Geoscience Reference
In-Depth Information
5
Predicting Hydrographs Using
Distributed Models Based on
Process Descriptions
Until the knowledge gained through research in the sciences concerned with hydrologic
phenomena becomes adequate enough to permit good quantitative descriptions of these
phenomena and their functional relationships, a very strong subjective influence will
pervade the entire endeavor. As long as this is true, the efforts of practising hydrologists will
remain largely in the realm of the arts. It is natural to expect that under such conditions there
may arise numerous emotional controversies regarding the relative merits of apparently
conflicting lines of attack to specific problems.
J. Amorocho and W. E. Hart, 1964
Models are thought experiments which help refine our understanding of the dominant pro-
cesses, . . . testing whether we have a sufficient and consistent theoretical explanation of
physical processes. The best model can only provide a possible explanation which is more
consistent with known data than its current rivals. Every field observation, and especially
the more qualitative or anecdotal ones, provides an opportunity to refute, or in some cases
overturn, existing models and the theories which lie behind them.
Mike Kirkby, 1996
5.1 The Physical Basis of Distributed Models
A general model of rainfall-runoff processes requires representations of the interacting surface and
subsurface processes. As noted in Section 2.5, an outline of the physics underlying such a description
was first published by Freeze and Harlan (1969), although the individual process descriptions had all
been established well before then. Most physically based models today are still based on the Freeze and
