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Newsletter and Technical Publications
Freshwater Management Series No. 5
Guidelines for the Integrated Management of
the Watershed
- Phytotechnology and Ecohydrology -
E. Examples of the use of phytotechnology and ecohydrology in
temperate and tropical catchments
In the developed countries
of Europe and North America commonly referred to as the G-7 countries,
phytotechnologies and ecohydrological approaches are gaining currency as
measures to be utilised in catchment management. Numerous examples of the use
of such measures can be found in the technical literature published since the
pioneering work of the International Joint Commission’s Pollution from Land Use
Activities Reference Group (PLUARG) during the 1970s. The PLUARG studies,
summarised in Thornton et al. (1999),
established not only the fact that human activities on and within the landscape
have both a direct and an indirect affect on water resources, but also the fact
that land management measures can influence the degree and extent of these
impacts. As a result of these studies,
and those of the OECD that followed, concepts such as conservation tillage,
grassed waterways, and vegetative buffer strips began to be more widely
accepted and implemented. Initial actions focused on rural, agricultural areas,
as these areas were focal points for the application of significant volumes of
fertilisers and other (artificial) agrochemicals.
Next to point sources such as sewage treatment plant discharges
and industrial discharges, agriculture was the single largest potential source
of nutrients to the Laurentian Great Lakes system. While these agrotechnologies
are not phytotechnologies, they do form the logical stepping off place for the
subsequent development of phytotechnologies. Recognition that vegetation can be
effective in reducing soil loss, maintaining the hydrological integrity of
waterways, and providing habitat for both terrestrial and aquatic life was to
follow.
Key advances in the
integration of hydrology into landscape planning and management included the
principles embodied in McHarg’s (1969) "design with nature" approach to urban
and regional planning. This approach recognised that the attempt of humans to
impose structural measures upon the environment, especially in the years
following the Second World War, had been less than effective in minimising
risks from "natural disasters," such as flooding. To the contrary, by managing
development so that structures were not placed within floodplains or on steeply
sloping and highly erodible lands, communities would benefit from fewer
economic losses while maintaining the aesthetic appeal of these open spaces.
During the 1980s, the Australians took this approach further by merging this
land use management strategy with the concept of wildlife corridors to create
networks of open lands within urban and urbanising areas to retain and maintain
the underlying ecological base. The integration of these land use planning and
management tools with the hydrological imperatives, as described herein, is the
next natural step forward in providing mechanisms whereby humans can achieve
their economic purposes with minimal risk from "natural disasters."
North America and Europe
One of the most important
tasks undertaken by the Southeastern Wisconsin Regional Planning Commission as
part of its regional planning efforts in the metropolitan Milwaukee (Wisconsin,
United States of America) area was the identification and delineation of those
areas within the region having high concentrations of natural, recreational,
historic, aesthetic, and scenic resources (Rubin and Emmerich 1981). These
areas were considered to be of such importance as to be preserved and protected
in order to maintain the overall quality of the environment. Such areas
normally included one or more of the following seven elements of the natural
resource base which are essential to the maintenance of both the ecological
balance and the natural beauty of the region:
- lakes, rivers, streams, and their
associated undeveloped shorelands and floodlands;
- wetlands;
- woodlands;
- prairies and undeveloped grasslands (= savannah areas);
- wildlife habitat areas;
- wet, poorly drained areas with organic soils; and
- rugged terrain with high-relief, steeply-sloped topography.
In addition to these seven
elements which were considered to constitute integral parts of the natural
resource base underlying the metropolitan region, there were five additional
elements that, although not a part of the natural resource base per se,
were closely related to, or
centred on, the natural resource base. These additional elements, therefore,
also are important elements to be considered in identifying and delineating
areas with scenic, recreational, and educational value. These additional
elements are:
- existing outdoor recreational sites;
- potential outdoor recreational and related
open space sites;
- historic, archaeological, and other
cultural sites;
- significant scenic areas and vistas; and
- natural areas and scientific areas.
The Southeastern Wisconsin Regional Planning Commission determined that the
delineation of these 12 natural resource and natural resource-related elements
on a map resulted in an essentially linear pattern of relatively narrow,
elongated areas which were termed "environmental corridors" by the Commission.
Those areas designated as primary environmental corridors included a wide
variety of important resource and resource-related elements. These areas were
at least 400 acres in area, two miles in length, and 200 feet in width.
