See WebHelp/index.html#WEAPApplication.htm
  • New API classes for Timestep, Timesteps: See help ( Advanced Topics, Automating WEAP, WEAPTimestep and WEAPTimesteps Classes ) for more information. See WebHelp/index.html#WEAPTimestep.htm
  • New API property: Variable.ScaleUnitText: Gets a string containing the scale and units of the variable (works with both data and results variables). See WebHelp/index.html#WEAPVariable.htm
  • ReadFromFile: See WebHelp/index.html#Read_From_File.htm
  • Aggregate or disaggregate: Daily data can be aggregated to match your timestep (e.g., monthly), using one of many aggregation methods (Average, Sum, Median, Minimum and Maximum). In cases where aggregate data needs to be disaggregated, such as extracting a daily time series from monthly climate data, one of many disaggregation methods can be used (Interpolate, Repeat, Divide, Divide with Gaps).
  • Missing data values: WEAP better handles missing values when reading data from a text file. See the help topic "ReadFromFile" for details. An optional fourth parameter to ReadFromFile specifies how to handle missing values. The options are: Interpolate, Repeat, Replace, Mark as Missing. Interpolate: linear interpolation from values before and after. Repeat: repeat the previous value. Replace: replace with the number specified as the 5th parameter (defaults to 0 if not given). Mark as Missing: the value will be -9999, which is the special value for missing values. A value of -9999 will not be shown on the graph or used in gauge comparisons. However, for all other calculations requiring a value, an error will occur.
  • Save to CSV options: new options to transpose rows and columns and to save in a format compatible with the ReadFromFile function (e.g., Year, Timestep, DataColumn1, DataColumn2, ...)
  • List separators in ReadFromFile: ReadFromFile will now use the Windows ListSeparator character when reading from CSV files. However, you can override this setting by using the $ListSeparator directive in your CSV file. For example, to use & as the list separator, add the following line to the beginning of the CSV file: $ListSeparator = & In this way, you will guarantee that the files can be read on any system, regardless of their setting of the Windows ListSeparator character.
  • Comments: Comment lines do not need to start with ; or # Any line that doesn't start with a number is considered a comment and is ignored.
  • ReadFromFile Date Format: Use the $DateFormat directive in a CSV file to specify the date format for daily data to be read in ReadFromFile, e.g., $DateFormat=mm/dd/yyyy This will avoid depending on the Windows system date format, which can vary from country to country.
  • CSV Export: Tables exported to CSV files can now have an unlimited number of columns (previously, the limit was 256, taken from Excel's 256 column limitation, for versions of Excel prior to 2007). The API method WEAP.ExportResults has a 4th parameter: set to true to export in ReadFromFile format. It is optional, and will default to false.
  • ReadFromFile: If you leave some parameters blank, WEAP will use the default values. E.g., for ReadFromFile(Filename , , YearOffset), WEAP will use the default value of 1 for the second parameter (DataColumn).
  • Column limit: Increased maximum number of columns that can be read from a CSV file from 1000 to 20,000.
  • Expressions/functions/constants:
  • Arccos and Arcsin: These two inverse trig functions now return an angle in degrees, not radians.
  • New function "Between": Between can be used in expressions to test if a value is between two other values. Between(x, LowerBound, UpperBound) can be used instead of And((x >= LowerBound), (x <= UpperBound)) See WebHelp/index.html#Between.htm
  • IsBlank function: The IsBlank function returns True if there is no expression entered for the named Branch:VariableName. Note: if there is an expression entered for a parent scenario (or Current Accounts), IsBlank will be false. See WebHelp/index.html#IsBlank.htm
  • Refer to Effective Precip: Can now refer to the results for effective precipitation (including effects of snow accumulation and snowmelt), e.g., PrevTSValue(Agriculture Catchment:Effective Precip for ET[m])
  • Random(LowerBound, UpperBound): Returns a different random real number, between LowerBound and UpperBound, for each timestep. If not specified, the lower and upper bounds default to 0 and 1. The value returned is a random but repeatable value for any given branch, scenario, year and month. This means that the numbers will be the same each time a scenario is calculated (for a given branch, year and timestep). See WebHelp/index.html#Random.htm
  • RandomInteger(LowerBound, UpperBound): Returns a different random integer, between LowerBound and UpperBound, for each timestep. If not specified, the lower and upper bounds default to 0 and 1. The value returned is a random but repeatable value for any given branch, scenario, year and month. This means that the numbers will be the same each time a scenario is calculated (for a given branch, year and timestep). See WebHelp/index.html#RandomInteger.htm
  • Random normal distribution: New function for use in expressions: RandomDistribution(Mean, StandardDeviation) produces random numbers with Gaussian distribution about the Mean. This is useful for simulating data with sampling errors and expected deviations from the Mean. See WebHelp/index.html#RandomDistribution.htm
  • Errors in expressions flagged: If the result of an expression is undefined (such as Log(0), which WEAP displays as NAN, or Not A Number), an entry will be made in the list of errors and warnings on the Messages tab in the Results View.
