ABSTRACT
In contrast to soil, water does not have an image problem. It is the subject of worship; it is breathtakingly beautiful; it falls free from the heavens, and we all know of its immediate significance in our daily lives. Yet this perspective is too narrow for a proper appreciation of the subject; it is useful to view water against the background of the hydrological cycle. This chapter therefore begins with a short résumé of the hydrological cycle before considering the practical aspects of studying water in the key terrestrial parts of the cycle. Inevitably, this involves considerations of water quality as well as quantity.
