International Archives of Photogrammetrv and Remote Sensing. Vol XXXII Part 7C2, UNISPACE III, Vienna 1999 
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/ssebk 
I5PR5 
UNISPACE III - ISPRS Workshop on 
“Resource Mapp ing from Space ” 
9:00 am -12:00 pm, 22 July 1999, VIC Room B 
Vienna, Austria 
I5PRS 
MONITORING WATER RESOURCES AND AGRO-ECOSYSTEM PRODUCTIVITY FROM SPACE 
Wim G.M. Bastiaanssen*/** 
* International Institute for Aerospace Survey and Earth Sciences (ITC), P.O. Box 6, 7500AA, Enschede, The Netherlands, Associate 
Professor in Water Management Analysis 
** International Water Management Institute (IWMI), P.O. Box 2075, Colombo, Sri Lanka. Consultant 
ISPRS Commission: Technical Forum, Working Group: Resource Mapping from Space 
KEY WORDS: Global water scarcity, water resources management, biomass growth, earth observations 
ABSTRACT 
There is a considerable shortage of water for drinking, sanitation and, most importantly, for growing crops in developing countries. 
This water crisis will expedite in the next century and will affect the living and growing conditions in densely populated river basins. 
The baseline question goes back to whether we have sufficient quantities of water to maintain living standards. Unfortunately we 
have to conclude that there are no proper clues on the utilization of water resources in river basins and on where water leaves the 
hydrological system through evaporation into the atmosphere. Hence, water managers can hardly present reliable figures on the water 
balance and the users of water, and there is a need to exploit new information technologies to help them. Operational low resolution 
satellites fly over river basins on a daily basis (e.g. NOAA-AVHRR), and provide the opportunity to monitor the status of land and 
water resources, providing that the sky is free of clouds. Low resolution satellites with a short revisit period are attractive to 
concurrently monitor large scale evaporation and vegetation growth processes in developing countries, if the data is provided free by 
the supplier and proper interpretation algorithms with a physical basis are applied. Some examples from Pakistan are presented. 
1. INTRODUCTION 
The renewed interest for water conservation and the 
productivity of resources directly follows the increasing water 
scarcity at the global scale. The world’s population has recently 
passed 6 billion and the finite amount of water resources has to 
be shared with more people in the next millennium. By 2025, 
more than a quarter of the world’s population or a third of the 
population in developing countries will live in regions that will 
experience severe water scarcity (Seckler et al., 1999). Food 
projections for 2040 reveal the need for a two to three-fold 
increase in food productivity, as compared to 1990 (Penning de 
Vries et al., 1995). Although the hydrological research 
community has endeavoured to solve issues in climate 
hydrology (e.g. Hutjes et al., 1998) and water balances of 
tropical forests (e.g. Shuttleworth, 1988), there is a need to 
investigate water resources management in developing countries 
where millions of people do not have access to sanitation and 
irrigation water. 
Information on regional water inflow through precipitation, 
snow melt and groundwater movement and outflow through 
evaporation from rainfed agriculture, irrigated agriculture, 
forests and natural vegetation, is often incomplete or inadequate 
for comprehensive water availability analysis (Burton et al., 
1999; Bastiaanssen, 1999). Proper water management at the 
river basin scale requires accurate information on the spatial 
distribution of rainfall, water storage and distribution through 
irrigation canals, and the vegetation growth resulting from that. 
Currently, a few number of meteorological stations, cross 
regulators and piezometers are used for hydrological analyses at 
the regional scale. Because conventional networks are 
characterized by insufficient spatial and temporal coverage of 
the Earth’s surface, earth observation data from space platforms 
is becoming increasingly important to supplement existing 
hydrological data networks at the ground (Rango and Shalabv. 
1998). 
The average annual per capita domestic water needs are 20,000 
liter, but Gambia and Haiti have 2,000 liter/capita to consiune 
domestically while Australia lias 606,000 liter/capita. One 
hectare of wheat evaporates 5,000,000 liter to form grains and 
wetlands under tropical condition may sometimes need 
15.000,000 liter/ha/yr to remain environmentally wet and 
maintain a healthy vegetation and bio-diversity. Hence, sowing 
one hectare of wheat gives 250 persons less to drink and bath, 
but it is unavoidable to feed the people. The difficulties in 
choosing between water allocations are most acutely 
experienced in river basin systems, where most citizens 
commonly live and work. Knowledge of the land and water use 
patterns in the rural areas is of prime importance for natural 
resources managers because it swallows the bulk of the water 
resources. The irrigation sector withdraws an estimated 70 to 90 
percent of freshwater resources in developing countries (World 
Bank, 1992; FAO. 1994). Although the public perception is that 
the irrigation sector wastes fresh water resources, this opinion is 
not necessarily correct. Vast volumes of canal water that 
initially missed the crop can be recaptured by pumping 
groundwater from shallow aquifers, downstream capillar)' rise 
to the root zone, and return flow into tributaries or the main 
river itself. Recycling of water resources considerably increases 
the overall productivity of water. New innovations involve the