The Water Erosion Prediction Project (WEPP) model is a physically based

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is distin ...

simulation model built on the fundamentals of

hydrology Hydrology () is the scientific study of the movement, distribution, and management of water on Earth and other planets, including the water cycle, water resources, and environmental watershed sustainability. A practitioner of hydrology is calle ...

plant science Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the Ancient Greek wo ...

hydraulics Hydraulics (from Greek: Υδραυλική) is a technology and applied science using engineering, chemistry, and other sciences involving the mechanical properties and use of liquids. At a very basic level, hydraulics is the liquid counter ...

, and

mechanics. The model was developed by an interagency team of scientists to replace the

Universal Soil Loss Equation The Universal Soil Loss Equation (USLE) is a widely used mathematical model that describes soil erosion processes. Erosion models play critical roles in soil and water resource conservation and nonpoint source pollution assessments, including: sedi ...

(USLE) and has been widely used in the United States and the world. WEPP requires four inputs, i.e.,

climate Climate is the long-term weather pattern in an area, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorologic ...

topography Topography is the study of the forms and features of land surfaces. The topography of an area may refer to the land forms and features themselves, or a description or depiction in maps. Topography is a field of geoscience and planetary sci ...

soil Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former te ...

, and management (

vegetation Vegetation is an assemblage of plant species and the ground cover they provide. It is a general term, without specific reference to particular taxa, life forms, structure, spatial extent, or any other specific botanical or geographic character ...

); and provides various types of outputs, including

water balance The law of water balance states that the inflows to any water system or area is equal to its outflows plus change in storage during a time interval. In hydrology, a water balance equation can be used to describe the flow of water in and out of ...

(

surface runoff Surface runoff (also known as overland flow) is the flow of water occurring on the ground surface when excess rainwater, stormwater, meltwater, or other sources, can no longer sufficiently rapidly infiltrate in the soil. This can occur when th ...

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. The rema ...

, and

evapotranspiration Evapotranspiration (ET) is the combined processes by which water moves from the earth’s surface into the atmosphere. It covers both water evaporation (movement of water to the air directly from soil, canopies, and water bodies) and transpi ...

), 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 Agricultural land is typically land ''devoted to'' agriculture, the systematic and controlled use of other forms of lifeparticularly the rearing of livestock and production of cropsto produce food for humans. It is generally synonymous with bot ...

rangeland Rangelands are grasslands, shrublands, woodlands, wetlands, and deserts that are grazed by domestic livestock or wild animals. Types of rangelands include tallgrass and shortgrass prairies, desert grasslands and shrublands, woodlands, savannas ...

forestry Forestry is the science and craft of creating, managing, planting, using, conserving and repairing forests, woodlands, and associated resources for human and environmental benefits. Forestry is practiced in plantations and natural stands. Th ...

fisheries Fishery can mean either the enterprise of raising or harvesting fish and other aquatic life; or more commonly, the site where such enterprise takes place ( a.k.a. fishing ground). Commercial fisheries include wild fisheries and fish farms, both ...

, and surface

coal mining Coal mining is the process of extracting 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 ...

Capability and strength

WEPP is applicable for a wide range of geographic and

land-use Land use involves the management and modification of natural environment or wilderness into built environment such as Human settlement, settlements and semi-natural habitats such as Arable land, arable fields, pastures, and managed Woodland, woo ...

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

, and plant/management conditions. In WEPP watershed applications, multiple hillslopes,

channels Channel, channels, channeling, etc., may refer to: Geography * Channel (geography), in physical geography, a landform consisting of the outline (banks) of the path of a narrow body of water. Australia * Channel Country, region of outback Austral ...

, and impoundments can be linked together, and

runoff Runoff, run-off or RUNOFF may refer to: * RUNOFF, the first computer text-formatting program * Runoff or run-off, another name for bleed, printing that lies beyond the edges to which a printed sheet is trimmed * Runoff or run-off, a stock market ...

and

sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand an ...

yield from the entire

catchment A drainage basin is an area of land where all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. A basin is separated from adjacent basins by a perimeter, the ...

