Evaluation of morphometric parameters of drainage networks derived from topographic maps and DEM in point of floods |
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Authors: | Hasan Ozdemir Deanne Bird |
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Institution: | (1) Faculty of Letters, Geography Department, Physical Geography Division, Istanbul University, Ordu Cad. No: 196, 34459, Laleli, Istanbul, Turkey;(2) Department of Physical Geography, Macquarie University, Sydney, NSW, 2109, Australia |
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Abstract: | An evaluation of morphometric parameters of two drainage networks derived from different sources was done to determine the
influence of sub-basins to flooding on the main channel in the Havran River basin (Balıkesir-Turkey). Drainage networks for
the sub-basins were derived from both topographic maps scaled 1:25.000 and a 10-m resolution digital elevation model (DEM)
using geographic information systems (GIS). Blue lines, representing fluvial channels on the topographic maps were accepted
as a drainage network, which does not depict all exterior links in the basin. The second drainage network was extracted from
the DEM using minimum accumulation area threshold to include all exterior links. Morphometric parameters were applied to the
two types of drainage networks at sub-basin levels. These parameters were used to assess the influence of the sub-basins on
the main channel with respect to flooding. The results show that the drainage network of sub-basin 4—where a dam was constructed
on its outlet to mitigate potential floods—has a lower influence morphometrically to produce probable floods on the main channel
than that of sub-basins 1, 3, and 5. The construction of the dam will help reduce flooding on the main channel from sub-basin
4 but it will not prevent potential flooding from sub-basin 1, 3 and 5, which join the main channel downstream of sub-basin
4. Therefore, flood mitigation efforts should be considered in order to protect the settlement and agricultural lands on the
floodplain downstream of the dam. In order to increase our understanding of flood hazards, and to determine appropriate mitigation
solutions, drainage morphometry research should be included as an essential component to hydrologic studies. |
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Keywords: | Morphometric parameters Drainage network DEM Geographic information system Havran River basin |
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