  • Check for invalid branches: During calculations, all branch references in expressions are checked for validity. (This will catch references to branches that have been deleted.)
  • Better error messages for expressions: Error messages are now more informative
  • New expression constant for missing value: MissingValue evaluates to -9999. For example, If(Catchment:Precipitation = MissingValue, 0, Catchment:Precipitation) See WebHelp/index.html#MissingValue.htm
  • Catchments:
  • Sped up ponding/rice calculations
  • Fixed bug in catchment ponding/rice: In cases when the surface storage was above the Minimum Depth (and therefore no need for irrigation), there still should have been a demand for the release requirement (if any).
  • Snow melt: Now using Latent Heat of Fusion (334 kJ/kg) instead of Latent Heat of Vaporization (2260 kJ/kg, at 100 C) for snow melt algorithm in submonthly models. For already calibrated models, you may want to continue using Latent Heat of Vaporization. To make this change, go to General, Basic Parameters. See WebHelp/index.html#BasicParameters.htm
  • Ignore irrigation data on catchments not marked as having irrigation: If a catchment had been marked as having irrigation and irrigation data had been entered for some of its branches, and then the user later turned off irrigation for the entire catchment (from the Schematic View), WEAP was still computing irrigation supply requirements and if the catchment still had a transmission link, was supplying water to meet the requirement. This bug has been fixed.
  • Error checking on upper and lower irrigation thresholds: WEAP now requires that lower threshold is less than upper threshold
  • Refer to catchment and demand site results in expressions, including sub-branches: Various catchment results (interflow, base flow, surface runoff, evapotranspiration, snow melt, snow accumulation, irrigation) and demand site results (water demand, supply requirements) can now be referenced using PrevTSValue in expressions. In the Expression Builder, drag the branch down to the expression edit box to choose from a list of all data and result variables. You can refer to results from any level of the demand tree, e.g., catchments as a whole or land class branches underneath catchments. If a referred branch has several subbranches, they will be totaled automatically.
  • Miscellaneous:
  • Windows 7 and 64-bit Windows Compatible
  • Transmission link terminology: On the Data View tree, the branch for transmission links has been renamed from "Supply and Resources\Linking Demands and Supply" to "Supply and Resources\Transmission Links"
  • Other Supply inflow to Reservoir or River: To have a supply source of type Other Supply flow into a reservoir (e.g., to model a desalination plant whose output is stored in a reservoir) or to a river, use a transmission link to connect the Other Supply to the Reservoir or River. The flow in the Other Supply will not flow along the transmission link unless there is a downstream demand that requests it, including the reservoir filling demand.
  • Sub-annual variation of priorities: Priorities for demand sites, flow requirements and reservoirs (separately for filling and for hydropower) may now vary by timestep (e.g., monthly), via the expression for the priority variables in the Data View.
  • Negative groundwater recharge: For groundwater nodes, "Natural recharge" variable is now allowed to be less than zero, for example, to model lateral outflow from an aquifer to another aquifer outside the system.
  • Improved result view display of user-defined variables: Sped it up and eliminated extraneous branches from displaying.
  • Selecting river nodes: River node and reach names, when selecting which to display in the Results View, now correspond with the names given in the chart legend.
  • Leap years: An option to add an extra day for Febrary 29 in leap years (e.g., 2000, 2004, 2008). Go to General, Years and Time Steps and check "Add Leap Days?" If the time step is daily (365 time steps per year), there will be 366 time steps in the leap years. Otherwise, the time step that includes February 28th will have an extra day in leap years. See WebHelp/index.html#Years_and_Time_Steps.htm
  • Create MODFLOW file for all WEAP timesteps: WEAP will create one aggregate MODFLOW input file for each scenario, in which each WEAP timestep becomes a MODFLOW stress period. Data for the RIV, RCH, WEL and DRN packages will be aggregated for all timesteps. Each scenario also includes data for the Current Accounts year. Each multi-stress period MODFLOW input file (one per scenario) can be run outside of WEAP to create a MODFLOW results file that spans the entire WEAP study period. The MODFLOW file will be named with the original MODFLOW filename, with _S## appended on the end, where ## is the number of the scenario (Current Accounts = 01, the first scenario will be = 02, etc.). For example, if the original MODFLOW name file was Tutorial.NAM, the aggregate MODFLOW name file for the reference scenario would be Tutorial_S02.NAM.
  • Diversion flow from reservoirs: A diversion can now flow directly out of a reservoir. To do this when creating a diversion, drag the diversion symbol from the legend and drop it on the reservoir. If the diversion already exists, drag its headflow point and drop it on the reservoir.
  • WARNING: After you read a WEAP area with this new version, that area CANNOT be read with an older version of WEAP (prior to August 2008). Therefore, if you will be giving your datasets to other people, they must also update to at least this version of WEAP.

