There are a couple of different methods being discussed as possible ways to maintain the water supply for the future. These methods include the development of new resources and management of demand for water. New water resources can be developed through projects such as building dams or diverting rivers. However, these projects are often expensive and may not be environmentally sound. The second method, demand management, involves finding ways to use our current resources more efficiently.
Water managers define efficiency as the fraction of the applied water that is absorbed by the soil.
However, the author raises the question of whether or not it is more important to focus on using water more efficiently or more effectively. If water can be used several times before it makes its way to the ocean, it would be more effective. The author concludes that when planning water management systems it is important to consider not only efficiency but also effectiveness if we are to get the most benefit from the limited supply of irrigation water.