
Interpreting L-THIA's Results: About L-THIA
L-THIA
(Long-Term Hydrologic Impact Assessment) has been
developed as a straightforward analysis tool that
provides estimates of changes in runoff,
recharge and nonpoint
source pollution resulting from past
or proposed land use changes. It gives long-term
average annual runoff for a land use configuration,
based on actual long-term climate data
for that area. By using many years of climate
data in the analysis, L-THIA focuses on the average
impact, rather than an extreme year
or storm.
L-THIA
results do not predict what will happen in a specific
year. As a quick and easy approach,
L-THIA results are intended to provide insight
into the relative hydrologic impacts of different
land use scenarios. The results can be used to
generate community awareness of potential long-term
problems and to support physical planning aimed
at minimizing disturbance of critical areas.
It
is an ideal tool to assist in the evaluation of
potential effects of land use change and to identify
the best location of a particular land use so
as to have minimum impact on the natural environment
of the area. Recent concern over urban sprawl
has focused on several land use change issues,
including the failure to account for hydrologic
aspects of land use change that can result in
flooding, stream degradation, erosion, and loss
of groundwater supply.
L-THIA
was developed to provide a quick, accessible tool
to use in assessing the long-term impacts of land
use change. This site suitability analysis tool
is designed to make use of information that
is readily available from municipal databases.
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