6/16/08, Version 2.2054

  • New background layer point symbols: For background GIS layers that have points (as opposed to lines or polygons), many symbols are now available for displaying the points. To change the symold displayed, double click on the background layer in the legend and choose the Appearance tab of the Map Layer dialog box.
  • Greek version: The WEAP program has been translated into Greek by Spyros Michas.
  • Russian Help: The online help has been translated into Russian by Andre Savitsky.

5/31/08, Version 2.2052

  • Widespread release to all WEAP users
  • Handles OPEN/CLOSE and EXTERNAL in MODFLOW files: WEAP can now handle OPEN/CLOSE and EXTERNAL in MODFLOW input files, in any format (FREE, fixed or BINARY).

5/30/08, Version 2.2051

  • Fixed bug with display of Soil Moisture results

5/25/08, Version 2.2050

  • VolumeToElevation and ElevationToVolume: Improved error checking; documented in help file.

5/19/08, Version 2.2048

  • VolumeToElevation and ElevationToVolume functions: New functions for expressions to convert between reservoir volume and elevation, using the Volume-Elevation curve data. Here is an example that uses elevation data (in feet) to set the Top of Conservation zone data: ElevationToVolume(MonthlyValues(May, 625.0, Jun, 625.0, Jul, 610.0, Aug, 610.0, Sep, 630.0, Oct, 630.0, Nov, 625.0)) Assumes the elevation and volume units are those as set for reservoirs under General, Units, Reservoir. See WebHelp/index.html#VolumeToElevation.htm

5/15/08, Version 2.2047

  • Paste multiple values into expressions: Paste a vector of annual or monthly values from Excel or other programs. Also, paste a volume-elevation array into the Volume-Elevation Curve tab for a reservoir.

5/12/08, Version 2.2045

  • Individual result files: In order to accommodate very large models, the results file are now split into many smaller files. This should allow larger models to be calculated, as well as faster access to result tables and charts in the Results View.

4/9/08, Version 2.2039

  • Sped up calculations a bit

4/7/08, Version 2.2038

  • Terminology change: "revenue" broadened to "benefit." Benefits can include revenues, or other positive impacts, such as the value of ecosystem services.
  • Smaller results files: automatic packing of results file will save disk space and speed viewing of results.
  • Reduced memory use: WEAP now uses less memory (RAM) during calculations, especially on larger datasets.
  • API LoadOverview: Using the API, use WEAP.LoadOverview(overviewName) to load a previously saved overview.
  • API ExportResults to Excel: ExportResults can save to either a CSV or Excel file, depending on the extension for the file name you give. E.g., WEAP.ExportResults(C:\Overview.xls) or WEAP.ExportResults(C:\Groundwater.csv). Also, you can now export results from the Overview View.

4/1/08, Version 2.2037

  • Handles PARAMETERs in MODFLOW files: WEAP can now handle PARAMETERs, including time-varying parameters (with instances), for the following MODFLOW packages: WEL, DRN, RIV, RCH.
  • Handles OPEN/CLOSE in MODFLOW files: WEAP can now handle OPEN/CLOSE in MODFLOW input files. For now, it can only read in FREE format files, but soon will also be able to handle formatted and binary files, in addition to EXTERNAL files.

3/21/08, Version 2.2036

  • New reservoir evaporation report

3/14/08, Version 2.2034

  • Terminology: Renamed "Leaf Area Index (LAI)" to "Runoff Resistance Factor." Runoff Resistance Factor incorporates factors such as LAI and land slope to determine surface runoff. Higher values of Runoff Resistance Factor lead to lower values of runoff.
  • Fixed bug with startup year

3/7/08, Version 2.2033

  • Fixed bug with PrevTSValue: There was a problem with complex PrevTSValue expressions.

