193
wetland preservation began to be written in the
late 1970s. Individuals recognised that defi nitions were having an impact on what they could
or could not do with their land. Further, the defi -
nition of a wetland with implications in its boundaries (which is referred to delineation in the
USA) became important when society began to
recognise the values of these systems and also
began to translate that recognition into laws to
protect itself from further wetland loss.
11.7.1 Formal Defi nitions
Precise defi nition of wetland is needed by two
distinct interest groups, namely, (a) wetland scientists and (b) wetland managers and regulators. The
wetland scientist is interested in a fl exible yet rigorous defi nition which facilitates classifi cation,
inventory and research. Conversely, the wetland
manager is more concerned with laws of regulations which are designed to prevent or regulate
modifi cations of wetlands. Thus, the latter group
needs clear, legally binding defi nitions. Different
defi nitions have, thus, evolved for the two groups
because of their differing needs. In the USA, the
distinction between the regulatory defi nition of
jurisdictional wetlands and other defi nitions has
led to confusion. For example, the maps which
have been developed for wetland inventory purposes cannot be used for regulating wetland development. This is, thus, a source of considerable
confusion to wetland regulators and landowners.
11.7.2 Scientifi c Defi nitions
Various scientists have defi ned a wetland from
various points of views. Some of these are discussed below:
11.7.3 Early US Defi nition: Circular
39 Defi nition
One of the earliest definitions of the term
‘wetland’ was presented by the US Fish and
Wildlife Service in 1956 in a publication
which is often referred to as the Circular 39
(Shaw and Fredine 1956 ):
The term “wetlands” refers to lowlands covered
with shallow and sometimes temporary or intermittent waters. They are referred to by such names
as marshes, swamps, bogs, wet meadows, potholes, sloughs and river-overfl ow lands. Shallow
lakes and ponds, usually with emergent vegetation
as conspicuous feature, are included in the defi nition. But, the permanent waters of streams, reservoirs and deep lakes are not included. Neither are
water areas that are so temporary as to have little or
no effect on the development of moist-soil
vegetation.
It may be mentioned here that the Circular 39
defi nition:
(a) Emphasised wetlands that were important as
waterfowl habitats.
(b) Included 20 types of wetlands which served
as the basis for the main wetland classifi cation used in the USA until the 1970s. It, thus,
served the limited needs of both the wetland
managers and the wetland scientists.
11.7.4 US Fish and Wildlife Service
Defi nition
Perhaps, the most comprehensive defi nition of
wetlands was adopted by wetland scientists in the
US Fish and Wildlife Service in 1979, after several years of review. The defi nition was presented
in a report entitled, Classifi cation of Wetlands
and Deepwater Habitats of the United States
(Cowardin et al. 1979 ):
Wetlands are lands transitional between terrestrial
and aquatic systems where the water table is usually at or near the surface or the land is covered by
shallow water…..Wetlands must have one or more
of the following three attributes:
(a) At least periodically, the land supports predominantly hydrophytes;
(b) The substrate is predominantly undrained
hydric soil.
(c) The substrate is non-soil and is saturated with
water or covered by shallow water at some
time during the growing season of each year.
This defi nition was signifi cant for introduction of a number of important concepts in wetland ecology. It was one of the fi rst defi nitions to
11.7 Defi nitions of Wetlands
wetland preservation began to be written in the
late 1970s. Individuals recognised that defi nitions were having an impact on what they could
or could not do with their land. Further, the defi -
nition of a wetland with implications in its boundaries (which is referred to delineation in the
USA) became important when society began to
recognise the values of these systems and also
began to translate that recognition into laws to
protect itself from further wetland loss.
11.7.1 Formal Defi nitions
Precise defi nition of wetland is needed by two
distinct interest groups, namely, (a) wetland scientists and (b) wetland managers and regulators. The
wetland scientist is interested in a fl exible yet rigorous defi nition which facilitates classifi cation,
inventory and research. Conversely, the wetland
manager is more concerned with laws of regulations which are designed to prevent or regulate
modifi cations of wetlands. Thus, the latter group
needs clear, legally binding defi nitions. Different
defi nitions have, thus, evolved for the two groups
because of their differing needs. In the USA, the
distinction between the regulatory defi nition of
jurisdictional wetlands and other defi nitions has
led to confusion. For example, the maps which
have been developed for wetland inventory purposes cannot be used for regulating wetland development. This is, thus, a source of considerable
confusion to wetland regulators and landowners.
11.7.2 Scientifi c Defi nitions
Various scientists have defi ned a wetland from
various points of views. Some of these are discussed below:
11.7.3 Early US Defi nition: Circular
39 Defi nition
One of the earliest definitions of the term
‘wetland’ was presented by the US Fish and
Wildlife Service in 1956 in a publication
which is often referred to as the Circular 39
(Shaw and Fredine 1956 ):
The term “wetlands” refers to lowlands covered
with shallow and sometimes temporary or intermittent waters. They are referred to by such names
as marshes, swamps, bogs, wet meadows, potholes, sloughs and river-overfl ow lands. Shallow
lakes and ponds, usually with emergent vegetation
as conspicuous feature, are included in the defi nition. But, the permanent waters of streams, reservoirs and deep lakes are not included. Neither are
water areas that are so temporary as to have little or
no effect on the development of moist-soil
vegetation.
It may be mentioned here that the Circular 39
defi nition:
(a) Emphasised wetlands that were important as
waterfowl habitats.
(b) Included 20 types of wetlands which served
as the basis for the main wetland classifi cation used in the USA until the 1970s. It, thus,
served the limited needs of both the wetland
managers and the wetland scientists.
11.7.4 US Fish and Wildlife Service
Defi nition
Perhaps, the most comprehensive defi nition of
wetlands was adopted by wetland scientists in the
US Fish and Wildlife Service in 1979, after several years of review. The defi nition was presented
in a report entitled, Classifi cation of Wetlands
and Deepwater Habitats of the United States
(Cowardin et al. 1979 ):
Wetlands are lands transitional between terrestrial
and aquatic systems where the water table is usually at or near the surface or the land is covered by
shallow water…..Wetlands must have one or more
of the following three attributes:
(a) At least periodically, the land supports predominantly hydrophytes;
(b) The substrate is predominantly undrained
hydric soil.
(c) The substrate is non-soil and is saturated with
water or covered by shallow water at some
time during the growing season of each year.
This defi nition was signifi cant for introduction of a number of important concepts in wetland ecology. It was one of the fi rst defi nitions to
11.7 Defi nitions of Wetlands