Remote Sensing of Wetlands: Case Studies Comparing Practical Techniques

KLEMAS, V., 2011. Remote sensing of wetlands: case studies comparing practical techniques. Journal of Coastal Research, 27(3), 418–427. West Palm Beach (Florida), ISSN 0749-0208. To plan for wetland protection and sensible coastal development, scientists and managers need to monitor the changes in coastal wetlands as the sea level continues to rise and the coastal population keeps expanding. Advances in sensor design and data analysis techniques are making remote sensing systems practical and attractive for monitoring natural and man-induced wetland changes. The objective of this paper is to review and compare wetland remote sensing techniques that are cost-effective and practical and to illustrate their use through two case studies. The results of the case studies show that analysis of satellite and aircraft imagery, combined with on-the-ground observations, allows researchers to effectively determine long-term trends and short-term changes of wetland vegetation and hydrology. ADDITIONAL INDEX WORDS: Wetland remote sensing, wetland case studies, remote sensor comparison, coastal ecosystems, sea level rise. INTRODUCTION AND BACKGROUND Wetlands and estuaries are highly productive and act as critical habitats for a variety of plants, fish, shellfish, and other wildlife. Wetlands also provide flood protection, protection from storm and wave damage, water quality improvement through filtering of agricultural and industrial waste, and recharge of aquifers (Morris et al., 2002; Odum, 1993). However, wetlands have been exposed to a range of stress-inducing alterations, including dredge and fill operations, hydrologic modifications, pollutant runoff, eutrophication, impoundments, and fragmentation by roads and ditches. Recently, there has also been considerable concern regarding the impact of climate change on coastal wetlands, especially due to relative sea level rise, increasing temperatures, and changes in precipitation. Climate change is considered a cause for habitat destruction, shift in species composition, and habitat degradation in existing wetlands (Baldwin and Mendelssohn, 1998; Titus et al., 2009). Coastal wetlands have already proved susceptible to climate change, with a net loss of 33,230 acres from 1998 to 2004 in the United States alone (Dahl, 2006). This loss was primarily due to conversion of coastal salt marsh to open saltwater. Rising sea levels not only can cause the drowning of salt marsh habitats but also can reduce germination periods (Noe and Zedler, 2001). The impact of global change in the form of accelerating sea level rise and more frequent storms is of particular concern for coastal