3/5/08, Version 2.2032

  • Fixed bug in startup year: Scenario were incorrectly inheriting the "Startup year" value from their parent scenario.

3/4/08, Version 2.2031

  • Cloudiness fraction for catchments: New variable "Cloudiness fraction" for catchments and river reaches (on which river water temperature is calculated), to help refine the calculation of net solar radiation.
  • New API property Branch.Variable: Can be used to refer to a named variable for a branch, e.g., WEAP.Branch("\Demand Sites\South City").Variable("Consumption").Expression = 30

3/2/08, Version 2.2029

  • Select branches in Results View: Choose a subset of branches to display in the Results View.

3/1/08, Version 2.2028

  • Catchment results in mm: See catchment results (e.g., Land Class Inflows and Outflows) in terms of depth, such as in mm, in addition to volume (cubic meters) and flow (cubic meters per second) units.

2/26/08, Version 2.2024

  • New API functions BranchExists and VariableExists: Test if a branch or variable exists from the API, e.g., IF WEAP.BranchExists("\Demand Sites\Big City") THEN ..., or IF WEAP.Branch("\Demand Sites and Catchments\Upper Watershed").VariableExists("Wind") THEN ...
  • Incremental calculation in the API: The API function Calculate now takes optional parameters to specify how far to calculate. E.g., WEAP.Calculate(2005, 6) will stop calculations at the 6th timestep of 2005.

2/7/08, Version 2.2019

  • Handles irregular MODFLOW grids: When creating a shape file to link the WEAP model to the MODFLOW model, WEAP will now handle irregular MODFLOW grids (where the rows or column widths vary). Also, it can handle either UTM and latitude/longitude shape files.

2/4/08, Version 2.2018

  • Display results in units of flow (e.g., CFS): For any results in the Results View that use volume units, such as cubic meters or acre feet (e.g., Streamflow, Supply Requirement), the results can now be display also in flow units (e.g., cubic meters per second or cubic feet per second).

1/29/08, Version 2.2016

  • Support of confined and multi-aquifer systems (MODFLOW): On the "Link to MODFLOW" screen, click the "Define Aquifers" button to specify which MODFLOW layers should be grouped into which aquifers. In the Results View, there are two new reports in the MODFLOW section: "Groundwater Inflows and Outflows by Layer" (available only if the MODFLOW model has more than one layer) and "Groundwater Inflows and Outflows by Aquifer" (available only if the MODFLOW model has more than one layer and you have created more than one aquifer).
  • Improved inflows and outflows reports: these reports (such as Groundwater Inflows and Outflows) now have more details on flows; choose "Selected Sources and Destinations" above the legend to choose a subset to display

12/16/07, Version 2.2014

  • Climate data can vary by land use: One can choose whether all land use branches within a catchment will have the same climate data, or whether each branch can have different climate data. This second option might be necessary if there is a large variation in the elevation among different land uses with a catchment. Alternatively, the catchment could be divided into several different catchment nodes according to elevation, so that the climate within each catchment did not vary by land use. Go to General, Basic Parameters to make the choice.

12/15/07, Version 2.2013

  • Speed up for API: Making WEAP not visible (WEAP.Visible = False) now results in faster calculations when using the API.

12/12/07, Version 2.2011

  • Create MODFLOW linkage shape file in WEAP: Using parameters from the MODFLOW discretization file and user-supplied parameters, WEAP can create a GIS shape file that can be used to link a WEAP model to a MODFLOW model. This means that separate GIS software, such as ArcMap, is not required to link MODFLOW to WEAP. Go to General, MODFLOW Link. Click button "Choose shape file that...." Choose < Create new shape file > under "Background shape file with MODFLOW linkage information"
  • Access to MODFLOW results in expressions: To access MODFLOW results for individual cells, use PrevTsValue(MODFLOWVariableName[layer, row, column], ...), for example, PrevTSValue(Cell Head[1,57,30], 1, 12, 2) will give the minimum value of the cell head elevation for layer 1, row 57, column 30 over the previous twelve months. In API, use WEAP.ResultValue(MODFLOWVariableName[layer, row, column], ...), for example, WEAP.ResultValue("Cell Head[1, 57, 30]", 2005, 1)

