WEPP
Encyclopedia
The Water Erosion Prediction Project (WEPP) Model is a physically based erosion simulation model built on the fundamentals of hydrology
, plant science, hydraulics
, and erosion
mechanics. The model was developed by an interagency team of scientists to replace the Universal Soil Loss Equation
(USLE) and has been widely used in the United States and the world. WEPP requires four inputs, i.e., climate
, topography
, soil
, and management (vegetation
); and provides various types of outputs, including water balance
(surface runoff
, subsurface flow
, and evapotranspiration
), soil detachment
and deposition
at points along the slope, sediment delivery
, and vegetation growth. The WEPP model has been improved continuously since its public delivery in 1995, and is applicable for a variety of areas (e.g., cropland, rangeland
management, forestry
, fisheries, and surface coal mining
).
and management conditions, and capable of predicting spatial and temporal distributions of soil detachment and deposition on an event or continuous basis at both small (hillslopes, roads, small parcels) and large (watershed
) scales. Hillslope applications of the model can simulate a single profile having various distributions of soil
, vegetation
, and plant/management conditions. In WEPP watershed applications, multiple hillslopes, channels
, and impoundments can be linked together, and runoff
and sediment
yield from the entire catchment
predicted. The model has been parameterized for a large number of soils across the U.S. and model performance has been assessed under a wide variety of land-use
and management conditions. In addition, WEPP can generate long-term daily climatic data with CLIGEN, an auxiliary stochastic
climate generator. The CLIGEN database contains weather statistics
from more than 2,600 weather stations
in the United States. The WEPP climate database is supplemented by the PRISM database, which further refines the climatic data based on longitude
, latitude
, and elevation
. WEPP can provide daily runoff
, subsurface flow
, and sediment
output categorized into five particle-size
classes: primary clay
, primary silt
, small aggregates
, large aggregates
, and primary sand
, allowing calculation of selective sediment transport
, and enrichment of the fine sediment sizes.
to simulate the effect of hydraulic structures
and impoundments on runoff
and sediment delivery
, the addition of Penman-Monteith ET
algorithms, subsurface converging lateral flow to represent variable source area runoff
, improved canopy biomass
routines
for forested applications, and the incorporation of an alternative, energy-balance
-based winter hydrologic routine
. A number of modern graphical user interface programs have also been created, to assist in easier application of WEPP. The main interface for the model is a standalone Windows application (downloadable via: http://www.ars.usda.gov/Research/docs.htm?docid=10621), that allows a user to simulate hillslope profiles and small watersheds and have full control over all model inputs (Figure 1). Additionally, web-based interfaces allow very easy and rapid use of the model while accessing existing soil
, climate
, and management databases (Figure 2).
A number of geospatial
interfaces
to WEPP (example in Figure 3) are also available:
has developed a suite of internet interfaces
, the Forest Service WEPP (FS WEPP) interfaces, for easier applications by stakeholders in forest and rangeland management (forest engineers, rangeland scientists, federal and state regulatory personnel) and the general public. The interfaces can be readily accessed and run through the internet (http://forest.moscowfsl.wsu.edu/fswepp/), and do not require any in-depth understanding of the hydrology
, hydraulic
and erosion
principles
embedded in the WEPP model. The FS WEPP interfaces include:
Hydrology
Hydrology is the study of the movement, distribution, and quality of water on Earth and other planets, including the hydrologic cycle, water resources and environmental watershed sustainability...
, plant science, hydraulics
Hydraulics
Hydraulics is a topic in applied science and engineering dealing with the mechanical properties of liquids. Fluid mechanics provides the theoretical foundation for hydraulics, which focuses on the engineering uses of fluid properties. In fluid power, hydraulics is used for the generation, control,...
, and erosion
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...
mechanics. The model was developed by an interagency team of scientists to replace the Universal Soil Loss Equation
Universal Soil Loss Equation
The Universal Soil Loss Equation is a mathematical model used to describe soil erosion processes.Erosion models play critical roles in soil and water resource conservation and nonpoint source pollution assessments, including: sediment load assessment and inventory, conservation planning and design...
(USLE) and has been widely used in the United States and the world. WEPP requires four inputs, i.e., climate
Climate
Climate encompasses the statistics of temperature, humidity, atmospheric pressure, wind, rainfall, atmospheric particle count and other meteorological elemental measurements in a given region over long periods...
, topography
Topography
Topography is the study of Earth's surface shape and features or those ofplanets, moons, and asteroids...
, soil
Soil
Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...
