Geoscience Reference
In-Depth Information
across agencies working to protect and enhance
wetland resources. The Interagency Workgroup
on Wetland Restoration (IWWR) within the
United States, which includes the National
Oceanic and Atmospheric Administration, Envi-
ronmental Protection Agency, Army Corps of
Engineers, Fish and Wildlife Service and Natural
Resources Conservation Service, provided the
following dei nitions for standard wetland repair
projects undertaken (IWWR 2003). Variations of
these dei nitions are used in other geographic
contexts and by other non-governmental and
conservation organizations.
Wetland restoration
is the return of a
“degraded wetland or former wetland to a pre-
existing condition or as close to that condition
as is possible” (IWWR 2003). In restoration,
efforts are made to repair damage to the struc-
ture and functions of natural ecosystems. For
instance, if hydrologic changes brought about
by the construction of dams or ditches have
caused the desiccation of a wetland, then a res-
toration project might attempt to re-establish
wetlands through engineering efforts that
remove or adjust impoundment structures, i ll
in ditches, or take out agricultural drainage tiles.
Reclamation
, on the other hand, usually involves
conversion of wetland to another type of land
use such as agriculture or forestry (Quinty and
Rochefort 2003).
Restoration projects typically emphasize
restoring function and process within a wetland
ecosystem. For example, the Nature Conserv-
ancy has worked at the Cheyenne Bottoms
wetland complex in central Kansas by restoring
former agricultural i elds into wetlands through
contouring shallow seasonal water-accumulating
depressions, prescribed burns, grazing, remov-
ing fences, and allowing wetland plants from
adjacent wetland sites to re-colonize through
natural regeneration processes (Fig. 13-2). Res-
toration projects are undertaken across the
world. However, due to substantial capital and
resource investments, such projects are concen-
trated mostly in developed countries and for the
most part are limited in geographic scale. Even
so, some restoration projects including those
undertaken in the Florida Everglades and within
the deltaic marshes of the Tigris and Euphrates
rivers and the Mississippi Delta are notable for
their size and scope.
Wetland enhancement
includes increasing
one or more of the functions performed by an
existing wetland beyond what currently or pre-
viously existed in the wetland. There is often an
accompanying decrease in other functions
(IWWR 2003). Enhancements may be under-
taken on functioning wetland sites or those that
have witnessed some degradation. Enhance-
ments serve to deliberately augment certain
wetland functions for specii c purposes. The
construction of bird habitat through the build-
ing of nesting sites and bird islands or the
deliberate control of water levels to deter inva-
sive species and encourage native wetland veg-
etation are examples of such measures. These
efforts may yield unexpected benei ts. At Quivira
National Wildlife Refuge, for instance, water
level in the Big Salt Marsh was lowered in 2010
in order to control invasive plants (Fig. 13-3).
When much of the marsh dried up, many carp
(
Cyprinus carpio
) died, which provided a i sh
feast for birds, including whooping cranes (
Grus
americana
) and more than 200 bald eagles
(
Haliaeetus leucocephalus
), the most ever seen
at the refuge (Pearce 2010).
Wetland creation
involves converting a non-
wetland (either dryland or unvegetated water)
to a wetland (IWWR 2003). In this case, wetland
conditions including hydrology, vegetation and
wildlife are established with appropriate soil
that may, over time, support wetland ecosystems.
Wetland creation is undertaken for a variety of
purposes. Within the United States, Section 404
of the Clean Water Act requires wetland creation
or enhancement projects to be undertaken when-
ever wetlands are destroyed or converted for
development activity. Wetland creation may serve
socio-ecological functions and balance the
impacts of development on the environment.
Wetland creation is a signii cantly larger engi-
neering undertaking than wetland enhancement
or even, in some cases, restoration. Studies have
indicated that such efforts may not always live
up to expectations and result in wetlands that
have limited functions or are expensive to
