Application of remotely sensed imagery to watershed analysis a case study of Lake Karoun, Egypt
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ORIGINAL PAPER
Application of remotely sensed imagery to watershed analysis a case study of Lake Karoun, Egypt Noha Donia
Received: 14 March 2012 / Accepted: 25 June 2012 / Published online: 19 July 2012 # Saudi Society for Geosciences 2012
Abstract Delineation of Lake Karoun watershed in Egypt was carried out and various watershed parameters and environmental characteristics were extracted using geographic information system and remote sensing. Environmental characteristics including normalized vegetation index (NDVI), moisture index, land surface temperature, and land use classes were obtained from high spatial resolution images (Landsat TM). Moreover, hydrological parameters, drainage flow directions, drainage networks, and catchments from digital elevation model have been delineated using the Advanced Space-borne Thermal Emission and Reflection Radiometer (ASTER) satellite images. As a result, the lake's watershed characteristics including the environmental and hydrological factors for each watershed zone were presented and analyzed. The information generated would be of immense help in hydrological modeling of watershed for prediction of runoff and sediment yield, thereby providing necessary inputs for developing suitable developmental management plans with sound scientific basis. Keywords Lake Karoun watershed . Remote sensing . Catchment delineation . GIS
Introduction There are many instances where watershed planning requires interpretation by superimposing for overlaying various thematic maps on the same area under study. Manually, this process is very tedious and suffers from many drawbacks. A computer-based system, on the other hand, is an N. Donia (*) Environmental Engineering Department, Institute of Environmental Studies and Researches, Ain Shams University, Cairo, Egypt e-mail: [email protected]
excellent tool that is not only speedy but also relatively free from most drawbacks. The utility of geographic information system (GIS) techniques is timely aiding the watershed management and planning processes and has gained considerable attention throughout the world. Further, GIS offers many new opportunities for hydrological modeling of watersheds (Schumann et al. 2000; Jurgen et al. 2001; Ambast et al. 2000; Tiwari et al. 2000). Creation of data base, composite map generation, and calculation of area statistics are performed much faster and more accurately by these techniques than conventional methods. Rapid parameterization is possible using a digital elevation model (DEM) generated from topographic maps to compute various topographical parameters, which are subsequently used to generated flow direction, flow accumulation, and drainage network in a watershed (Garg 1996). The parameterization of a watershed is time-consuming and is subject to errors related to manual operations (Lyon 2003) using traditional methods such as digitizing from paper maps and satellite image or aerial photograph interpretation. The automated watershed segmentation and extraction of channel network and sub-watershed propertie
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