, and management (vegetation
Vegetation
Vegetation is a general term for the plant life of a region; it refers to the ground cover provided by plants. It is a general term, without specific reference to particular taxa, life forms, structure, spatial extent, or any other specific botanical or geographic characteristics. It is broader...
); and provides various types of outputs, including water balance
Water balance
In hydrology, a water balance equation can be used to describe the flow of water in and out of a system. A system can be one of several hydrological domains, such as a column of soil or a drainage basin....
(surface runoff
Surface runoff
Surface runoff is the water flow that occurs when soil is infiltrated to full capacity and excess water from rain, meltwater, or other sources flows over the land. This is a major component of the water cycle. Runoff that occurs on surfaces before reaching a channel is also called a nonpoint source...
, subsurface flow
Subsurface flow
Subsurface flow, in hydrology, is the flow of water beneath earth's surface as part of the water cycle.In the water cycle, when precipitation falls on the earth's land, some of the water flows on the surface forming streams and rivers...
, and evapotranspiration
Evapotranspiration
Evapotranspiration is a term used to describe the sum of evaporation and plant transpiration from the Earth's land surface to atmosphere. Evaporation accounts for the movement of water to the air from sources such as the soil, canopy interception, and waterbodies...
), soil detachment
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...
and deposition
Deposition (chemistry)
In chemistry, deposition is the settling of particles or sediment from a solution, suspension and mixture or vapor onto a pre-existing surface...
at points along the slope, sediment delivery
Sediment transport
Sediment transport is the movement of solid particles , typically due to a combination of the force of gravity acting on the sediment, and/or the movement of the fluid in which the sediment is entrained...
, and vegetation growth. The WEPP model has been improved continuously since its public delivery in 1995, and is applicable for a variety of areas (e.g., cropland, rangeland
Rangeland
Rangelands are vast natural landscapes in the form of grasslands, shrublands, woodlands, wetlands, and deserts. Types of rangelands include tallgrass and shortgrass prairies, desert grasslands and shrublands, woodlands, savannas, chaparrals, steppes, and tundras...
management, forestry
Forestry
Forestry is the interdisciplinary profession embracing the science, art, and craft of creating, managing, using, and conserving forests and associated resources in a sustainable manner to meet desired goals, needs, and values for human benefit. Forestry is practiced in plantations and natural stands...
, fisheries, and surface coal mining
Coal mining
The goal of coal mining is to obtain coal from the ground. Coal is valued for its energy content, and since the 1880s has been widely used to generate electricity. Steel and cement industries use coal as a fuel for extraction of iron from iron ore and for cement production. In the United States,...
).
Capability and Strength
WEPP is applicable for a wide range of geographic and land-useLand use
Land use is the human use of land. Land use involves the management and modification of natural environment or wilderness into built environment such as fields, pastures, and settlements. It has also been defined as "the arrangements, activities and inputs people undertake in a certain land cover...
and management conditions, and capable of predicting spatial and temporal distributions of soil detachment and deposition on an event or continuous basis at both small (hillslopes, roads, small parcels) and large (watershed
Drainage basin
A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...
) scales. Hillslope applications of the model can simulate a single profile having various distributions of soil
Soil
Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...
, vegetation
Vegetation
Vegetation is a general term for the plant life of a region; it refers to the ground cover provided by plants. It is a general term, without specific reference to particular taxa, life forms, structure, spatial extent, or any other specific botanical or geographic characteristics. It is broader...
, and plant/management conditions. In WEPP watershed applications, multiple hillslopes, channels
Stream channel
Stream channel is the physical confine of a stream consisting of a bed and stream banks.Stream channels exist in a variety of geometries. The stream channel development is controlled by both water and sediment movement. There is a difference between low gradient streams and high gradient streams...
, and impoundments can be linked together, and runoff
Surface runoff
Surface runoff is the water flow that occurs when soil is infiltrated to full capacity and excess water from rain, meltwater, or other sources flows over the land. This is a major component of the water cycle. Runoff that occurs on surfaces before reaching a channel is also called a nonpoint source...
and sediment
Sediment
Sediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....
yield from the entire catchment
Drainage basin
A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...
predicted. The model has been parameterized for a large number of soils across the U.S. and model performance has been assessed under a wide variety of land-use
Land use
Land use is the human use of land. Land use involves the management and modification of natural environment or wilderness into built environment such as fields, pastures, and settlements. It has also been defined as "the arrangements, activities and inputs people undertake in a certain land cover...
