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| Titel |
Evolutionary geomorphology: thresholds and nonlinearity in landform response to environmental change |
| VerfasserIn |
J. D. Phillips |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 10, no. 5 ; Nr. 10, no. 5 (2006-10-09), S.731-742 |
| Datensatznummer |
250008197
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| Publikation (Nr.) |
 copernicus.org/hess-10-731-2006.pdf |
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| Zusammenfassung |
| Geomorphic systems are typically nonlinear, owing largely to their
threshold-dominated nature (but due to other factors as well). Nonlinear
geomorphic systems may exhibit complex behaviors not possible in linear
systems, including dynamical instability and deterministic chaos. The latter
are common in geomorphology, indicating that small, short-lived changes may
produce disproportionately large and long-lived results; that evidence of
geomorphic change may not reflect proportionally large external forcings;
and that geomorphic systems may have multiple potential response
trajectories or modes of adjustment to change. Instability and chaos do not
preclude predictability, but do modify the context of predictability. The
presence of chaotic dynamics inhibits or excludes some forms of
predicability and prediction techniques, but does not preclude, and enables,
others. These dynamics also make spatial and historical contingency
inevitable: geography and history matter. Geomorphic systems are thus
governed by a combination of "global" laws, generalizations and
relationships that are largely (if not wholly) independent of time and
place, and "local" place and/or time-contingent factors. The more factors
incorporated in the representation of any geomorphic system, the more
singular the results or description are. Generalization is enhanced by
reducing rather than increasing the number of factors considered. Prediction
of geomorphic responses calls for a recursive approach whereby global laws
and local contingencies are used to constrain each other. More specifically
a methodology whereby local details are embedded within simple but more
highly general phenomenological models is advocated. As landscapes and
landforms change in response to climate and other forcings, it cannot be
assumed that geomorphic systems progress along any particular pathway.
Geomorphic systems are evolutionary in the sense of being path dependent,
and historically and geographically contingent. Assessing and predicting
geomorphic responses obliges us to engage these contingencies, which often
arise from nonlinear complexities. We are obliged, then, to practice
evolutionary geomorphology: an approach to the study of surface processes
and landforms which recognizes multiple possible historical pathways rather
than an inexorable progression toward some equilbribrium state or along a
cyclic pattern. |
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