A measure of social or economic activity. When used in WEAP's Demand analysis, activity levels are multiplied by water use rates to yield overall levels of annual water demand. See Water Use Rate.
To summarize by grouping together. See Disaggregate
Fraction of solar radiation striking a land class that is reflected--albedo increases as snow accumulates.
The actual calculation order, assigned to transmission links and instream flow requirements, used by WEAP for allocating water. WEAP automatically determines the allocation order based on the demand priorities and supply preferences. See Demand Priority, Supply Preference.
Application Programming Interface. WEAP can act as an \"COM Automation Server,\" meaning that 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.
The water system being studied, often a river basin.
A .dbf file associated with a GIS shape file ( .shp) that contains one row for each geographic feature (point, line or polygon) and one or more columns of information about that feature.
Streamflow coming from ground-water seepage into a stream
Best Management Practice for managing stormwater.
\"Biochemical Oxygen Demand\" - a measurement of the oxygen consumption capacity in water brought about by the degradation of organic matter, typically from a wastewater source, by bacteria. It is expressed as a concentration.
An item on the tree, e.g., \"Supply and Resources\" or \"Key Assumptions\".
A reference to a soil layer in the Soil Moisture Method, which contains two layers, or buckets
A land area with defined geographic boundaries that captures precipitation and partitions it into evapotranspiration, runoff to surface water and infiltration to groundwater.
The Current Accounts represent the basic definition of the water system as it currently exists. Establishing Current Accounts requires the user to \"calibrate\" the system data and assumptions to a point that accurately reflects the observed operation of the system. The Current Accounts are also assumed to be the starting year for all scenarios. Note that the Current Accounts Year, also called the Base Year, is not meant to be an \"average\" year, but the best available estimate of the current system in the present. The Current Accounts include the specification of supply and demand data (including definitions of reservoirs, pipelines, treatment plants, pollution generation, etc.) for the first year of the study on a monthly basis.
The first year of the analysis period, and the year for which the system is 'calibrated.'
Conductivity rate (length/time) of the deep layer (bottom \"bucket\") at full saturation (when relative storage z2 = 1.0), which controls transmission of baseflow. This is given as a single value for the catchment and does not vary by land class type. Baseflow will increase as this parameter increases.
Digital Elevation Model - a representation of terrain, used to determine drainage directions and catchment boundaries.
Demand-Side Management, or Demand Management, refers to strategies for reducing demand for water, such as a program to reduce leakage or unauthorized withdrawals from the system, a program to encourage reuse or more efficient use of water, or programs that use price as an incentive to reduce demands.
The area-wide priority for allocating water to demand sites, instream flow requirements and reservoirs, ranging from 1 (highest priority) to 99 (lowest). These priorities represent the user's priorities for delivery of water for each demand site, instream flow requirement and reservoir. See also Supply Preference and Allocation Order.
A set of water users that share a physical distribution system, that are all within a defined region, or that share an important withdrawal supply point.
To break something down into sub-categories (e.g. breaking a municipal demand site into urban and rural sectors). See Aggregate, Sector, Subsector.
Optional order of allocation among branches within a demand site or catchment, to be used in case of shortage.
A canal or pipeline that is supplied by water diverted from a river. A diversion is represented as a river in WEAP--composed of a series of reservoirs, run-of-river hydropowers, flow requirements, withdrawals, diversions, tributaries and return flow nodes. See Diversion Node.
A point at which water is diverted from a river or other diversion into a canal or pipeline called a diversion. See Diversion.
A DLL is a \"dynamic link library\" file that contains one or more functions. A DLL is a compiled executable program written in a standard programming language, such as C, Visual Basic or Delphi. The ability of WEAP to call DLL functions is very powerful, as it allows the user to add new functions or even complete models to WEAP. See WEAP's Call function.
\"Dissolved Oxygen\" - the concentration of dissolved oxygen in water.
See Demand-Side Management
Something calculated internally in a model.
European Space Agency Climate Change Initiative Land Cover database (ESA-CCI-LC)
A value explicitly specified (i.e., not calculated internally by the model).
A mathematical formula used to specify how the values of a variable changes over time.
A result chart saved by the user, complete with all formatting, for later retrieval, or inclusion in an Overview. See Overview.