Many interlocking and
interacting relationships were determined to exist within these corridors
between the living organisms and their environment. The destruction or
deterioration of one element of this environment could lead to a chain reaction
of deterioration and destruction. For example, the drainage of wetlands may
have far-reaching effects on other elements of the environment. The drainage of
wetlands can destroy fish spawning grounds, wildlife habitat, groundwater
recharge areas, and natural filtration and floodwater storage areas for their
interconnecting lake and stream systems. The resulting deterioration of surface
water quality may, in turn, lead to the deterioration of the quality of the
groundwater. Groundwater, in turn, serves as a source of domestic, municipal,
and industrial water supply and provides a basis for low flows in rivers and
streams. Similarly, the destruction of woodland cover, which may have taken a
century or more to develop, may result in soil erosion and stream siltation and
in more rapid runoff and increased flooding, as well as destruction of wildlife
habitat. Although the effects of any one of these environmental changes may
not, in and of itself, be overwhelming, the combined effects of these
sequential changes may lead eventually to the deterioration of the underlying
and supporting natural resource base and overall quality of the environment for
life.
The primary environmental
corridors in Southeastern Wisconsin generally lie along major stream valleys
and around major lakes, and contain almost all of the remaining high-value
woodlands, wetlands, and wildlife habitat areas, and all of the major bodies of
surface water and related undeveloped floodlands and shorelands within the
region. Primary corridors may be subject to urban encroachment because of their
desirable natural resource amenities. Unplanned or poorly planned intrusion of
the urban development into these corridors not only tends to destroy the very
resources and related amenities sought by the development, but it tends to
create severe environmental and development problems as well.
In addition to the primary
corridors, the Commission identified and delineated secondary environmental
corridors. These areas were located generally along intermittent streams or in areas
that served as links between segments of primary environmental corridors. These
secondary environmental corridors contained a variety of resource elements,
often comprised as remnants of primary environmental corridors that have been
developed for intensive agricultural purposes or urban land uses. Such
secondary environmental corridors facilitate surface water drainage, maintain
"pockets" of natural resource features, and provide for the movement of
wildlife, as well as for the movement and dispersal of seeds for a variety of
plant species. Such corridors, while not as important as the primary
environmental corridors, also were determined to be preserved in essentially
open, natural uses as urban development proceeds. These areas, within
catchments, can be incorporated within urban stormwater detention areas,
associated drainageways, and neighborhood parks.
Finally, in addition to the
primary and secondary environmental corridors, other, smaller concentrations of
the natural resource base elements exist that are isolated from the
environmental corridors by urban development or agricultural uses. Even though
these areas are separated from the environmental corridor network, they can
have important natural values. Isolated natural areas can provide the only
available wildlife habitat in a specific area, good locations for local parks
and nature study areas, and areas with outstanding aesthetic character or
natural diversity within an area. Important isolated natural features within
southeastern Wisconsin included geographically well-distributed, isolated
wetlands, woodlands, and wildlife habitats.
Riverbanks and lakeshores
located within environmental corridors were determined to be ideal candidates
for protection through proper land use zoning and/or through public acquisition
and ownership. In addition, isolated natural features, determined to be worthy
of protection and preservation in a natural state were also recommended for
protection and preservation whenever possible, but especially when such areas
were five or more acres in area.
Recently, building upon this
concept and implementing the principles of phytotechnology and ecohydrology,
the Minnesota Department of Natural Resources - and more recently the Wisconsin
Department of Natural Resources and University of Wisconsin-Extension - have
promoted the concept of "lakescaping" as a means of maintaining and enhancing
shoreland vegetation. As the development of the lakeshore areas of the north
central United States has progressed following the Second World War, the
shoreland vegetation, grasses, brush, and tree canopy have been progressively
removed and replaced with lawns and dwelling units. This has had repercussions
on the songbirds, amphibians, and other shoreland wildlife, which populations
have diminished, being replaced by more urban species or invasive species that
can utilise these disturbed shoreland areas. In addition, the removal of
shoreland structure has limited the presence of large woody debris, comprised
of treefalls, in nearshore waters, reducing breeding habitat for fishes,
amphibians, and shore-dwelling reptiles. To counteract these trends, programs
have been developed to encourage riparian property owners to maintain or
restore native plants within a zone extending from about 35 feet landward of
the shoreline and 30 feet or more lakeward of the shoreline. The extent to
which native plants and vegetation is disturbed is proposed to be limited to
only those areas necessary to accommodate a pier and swimming area, if desired,
while the balance of the shoreland is recommended to be maintained in a natural
state.
As a consequence of this major shift in management
approach, there has been a significant amount of public debate surrounding this
concept. Because of the resistance encountered among the public, efforts have
been made by the agencies to promote the concept of lakescaping as one wherein
the homeowner can maintain a manicured, landscaped appearance while
simultaneously achieving enhanced water quality and habitat benefit. In keeping
with this approach, efforts to encourage the use of native, rather than exotic,
grasses within the lawns, and the planting of native (prairie) plants - especially flowering perennials
- have been widely undertaken with some
success.
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