Abstract
The accuracy of digital elevation models (DEMs) is very critical to planning adaptation strategies for coastal areas under changing scenarios of global climate and sea-level rise. This research assesses the accuracy of the interferometric DEM from the SRTM mission as it is one of the free available DEMs that have been widely used in many applications. The SRTM model is enhanced using the best fit global geoid model for Egypt instead of EGM96 and by applying a mathematical scale factor formula. This research aims to obtain a higher vertical accuracy of the SRTM model that achieves the requirements for coastal inundation studies with minimum field measurement data. The methodology approach consists of three phases. In the first phase, the enhancement scale factor formulas were derived using uniformly distributed ground control points (GCPs) at two different terrains data in Egypt. The second phase contains the evaluation and validation process. It was observed that the enhanced accuracy achieved ranged from 45% to 60 % based on the type of terrains. In the last phase, the sensitivity of these DEMs to sea-level projections using the recent available local tide gauge data was analyzed. It is recommended to investigate this method approach to determine the optimal size and distribution of reference ground control points needed to adjust various free open DEMs of low vertical accuracy for further studies and other applications.
Highlights
Nowadays, planning, development, and risk management along the Egyptian coasts need to conduct several studies including topography, water resources, climate change, and sea-level rise [1,2]
It can be realized that compared with the Shuttle Radar Topography Mission (SRTM), the digital elevation model (DEM) after enhancement and scaling (Scale SRTM) produces the smallest differences with a standard deviation equalling ± 0.18 m and ±5.56m at the Nile delta coast and the red sea coast study areas
The present study was an attempt to obtain a practical framework for enhancing the vertical accuracy of freely available DEM such as SRTM model at two different terrains along the Egyptian coasts
Summary
Nowadays, planning, development, and risk management along the Egyptian coasts need to conduct several studies including topography, water resources, climate change, and sea-level rise [1,2]. During the period 1901–2010, the global mean sea level rose by 19 centimetres and it is very likely that the SLR will exceed the observed rate of 2.0 mm/year during 1971–2010, with the rate of 8 to 16 mm/year during 2081–2100[3]. The existence of a reliable and precise digital elevation model (DEM) is greatly required to support the decision-makers for planning the needed adaptation strategies to sea level rise. A DEM can be obtained using different sources such as Terrestrial survey, Aerial photo, LIDAR, and Satellite survey.
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