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Acoustical geophysical devices depend on sound source to transmit sound waves that reflected, diffracted or scattered off the sea bed. The frequency used by each device controls the output information that related to the sea floor properties. The present study aims to get a recent mapping of the seabed texture mostly related to acoustic imagery, se...
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... general slope configuration of the seafloor inside the harbor slightly increases toward the western El-Boughaz outlet (Figs. 5 and 6). The Eastern Harbor basin is characterized by smooth slope with no abrupt depth variation. While the out- side the Harbor it is characterized by steep slope northward in front of El-Boughaz outlet. The gentle slope is observed behind the middle breakwater. Inside the harbor, the 6 m con- tour line is asymmetrically distributed at the ...
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... The seafloor scanning was done using side scan sonar (Edgetech 4200, 300/600 kHz), where both high and low frequencies were used to define the seabed with high-resolution imaging and reveal the seabed textures and the possible archaeological sites based on the acoustic backscatter strength [21][22][23]. A 12 m layback correction was applied, and the track range was 150 m for both tow-fish sides. ...
A marine geophysical survey was carried out over the ruins of the ancient Eunostos harbor, in front of the recent western harbor of Alexandria. The survey works aimed to study the seafloor and the subsurface layers over the survey area using side-scan sonar and sub-bottom profiler. It is attempted to identify the impact of nature and geo-hazards on the coast of the submerged ancient harbor. Numerous ridges, reefs and breakwaters which protected the port from the northern swells were detected on the acoustic images of the side-scan sonar. In addition to some undefined artifacts and ancient coastal scars were noticed across the seafloor. Seismic interpretations also showed series of shallow diffractions that generally intensified towards east and north. Also deformed and disturbed subsurface layers were noticed beneath the area of the submerged ancient harbor. Side-scan sonar and sub-bottom profiler findings are concordant with the descriptions of the ancient literature and succeeded to confirm the vulnerability of the ancient coastal harbor to natural disasters during the past times.
... A Geotiff mosaic map was then constructed by assembling geo-referenced sonar images from adjacent track lines of the high frequency dataset (600 kHz), the mosaic map showed the different seafloor textures according to the degree of backscatter strength. Different materials carry different backscatter properties, hence they appear in different color shades on the sonographs (Klaucke, 2018), where a rough, hard and prominent seafloor produces strong backscatter acoustic signals and light tone on the sono-graph, whereas a flat, soft, and concave seafloor generates weak echoes (Hamouda et al., 2021c;Hamouda et al., 2016). ...
Underwater sonar survey using Side Scan Sonar (SSS) and Single beam Echo-sounder (SBES) was used for the investigation of the old Nubian archaeological villages buried within the bottom topography of Nasser Lake. The research objective involved emphasizing the efficiency of marine geophysical techniques in the detection of the submerged old Nubian Villages in Nasser Lake behind the High Dam, the study also aimed to study riverbed topography and determining the old course of the Nile River in the area. The resulted bathymetric maps showed that the two former banks of the Nile River in the study area were characterized by two distinct natures, while the shoreline has retreated with different extents starting from 250 m at the southern regions up to 3 km in the northern parts. The high-resolution sonar images of the bottom uncovered distinctive acoustic patterns according to difference in the returned backscatter strength. Submerged Nubian houses were detected along some areas of the eastern bank, which were found either standing over elevated rocky cliffs or built on multiple tiered levels. Precise target measurements were applied on the detected houses and different dimensions were obtained, which suggest that these houses were built according to the availability of suitable land to construct such dwellings.
... Moreover, the EH has a cultural significance as it includes considerable amounts of artifacts from ancient Egypt, as well as its economic and ecological importance as a fishing ground and a hub for yachting, boat building, diving, and marine recreation (Abdelsalam et al., 2017). Its valuable status is due to its definite shape, location, geological topography, and historical background (Hamouda et al., 2016). ...
The Eastern Harbour of Alexandria, on the Egyptian Mediterranean coast, is characterized by environmental complications due to different types of anthropogenic stressors associated with water dynamics inside the harbor as well as the rapid water exchange with the open sea. These conditions caused chronic eutrophication conditions, with variable levels in the long term. The present study followed daily some physicochemical parameters, nutrients, and phytoplankton biomass, for a complete year. The results indicate coincidence on the short-time scale between the nutrients, phytoplankton biomass, pH, and dissolved oxygen. Spearman’s correlation illustrated strong positive correlations between algal blooms and both pH and dissolved oxygen. The present study recorded twelve separate algal blooms, with an average of chlorophyll-a > 16.7 μg/L, confirming the continuity of high eutrophication in the Eastern Harbour. The seasonal Mann–Kendall tests showed that summer attained significant increasing trends for chlorophyll-a, silicate, nitrite, and nitrate, while winter has a significant decreasing trend for chlorophyll-a and pH.