and management conditions. In addition, WEPP can generate long-term daily climatic data with CLIGEN, an auxiliary stochastic
Stochastic
Stochastic refers to systems whose behaviour is intrinsically non-deterministic. A stochastic process is one whose behavior is non-deterministic, in that a system's subsequent state is determined both by the process's predictable actions and by a random element. However, according to M. Kac and E...
climate generator. The CLIGEN database contains weather statistics
Statistics
Statistics is the study of the collection, organization, analysis, and interpretation of data. It deals with all aspects of this, including the planning of data collection in terms of the design of surveys and experiments....
from more than 2,600 weather stations
Weather station
A weather station is a facility, either on land or sea, with instruments and equipment for observing atmospheric conditions to provide information for weather forecasts and to study the weather and climate. The measurements taken include temperature, barometric pressure, humidity, wind speed, wind...
in the United States. The WEPP climate database is supplemented by the PRISM database, which further refines the climatic data based on longitude
Longitude
Longitude is a geographic coordinate that specifies the east-west position of a point on the Earth's surface. It is an angular measurement, usually expressed in degrees, minutes and seconds, and denoted by the Greek letter lambda ....
, latitude
Latitude
In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...
, and elevation
Elevation
The elevation of a geographic location is its height above a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational surface ....
. WEPP can provide daily runoff
Surface runoff
Surface runoff is the water flow that occurs when soil is infiltrated to full capacity and excess water from rain, meltwater, or other sources flows over the land. This is a major component of the water cycle. Runoff that occurs on surfaces before reaching a channel is also called a nonpoint source...
, subsurface flow
Subsurface flow
Subsurface flow, in hydrology, is the flow of water beneath earth's surface as part of the water cycle.In the water cycle, when precipitation falls on the earth's land, some of the water flows on the surface forming streams and rivers...
, and sediment
Sediment
Sediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....
output categorized into five particle-size
Particle size (grain size)
Particle size, also called grain size, refers to the diameter of individual grains of sediment, or the lithified particles in clastic rocks. The term may also be applied to other granular materials. This is different from the crystallite size, which is the size of a single crystal inside the...
classes: primary clay
Clay
Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...
, primary silt
Silt
Silt is granular material of a size somewhere between sand and clay whose mineral origin is quartz and feldspar. Silt may occur as a soil or as suspended sediment in a surface water body...
, small aggregates
Construction Aggregate
Construction aggregate, or simply "aggregate", is a broad category of coarse particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates. Aggregates are the most mined material in the world...
, large aggregates
Construction Aggregate
Construction aggregate, or simply "aggregate", is a broad category of coarse particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates. Aggregates are the most mined material in the world...
, and primary sand
Sand
Sand is a naturally occurring granular material composed of finely divided rock and mineral particles.The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal...
, allowing calculation of selective sediment transport
Sediment transport
Sediment transport is the movement of solid particles , typically due to a combination of the force of gravity acting on the sediment, and/or the movement of the fluid in which the sediment is entrained...
, and enrichment of the fine sediment sizes.
Recent Improvement
Over the last decade, researchers have made significant improvements to the WEPP model. These include improved algorithmsAlgorithm
In mathematics and computer science, an algorithm is an effective method expressed as a finite list of well-defined instructions for calculating a function. Algorithms are used for calculation, data processing, and automated reasoning...
to simulate the effect of hydraulic structures
Hydraulic structure
A hydraulic structure is a structure submerged or partially submerged in any body of water, which disrupts the natural flow of water. They can be used to divert, disrupt or completely stop the flow...
and impoundments on runoff
Surface runoff
Surface runoff is the water flow that occurs when soil is infiltrated to full capacity and excess water from rain, meltwater, or other sources flows over the land. This is a major component of the water cycle. Runoff that occurs on surfaces before reaching a channel is also called a nonpoint source...
and sediment delivery
Sediment transport
Sediment transport is the movement of solid particles , typically due to a combination of the force of gravity acting on the sediment, and/or the movement of the fluid in which the sediment is entrained...
, the addition of Penman-Monteith ET
Penman-Monteith
Like the Penman equation, the Penman–Monteith equation predicts net evapotranspiration, requiring as input daily mean temperature, wind speed, relative humidity, and solar radiation...
algorithms, subsurface converging lateral flow to represent variable source area runoff
Surface runoff
Surface runoff is the water flow that occurs when soil is infiltrated to full capacity and excess water from rain, meltwater, or other sources flows over the land. This is a major component of the water cycle. Runoff that occurs on surfaces before reaching a channel is also called a nonpoint source...
