Causes

People have a tendency to move towards the drier side of the climatic spectrum [semiarid].

Large urban population concentrations [particularly in semiarid regions such as San Diego and Los Angeles] demand increasing amounts of water to be conveyed longer distances to satisfy the demand.

Effects

Increasing use of energy to transport water from place of supply to place of demand.

The system is unsustainable in the long run (See Reisner: Cadillac Desert).

Solution

Conserve water where it is in short supply [semiarid regions].

Limit urban sprawl.

Provide incentives for people to move back to the rural areas.