... The calculation of the transmit and return angles for each beam with measure the elapsed time between the pulse transmit and the received of the return signals scattered or reflected from the seafloor, enables the MBES to produce depth profiles. The MBES has the ability to perform and create detailed bathymetric maps, threedimensional mapping of the seafloor, and data about terrain geo-morphology, such as the slope, or rugosity (i.e., terrain variability), [2,3]. The side-scan sonar techniques comprise two sidewayslooking transducers that transmit out two across-track wide sound beams, so the backscatter intensity of the seafloor is recorded at fixed time intervals [4]. ...
The Alamein New City is one of the newly established capital cities in Egypt. The study of the offshore extension is important to define the morpho-sedimentary seafloor features and evaluate the structure of the seafloor, sand resources, and the quantities of sediments that are responsible for beach renourishment. To achieve the purpose of the study, the marine acoustic geophysical techniques (MBES, SSS, and SBP) with video-camera attached in the ROV as a ground truth tool, were used. That has proven to be extremely powerful techniques in coastal applications.
The integration of the marine geophysical data obtained from the bathymetric, shallow seismic surveys, and the validity of these data that was confirmed by SSS backscatter sonograph, in addition, the images obtained by using the ROV, divided the study area into three main zones. The southern zone (Z1) was rugged, which coincided with sandy mounds in the area, and has gradual backscatter strength from high to moderate with the direction of the prevailing current describing the rugosity of sand ripple. This zone has characterized by the thickest layer of sediment in the study area. Whereas the middle zone (Z2) showed the highest values of rugosity due to the slope where the ridge exists and has complex backscatter strength with finer thick of sediment. The northern zone (Z3) was characterized mostly by intermediate rugosity and gradual backscatter strength from high to moderate aligned with the direction of the current, describing the rugosity of sand ripple. The northern zone has the second thickest layer of sediment.
The gentle sloping of the seafloor with the existence of the mounds and the submerged ridge are allowing the waves to break and scatter their energy provide natural protection for the beaches of Alamein New City.
... The bathymetric survey was applied for mapping the seafloor topography and determining the borders of possible archaeological sites [21,22]. A side scan sonar survey was carried out to provide clear images for the seabed textures and detect the exposed archaeological artifacts on the seafloor [23][24][25]. A seismic profiling survey has been used to trace the subsurface discontinuities, detect the semi-buried archaeological relics, also to study the changes of the coastal geomorphology [26][27][28], ROV video camera and grab sampler have been used for ground-truthing. ...
... The mosaic map of the stacked side scan sonar images ( Figure 5) defined the recent seafloor acoustic pattern of the study area according to variation in the backscatter intensity [22,25]. Generally, different forms of backscattered intensities were detected in the study area, the first form was characterized by a bright appearance due to the high backscatter intensity which defined the submerged archaeological remains, the outcropping reefs, and the coarse-grained sediments (Table 1). ...
... Different features were captured ( Figure 6) on the study area around the sampling locations, where outcropping reef area (Figure 6a (Table 1) were compared with the backscattered sonographs ( Figure 5) and ROV dives images ( Figure 6). Sediment types were classified on the mosaic map of the side scan sonar [25], where the poorly sorted coarse and mediumgrained sands were represented by bright color tones on the sonographs, and appeared in the form of ripple marks which mainly located in high silting areas [34] especially around the submerged breakwaters and the outcropping reefs. While the dark color tones were represented by the moderately sorted fine-grained sediments that widely spread in the north-western and north-eastern parts of the study area. ...
Marine geophysical surveys were carried out at the underwater site in the south-western sector of the Eastern Harbor of Alexandria, opposite to the Egyptian Sea Scout Club. Survey works aimed to detect and study the surface and subsurface geomorphological changes caused by historic sea-level rise and natural hazards, by integrating the results of high-resolution geophysical mapping for the seafloor textures and the subsurface layers with previously published core data and sea-level records, the survey works employed echo-sounder, side scan sonar, and sub-bottom profiler. Acoustic data were ground-truthed using an ROV camera and sediment grab sampler. Results of bathymetric mapping and sonar imaging outlined two breakwaters and quay corresponding to a submerged ancient port; also, sediment types were classified according to variation in the magnitude of the backscattered intensities. Interpretation of sub-bottom profiles illustrated the depositional sequence of the topmost sedimentary layers where the sediment thicknesses were thickened by rates that perfectly matched with the recorded sea-level rise rate during the last two millennia, as indicated by isopach maps. Anthropogenic activities were noticed in particular outcropping areas on the sub-bottom profiles. The results explained the role of natural hazards and sea-level rise in changing the geomorphology of the coastline and seabed features.