, improved canopy biomass
Biomass
Biomass, as a renewable energy source, is biological material from living, or recently living organisms. As an energy source, biomass can either be used directly, or converted into other energy products such as biofuel....
routines
Subroutine
In computer science, a subroutine is a portion of code within a larger program that performs a specific task and is relatively independent of the remaining code....
for forested applications, and the incorporation of an alternative, energy-balance
Energy balance
Energy balance may refer to:* First law of thermodynamics, according to which energy cannot be created or destroyed, only modified in form* Energy balance , a measurement of the biological homeostasis of energy in living systems...
-based winter hydrologic routine
Subroutine
In computer science, a subroutine is a portion of code within a larger program that performs a specific task and is relatively independent of the remaining code....
. A number of modern graphical user interface programs have also been created, to assist in easier application of WEPP. The main interface for the model is a standalone Windows application (downloadable via: http://www.ars.usda.gov/Research/docs.htm?docid=10621), that allows a user to simulate hillslope profiles and small watersheds and have full control over all model inputs (Figure 1). Additionally, web-based interfaces allow very easy and rapid use of the model while accessing existing soil
Soil
Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...
, climate
Climate
Climate encompasses the statistics of temperature, humidity, atmospheric pressure, wind, rainfall, atmospheric particle count and other meteorological elemental measurements in a given region over long periods...
, and management databases (Figure 2).
A number of geospatial
Geospatial
Geospatial analysis is an approach to applying statistical analysis and other informational techniques to geographically based data. Such analysis employs spatial software and analytical methods with terrestrial or geographic datasets, including geographic information systems and...
interfaces
Interface (computer science)
In the field of computer science, an interface is a tool and concept that refers to a point of interaction between components, and is applicable at the level of both hardware and software...
to WEPP (example in Figure 3) are also available:
- GeoWEPP – an ArcViewArcViewArcView 3.x was a geographic information system software product produced by ESRI.-History:ArcView started as a graphical program for spatial data and maps made using ESRI's other software products. Over time more and more functionality was added to ArcView and it became a real GIS program capable...
or ArcGISArcGISArcGIS is a suite consisting of a group of geographic information system software products produced by Esri.ArcGIS is a system for working with maps and geographic information...
extension that runs in conjunction with the WEPP Windows interface - On-line web-based GIS interface to WEPP using the open source MapServerMapServerMapServer is an open source development environment for building spatially-enabled internet applications. It can run as a CGI program or via MapScript which supports several programming languages . MapServer was developed by the University of Minnesota — so, it is often and more specifically...
GISGeographic Information SystemA geographic information system, geographical information science, or geospatial information studies is a system designed to capture, store, manipulate, analyze, manage, and present all types of geographically referenced data...
program - Iowa Daily Erosion Project
- NetMap
Forest and Rangeland Applications
The U.S. Forest ServiceUnited States Forest Service
The United States Forest Service is an agency of the United States Department of Agriculture that administers the nation's 155 national forests and 20 national grasslands, which encompass...
has developed a suite of internet interfaces
Interface (computer science)
In the field of computer science, an interface is a tool and concept that refers to a point of interaction between components, and is applicable at the level of both hardware and software...
, the Forest Service WEPP (FS WEPP) interfaces, for easier applications by stakeholders in forest and rangeland management (forest engineers, rangeland scientists, federal and state regulatory personnel) and the general public. The interfaces can be readily accessed and run through the internet (http://forest.moscowfsl.wsu.edu/fswepp/), and do not require any in-depth understanding of the hydrology
Hydrology
Hydrology is the study of the movement, distribution, and quality of water on Earth and other planets, including the hydrologic cycle, water resources and environmental watershed sustainability...
, hydraulic
Hydraulics
Hydraulics is a topic in applied science and engineering dealing with the mechanical properties of liquids. Fluid mechanics provides the theoretical foundation for hydraulics, which focuses on the engineering uses of fluid properties. In fluid power, hydraulics is used for the generation, control,...
and erosion
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...
principles
Principle
A principle is a law or rule that has to be, or usually is to be followed, or can be desirably followed, or is an inevitable consequence of something, such as the laws observed in nature or the way that a system is constructed...
embedded in the WEPP model. The FS WEPP interfaces include:
- Cross Drain - to predict sediment yield from a road segment across a bufferRiparian zoneA riparian zone or riparian area is the interface between land and a river or stream. Riparian is also the proper nomenclature for one of the fifteen terrestrial biomes of the earth. Plant habitats and communities along the river margins and banks are called riparian vegetation, characterized by...
