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MS-DOS |
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v5.00v3.65 |
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Dec. 1996 |
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Yes (Word/WP) |
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USDA ARS |
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AGNPS (Agricultural Non-Point Source Pollution Model)
is an event-based model that simulates surface runoff, sediment, and nutrient
transport primarily from agricultural watersheds. The nutrients considered
include nitrogen (N) and phosphorous (P), both essential plant nutrients and
major contributors to surface water pollution. Basic model components include
hydrology, erosion, and sediment and chemical transport.
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In addition, the model
considers point sources of water, sediment, nutrients, and chemical oxygen demand
(COD) from animal feedlots, and springs. Water impoundments, such as
tile-outlet terraces, also are considered as depositional areas of sediment and
sediment-associated nutrients.
The model has the ability to output water quality characteristics at
intermediate points throughout the watershed network. This capability is based
on the model's implementation of the 'cell'. Cells are uniformly square areas
subdividing the watershed, and all watershed characteristics and inputs are
expressed at the cell level.
Model components use equations and methodologies that have been well established
and are extensively used by agencies such as the USDA Soil Conservation Service.
Runoff volume and peak flow rate are estimated using the SCS runoff curve number
method. Peak runoff rate for each cell is estimated using an empirical
relationship proposed by Smith and Williams (1980) and which is also used in CREAMS
(Frere et al., 1980).
Upland erosion and sediment transport is estimated using a
modified form of the Universal Soil Loss Equation, USLE (Wischmeier and Smith, 1978).
Sediment is routed from cell to cell through the watershed to the outlet using a
sediment transport and depositional relationship described by Foster et al. (1981)
which is based on a steady-state continuity equation. Chemical transport is
calculated based on the relationships adapted from CREAMS and a feedlot evaluation
model (Young et al., 1982).
Feedlots are treated as point sources and chemical contributions
are estimated using the feedlot pollution model developed by Young et al.
Other point-source inputs of water and nutrients, such as springs, and wastewater
treatment plant discharges are accounted for by inputting incoming flow rates and
concentrations of nutrients to the cells where they occur.
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Detailed AGNPS model description is available.
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Unix version of AGNPS binary is also available.
File |
Size |
Download |
AGNPS v5.00 (program and user manaual) |
2.45 MB |
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AGNPS v5.00 (program and user manaual) |
2.45 MB |
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AGNPS v5.00 User manaual in MS Word format (self-extractable) |
0.57 MB |
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AGNPS v5.00 User manual in WordPerfect format (self-extractable) |
0.64 MB |
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AGNPS v3.65 (program only, Self-extractable) |
0.43MB |
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