11/27/07, Version 2.2009

  • Individual result values in status bar: Move the mouse over any line or bar in a chart (in the Data View, Results View or Overview View) and its value will be displayed in the WEAP status bar below. (No need to click the mouse.) See a video demonstration:
  • Schematic elements named in Status bar: Move the mouse over any WEAP element (e.g., Demand Site, River, Reservoir) in the Schematic View and its name will be displayed in the WEAP status bar below. (No need to click the mouse.)
  • Zoom and pan result charts: To zoom in on charts in the Data and Results Views, hold down the control key and click and drag a rectangle on the chart. To zoom in, click and drag from upper left to lower right. To zoom back out again, click and drag from lower right to upper left. When zoomed in, hold the shift key and click and drag to pan the chart. These shortcut keys--control drag to zoom, shift drag to pan--also work on the Schematic.
  • Easily change labels for background layers: Right click on a background layer name (e.g., Country) and choose the label to use on the "Set label to" menu.
  • Edit shape file data: Double click the background layer name in the Schematic to edit the values in its attribute table. See a video demonstration:
  • MODFLOW Tutorial: New chapter of Tutorial on MODFLOW with matching dataset: Tutorial

10/31/07, Version 2.2003

  • Circular reference error: Improved diagnostic error reporting for circular references
  • New expression constants: In addition to the constants (which can be used in expressions) Y, Year, PrevYear, Month, TS, and Days, new constants have been added: DaysBefore, JulianDaysBefore and TotalDaysBefore

10/25/07, Version 2.2001

  • Trig functions: Added arccos, arcsin and arctan

9/21/07, Version 2.2

  • Major new version of WEAP released: highlights include:
  • Link to MODFLOW: Link WEAP's groundwater nodes to one or more MODFLOW groundwater cells for detailed modeling of groundwater.
  • Link to QUAL2K: Calculate instream water quality using the US EPA model QUAL2K. Constituents modeled include: Ammonia, nitrate, organic and inorganic phosphorous, algae, sediment, pH and pathogens.
  • Application Programming Interface (API): Run WEAP from other programs (e.g., Excel via VBA), programming languages (e.g., Visual Basic, C) or scripts (e.g., Visual Basic Script (VB script), JavaScript, Perl, Python) can control WEAP directly--changing data values, calculating results, and exporting them to text files or Excel spreadsheets. Can be used to automatic sensitivity analysis or calibration. Compatible with Parameter Estimation tool (PEST), for automatic calibration.
  • Call DLL functions from WEAP expressions: To call a dll function, use the following syntax: Call( DllFileName ! DllFunctionName, parameter1, parameter2, ...)
  • Refer to result values in data expressions: Using PrevTSValue function, results from the previous timesteps can provide feedback for data expressions. Results include: Demand Site: Supply Requirement, Supplied, Coverage, Unmet Demand, Reliability; Transmission Link: Flow; River nodes and reaches: Streamflow; Reservoir: Storage Volume, Storage Elevation, Hydropower; Flow Requirement: Requirement, Requiremend Delivered, Requirement Coverage; Groundwater: Storage; Return Flow: Flow
  • Rice paddy module: Track requirements for and hydrological effects of ponding / flooding in rice cultivation (and wetlands).
  • Infiltration basins and retention ponds: Seepage losses from reservoirs can be significant, particularly in lakes and unlined reservoirs. To model these losses, specify the groundwater node and flow to it for each timestep. Net gains from groundwater to the reservoir should be entered as negative numbers. You can also model infiltration basins and retention ponds, which can be used for artificial recharge of aquifers.
  • Tiered water pricing: Added function BlockRate for tiered pricing structure of demand site customer water charges.
  • Combined sewer overflows (CSO): Model CSOs by routing a catchment's stormwater runoff to a wastewater treatment plant, which can overflow if its maximum treatment capacity is exceeded.
  • Key Assumptions in Results View: Display one or more user-defined variables from Key Assumptions in the Results View.
  • Return flow gain from groundwater: Infiltration from groundwater into the return flow link, typically via cracked pipes, can lead to sewer overflows and increased wastewater treatment costs.
  • Rivers can now flow into groundwater nodes: drag the endpoint of a river and drop it on top of an groundwater node to connect them. (WEAP will ask you if you want to connect them.) Once connected, any water that flows out of the last river reach will flow into the groundwater node.
  • Transmission and return flow link losses to groundwater: transmission links and return flow links have two variables for losses: "Loss from System" and "Loss to Groundwater," each entered as a percent of flow through the link. Loss from system will disappear, whereas Loss to Groundwater will flow into the named groundwater node.
  • Units shown for variable references: WEAP now shows the unit, and allows scale and unit conversions, when referring to variables in data expressions. This should greatly reduce the incidence of conversion errors.
  • Faster calculations: Calculations take less time now to complete, especially on computers with at least 512 MB RAM.
  • Scenario comparison: In Results View, see the difference between one scenario and one or more other scenarios.
  • Multiline epxressions: When editing expressions in the Expression Builder, you can add line breaks to enhance readability for complex expressions.
  • Renormalize monthly data: The Monthly Time Series Wizard now has a "Renormalize" option, to proportionally change all values so that they sum to 100%.
  • Wastewater Treatment Plant Overflow Report: Overflow is defined as inflow to a wastewater treatment plant that exceeds its capacity.
  • View input data in Results View: Access all data inputs on Result View charts, tables and maps.
  • Change Y-axis origin: Whereas previously, the y-axis of all graphs always started at 0, now there is an option to use the minimum value as the origin. This will exaggerate changes on the graph--thus making it easier to see differences, but potentially misleading. Click the "Y=0" button on the toolbar to the right of the graph to toggle the Y-axis origin.
  • Language Translations: full or partial translations into Chinese, Korean, French, Spanish, Portuguese, Arabic, Farsi, Russian and Thai.