- Rock:Clime - to create and download a modified WEPP climate file
- WEPP:Road - to predict erosion from a forest road segment
- WEPP:Road Batch - to predict erosion from multiple forest road segments
- Disturbed WEPP - to predict erosion from rangeland and forest disturbances (wildfireWildfireA wildfire is any uncontrolled fire in combustible vegetation that occurs in the countryside or a wilderness area. Other names such as brush fire, bushfire, forest fire, desert fire, grass fire, hill fire, squirrel fire, vegetation fire, veldfire, and wilkjjofire may be used to describe the same...
, harvest operationsLoggingLogging is the cutting, skidding, on-site processing, and loading of trees or logs onto trucks.In forestry, the term logging is sometimes used in a narrow sense concerning the logistics of moving wood from the stump to somewhere outside the forest, usually a sawmill or a lumber yard...
) - Tahoe Basin Sediment Model (under construction) - to predict runoff and erosion for the Lake TahoeLake TahoeLake Tahoe is a large freshwater lake in the Sierra Nevada of the United States. At a surface elevation of , it is located along the border between California and Nevada, west of Carson City. Lake Tahoe is the largest alpine lake in North America. Its depth is , making it the USA's second-deepest...
Basin - WEPP FuME (Fuel Management) - to predict erosion from fuel management practices
- ERMiT (Erosion Risk Management Tool) - to predict the probabilityProbabilityProbability is ordinarily used to describe an attitude of mind towards some proposition of whose truth we arenot certain. The proposition of interest is usually of the form "Will a specific event occur?" The attitude of mind is of the form "How certain are we that the event will occur?" The...
of sediment deliverySediment transportSediment transport is the movement of solid particles , typically due to a combination of the force of gravity acting on the sediment, and/or the movement of the fluid in which the sediment is entrained...
with various mitigation treatments in each of five years following wildfireWildfireA wildfire is any uncontrolled fire in combustible vegetation that occurs in the countryside or a wilderness area. Other names such as brush fire, bushfire, forest fire, desert fire, grass fire, hill fire, squirrel fire, vegetation fire, veldfire, and wilkjjofire may be used to describe the same...
See also
- ErosionErosionErosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...
- Erosion predictionErosion predictionThere are dozens of erosion prediction models. Most have been developed for agricultural areas and are design to compare predicted annual rates of soil loss from broad areas under various cropland and rangeland management techniques. Some are purely statistical models, others mechanistic...
- Erosion controlErosion controlErosion control is the practice of preventing or controlling wind or water erosion in agriculture, land development and construction. Effective erosion controls are important techniques in preventing water pollution and soil loss.-Introduction:...
- Sediment controlSediment controlA sediment control is a practice or device designed to keep eroded soil on a construction site, so that it does not wash off and cause water pollution to a nearby stream, river, lake, or bay...
- Hydrology (agriculture)Hydrology (agriculture)Agricultural hydrology is the study of water balance components intervening in agricultural water management, notably in irrigation and drainage.-Water balance components:...
- Hydrological modellingHydrological modellingHydrologic models are simplified, conceptual representations of a part of the hydrologic cycle. They are primarily used for hydrologic prediction and for understanding hydrologic processes. Two major types of hydrologic models can be distinguished:...
- Hydrological transport modelHydrological transport modelAn hydrological transport model is a mathematical model used to simulate river or stream flow and calculate water quality parameters. These models generally came into use in the 1960s and 1970s when demand for numerical forecasting of water quality was driven by environmental legislation, and at...
- Runoff model (reservoir)Runoff model (reservoir)A runoff model is a mathematical model describing the rainfall - runoff relations of a rainfall catchment area, drainage basin or watershed. More precisely, it produces the surface runoff hydrograph as a response to a rainfall hydrograph as input...
External links
- WEPP - Official site - National Soil Erosion Research Laboratory (NSERL), USDA Agricultural Research Service
- WEPP Web Interfaces - NSERL, USDA Agricultural Research Service
- Forest Service WEPP Interfaces - USDA Forest Service Rocky Mountain Research StationRocky Mountain Research StationThe Rocky Mountain Research Station is one of five regional units that make up the US Forest Service Research and Development organization — the most extensive natural resources research organization in the world. The station headquarters are located in Fort Collins, Colorado. The director is...
- GeoWEPP - SUNY Buffalo
- NetMap - Earth Systems Institute