TITLE:
Geomorphologic Domination on Urban Sprawl of Southern Riyadh, Saudi Arabia Using Differential Interferometric Synthetic Aperture Radar (DInSAR)
AUTHORS:
Mohamed Daoudi, Kamel Hachemi, Abdullah O. Bamousa
KEYWORDS:
Landscape Morphology, SAR, DInSAR, Wadi Awsat, Wadi Nisah, Riyadh City
JOURNAL NAME:
International Journal of Geosciences,
Vol.12 No.6,
June
17,
2021
ABSTRACT: This study tests the southern part of the Riyadh City growth domination
by the Early Quaternary-Holocene trans-tensional Central Arabian graben system
reactivation and the subsequent dissolution-induced collapses and
karstification. This study utilizes Synthetic Aperture Radar (SAR) and
Differential Interferometric Synthetic
Aperture Radar (DinSAR) to examine the morphology of arid landscape,
south of Riyadh. Eight Single Look Complex (SLC) amplitude images are
calibrated, filtered, georeferenced and orthorectified at a resolution of 20
meters, and compared with one another by producing 17 diachronic images of the
pairs at different intervals (1996, 2003-2005, 2008). The diachronic SAR
intensity imageries suggest a downthrown displacement reaching 600 m and
eastward tilting at the bottoms of the grabens. Also, the
structurally-controlled valleys are developing an eastward-running drainage system
towards the oasis of Al-Kharj and capturing an older hydrologic system.
Moreover, a 12-year period (1996-2008) of the SAR data was obtained to examine
the average annual rate of southern Riyadh’s urban sprawl, which is estimated
at approximately 390 metres/year over the 12 years and constrained by
geomorphological features towards the deformed area. DInSAR imageries show the
primary results obtained from the 26 May 2004 and 31 Jan. 2005 pair of images,
merged with 30 m resolution DEM-SRTM data for the arid region south of Riyadh
to eliminate the influence of topography. DInSAR is applied in this study for
its ability to detect small displacements at the centimetre scale (1/2 wavelength). Although
the DInSAR’s coherence and phase imageries suggest a fairly stable region since
the last tectonic and subsequent geomorphic events, erosional and artificial
changes are observed, bounded within the
valleys and depressions, primarily due to aeolian and fluvial processes
and agriculture. It is highly recommended to preserve the area for
sustainability and economy.