Geoscience Reference
In-Depth Information
the core components of the effort. Imperviousness possesses both a dynamic and an
“unplanned” nature in the sense that it results from land use and land cover change
over a period of time from years to more than decades. The drivers, nature, and
extent of these changes must be considered in the context of a state where 92% of
its land area is under private ownership (Kentucky Department of Fish and Wildlife
Resources
2009
). This fact also strengthens the case for the use of remote sensing
as the preferred way to measure changes in imperviousness in a routine, timely, and
cost-efficient way to encompass large areas with relatively good accuracy data.
The implications of seemingly modest TIA increases such as the ones revealed
by the previous analysis (about 5 ha/day in the 2001-2005 time interval) are obvi-
ous. Kentucky possesses a large and complex hydrologic surface network totaling
146,000 km (Kentucky Division of Water
2008
), that drains a 30-year average
annual precipitation of 1,242 mm (Kentucky Climate Center
2009
). Examples of
land development codes seeking to manage and mitigate increases in impervious-
ness at the subwatershed level exist in some parts of Kentucky (Louisville-Jefferson
County Metro Government
2009
). To further illustrate the public policy implications
of increases in imperviousness and the time lag in the creation of watershed man-
agement infrastructure (e.g. stormwater sewers), the case of Lexington, Kentucky is
used as an example.
Stormwater management in Central Kentucky has become an issue of public con-
cern. For example, the Lexington-Fayette Urban County Government is involved
with the US Environmental Protection Agency through a legal agreement to correct
storm and sanitary sewer systems over the next decade or so with anticipated cost
of several hundred million dollars (Lexington-Fayette Urban County Government
2008a
).
The Lexington-Fayette Urban County Council approved a settlement agreement
with state and federal governments that requires Lexington to fix problems with
its storm and sanitary sewer systems over the next 11-13 years; outreach efforts to
inform the population on the consequences and outlook of these developments are
also on-going Lexington-Fayette Urban County Government (
2008b
,
c
).
In particular, the stormwater system is directly affected by the amount of imper-
viousness and the changing amount of imperviousness found in subwatersheds
and portions of them. Therefore, the impact of imperviousness and its rate of
increase in urban and mixed-use subwatersheds are of extreme relevance for com-
munities trying to mitigate or ameliorate violations of the federal Clean Water
Act and/or related Acts. This issue has dimensions of addressing current condi-
tions as well as conditions that likely to be developing during future decades from
now. If current conditions are mitigated but urbanization is allowed to continue
following recent historic patterns and practices, forward progress is likely to be
minimal if any is made since it appears the urbanization change begets urbanization
change.
There are a variety of “carrot and stick” technological, economic, policy, and
regulatory options that can help on several levels but are beyond the scope of
how specifically geospatial technologies and data can be utilized in environmental
resource management.
