Introduction

The scientific objectives of the project are described in the following publication:
The Global Water System Project: Science Framework and Implementation Activities. Framing Committee of the GWSP (2005). Earth System Science Partnership. Available online.

Water is essential to life on earth, plays a key role in the development and functioning of society and is recognised 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. The various human and physical, biochemical, and biological facets of the cycle make up the global water system (see diagram below).

The global water system is being transformed by major syndromes including climate change, erosion, pollution and salinisation. Major human-induced perturbations to the global water system include the following (numbers refer to figure):

• Hydrological cycle accelerated (1)
• Mountain snow/ice lost (2)
• Trees removal increases runoff, reduces transpiration, affects water table and landscape salinity (3)
• Wetlands dried up or drained (4)
• Ground- and surface water used for irrigated agriculture (5,6)
• Dams alter flow and reservoirs increase evaporation (7,8)
• Industrial water coolers release water vapour (9)
• Transfers between basins (10)
• Urban, mining and construction areas alter water flows and quality (11)
• Coastal salt water intrudes inland (12)
• Impoundments reduce flows (13)
• Siltation, erosion and nutrient flows change coastlines and affect water quality (14)
• Levees and locks modify flows and channels (15)
• Settlements alter floodplain landscapes (16)
• Grazing affects runoff and water quality (17)
• Industry causes acid rain (18)
• Coastal waters polluted and species lost (19)