to very many different problems. The books many examples include: analysis of time intervals between el Niqo events, frequency of dry spells, the relation between heavy rainfall and flooding, occurrences of gravel disturbance in upland trout streams which damages trout spawn deposits and the cellular structure of rainfall. The book does not aim to be an exhaustive treatment of all possible applications of stochastic process models in the environmental sciences, but should be regarded as a source book. Its aim is to encourage students and research workers to see how environmental problems can be put into a probabilistic framework, and to draw their attention to analogous problems and solutions in other fields of environmental science in which water, and the transport of material by water, is an essential characteristic.