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Figure 13-2. High-spatial-resolution satellite image of the Nature Conservancy marshes in Cheyenne Bottoms, near
Hoisington, central Kansas, United States. Water bodies are black, and active vegetation is light gray to white.
Asterisk (*) indicates site for long-term observations with small-format aerial photography. Ikonos panchromatic
(green
+
+
red
near-infrared) band, 11 July 2003. Image processing by J.S. Aber.
maintain (IWWR 2003). Many require constant
management and long-term oversight. An alter-
native focus of wetland creation across the
world has also been to serve as water-quality
treatment systems. These artii cially created
treatment wetlands serve numerous purposes,
including waste-water treatment and managing
non-point-source pollution (DeBusk and DeBusk
2001; Mitsch and Gosselink 2000; van der Valk
2009).
Wetland mitigation is a term frequently used
in the United States and generally associated
with Section 404 of the Clean Water Act of 1972
and as amended in 1977. This act mandated that
any development or conversion activity directly
impacting wetlands must be balanced with the
restoration, enhancement or creation of a
wetland or wetland features elsewhere (Lewis
1989). Mitigation is expressly undertaken within
the United States to ensure that wetland destruc-
tion at one site is suitably compensated with its
creation or enhancement elsewhere. Such miti-
gation wetlands are often seen in connection
with highway construction (Fig. 13-4). The
United States' No Net Loss Policy similarly
endorses wetland mitigation activities to ensure
that there is no further decline in the total
wetland base of the country.
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