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

and management conditions. In addition, WEPP can generate long-term daily climatic data with CLIGEN, an auxiliary

stochastic Stochastic (, ) refers to the property of being well described by a random probability distribution. Although stochasticity and randomness are distinct in that the former refers to a modeling approach and the latter refers to phenomena themselv ...

climate generator. The CLIGEN database contains weather

statistics Statistics (from German language, German: ''wikt:Statistik#German, Statistik'', "description of a State (polity), state, a country") is the discipline that concerns the collection, organization, analysis, interpretation, and presentation of ...

from more than 2,600

weather station A weather station is a facility, either on land or sea, with instruments and equipment for measuring atmospheric conditions to provide information for weather forecasts and to study the weather and climate. The measurements taken include tempera ...

s in the United States. The WEPP climate database is supplemented by th
PRISM database
which further refines the climatic data based on

longitude Longitude (, ) is a geographic coordinate that specifies the east–west position of a point on the surface of the Earth, or another celestial body. It is an angular measurement, usually expressed in degrees and denoted by the Greek letter l ...

latitude In geography, latitude is a coordinate that specifies the north– south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from –90° at the south pole to 90° at the north pol ...

, and

elevation The elevation of a geographic location is its height above or below a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational surface (see Geodetic datum § Vert ...

. WEPP can provide daily

, and

output categorized into five particle-size classes: primary

clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4). Clays develop plasticity when wet, due to a molecular film of water surrounding the clay par ...

, primary

silt Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension with water. Silt usually has a floury feel when ...

, small aggregates, large aggregates, and primary

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class of s ...

, allowing calculation of selective

sediment transport Sediment transport is the movement of solid particles (sediment), typically due to a combination of gravity acting on the sediment, and/or the movement of the fluid in which the sediment is entrained. Sediment transport occurs in natural system ...

, 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

algorithm In mathematics and computer science, an algorithm () is a finite sequence of rigorous instructions, typically used to solve a class of specific Computational problem, problems or to perform a computation. Algorithms are used as specificat ...

s to simulate the effect of

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. An example of a hydraulic structure would be a da ...

s and impoundments on

and sediment delivery, the addition of Penman-Monteith ET algorithms, subsurface converging lateral flow to represent variable source area

, improved

canopy Canopy may refer to: Plants * Canopy (biology), aboveground portion of plant community or crop (including forests) * Canopy (grape), aboveground portion of grapes Religion and ceremonies * Baldachin or canopy of state, typically placed over an a ...

biomass Biomass is plant-based material used as a fuel for heat or electricity production. It can be in the form of wood, wood residues, energy crops, agricultural residues, and waste from industry, farms, and households. Some people use the terms bi ...

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 Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for serv ...

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

, and management databases (Figure 2). A number of

geospatial Geographic data and information is defined in the ISO/TC 211 series of standards as data and information having an implicit or explicit association with a location relative to Earth (a geographic location or geographic position). It is also call ...

interfaces Interface or interfacing may refer to: Academic journals * Interface (journal), ''Interface'' (journal), by the Electrochemical Society * ''Interface, Journal of Applied Linguistics'', now merged with ''ITL International Journal of Applied Lin ...

to WEPP (example in Figure 3) are also available:
GeoWEPP
– an

ArcView ArcView is the entry level licensing level of ArcGIS Desktop, a geographic information system software product produced by Esri. It is intended by Esri to be the logical migration path from ArcView 3.x. ArcView is now referred to as ArcGIS fo ...

ArcGIS ArcGIS is a family of client, server and online geographic information system (GIS) software developed and maintained by Esri. ArcGIS was first released in 1999 and originally was released as ARC/INFO, a command line based GIS system for manipula ...

extension that runs in conjunction with the WEPP Windows interface
On-line web-based GIS interface to WEPP
using the open source

MapServer MapServer is an open-source development environment for building spatially enabled internet applications, built in the C language, and is widely known as one of the fastest Web mapping engines available. It can run as a CGI program or via MapSc ...

