RAINS-Asia: The Deposition and Critical Loads (DEP) Module
The DEP module of RAINS-Asia enables the user to:
- calculate the levels and patterns of sulfur deposition resulting from
various energy/emissions scenarios generated by the
RESGEN and
ENEM modules; and
- compare the estimated sulfur deposition with data on environmental
sensitivities that are presented in the form of
critical loads maps.
The estimation of acid deposition for future emission scenarios is based on
atmospheric source/receptor relationships, calculated using an
atmospheric transport/deposition model, in this case,
the National Oceanic and Atmospheric Administration's (NOAA)
Branching Atmospheric Trajectory (BAT) model.
The model can be run for an entire year for each identified source, calculating
the total annual deposition attributable to that source. Similarly, when run
for all sources and areas, the model calculates the total annual deposition
over the entire model region.
The DEP module uses input data on emissions and source locations from the ENEM
module, comprising both anthropogenic and natural sources, including:
- large point sources (LPS's)
- area emissions (subdivided by industrial, domestic, and transportation
categories)
- shipping activities (including regional shipping lanes and in-port
activities)
- active volcanoes.
Thus DEP can be used to answer questions such as:
- How do changes in energy consumption and emissions from a specific area,
or a single large point source, affect levels of acid deposition in other areas?
- What sources or areas contribute to sulfur deposition in a given region?
RAINS-Asia: Sulfur deposition, 1990
In addition to estimating deposition loads, the DEP module also allows the
assessment of the environmental impacts of sulfur deposition on ecosystems.
By estimating critical loads
for various regions and ecosystems, and comparing
these natural sensitivities to deposition levels, the DEP module allows
users to assess the environmental effects of different energy and emissions
scenarios, answering questions such as:
- What regions and ecosystems are most sensitive to acid deposition?
- What are the geographic scope and extent of ecosystem damage which
results from a particular energy scenario?
- What environmental benefits would be realized if a particular emission
control strategy were implemented?
RAINS-Asia: Exceedance of Critical Loads
Several simplifying factors have been incorporated into the present version of
the DEP module. Only the indirect environmental effects of sulfur deposition
(i.e., acidification) have been considered in the present approach; other,
direct effects such as damage to vegetation from elevated SO2 air
concentrations, are not yet considered. As is the case with all
other parts of the RAINS-Asia model, the DEP module considers only the role
of sulfur in acidification. While nitrogen also plays an important role in the
acidification process, for the first phase of the project, emphasis was placed
on the effects of large-scale SO2 emissions and deposition.
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International Institute for Applied Systems Analysis