8/5/05, Version 2.0016

  • Financial planning module: Attach revenues, capital costs and operating costs to individual elements (demand sites, transmission links, return flow links, wastewater treatment plants, groundwater sources, reservoirs, etc.), either as fixed annual costs or as costs per unit of water. Other uncategorized costs can be entered as "other system costs" (capital, operating and revenue). All of these annual costs could vary by year or by scenario. Use LoanPayment function to calculate loan payments on capital costs. Results include net costs, average cost of supplied water, and net present value.
  • Water quality inflow constraints: Set optional constraints on maximum concentration of inflow to a demand site, from all sources mixed.
  • Water quality gauge data: Enter data for water quality concentrations at various points in the river. WEAP will display a report comparing these data with model results. This ability is similar to the current option for entering water flow data in streamflow gauges, for reporting.
  • Disaggregated pollution generation: Data on demand site pollution generation, either by intensity or concentration, can now be entered at any level of disaggregation under the demand site level on the tree.
  • Running count of model elements: The legend on the Schematic View shows the total number of each element defined, e.g., if 5 demand sites exist, it will read Demand Site (5).
  • Save small models in evaluation version: The unregistered evaluation version of WEAP can now save small models--up to 6 nodes and 3 rivers.

6/8/05, Version 2.0005

  • New version of WEAP released: highlights include:
  • Hydrologic models: Using data on climate and land use, WEAP can model runoff, infiltration, baseflow, evapotranspiration, irrigation requirements and crop yields from catchments.
  • Two hydrologic models are available: a simplified model using the FAO crop requirements method, and a more detailed model which tracks soil moisture in two soil layers via a lumped-parameter hydrologic representation.
  • Surface water/groundwater interactions: Simulate flows between surface water and groundwater, based on their head difference and various aquifer parameters.
  • Instream water quality: Models for water temperature, BOD, DO, conservative substances (e.g., salt) and non-conservative substances (which follow first-order exponential decay) in river reaches.
  • Wastewater reuse: Wastewater return flows from demand sites and wastewater treatment plants can be used directly by other demand sites.
  • View results on the map: Results from one or more variables (e.g., demand, streamflow, water quality, reservoir storage) can be displayed on the map, both in numerical form and as varying widths/sizes of elements (e.g., demand sites, reservoir, river reach lines).
  • Automatic data backup: WEAP maintains multiple versions of each dataset (as it changes over time), which can be useful in case of data corruption or a desire to undo many changes.
  • Multilingual: English, French and Korean, with partial translations into Chinese, Spanish and Portuguese.

4/8/05, Version 1.0435

  • Area Save As: Save open area, along with any as yet unsaved changes, to a new area. Main menu: Area, Save As...
  • Automatic versioning of areas: WEAP will automatically keep multiple versions of each area's data so that you can revert to a previous version.
  • Create milestone copy: Save a version of the area (with an optional comment). Main menu: Area, Save Version...
  • Revert to previous version: Discard the current version of an area's data and replace with a previously saved version. Can be used to easily undo all changes made since last save. Main menu: Area, Revert to Version

4/7/05, Version 1.0434

  • Exclude results: When backing up or emailing an area from Manage Areas, there is now the option to exclude the result files to save space.

3/10/05, Version 1.0418

  • Batch export and import of data expressions to/from excel: After exporting to workbook, you can modify the expressions and then import them back into WEAP. With autofilter turned on, Excel becomes an excellent way to view the expressions, perhaps better than the text Data Report.