A graph of flow in which the flows have been sorted from highest to lowest values. Also called an \"Exceedance\" graph because the x-axis shows the percentage to time that a given value is exceeded.
Minimum instream flow required at a point on a river or diversion to meet water quality, fish & wildlife, navigation, recreation, downstream or other requirements.
Geographic Information System. WEAP allows you to load GIS maps, in standard ArcView Shape and Grid format, as background layers for the Schematic.
Hydropower is generated when water falls from a height into a turbine. This height is called the head, or head difference. Also refers to the elevation of the groundwater table.
The time-series of monthly inflows to the system, specified using either the Water Year Method or the Read from File Method. See Inflow, Water Year Method, Read from File.
Hydrological data and maps based on SHuttle Elevation Derivatives at multiple Scales. Used by WEAP as the DEM data for catchment delineation.
precipitation or other sources of water (such as excess irrigation) that percolates into and through the soil, or, inflow of groundwater into return flow links
Flows into the WEAP system: Groundwater recharge, River Headflow, and Inflow to River Reaches, Local Reservoirs and Other Local Supplies. See Hydrology.
Used to place demand site return flow deep underground.
Independent user-defined variables used to \"drive\" the calculations in your analyses. See Tree.
A linear program (LP) is used by WEAP to maximize satisfaction of requirements for demand sites, reservoir filling, user-specified instream flows and hydropower, subject to demand priorities, supply preferences, mass balance and other constraints. The LP solves all the simultaneous equations listed above.
Supply sources not connected (or not modeled as connected) to a river, i.e., Groundwater, Local Reservoirs, and Other Local Supplies.
See: Linear Program
The principal course of a river or stream.
MEdium Resolution Imaging Spectrometer (MERIS) satellite - produced data used by the European Space Agency Climate Change Initiative Land Cover database (ESA-CCI-LC)
A three-dimensional finite-difference groundwater flow model created by the U.S. Geological Survey (USGS).
The future stream of benefits and costs converted into equivalent values today. This is done by assigning monetary values to benefits and costs, discounting future benefits and costs using an appropriate discount rate, and subtracting the sum total of discounted costs from the sum total of discounted benefits.
Network Common Data Form - NetCDF is a set of software libraries and self-describing, machine-independent data formats that support the creation, access, and sharing of array-oriented scientific data. Used by WEAP for land cover and climate data.
A pollution source that cannot be defined as originating from discrete points such as pipe discharge. Areas of fertilizer and pesticide applications, atmospheric deposition, manure, and natural inputs from plants and trees are types of nonpoint source pollution.
A water year type that represents an average hydrological conditions. Note: the Current Accounts Year is not necessarily a Normal Water Year Type. See Water Year Type.
Element or compound essential for animal and plant growth. Common nutrients include nitrogen, phosphorus, and potassium.
Sources with predetermined water quantities available on a monthly basis, but with no storage capability between months (e.g., streams or other unconnected rivers, inter-basin transfers or other imports, and desalination plants).
Side-by-side display of multiple result charts, constructed from user-defined \"Favorites.\" See Favorite.
The Plant Growth Model (PGM) Method is a daily simulation of plant growth, transpiration,evaporation, irrigation requirements and scheduling, and yields.
A plugin is a set of user-defined variables that are packaged together, enabling them to be loaded into a WEAP area.
A pollution source at a discrete location such as a discharge pipe, drainage ditch, tunnel, well, or concentrated livestock operation.
Synonym for Reservoir Zone. See Zone.
The point on a surface at which water flows out of an area. Also called an outlet. All area upstream of the pour point drains into the pour point. If you choose a streamflow gauge point as the pour point for a catchment, you will be able to compare WEAP's simulated flow at the point to the measured data.
See Demand Priority
Display of geographic features from grid cells in a matrix. A raster display builds an image from pixels, pels, or elements of coarse or fine resolution, from centimeters to kilometers. Many satellites, like Landsat, transmit raster images of the earth's surface.
A detailed means for projecting inflows in the future. Inflow values for every month for one or more supply sources are read in from an ASCII file. Typically, this file contains either historical data or outputs from another model (e.g., a climate change model). See Inflow.