... In past years, Considerable efforts have been employed on the remote seabed classification by using acoustic tools such as side scan sonar and sub-bottom profilers (Lee et al., 2009). Side scan sonar is a powerful system for geoarchaeological research as it can image structures elevated from the seabed and the backscatter strength of the acoustic image can provide information about seabed type (Hamouda et al., 2016) and reflects high-resolution seafloor image. While the sub-bottom profiler uses a chirp sonar to produce vertical images of the sub-bottom sediments which can detect any buried underwater heritage. ...
... While the sub-bottom profiler uses a chirp sonar to produce vertical images of the sub-bottom sediments which can detect any buried underwater heritage. For these reasons, the marine geophysical methods are frequently used today for geoarchaeological investigations to provide a precise and clear image for the underwater situation remotely (Hamouda et al., 2015;2016;Chalari et al., 2009). ...
... This period mainly represents the Byzantine and Arabic periods until the recent time (Stanley et al., 2007). The recent bathymetry (Fig. 9) showed depths ranging from 2.5 m to 7 m below the current sea-level, where the depth values varied gently from 3.5 m to 5.5 m in the western part of the port basin, while steeply sloped from 3 m to 6 m within the South-eastern part causing asymmetric distribution for depth values (Hamouda et al., 2016), this estimated topography indicated much burial for the Royal port due to the annual currents and the periodical swashing waves that sweep the port basin floor (Goiran et al., 2014). ...
Marine geophysical methods are quite valuable in geoarchaeological investigations and remote seabed classifications due to their capability to cover vast areas in a short time and reveal fine details of the seafloor and subsurface features in unexcavated sites. The present study aimed to reconstruct the depositional history of the uppermost sediment sequence of the ancient Royal port of Alexandria during different historical periods, and point out the impact of the post-glacial eustatic sea-level rises and natural hazards that took place through the last 2000 years. To resolve this riddle, seismic and geomorphologic surveys were conducted by using a sub-bottom profiler and side scan sonar respectively in integration with previous sediment core data, to extrapolate the vertical extent of the strata and monitor the recent seafloor situation. The results of this study confirmed the subsidence of the ancient port mainly as a result of sea-level rises and the 365 AD tsunami. Seismic interpretations suggested a depositional scenario through successive stages from the Royal port’s construction until its abandonment, also the detailed analyses of backscatter images showed significant variations on the seafloor geomorphology that took place through the recent years which in turns give prominence to the impact of the short-term winds and storms as well.
... However, the geology of different ages also has common characteristics and structural distributions. This is the non-temporal nature of geological data [12]. 4) Causality and non-causality of geological data This is a more in-depth explanation of geological big data. ...
In recent years, China’s earthquakes have occurred frequently, and various problems have occurred in many coal mining areas. Geological information is informatized, which helps geological researchers to study information data, analyze the geological situation, and make corresponding countermeasures. The extensive application of information technology in geological surveys will greatly improve the modernization level of geological surveys. At present, the geological survey informationization work has entered the era of big data. How to break the limitation of independent management of the geological survey database and effectively integrate and share the massive geological survey data that has been accumulated, now it has become an ardent concern and urgent for geological survey informationization workers. Hope to solve the problem. The emergence and maturity of cloud computing technology provides a feasible solution to this problem. The research purpose of this paper is based on the research of information data in geological informationization of cloud computing. This article starts with geological information data, analyzes the characteristics of geological data, explains the necessity of geological informationization, builds a cloud computing information management platform, Geological information is realized in the function, and the research and analysis of the geological information data are performed. After simulation experiments, the cloud computing geological information platform built in this paper has high accuracy, and the error is not more than 5%, which verifies the feasibility of the platform.
... Considering that the acoustic backscatter intensity depends on seafloor properties, this was characterized based on the different acoustic patterns identified, assuming that hard bottoms, such as rocky outcrops and coarse sediment result in a strong acoustic backscatter, while the softer bottoms (fine sand and mud) generate a weaker acoustic return signal (e.g. Davis et al., 1996;Collier and Brown, 2005;Hamouda et al., 2016). Moreover, height and wavelength of the bedforms identified, were also measured based on the acoustic shadows of these "objects", using the slant range to the target object (time that the signal takes to return) and the height of the side-scan above the seafloor. ...
