Remote Sensing of Water in Wetlands: Inundation Patterns and Extent

Seasonally varying inundation extent and duration are key properties of wetlands, but are poorly quantified, particularly in tropical, boreal, and coastal regions. Optical sensors such as Landsat are limited by cloud cover, although sensors such as MODIS, with high repeat frequency, partly compensate for this limitation. Synthetic aperture radar (SAR) sensors are insensitive to cloud cover, and at longer wavelengths (C-band and L-band) are capable of detecting water beneath vegetation canopies. Time series of SAR data are effective for monitoring seasonal inundation dynamics, and combinations of different SAR wavelengths and polarizations can discriminate vegetation structure. Optical, SAR, and passive microwave sensors are being employed at global scale to characterize the role of wetlands in global hydrologic and biogeochemical cycles.