Comparative study of the drainage basin morphometry extracted from topographic maps and SRTM DEMs: an example from Ghadir watershed, Eastern Desert, Egypt

Document Type : Research and Reference

Authors

Geology Department, Faculty of Science, Tanta University, Tanta 31527, Egypt

Abstract

The drainage network of Wadi Ghadir watershed, southeastern Desert, Egypt
was extracted from topographic maps (1:50. 000), and from the 30 m digital
elevation data (DEM) of the Shuttle Radar Topography Mapping Mission
(SRTM). Four topographic sheets were digitized and used for extraction.
Archydro function in ArcGIS 10x was utilized for network extraction and for
morphometric analysis. Networks derived from topographic sheets and DEM
were considerably coincident. Different morphometric parameters from both
sources were evaluated to examine the accuracy of DEM for hydrologic
applications. Results clarified 6th order streams for both drainage networks with
moderate to high drainage density (D) of 2.51 km.km2 (topographic) and 2.54
km.km2 (DEM) reflecting that W. Ghadir drainage basin is impermeable with
considerable surface runoff. DEM showed higher stream frequency (F) of 4.49
than those derived from topographic maps (4.38). Calculated bifurcation ratio
(Rb) of streams derived from topographic sheets reached about 3.47 and about
4.60 for those derived from DEM. DEM-derived morphometric parameters
provided good and satisfactory information about the catchment characteristics
and revealed accurate watershed delineation confirming high potential of
surface runoff of the W. Ghadir drainage basin. Finally, SRTM DEM proved
advantageous over the topographic sheets for drainage delineation and basin
morphometry for hydrologic analysis underpinned with the finer spatial
resolution and the vertical accuracy.

Keywords

Delta Journal of Science
Volume 39, Issue 2
December 2018
Pages 52-64

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