GIS A geographic information system (GIS) is a type of database containing Geographic data and information, geographic data (that is, descriptions of phenomena for which location is relevant), combined with Geographic information system software, sof ...

program
Iowa Daily Erosion Project

NetMap

Forest and rangeland applications

The

U.S. Forest Service The United States Forest Service (USFS) is an agency of the U.S. Department of Agriculture that administers the nation's 154 national forests and 20 national grasslands. The Forest Service manages of land. Major divisions of the agency in ...

has developed a suite of internet

, th
Forest Service WEPP (FS WEPP) interfaces
for easier applications by stakeholders in forest and

rangeland management Rangeland management (also range management, range science, or arid-land management) is a professional natural science that centers around the study of rangelands and the "conservation and sustainable management f Arid-Landsfor the benefit of cur ...

(forest engineers, rangeland scientists, federal and state regulatory personnel) and the general public.Elliot, W.J. 2004. WEPP internet interfaces for forest erosion prediction. ''Journal of the American Water Resources Association'' 40(2): 299–309. 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

hydraulic Hydraulics (from Greek: Υδραυλική) is a technology and applied science using engineering, chemistry, and other sciences involving the mechanical properties and use of liquids. At a very basic level, hydraulics is the liquid counter ...

and

principle A principle is a proposition or value that is a guide for behavior or evaluation. In law, it is a Legal rule, rule that has to be or usually is to be followed. It can be desirably followed, or it can be an inevitable consequence of something, suc ...

s embedded in the WEPP model. The FS WEPP interfaces include: * Cross Drain - to predict sediment yield from a road segment across a

buffer Buffer may refer to: Science * Buffer gas, an inert or nonflammable gas * Buffer solution, a solution used to prevent changes in pH * Buffering agent, the weak acid or base in a buffer solution * Lysis buffer, in cell biology * Metal ion buffer * ...

* 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 (

wildfire A wildfire, forest fire, bushfire, wildland fire or rural fire is an unplanned, uncontrolled and unpredictable fire in an area of Combustibility and flammability, combustible vegetation. Depending on the type of vegetation present, a wildfire ...

harvest operations Harvest Operations Corp. is a Canadian oil and natural gas company based in Calgary, Alberta. Unlike many oil and gas trusts, which consist only of production fields, Harvest had both "upstream" (oil and gas wells) and "downstream" (refining and ...

) * Tahoe Basin Sediment Model (under construction) - to predict runoff and erosion for the

Lake Tahoe Lake Tahoe (; was, Dáʔaw, meaning "the lake") is a Fresh water, freshwater lake in the Sierra Nevada (U.S.), Sierra Nevada of the United States. Lying at , it straddles the state line between California and Nevada, west of Carson City, Nevad ...

Basin * WEPP FuME (Fuel Management) - to predict erosion from fuel management practices * ERMiT (Erosion Risk Management Tool) - to predict the

probability Probability is the branch of mathematics concerning numerical descriptions of how likely an Event (probability theory), event is to occur, or how likely it is that a proposition is true. The probability of an event is a number between 0 and ...

of sediment delivery with various mitigation treatments in each of five years following

References

{{Reflist

External links

WEPP - Official site

* ttp://milford.nserl.purdue.edu/wepp/weppV1.html WEPP Web Interfaces
NSERL, USDA Agricultural Research Service

Forest Service WEPP Interfaces
-

USDA Forest Service The United States Forest Service (USFS) is an agency of the U.S. Department of Agriculture that administers the nation's 154 national forests and 20 national grasslands. The Forest Service manages of land. Major divisions of the agency inc ...

Rocky Mountain Research Station The Rocky Mountain Research Station (RMRS) 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 ...

GeoWEPP
-

SUNY Buffalo The State University of New York at Buffalo, commonly called the University at Buffalo (UB) and sometimes called SUNY Buffalo, is a public research university with campuses in Buffalo and Amherst, New York. The university was founded in 1846 ...

NetMap
- Earth Systems Institute Environmental science Environmental soil science Water and the environment Water pollution Water resources management Hydrology models

Capability and strength

Recent improvement

Forest and rangeland applications

See also

References

External links