Earth observation methods for wetlands: Overview

Abstract

Across their range, wetlands are highly complex and dynamic and have been observed by a wide and diverse range of ground, airborne, and spaceborne sensors. The methods applied for characterizing, mapping, and monitoring mangroves are therefore diverse but have focused primarily on mapping state (i.e., water, ice, or snow) and extent as well as persistence and duration, sediment loads, substrate characteristics, and tidal fluctuations. A number of indices, algorithms, and models have been specifically developed to understand the changing states of wetlands, with these including mangroves, sea grasses, bogs, mires and fens, tropical floodplains, and semiarid wetlands. Many wetlands are also subject to anthropogenic disturbance as well as natural events and processes. Remote sensing data provide a unique opportunity to track such changes but also to classify these according to the different disturbance types. A number of international programs have also been put in place to advance the use of remote sensing data for wetland observations, with these including the European Space Agency's (ESA) Globwetland (I, II), the Japan Aerospace Exploration Agency (JAXA's) Kyoto and Carbon (K&C) Initiative, and the NASA's Making Earth System Data Records for Use in Research Environments (MEaSUREs) projects.