Abstract
This study demonstrates the use of ASTER data to map the siltation of the Al-Khod Dam constructed at the lower reaches of Samail Catchment area, north Muscat, Sultanate of Oman. In this study, the decorrelated image of spectral bands 6, 3, and 1 clearly discriminated the distribution of siltation. The occurrence of siltation is confirmed by the detection of minerals using the VNIR-SWIR bands by the Spectral Angle Mapper (SAM) method. In addition, the siltation of the dam is studied for the years 1987 to 2018 using Landsat satellite images. Interpretation of images showed a gradual increase of the siltation. Mapping accuracy for the occurrence of siltation is assessed by a confusion matrix which produced an overall accuracy of 97.88% and Kappa coefficient of 0.98 in the Maximum Likelihood method. Results of image analyses are verified in the field and confirmed through laboratory analyses. The study of spectral absorption characters of field samples using a Portable Infrared Mineral Analyzer (PIMA) showed the presence of OH molecule bearing minerals (clays, serpentines, etc.) and carbonate minerals (calcite and dolomite) in the silt deposits. The occurrence of these minerals is confirmed further by X-ray diffraction (XRD) and Scanning Electron Microscope (SEM) analyses.
Highlights
This study demonstrates the use of ASTER data to map the siltation of the Al-Khod Dam constructed at the lower reaches of Samail Catchment area, north Muscat, Sultanate of Oman
The Al-OH absorption of spectral band 6 is studied by measuring spectra over field samples having kaolin (Al2Si2O5(OH)4) (AKD_K9a to AKD_Ka6c), illite ((K, H3O) (Al, Mg, Fe)2(Si, Al)4O10[(OH)2,(H2O)) (AKD_ill[24] to AKD_ill47) and montmorillonite ((Na, Ca)0,3(Al, Mg)2Si4O10(OH)2·n(H2O)) (AKD_clMo12 to AKD_clMo7) using a Portable Infrared Mineral Analyzer (PIMA) spectrometer in the 1.3 to 2.5 μm wavelength and confirmed by resampling the spectra with the SWIR spectral bands of ASTER (Fig. 3b)
The spectra of the samples resampled to SWIR spectral bands of ASTER in the 1.3 to 2.5 μm showed the Al-OH absorption in ASTER band 6 and Mg-OH and CO3 absorptions near ASTER band 8 (Fig. 3b)
Summary
This study demonstrates the use of ASTER data to map the siltation of the Al-Khod Dam constructed at the lower reaches of Samail Catchment area, north Muscat, Sultanate of Oman. A suitable technique to map and assess the silt deposits and sedimentation, an alternative to expensive and time-consuming methods[20,21], is essential and urgently needed by scientists and engineers to remove or protect the deposits of the recharge dams In this context, satellite images obtained using the remote sensing technique is helpful in the mapping of earth’s resources and monitoring of earth’s environments. The technique is more suitable for mapping and study of siltation deposits of recharge dams found in the arid region since the region is directly exposed to the sensor of the satellite without any vegetation disturbance. The objective of this study is to demonstrate the use of satellite data to map the siltation occurrence of a recharge dam found in the arid region. The periodic distribution of precipitation and the ephemeral nature of floodwaters deposit silts in the recharge dam and the arid climate keeps the dam dry in most of the months[4–6], which permits researchers to carry out a study over the catchment and recharge dam[4–6] and allows studying and monitoring the siltation of the dam using satellite data since the area is directly exposed to the sensor of the satellite without vegetation disturbance[25]
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