1 - Hydrological uncertainty in perspective

Summary

ABSTRACT Different aspects and meanings of uncertainty are reviewed. This introductory review forms a basis for putting recent developments in hydrological and water resources applications of uncertainty concepts into perspective. The understanding of the term uncertainty followed herein is a logical sum of all the notions discussed. An attempt is made to justify the structure of the present volume and to sketch the areas of particular contributions in the volume and to point out their connections to different facets of uncertainty.

INTRODUCTION

It seems that there is no consensus within the profession about the very term of uncertainty, which is conceived with differing degrees of generality. Moreover, the word has several meanings and connotations in different areas, that are not always consistent with the colloquial understanding.

In the following section the notions and concepts of uncertainty both beyond and within the water resources research are discussed. Further, particular contributions in this volume are reviewed in the context of their connections to different facets of uncertainty. This is done in the systematic way, following the structure of the book.

NOTIONS OF UNCERTAINTY

Let us take recourse to established dictionaries and see how the words ‘uncertain’ and ‘uncertainty’ are explained. Among the meanings of the word ‘uncertain’, given by Hornby (1974) and Webster's (1987) dictionaries, are the following: not certain to occur, problematical, not certainly knowing or known, doubtful or dubious, not reliable, untrustworthy, not clearly identified or defined, indefinite, indeterminate, changeable, variable (not constant).