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Logo: Global Water System ChallengeESSP Joint Projects
Global Water System Project (GWSP)

The Global Water System Challenge

Water is essential to life on earth, plays a key role in the development and functioning of society, and is recognized as a high priority resource for sustainable development. Over the past few decades, environmental science has produced insights into the linkages, interconnections and interdependencies in the global water cycle. Various human and physical, biochemical, and biological facets of the cycle make up the global water system.

The global water system is being transformed by major syndromes including climate change, erosion, pollution and salinisation. We know more about the physical aspects of the global water system and much less about the nutrient flows, biodiversity loss and human dimensions. Examples of major perturbations to the global water system include the following:

  • Extreme precipitation events cause significant losses of lives and properties. These events also affect food security because of the destruction of crops and livestock.
  • Nitrogen loads on land masses now exceed natural nitrogen fixation levels and cause significant changes to water chemistry and ecology.
  • The past century has seen the extinction of more than 80 species of freshwater fish and many more are endangered.

Photo: Ythan catchment© D.Raffaelli


Photo: Lake© J.-M. Dreuillaux


Photo: Water pump © WHO / P. Virot

ESSP’s Response

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The Global Water System Project (GWSP) seeks to answer two fundamental and multi-faceted questions: How are humans changing the global water cycle, the associated biogeochemical cycles, and the biological components of the global water system? and What are the social feedbacks arising from these changes?

Research is needed to:

  • assess the magnitude and mechanisms of change in the global water system;
  • determine the main linkages and feedbacks within the Earth system arising from changes in the global water system;
  • better understand the resilience and adaptability of the global water system; and
  • identify the best strategies for sustainable water management.

The agenda for the GWSP will incorporate impact studies on water governance, land cover change, major diversions, climate change and nutrient and sediment flows. Linkages at different scales and the legacy of past human impacts will also be included. For example, researchers will undertake a comprehensive study to compare the requirements of human society with that of aquatic ecosystems, as well as studying the ecosystem services provided by freshwater.

The GWSP will undertake key cross-cutting activities such as generating an information database on the global water system, facilitating a discourse on water between the social and natural sciences, and developing models to define scenarios for the global water system.

Next Steps

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Over the past two years, a series of meetings has provided the rationale and defined the scope for the Global Water System Project. These activities culminated in a draft scientific framework that was devised by a committee of 12 international experts chaired by Prof. Dr. Joseph Alcamo, University of Kassel. In May 2004, the Chairs and Directors of the four Global Change programmes endorsed the Scientific Framework document and appointed a Scientific Steering Committee. The Scientific Framework will be finalised by the end of 2004 and the project will be in full swing.


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One of the important consequences of the rapid growth of global environmental science has been our growing awareness of the linkages, interconnections and interdependencies in the global water cycle. It is clear that human-induced changes to the global water system are now globally significant and are being modified without adequate understanding of how the system works.

While the global water system is an essential aspect of the dynamics of the Earth system, it also plays a central role in human society. It can be argued that the global water system is a product of the increasingly tight economic, social, technological and other couplings among society we term 'globalisation'. As an example, the water policies carried out by large international organisations have direct impacts on the levels of water abstraction and water diversions worldwide, and hence on the level of wastewater discharges, hydrologic regimes, the biogeochemistry of waters, and the state of aquatic ecosystems.

Therefore the major components of the global water system that require further study are:

  1. Human components - These are the sum of water-related organisations, engineering works, and water use sectors. Society is both a component of the global water system and a significant agent of change within the system.
  2. Physical components - These are the physical attributes and processes of the traditional global hydrologic or water cycle, including runoff, geomorphology, and sediment processes.
  3. Biological and biogeochemical components - This category includes the sum of aquatic and riparian organisms and their associated ecosystems and biodiversity. Much more than simply recipients of changes in the physico-chemical system, these organisms are also integral to the geochemical functioning of the global water system.


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Dr. Lydia Dümenil Gates

Executive Officer, International Project Office (IPO)
Walter-Flex-Str. 3
53113 Bonn, Germany

Tel: + 49 228 73 61 87
Fax: + 49 228 73 60 834
Email Dr. Lydia Dümenil Gates


Last updated: 29 November 2006

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