2/3/05, Version 1.0404

  • Map multiple results: Multiple variables can be mapped at once in Results View (on the Map tab)

1/28/05, Version 1.04

  • Wastewater reuse: (transmission link from one demand site to another demand site, or from a wastewater treatment plant to a demand site) This change necessitates two new variables--Demand Site Consumption and Wastewater Treatment Plant Consumption--and a redefinition of return link routing fractions (now they are as a fraction of outflow, not a fraction of inflow)
  • Flow duration curve: aka exceedance graphs
  • View "data" variables in the results view: e.g., Reservoir top of conservation pool
  • User-defined results tables: In the Overview View, you can now see all the numbers behind the graphs
  • View results on the map: In the Results View, there is now a map tab. Move the slider below the map to animate it over time. Cick the chart icon on the right to see the variable graphed below.

11/11/04, Version 1.0351

  • Catchment runoff symbol: a new symbol on the legend for catchment runoff--blue dotted line, instead of a red return flow link.
  • Specify catchment inflow: You can specify on the General Info for a catchment which river it flows into, whether that inflow represents the headflow for that river, which groundwater node (if any) receives recharge from the catchment, and whether it includes any irrigated areas.
  • Catchment runoff as headflow: If a catchment is the headflow for a river, you cannot also enter data for that river's headflow. This prevents double counting.

4/16/04, Version 1.0342

  • Read from file with dates: You may specify data dates in files to be read using ReadFromFile using mm/dd/yyyy syntax, in addition to having the year be in column 1 and the time step in column 2. (This only works if your timestep is monthly or daily.)

3/19/04, Version 1.0327

  • Turn off automatic calculation: In the Data View, go to the Main Menu: Edit, Automatic Calculation to turn on or off calculation and dispaly of results in the Data View (does not affect Results View). If Auto Calc is off, hit F9 to do a calculation (this will not turn auto calc back on).

1/23/04, Version 1.0304

  • Graph river results according to distance downstream: In results, all river reports (e.g., streamflow, gauges, surface water quality) can display the results along the X axis spaced porportionally to their distance along the river. Choose "Nodes and Reaches" for the X axis dimension, then check off "Represent true relative distance?"

1/2/04, Version 1.031

  • River Reach Length report: in Results, choose: Supply and Resources, River, Reach Length. Reach Length is used in calculating temperature, BOD, DO, and other water quality constituents that decay

12/31/03, Version 1.0299

  • Order branches alphabetically: When sorting branches in the tree (right-click on a branch), you can choose "Sort by Name (all levels below)" or "Sort by Name (just one level below)". For example, to order the list of demand sites alphabetically, but leave each demand site's sector branches unsorted, right-click on "Demands Sites" branch and choose "Sort by Name (just one level below)".

10/28/03, Version 1.0292

  • Reservoir priorities: priorities (on order of filling and releases) can now change over time, similar to demand sites and flow requirements.

9/23/03, Version 1.0285

  • Branches flash on map: In Data View, when you click on a branch in the tree, the corresponding object in the schematic will flash on the inset map (below the tree).

8/25/03, Version 1.028

  • Reservoir Elevation report

7/22/03, Version 1.0264

  • Mouse wheel: Use mouse wheel to zoom in and out of schematic.

7/3/03, Version 1.0257

  • Help button for data variables: Click the "Help" button (next to the description of the variable) for help on current data variable.

6/27/03, Version 10255

  • Enter monthly demand: Option to enter monthly demand directly, rather than enter annual demand and monthly variation. Choose "Specify Monthly Demand" for the Method on the Advanced button in the Data View. You may use ReadFromFile function (see description below) to read in monthly demands from a file for multiple years.

5/30/03, Version 1.0234

  • Land class area report: New report that details area by catchment and land class. Choose Levels = 2 to see land class detail. Then check the "Group?" box to see subtotals by land class.

5/23/03, Version 1.0231

  • Patterned charts: charts with more than twenty items in the legend use patterns to differentiate the bars.
  • Restore area from FTP site: Go to Manage Areas, click the Restore button, then enter your ftp site in the "File Name" box to browse for a WEAP area file to restore. For example, enter and you should be able to see Weaping River

4/7/03, Version 1.0224

  • New Flow Requirements reports: three new flow requirements reports have been added: Instream Flow Requirement, Instream Flow Requirement Delivered, and Unmet Instream Flow Requirement. They can be found grouped with the other Demand reports. (Previously, the Flow Requirement Covevage report was under Supply and Resources, River.)

4/3/03, Version 1.0223

  • Fixed "Table is full" error: increased the maximum size of the results file from 128MB to 1 GB.

