[103]. Since most freshwater discharges in wetlands and in shallow waters are
small, high spatial resolution remote sensors must be used to detect them.
New advanced techniques have been developed for mapping wetlands and even
identifying wetland types and plant species indicating the presence of water [91, 98,
104–107]. The integration of hyperspectral imagery and Lidar-derived elevation
has also significantly improved the accuracy of mapping wetland vegetation.
Hyperspectral images help distinguish wetland species, and the Lidar data help
separate species by their height [108]. Major plant species within a complex,
heterogeneous wetland have been classified using multi-temporal high-resolution
QuickBird satellite images, field reflectance spectra, and Lidar height information
[109]. Using Lidar, hyperspectral and radar imagery, and narrow-band vegetation
indices, researchers can discriminate between some wetland species and also
estimate biochemical and biophysical parameters of wetland vegetation, such as
water content, biomass, and leaf area index [69, 109–112].
SAR sensors on satellites provide the increased spatial resolution that is necessary in regional wetland mapping. SAR data have been used extensively for this
purpose [113–118].
The sensitivity of microwaves to water and their ability to penetrate vegetative
canopies make SAR also ideal for the detection of hydrologic features below the
vegetation [119–125]. The presence of standing water interacts with the radar signal
Fig. 6 The wetlands map shown on the left was derived from an airborne ADS-40 digital camera
image on the right. Note that three different marsh vegetation species were identified. Credits:
NOAA National Ocean Service, Charleston, SC, USA
50
V. Klemas and A. Pieterse
small, high spatial resolution remote sensors must be used to detect them.
New advanced techniques have been developed for mapping wetlands and even
identifying wetland types and plant species indicating the presence of water [91, 98,
104–107]. The integration of hyperspectral imagery and Lidar-derived elevation
has also significantly improved the accuracy of mapping wetland vegetation.
Hyperspectral images help distinguish wetland species, and the Lidar data help
separate species by their height [108]. Major plant species within a complex,
heterogeneous wetland have been classified using multi-temporal high-resolution
QuickBird satellite images, field reflectance spectra, and Lidar height information
[109]. Using Lidar, hyperspectral and radar imagery, and narrow-band vegetation
indices, researchers can discriminate between some wetland species and also
estimate biochemical and biophysical parameters of wetland vegetation, such as
water content, biomass, and leaf area index [69, 109–112].
SAR sensors on satellites provide the increased spatial resolution that is necessary in regional wetland mapping. SAR data have been used extensively for this
purpose [113–118].
The sensitivity of microwaves to water and their ability to penetrate vegetative
canopies make SAR also ideal for the detection of hydrologic features below the
vegetation [119–125]. The presence of standing water interacts with the radar signal
Fig. 6 The wetlands map shown on the left was derived from an airborne ADS-40 digital camera
image on the right. Note that three different marsh vegetation species were identified. Credits:
NOAA National Ocean Service, Charleston, SC, USA
50
V. Klemas and A. Pieterse