"The Role of Satellite Derived Information in the Restoration of the Great Lakes", Dr. Robert Shuchman,
Co-Director of the Michigan Tech Research Institute, Ann Arbor, Michigan (MTRI), a Michigan Technological University facility.
The White House has budgeted and Congress has approved over one billion dollars to fund the Great Lakes Restoration Initiative (GLRI). The GLRI addresses a multitude of issues including: mapping pollution, beach closures, wetland assessment and restoration, invasive species identification, reduction of Beneficial Use Impairments (BUIs) at Areas of Concern (AOCs), water quality assessment, Harmful Algae Blooms (HABs), legacy mine tailings, ecosystem understanding and management, and habitat assessment and restoration.
Satellite remote sensing systems that operate in the visible, infrared and microwave portion of the electromagnetic spectrum are being used to support the GLRI. Satellite data allows for the generation of synoptic Great Lakes basin-wide maps. Additionally, historical satellite observations dating back to the early 1970s are being used to create baselines as well as change detection maps.
Landsat data is being used by GLRI-funded scientists to map the nuisance benthic algae Cladophora in all of the Great Lakes except Superior. Using visible reflected light in the green and red bands, a depth invariant algorithm (corrects radiance values for changing water depth) maps Cladophora extent and biomass. Cladophora, a food source for the Asian Carp, grows on a solid substrate of the lake bottom and sloughs during storm events piling up on the shoreline where it fouls the beach and creates an environment for avian botulism.
The ability of Landsat to map the bottom substrate of the Great Lakes has greatly increased since the early 1970s. The optical depth (water clarity) for Lake Michigan was approximately 3 meters in 1974; it is now approximately 20 meters. This dramatic increase in water clarity (a GLRI-funded SOLEX water quality parameter) is a result of both good and bad forcing functions. The good contribution was the signing and enactment of the International Great Lakes Water Quality Agreement, the bad was the introduction of the invasive Zebra and Quagga mussels.
MODIS and MERIS are satellite systems that also operate in the visible and infrared region of the spectrum. These satellites image the entire Great Lakes multiple times per day at a ground spatial resolution of approximately 250-1000 meters. MODIS and MERIS use multiple band combinations (ratios and differencing) to map chlorophyll, dissolved organic carbon (doc), sediment plumes, HABs, and lake surface temperature (LST). The above-mentioned derived products obtained from these satellite systems support the GLRI-AOC, HABs mapping, beach closure, and water quality characterization activities.
Spaceborne Synthetic Aperture Radar (SAR), an active microwave sensor, is also a remote sensing tool being utilized in the GLRI effort. Phragmites is a non-native plant that grows in excess of 5 meters height that is negatively impacting wetland ecosystems throughout the Great Lakes basin. L-band (23.5cm wavelength) SAR data obtained from the Japanese PALSAR satellite system is being used to map the status and extent of the Phragmites infestation within the Great Lakes. Presently no maps exist. The maps will be used by stakeholders to aid in the remediation of the infestation.