3/31/03, Version 1.0221

  • New Manage Areas: greatly enhanced the "Manage Areas" screen.
  • Minimal diversion: Modified behavior of diversions, so that WEAP will not divert more than is requested on the diversion. (Essentially, there is now a priority 100 (i.e., last) iteration in which the flows diverted from rivers into diversions are minimized (subject to the constraints of how much needs to be diverted, based on instream flow requirements and offstream demands on the diversions).)
  • Temperature and Observed Precip reports: Results View, Land Use, Yates Runoff Method, Temperature and Observed Precipitation. Look at monthly averages to compare climate change.
  • Flow from Groundwater into River report: For flows surface water-groundwater interactions modeled, see Supply and Resources, Groundwater, Flow from Groundwater into River. (Negative values represent flows from river into groundwater.)
  • Monthly averages: When viewing result charts with time along the x-axis, click the "Monthly Average?" checkbox above the chart to see the average for each month.
  • Interrupt calculations: Calculations can be stopped via a Cancel button.
  • Changes logged: The text file Changes.txt (stored in the subdirectory for a WEAP area) has a record of every change made to data, in the order the changes were made, along with who made the change.
  • User login: Users enter their initials when WEAP starts, so that changes to data can be associated with the person who made them.

1/7/03, 1.0177

  • User-defined units: To add new units, go to the main menu and select General, Units, then click the "Units Definitions" button.
  • Statistics: When viewing tables of results in the Results View, click the "Stat" button on the right to see the minimum, maximum, average, standard deviation and root mean square.
  • Browse map data: To view the data associated with a GIS layer (*.shp files), right-click on the layer name, then select Edit to go to the Edit Layer window. Click the "Browse Data" button to see data for all map elements, or click on an element in the map to see its data in the grid to the left of the map.
  • Monthly variation of demand: Each branch within a demand site can have a different monthly variation. On the main menu, select General, Basic Parameters.
  • Streamflow gauges: Use the streamflow gauge objects to facilitate comparing calculated and observed streamflow. On the schematic, place a gauge on a river. Edit its data to specify observed flow, typically using the ReadFromFile function. In results, look at the Supply and Resources, River, Streamflow Relative to Gauge report to compare.
  • Variable Time Step: The time step can be set anywhere from one day to 365 days. Every year and scenario in an area must have the same time step. Go to the main menu and select General, Years and Time Steps.
  • Variable water year start month: The water year can start on any month. Go to the main menu and select General, Years and Time Steps.
  • Group small results into "All Others": If there are more than 12 items in the results legend, you can click the "Grp" button on the right to group the smallest items together.
  • Turn off individual scenarios: To show or hide results for individual Scenarios, go to the menu main and select Area, Manage Scenarios, then check or uncheck "Show Results for Scenario" for each scenario. If this box is unchecked, then WEAP will not calculate results for that scenario.
  • ReadFromFile function: Use the expression ReadFromFile(FileName, ColumnNumber) to import monthly or annual data. The file should be an ASCII, comma separated value file, with the year in the first column, month in the second column (for monthly data), then one or more data columns. In the ReadFromFile function, the first data column is ColumnNumber = 1.
  • Annual totals: In the Results View, you can sum monthly results to see Annual Totals--check the "Annual Total" box in the chart subtitle (Years must be selected for the X-axis).
  • Disaggregated Demand results: On the Water Demand and Supply Requirement reports, use the "Levels" button (located underneath the report title) to show more or less detail. For example, on Weaping River Basin results, choose "All Branches" for the legend. Level 1 shows demand for each demand site; Level 2 disaggregates demand by agricultural county and crop type (Agriculture West), industrial water use (Industry East), irrigation technology (Agriculture North), and single and multi family (South City). When Levels is greater than 1, a "Group?" checkbox appears, that will group together branches with the same name. Set Levels = 3 and check Group?, to see that Flood Irrigation consumes nearly 50% of the total Weaping River Basin demand in the Current Accounts.
  • Wastewater Treatment Plant capacity: Wastewater Treatment Plants can have a maximum processing daily capacity.
  • Save or print schematic as graphic: The Schematic can be copied to the Windows clipboard, for pasting into Word or other applications. In the Schematic View, go to the menu main and select Schematic, Copy Schematic to clipboard.
  • Reservoir priorities: Reservoir can be assigned supply priorities, which are used to determine the order in which they are filled. They default to 99--the lowest priority.
  • Data Report: A "Data Report" lists all data for the active scenario. In Data View, click "Data Report" button in upper right corner of screen.

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