Vol. 7 No. 4 (2016)
Research Article

DETERMINATION OF A TOPOGRAPHIC WETNESS INDEX USING HIGH RESOLUTION DIGITAL ELEVATION MODELS

Majid HOJATI
Tehran University, Department of GIS and remote sensing, Tehran, Iran
Marzieh MOKARRAM
Shiraz University, Department of Range and Watershed, Agriculture College and Natural Resources of Darab, Shiraz, Iran

Published 2023-04-26

How to Cite

HOJATI, Majid, and Marzieh MOKARRAM. 2023. “DETERMINATION OF A TOPOGRAPHIC WETNESS INDEX USING HIGH RESOLUTION DIGITAL ELEVATION MODELS”. European Journal of Geography 7 (4):41-52. https://eurogeojournal.eu/index.php/egj/article/view/382.

Abstract

Topographic wetness indices (TWIs) computed from digital elevation models (DEMs) are
means to forecast the amount of moisture in the soil. In this study, using sub-pixel/pixel
attraction the spatial resolution of digital elevation models (DEM) was increased. In the
attraction, model scale factors of (2,3,4) with two neighboring methods of touching and
quadrant are applied to DEMs in Matlab software for the study area. The algorithm is
evaluated using 148 sample points that were measured by the researchers. As a result, it was
shown that a spatial attraction model with a scale factor of (S=2) gives better results compared
to the scale factors greater than 2 and also touching neighboring are more accurate then
quadrant. The results showed that waterway obtaining from DEM with high spatial resolution
is more accurate than DEM 90m. So according to the results, it is suggested that the same
model for increasing spatial resolution of DEM in the studies must be used. Furthermore, the
results of TWI map with the new DEM extracting of attraction model as input data showed that
TWI has more details from the moisture of soil than the TWI map prepared with DEM 90m.

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