One area can illustrate that the supply of, and demand for, water varies over time and space.

The interconnecting factors that influence water supply are
(a) physical;
     i)   geology
     ii)  relief
     iii) climate
(b) technological;
(c) political

The factors that influence demand are
(a) demographic
(b) economic

Thus the physical processes and conditions for successful water storage may not occur in the same locations as urban growth.

Strategies used to match water supply and demand in one country involve both storage and transportation.

The development of a water resource scheme can bring about linked:
(a) physical
(b) economic
(c) social
changes in the immediate environment

These may be both positive and negative depending on the context, but can lead to conflict.

Whether or not a scheme is sustainable can be evaluated by assessing the relative importance of:
(a) the appropriateness of the level of technology
(b) social impact of the scheme
(c) environmental impacts