From the DARWin SP screen, the 19 vegetation indices including WBI and NDWI
are accessed via a pull down menu.
Using Vegetation Indices to measure
forest canopy water content
1 Canal Street ◊ Unit B1
Lawrence, MA 01840 USA
Tel: 978 687-1833 ◊ Fax: 978 945-0372
Copyright © 2012 Spectral Evolution, Inc
Water content is an important indication of vegetation health.
Canopy water content vegetation indices provide a way to gauge
canopy water content based on reflectance spectra measured by a
field portable spectroradiometer such as the PSR+ and RS-3500.
These instruments come equipped with DARWin SP Data Acquisition
software and 19 built-in vegetation indices including WBI (Water
Band Index) and NDWI (Normalized Difference Water Index).
WBI is sensitive to increases in water content measured by the
strength of an absorption at 970nm related to that of a feature at
900nm. As the feature at 970nm increases, so does water content in
a canopy. WBI can be used for canopy stress analysis, production
prediction and modeling of crops, fire hazard condition analysis and
ecosystem physiology studies. Values for green vegetation in the
WBI index range from 0.8 to 1.2.
For NDWI, reflectance features at 857nm and 1241 nm are used in
calculations of water content. The weak water absorption feature at
1241nm is enhanced by the scattering of light by a forest canopy. The
values for this index range from –1 to 1. The typical range for green
vegetation is –0.1 to 0.4. You can use the NDWI to measure canopy
stress, leaf area index studies and fire hazard analysis.
The PSR+ and RS-3500 provide high resolution/high sensitivity for
field measurements. They deliver fast, accurate and non-destructive
measurements for field use. They are rugged and reliable so you can
get immediate measurements and vegetation indices results. They
both cover the full UV/VIS/NIR range from 350-2500nm. They are
accessed from DARWin’s pull-down menus along with the other 17
included vegetation indices.
The PSR+ 3500 is a field portable spectroradiometer for
remote sensing applications including vegetation studies. With
DARWin SP Data Acquisition Software included, it provides
instant access to 19 vegetation indices for your research.