Environmental Engineering Reference
In-Depth Information
KINematic Runoff and EROSion (KINEROS2) hydrological models that frequently require
signiicant data preparation. Using the two models with AGWA, hydrological modeling and
watershed assessments at various temporal and spatial scales can be performed. For large
river basins, usually SWAT is used. AGWA can provide outputs of runoff (volumes and peaks)
and sediment yield, plus nitrogen and phosphorus with the SWAT model (USEPA, 2011).
Various simulation models were examined by NIFA-CEAP (Arabi et al., 2012) used for
agrjcultural watershed projects. It was found that SWAT was used the most. Other models
included Agricultural Non-Point Source (AnnAGNPS), Water Erosion Prediction Project
(WEPP) and GWLF. Various lessons learned regarding the use of these tools for watershed
conversation projects are elucidated, in addition to the relationship between monitoring
data and modeling in conservation practice evaluation.
It is a combination of EPIC and Groundwater Loading Effects of Agricultural Management
Systems (GLEAMS). GLEAMS was developed to determine the effect of various manage-
ment practices on pesticide and nutrient leaching at, through, and below the root zone. The
model simulates the downwater movement of pesticides via percolated water, runoff, and
sediment or upward movement of pesticides via plant uptake by evaporation and transpi-
ration. More pesticides have been incorporated in to the database and other updates have
been performed.
CREAMS (Knisel, 1980) is a ield scale model for prediction of runoff, erosion, and chemi-
cal transport from agricultural management systems. It is suitable for application to indi-
vidual storms or long-term averages over a period of 2 to 50 years. It is able to estimate
runoff, percolation, erosion, adsorption of plant nutrients, and pesticides. CREAMS (Knisel
and Davis, 1999) is a forerunner of SWAT and was also the basis for GLEAMS. The model
has shown promise for the development of best management practices in reducing non-
point source pollution in watersheds (USEPA, 1997). SWAT has been used by decision mak-
ers and could be used to protect water quality, if it is adequately tested.
PRZM3 is the most recent version (version 3.12.3 was released June 2006) of a model-
ing system developed by the EPA that includes PRZM and VADOFT to predict pesticide
transport and transformation down through the crop root and unsaturated zone (Suárez,
2005). PRZM is a one-dimensional, inite-difference model that predicts the fate of pes-
ticides and nitrogen in the root zone of crops. It can also predict pesticide concentration
in runoff water and solid particles. The latest version (PRZM3) includes the capability
to simulate soil temperature, volatilization and vapor phase transport in soils, irrigation
simulation, and microbial transformation, in addition to the transport and transformation
of the parent compound and up to two daughter species. The input parameters include
the characteristics of the pesticide, the application of the pesticide, crop, climatic, and site
information (soil and hydrological properties, agricultural practices, topography, etc.).
VADOFT is a one-dimensional, inite-element code that solves the Richard's equation for
low in the unsaturated zone. Several versions of the PRZM system are available from the
EPA web site (USEPA, 2014). PRZM can also be used with the EXAMS model to simulate
the fate and transport of the pesticide in water. Volatilization, sorption, hydrolysis, bio-
transformation, and photolysis are processes that are included in the model structure. An
aseptic system module is available for evaluating nitrogen fate and transport.
LEACHM is a suite of models for simulating the leaching and fate of water and chem-
icals within the soil (Hutson and Wagenet, 1989). Input data are similar to the PRZM-
EXAMS model. One or more growing seasons can be simulated. Output includes a proile
of the pesticide concentration throughout the soil and water and pesticides luxes in the
groundwater (Ecobas, 2007).
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