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| Titel |
On the calculation of the topographic wetness index: evaluation of different methods based on field observations |
| VerfasserIn |
R. Sørensen, U. Zinko, J. Seibert |
| 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. 1 ; Nr. 10, no. 1 (2006-02-15), S.101-112 |
| Datensatznummer |
250007918
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| Publikation (Nr.) |
 copernicus.org/hess-10-101-2006.pdf |
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| Zusammenfassung |
| The topographic wetness index (TWI, ln(a/tanβ)), which combines local upslope
contributing area and slope, is commonly used to quantify topographic
control on hydrological processes. Methods of computing this index differ
primarily in the way the upslope contributing area is calculated. In this
study we compared a number of calculation methods for TWI and evaluated them
in terms of their correlation with the following measured variables:
vascular plant species richness, soil pH, groundwater level, soil moisture,
and a constructed wetness degree. The TWI was calculated by varying six
parameters affecting the distribution of accumulated area among downslope
cells and by varying the way the slope was calculated. All possible
combinations of these parameters were calculated for two separate boreal
forest sites in northern Sweden. We did not find a calculation method that
performed best for all measured variables; rather the best methods seemed to
be variable and site specific. However, we were able to identify some
general characteristics of the best methods for different groups of measured
variables. The results provide guiding principles for choosing the best
method for estimating species richness, soil pH, groundwater level, and soil
moisture by the TWI derived from digital elevation models. |
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