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Wetland Mapping and Monitoring

LOOKNorth post-doctoral researcher improves understanding of boreal wetlands by fusing remote sensing data from multiple sources.

The most biologically diverse of all ecosystems, wetlands play an important role in environmental health, contributing to water purification, flood control and shoreline stability, as well as providing habitat for a wealth of plant and animal life. Yet wetlands in boreal systems remain poorly understood.  Today, new technologies are offering the potential to map our province’s wetlands in a thorough, detailed and cost-effective manner.

ABOVE: Meadow marsh (Photo courtesy of Ducks Unlimited Canada)

Funded in part through an Ignite Grant from Research and Development Corporation of Newfoundland and Labrador (RDC), LOOKNorth Remote Sensing Engineer Dr. Bahram Salehi is developing a novel automated system for mapping and monitoring wetland areas using multiple types of remotely-sensed data.  While traditional GIS maps are created by manually digitizing aerial photographs, the wetlands mapping and monitoring system (WMMS) ingests and integrates (or “fuses”) satellite-derived optical and radar imagery, as well as multispectral aerial orthophotographs; the fused data is then processed through advanced object-based image analysis techniques to extract features such as water levels and type of vegetation present in the areas imaged. This information will then be used to produce a map showing a detailed inventory of characteristics such as wetland size, location and land cover type(s).

The map will comprise four data layers: radar satellite data, supplying information on moisture levels and vegetation; rapid-eye satellite data, providing high-resolution optical imagery and colour information; aerial topographic photos; and a digital elevation map. Together, these data layers will allow the viewer to distinguish between the various types of wetland – bog, fen, marsh or swamp.

With assistance and support from Newfoundland and Labrador’s Department of Environment and Conservation (NL-DEC) and Ducks Unlimited Canada (DUC), the system will be tested on five pilot sites throughout the province; each 700 sq. km site, one in Labrador and four on the island of Newfoundland, has different wetland ecological characteristics. Throughout 2015 field teams will visit the sites to confirm (or “ground-truth”) the information extracted from the fused data.

LEFT: Boreal wetland support a broad range of plant and animal life, including waterfowl (Photo courtesy of DUC)

As well as providing baseline wetland information, the system also provides a platform for ongoing wetland monitoring using optical and radar satellite images of a particular area captured at different times during a season, showing growth or change over time. The WMMS will generate the fundamental information needed to support policies and programs for conservation and sustainable use of these valuable ecosystems.

WMMS can also provide critical information for water resource management, an emerging strategic priority for the Government of Canada. A number of federal agencies are working to investigate how current space-borne sensors can be used to better understand water levels, as well as the type and health of aquatic vegetation. Recently, the Canadian Centre for Mapping and Earth Observation (CCMEO) has explored the use of SAR polarimetric data for long-term monitoring of Canada’s wetlands. There are important synergies between this work and the WMMS project:  WMMS will help validate the approach scientists have developed at CCMEO and contribute to its ongoing work on wetlands monitoring, wetlands classification and surface water mapping. CCMEO is contributing Radarsat-2 data and valuable technical consultation to the WMMS project.

ABOVE: Bog (Photo courtesy of DUC)

The project is broadly collaborative, engaging a wide range of partners: LOOKNorth, Research and Development Corporation of Newfoundland and Labrador (RDC), Ducks Unlimited Canada (DUC), Newfoundland and Labrador’s Department of Environment and Conservation (NL-DEC), CCMEO, Environment Canada (EN) and Memorial University. The work is funded by LOOKNorth, RDC’s Ignite program and DUC, which is also providing advice, consultation and field personnel for ground-truthing. CCMEO is contributing technical advice and RADARSAT data support, while NL-DEC is providing access to its extensive orthophoto dataset as well as field personnel for ground-truthing. Dr. Salehi, who is also a cross-appointed to the Faculty of Engineering and Applied Science at Memorial University, will supervise a team of three Memorial graduate students whose research contributes to this project.

The information generated through the project will be used by DUC and NL provincial government departments and agencies to support wetland mapping and assist in wetland stewardship activities.