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Prototyping
Globwetland

Wetlands
satellite mapping scheme yielding first results

10
October 2005
Earth's wetlands
are havens for wildlife and vital to the water cycle, but they are
also under threat. An ESA-led initiative aims to develop a global
wetland information service based on Earth Observation for
conservation efforts. The Globwetland project has now entered a new
phase, with prototype products being developed based on sites across
four continents.

Abundant
water makes wetlands the most biologically diverse ecosystems on
Earth, more productive even than tropical rainforests. Unlike
rainforests, they are scattered across the world, providing regional
flood and erosion prevention, water purification and nutrient
recycling.

For much of the 20th Century, wetlands were drained or otherwise
degraded. However growing understanding of the vital importance of
wetlands led to the signing in 1971 of the Ramsar Convention on
Wetlands. Today more than 142930 wetlands have been designated as
Wetlands of International Importance, a total area of 125 million
hectares. The Convention's 145 national signatories commit to
maintaining the ecological character and are obliged to reporting on
the state of listed wetlands they have designated.

Field work
contributes to Globwetland
prototypes

Taking place as part of ESA's Earth Observation Data
User Element, the aim of Globwetland is to utilise satellite imagery
to provide detailed wide-area views of individual wetlands and their
surrounding catchment areas, and how they are changing. This will
assist with Ramsar reporting, and also aid national and local
conservation efforts – the success of which ultimately comes down to
individual wetland managers.

For this reason Globwetland is user-oriented, developing and
demonstrating a space-based information service based on the
specific requests of local and national users across 50 sites in 21
countries worldwide.

"Our aim is to provide what the wetland managers think is
useful," explained Kevin Jones of Vexcel Canada, the company
managing Globwetland. "So the first phase was carrying out a
detailed survey of user requirements, to know what sites should be
acquired, in what style.

"We also need to ensure that products that can be employed
locally are also standardised to be of use nationally and
internationally.

Wetland mobility can
be a problem

"Now comes the
stage of prototyping products, with specific products being
developed based on user requirements. In turn, wetland managers are
helping us with ground truthing our products – verifying that what
is shown in an image is really there."

Based on the user requirements, Globwetland core products include
base maps, land use-land cover (LULC) maps and change detection maps
– with historical satellite images being compared with current
acquisitions to see what changes have occurred during the last ten
years or more. Water cycle regime monitoring maps are also being
crated using Envisat and Radarsat radar data to show flood and
retreat patterns.

Specialised products available if requested include digital
elevation models (DEMs) and biophysical data acquired from
multispectral satellite sensors, showing vegetation health based on
chlorophyll levels or the sediment contents of wetland water bodies.

Land cover map for
Canada's Creston Valley

Cooperation in
Canada

Canada's Creston
Valley Wildlife Management Area is a Ramsar site in British
Columbia, whose management team is working with Globwetland on the
developing of prototype products.

Its area manager is Brian Stushnoff, who explains: "The Wildlife
Area covers 7 000 hectares. It is a pretty wild area, and there are
some difficult and waterlogged parts. What we need is an effective,
economic means of knowing how the entire area responds to changing
water levels.

"Globwetland has presented our team with a collective opportunity
to learn more about satellites, what they can and cannot do. Before
the project began, we never realised there were so many different
types of data available."

Creston Valley map
compared to field photos

Managing a
wetland such as the one in Creston Valley is a complex task. To
ensure continued high biodiversity, the water levels of its marshes
must be periodically drawn down. Such cycles of wet and dryness
mimic nature's droughts, providing oxygen to decompose dead plant
material and release nutrients.

In addition, this practice helps stop invasive plant species,
such as cattails or reed canary grass, filling open water and
pushing out other plants.

"We try to keep up an early stage of succession, and a high level
of wetland vegetation can tend to reduce diversity," Stushnoff
explained. "We have to rehabilitate areas that get choked with
vegetation, drying them up and then ploughing up the ground to get
rid of the seed bank that develops over time.

"What satellite multispectral
or radar images can do is allow us to map vegetation species, and
see where there are concentrations of invasive plants to give us
problems. Reed canary grass can stand two to three metres high, so
shows up well in a radar image. Radar also shows up the extent of
flooded areas well, so we can see how water levels are changing.

"Historical satellite images are useful to see patterns over time
– a lot can happen in 30 years, or just a decade. Annual satellite
updates will help us into the future."

View from Natal
Drakensberg Park

Classifying
wetlands from space

Another advantage of the project is that it should
increase our ability to recognise different types of wetlands using
Earth Observation, and by extension more accurately classify them
within land cover maps.

"Wetlands have been very difficult to identify from space,"
explained Doug Taylor of Wetlands International, a non-governmental
organisation that maintains the Ramsar Sites Database and is a
Globwetland partner. "The Millennium Ecosystem Assessment remote
sensing group identified this ecosystem as the least well recognised
from space.

"Although sensors detecting water are useful, most wetlands are
also associated with vegetation, so characteristic wetland surfaces
may be anything from forested or floating plants to rice paddies or
wet grassland. Building up a catalogue of characteristic signatures
for all latitudes has only just started, so the GlobWetland project,
by virtue of its wide geographical and temporal reach, is a very
useful platform."

High-altitude
Austrian wetland near
Transweg

Globwetland should mean that, for the first time,
wetlands should be capable of being recognised solely through Earth
Observation imagery.

In preparation, Wetlands International has worked with the
European Environment Agency to develop an extension to their Corine
Land Cover classification system, developed for the
300-metre-resolution Corine European land cover map derived from
satellites. This extension is based on the globally authoritative
'Ramsar Classification for Wetland Type' system, covering all known
wetland types.

There are 71 African
Ramsar sites

Kampala COP 9
will present progress

The Ninth Meeting of the Conference to the Parties
(COP 9) of the Ramsar Convention is due to take place in Kampala,
Uganda from 8 November 2005. The meeting will include a presentation
from the Globwetland team on the project's progress so far.

Globwetland involves sites across four continents: North and
South America, Europe (including European Russia) and Africa, the
countries involved here being Algeria, Egypt, Cameroon, Central
African Republic, Chad, Niger, Kenya, Nigeria, Senegal and South
Africa.

"This will be an important opportunity to demonstrate the
innovative work of the GLobWetland project, showing how Earth
Observation can be used fruitfully to support wetland managers on
the ground in their management planning for Ramsar sites" says Nick
Davidson, the Ramsar Convention's Deputy Secretary General. "Many of
us recognise the huge potential for satellite-derived information to
help,but for the non-expert it's much harder to find out just what
Earth Observation tools and sources can help us for each
site-specific management issue.

"The experience of the Earth Observation analysts and site
managers at these 50 Ramsar sites, many of them in Africa, will help
all of us involved in the conservation and wise use of wetlands,
wherever we are."

Wetlands are a
global resource

Globwetland partners

Vexcel Canada Inc is leading the Globwetland
consortium for ESA's DUE, with subcontractors Remote Sensing
Solutions GmbH of Germany and Synoptics Remote Sensing and GIS
Applications of the Netherlands. The Netherlands-based Wetlands
International organisation is also taking part, both as a
sub-contractor and also as a link to the global wetland science
community.

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Related links

Globwetland

Vexcel

Ramsar Convention

Wetlands International

Creston Valley Wildlife
Management Area (CVWMA)

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