Global water dynamics: issues for the 21st century.

Area of Science:

• Environmental Science
• Global Systems Modeling
• Water Resource Management

Background:

• Global water balance modeling is crucial for understanding future water availability and use.
• System dynamics offers a novel approach to analyzing complex, interconnected global systems.
• Previous models often underestimated the significance of water as a global issue.

Purpose of the Study:

• To model the global water balance using system dynamics.
• To capture the dynamic interactions between water availability, use, and global development.
• To evaluate various water-related scenarios and their impact on the global water balance.

Main Methods:

• Development and application of the WorldWater system dynamics model.
• Simulation of global water balance under different future scenarios.
• Analysis of feedback loops between water resources and sectors like food, industry, and pollution.

Main Results:

• Water availability is strongly linked to global development.
• Wastewater dilution significantly stresses the global water balance.
• Sectoral water use dynamics differ from classical forecasting predictions, exhibiting "shoot and collapse" behavior.
• Extreme scenarios like "Chaos" (business as usual) and "Ocean" (unlimited desalination) highlight critical water challenges.

Conclusions:

• Water scarcity is a major global concern, contrary to some assumptions.
• Effective wastewater management is vital for maintaining global water balance.
• Realistic "Conservation" scenarios are necessary for sustainable water resource management.
• Interconnectedness of water with other global systems necessitates integrated modeling approaches.