The natural inflow to a groundwater source. This does not include return flows and inflows from a river.
A scenario that represents the changes that are likely to occur in the future, in the absence of any new policy measure. Sometimes called a \"business as usual\" scenario.
Wastewater flows from demand sites and wastewater treatment plants, to treatment plants and receiving bodies of water. See Return Flow Node.
Point at which a return flow enters a river. (You may actually have return flows enter the river at any type of river node: Reservoir, Run-of-River Hydropower, Tributary, Diversion, Flow Requirement, Withdrawal Node, or Return Flow Node.) See Return Flow.
WEAP automatically saves multiple versions of each area's data; you may revert to any previous version.
A point on a river, of the following types: Reservoir, Run-of-River Hydropower, Withdrawal Node, Return Flow Node, Tributary Node, Diversion Node, Flow Requirement.
The portion of a river between two river nodes. See River Node.
Points on which run-of-river hydropower stations are located. Run-of-river stations generate hydropower based on varying streamflows but a fixed water head in the river. They have no storage.
Precipitation or other source of water (such as excess irrigation water) that travels overland
Used to control surface runoff response. Related to factors such as leaf area index and land slope. Runoff will tend to decrease with higher values of RRF (range 0.1 to 10).
A self-consistent storyline of how a future system might evolve over time in a particular socio-economic setting, for an assumed hydrologic sequence, and under a particular set of policy and technology conditions.
A user-created spatial layout that encompasses the physical features of the water supply and demand system. The Schematic View is the starting point for all activities in WEAP -- it is where the system of rivers, node and links is created, and from here you have one-click access to all data and results.
WEAP can act as an \"COM Automation Server,\" meaning that 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. These scripts or programs would use WEAP's \"Application Programming Interface\" (API) to communicate and automate WEAP.
A water-using sector of society, e.g., Agricultural, Municipal or Industrial. See Subsector, Disaggregate, Aggregate.
Changes that occur in a scenario because of different socio-economic, hydrologic or technology assumptions, rather than because of different policies.
Shuttle Radar Topography Mission: an international research effort to obtain high-resolution digital terrain data (DEM).
Detailed breakdown of a sector, e.g., urban and rural subsectors represent the municipal sector, or crop types, which represent subsectors for the agricultural sector. See Sector, Disaggregate, Aggregate.
The preference a demand site has for a particular source. Each transmission link has a preference number, ranging from 1 (highest preference) to 99 (lowest). See also Demand Priority, Allocation Order.
Surface water inflow to river reaches represents either non-point runoff into the river, or the confluence of streams or rivers not otherwise modeled.
Transmission links deliver water from local supplies, reservoir nodes, and withdrawal nodes to satisfy final demand at demand sites.
A hierarchical structure for organizing data, under six major categories: Key Assumptions, Demand Sites, Hydrology, Supply and Resources, Environment, and Other Assumptions.
Points where one river joins another.
Data that can change over time.
Display geographic features from points, using discrete X-Y locations. Lines are constructed from strings of points, and polygons (regions) are built from lines which close. Vector methods are sometimes contrasted with raster techniques which record geographic features within a matrix of grid cells.
WEAP automatically saves multiple versions of each area's data; you may revert to any previous version.
Treats wastewater from demand sites to remove pollutants, then returns treated effluent to one or more river nodes or local supply sources.
A term used to describe the chemical, physical, and biological characteristics of water, usually in respect to its suitability for a particular purpose.
The average water consumption of some device or end-use per unit of activity. See Activity Level.
A simplified means for projecting inflows in the future. Enter Current Accounts inflow data, then define the fluctuations of each water year type from the norm, and specify the sequence of water year types in the future. See Water Year Type, Inflow.
A water year type characterizes the hydrological conditions over the period of one year. The five types that WEAP uses-- Normal, Very Wet, Wet, Dry, and Very Dry--divide the years into five broad categories based on relative amounts of surface water inflows. See Water Year Method.
See Catchment.
Point where any number of demand sites receive water directly from a river.
Reservoir storage is divided into four zones, or pools. These include, from top to bottom, the flood-control zone, conservation zone, buffer zone and inactive zone. The conservation and buffer pools, together, constitute the reservoir's active storage.