Water resources are made up of many components associated with water in its three physical states (liquid, solid and gas). Under natural conditions water results from complex interactions between atmospheric, land surface and subsurface processes that affect its distribution and quality.

The need to develop more sustainable practices for the management and efficient use of water resources has fundamentally shifted public awareness and concern over the past decade. However, economic criteria and politically charged reasoning are still driving water resource development decisions at most local, regional, national, and international levels. Though the long-term benefits of an integrated approach to achieving sustainable water resources development have been cited in many of the global water conferences over the past decade, considerable time as well as policy changes will be required to implement such an approach. 

In the meantime, the pressures on our water resources are increasing.

Variations in seasonality and the episodic nature of rainfall, snowfall, snowmelt and evapotranspiration all contribute to temporal incongruities that show up as flooding, seasonal low flows and longer-term drought, challenging water managers to forecast conditions and specify water allocations under a cloud of uncertainty. 

Climate change is surperimposed on the complex hydrological landscape, making its signal difficult to isolate and its influence felt throughout the water supply, demand, and buffering system.

The response of management strategies to potential climate change threats is an opportunity to implement more resource-sustainable policies and practices.

Unless a worldwide effort is made to improve our knowledge and understanding of changes in the global water resource, its future management will face even greater uncertainty and risk.