Environmental Engineering Reference
In-Depth Information
added from experimental results of laboratory and ield studies. The code also now can
be used by other software programs for calculation of chemical reactions or distributions.
A number of models have been developed to integrate scientiic information to enable
policy development and future management practices. Integrated assessment modeling
in particular has been applied to determine the impacts and to predict climate change.
The California Agricultural Land Evaluation and Site Assessment (LESA) Model is used
to evaluate soil resource quality, using the indicators of the project's size, water resource
availability, surrounding agricultural lands, and surrounding protected resource lands.
For a given project, the factors are rated, weighted, and combined, resulting in a score that
determines project's potential signiicance.
The Global Change Assessment Model is an integrated assessment model linking energy,
agriculture, and land use with a climate model (JGCRI, 2014). In 5-year time steps from
1990 to 2095, the model can assess various climate change policies and technology strate-
gies for the globe over long time scales in 14 geographic regions. Emissions and atmo-
spheric concentrations of greenhouse gases (CO 2 and non-CO 2 ), carbonaceous aerosols,
sulfur dioxide, and reactive gases are estimated with the associated climate impacts, such
as global mean temperature rise and sea level rise.
Other models focus on predicting contaminant transport and leaching in the soil.
According to the USDA, Agricultural Research Service (ARS), Great Plains Systems
Research (Fort Collins, Colorado), the Nitrate Leaching and Economic Analysis Package
(NLEAP) is a ield-scale computer model developed to provide a rapid and eficient
method of determining potential nitrate leaching associated with agricultural practices. It
combines basic information concerning on-farm management practices, soils, and climate
and then translates the results into projected N budgets and nitrate leaching below the
root zone and to groundwater supplies and estimates the potential off-site effects of leach-
ing. The NLEAP model was designed to predict leaching of nitrate. The processes modeled
include movement of water and nitrate, crop uptake, denitriication, ammonia volatiliza-
tion, mineralization of SOM, nitriication, and mineralization-immobilization associated
with crop residue, manure, and other organic wastes. It can be used with various GIS
systems. An example is NLEAP GIS 4.2, Nitrogen Loss and Environmental Assessment
Package with GIS capabilities and a Nitrogen Trading Tool (NTT) application, which has
several components programmed in different computer languages. An interface for run-
ning the program in a Microsoft Excel ® environment was developed (Delgado and Shaffer,
2008). NLEAP GIS 4.2 with NTT application can be used to assess how one can reduce the
losses of reactive nitrogen, and also assess nitrogen dynamics and pools across various
landscapes to increase nitrogen use eficiency.
The Soil and Water Assessment Tool (SWAT) has been developed to model changing
land-use patterns and practices on nitrogen and phosphorus movement to surface and
groundwaters. It is a public domain model jointly developed by USDA-ARS and Texas
A&M AgriLife Research of the Texas A&M University System. SWAT is applicable for small
watersheds to river basin-scale models for the simulation of the quality and quantity of
surface and groundwater and predict the environmental impact of land use, land manage-
ment practices, and climate change, for assessing soil erosion prevention and controlling
non-point source pollution control and regional management in watersheds. Sediment
transport, crop growth, and nutrient cycling are simulated. It has also been used for pesti-
cide transport (Rekolainen et al., 2000). It is integrated into ArcView geographic informa-
tion systems (GIS) software and was developed by the USDA-ARS.
Developed by the USEPA, the USDA-ARS, and the University of Arizona, the Automated
Geospatial Watershed Assessment (AGWA) tool is a GIS interface used with the SWAT and
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