International Archives of Photogrammetry and Remote Sensing. Vol XXXII Part 7C2, UNISPACE III, Vienna 1999 
41 
I5PR5 
UNISPACE III - ISPRS Workshop on 
“Resource Mapping from Space” 
9:00 am -12:00 pm, 22 July 1999, VIC Room B 
Vienna, Austria 
I5PRS 
infrared spectral reflectances can be used in delineating 
vegetated from non-vegetated area. The growth of vegetation 
and biomass development are related to the Absorbed 
Photosynthetically Active Radiation, APAR (Monteith, 1972). 
APAR is the time-integrated solar radiation actually absorbed 
by canopies in the visible part of the spectrum between 0.4 and 
0.7 pm. APAR is the principal parameter that controls the total 
accumulated biomass of the crop by photosynthesis and 
assimilation using the concept of light use efficiencies (Field et 
al., 1995). Fig. 3 shows an example of the growth rates of above 
ground biomass in the Indus Basin on the same day as the 
evaporation interpreted image depicted in Fig. 2. The variations 
can be essentially explained by the farmer’s cultivation 
practices, such as sowing dates and timing of fertilizer and 
irrigation water applications. Large differences between 3 
gr/m 2 /day up to 11 gr/m 2 /day occur, and this simple example of 
the range in growth rates reveals that it is feasible to increase 
effective use of resources. The advantage of applying a biomass 
growth model is that all agro-ecosystems are included, thus the 
results also reveal the growth of native vegetation and forests 
(see the mountains ridge on the image). Time integrated above 
ground biomass can be converted into crop yields if the harvest 
index is experimentally known. Local water managers, water 
use associations and agricultural extension services usually 
don’t have the accessibility to such type of value added space 
information. It is expected that it can help them in learning the 
relationship between management practices and the productivity 
of land and water resources. 
Fig. 3 Example of above ground biomass growth for a wide variety of agro-ecosystems 
4. WATER RESOURCES MANAGEMENT IN THE 
NEXT CENTURY: VISTAS IN SPACE APPLICATIONS 
Several new space platforms will be launched in the next few 
years. A compiled overview can be found on the website 
www.itc.nl/~bakker/launch table.html which is regularly 
updated with the newest information provided by the space