Side-scan Sonar Research Articles

A Multidisciplinary Approach for A Better Knowledge of the Benthic Habitat and Community Distribution in the Central and Western English Channel

About 80% of the seabed of the English Channel (EC) is covered by coarse sediment, from coarse sand to pebbles. Quantitative data on the benthic macrofauna in these types of sediment remains are rare due to the difficulty of using grab corers in such hard substrates. The deepest central part of the EC (45–101 m depth) was prospected during two VIDEOCHARM surveys in June 2010 and June 2011 to increase knowledge of such sublittoral coarse sediment benthic habitats. Sampling focussed on a longitudinal transect in the deepest part of the EC (13 boxes), extending from the western approach to the Greenwich meridian. Both indirect (side scan sonar, Remote Operated Vehicule) and direct (grab sampling with benthos determination, and grain-size analyses) approaches were used and combined, permitting description of the benthic habitats and communities using seven methods. Five benthic EUNIS habitats (European Nature Information System) were reported: MC3215, MD3211, MC4, MC3212 and MC4215, of which two extended main habitats (MC3211 and M23212) corresponded to an eastern/western gradient from sandy gravel to sandy gravel and pebbles sediment. Three other spatially discrete habitats were associated with poor coarse sand and gravel habitats as well as sandy gravel and pebbles with the presence of the brittle star Ophiothrix fragilis. Taxonomic richness of both extended habitats was on the same order of magnitude as the coarse sand habitat reported elsewhere in the EC, whilst the abundances were among the lowest in deeper areas with low nutrient input and low primary production. The epifauna appeared relatively homogenous in this type of sediment at the scale of the sampling area and was not determined to assign a EUNIS habitat/class. ROV footage illustrated the presence of large epifauna and provided valuable information to ground truth in other sampling methods such as side scan sonar mosaic. Grab photos showing surface sediment was relevant to determine the sediment type, whilst granulometric analyses gave additional information on fine particles content (typically very low).

Morpho-stratigraphic evolution of a tectonically controlled canyon-channel system in the Gioia Basin (Southern Tyrrhenian Sea)

The Gioia-Mesima Canyon-Channel System (GMS) incises the northern part of the Gioia Basin, a post-Tortonian intra-slope basin located along the south-eastern Tyrrhenian margin. Integration of multibeam, side scan sonar and seismic reflection data allowed to reconstruct the morpho-stratigraphic evolution of the GMS and the main factors controlling its development and maintenance. The GMS drains the entire continental margin and displays a complex morphology consisting in two main courses: the Gioia-Petrace Canyon and the Mesima Canyon-Channel. These courses run parallel to each other, changing from narrow straight to meandering geometry until they merge into a single, relatively straight lower reach, which debouches in the Stromboli Valley. Seismic reflection profiles and morphometric analysis highlight a strong tectonic control on GMS location and morphology throughout its course. At large scale, tectonic structures cross cutting the GMS caused both the formation of a mini-basin in the upper slope and a larger confined sub-basin downslope. These features promote abrupt changes in slope gradients that in turn are reflected on the plan-view morphology and stratigraphic architecture (seismic facies and sediment depocenters) of the GMS. Particularly, the progressive infilling of the confined sub-basin caused changes in the GMS base level, determining a polyphased evolution of the system encompassing repeated erosional and depositional events. The complete infill of the sub-basin promoted a by-pass of turbiditic flows in the lower slope, leading to the development of the lower reach of the GMS and its connection with the Stromboli Valley. This connection favoured a base level lowering of the GMS, causing its rejuvenation by retrogressive upslope erosion. This stage was recorded only in the shelf-indenting Gioia Canyon, characterized by a narrow and entrenched course, with irregular longitudinal profile and multiple knickpoints. Based on these results, we propose an evolutionary architectural model of the GMS to point out how erosional and depositional processes of channel/canyon system in a tectonically controlled margin can rapidly change in space and time in relation to multiple factors.

Side-Scan Sonar Image Segmentation Based on Multi-Channel CNN for AUV Navigation.

The AUV (Autonomous Underwater Vehicle) navigation process relies on the interaction of a variety of sensors. The side-scan sonar can collect underwater images and obtain semantic underwater environment information after processing, which will help improve the ability of AUV autonomous navigation. However, there is no practical method to utilize the semantic information of side scan sonar image. A new convolutional neural network model is proposed to solve this problem in this paper. The model is a standard codec structure, which extracts multi-channel features from the input image and then fuses them to reduce parameters and strengthen the weight of feature channels. Then, a larger convolution kernel is used to extract the features of large-scale sonar images more effectively. Finally, a parallel compensation link with a small-scale convolution kernel is added and spliced with features extracted from a large convolution kernel in the decoding part to obtain features of different scales. We use this model to conduct experiments on self-collected sonar data sets, which were uploaded on github. The experimental results show that ACC and MIoU reach 0.87 and 0.71, better than other classical small-order semantic segmentation networks. Furthermore, the 347.52 g FOLP and the number of parameters around 13 m also ensure the computing speed and portability of the network. The result can extract the semantic information of the side-scan sonar image and assist with AUV autonomous navigation and mapping.

Seagrass meadows in the Greek Seas: presence, abundance and spatial distribution

Abstract Combined use of optical (satellite imagery) and acoustic (sidescan sonar) remote sensing techniques, as well as in situ methodologies (visual census; SCUBA diving, Towed Underwater Cameras, and Remotely Operated Vehicles) was employed to map the spatial distribution of seagrass habitats in the coastal waters of the Greek territory. Seagrass meadows were recorded over approximately 70% of the Greek coastline (Eastern Ionian, Aegean and Levantine Seas), and their surface area exceeded 2749.07 km2. Posidonia oceanica is clearly the dominant seagrass species in Greek Seas, covering the vast majority of seabed at depths between the shoreline and 25–30 m (or deeper in insular areas), followed by the species Cymodocea nodosa, Zostera noltei, and Halophila stipulacea, that are not widely distributed but are locally abundant in specific areas. Habitat suitability in terms of the of the seabed that is available for the growth of seagrass meadows (i.e., the spatial extent of coastal areas between the shoreline and the isobath of 20 m) and the seawater clarity conditions are highlighted as the critical factors for the formation of well-structured and extensive meadows. The results of this study are of great importance and usefulness for the effective management and conservation of valuable marine ecosystems and are given in the form of an openly accessible shapefile.

Sidescan Only Neural Bathymetry from Large-Scale Survey.

Sidescan sonar is a small and low-cost sensor that can be mounted on most unmanned underwater vehicles (UUVs) and unmanned surface vehicles (USVs). It has the advantages of high resolution and wide coverage, which could be valuable in providing an efficient and cost-effective solution for obtaining the bathymetry when bathymetric data are unavailable. This work proposes a method of reconstructing bathymetry using only sidescan data from large-scale surveys by formulating the problem as a global optimization, where a Sinusoidal Representation Network (SIREN) is used to represent the bathymetry and the albedo and the beam profile are jointly estimated based on a Lambertian scattering model. The assessment of the proposed method is conducted by comparing the reconstructed bathymetry with the bathymetric data collected with a high-resolution multi-beam echo sounder (MBES). An error of 20 cm on the bathymetry is achieved from a large-scale survey. The proposed method proved to be an effective way to reconstruct bathymetry from sidescan sonar data when high-accuracy positioning is available. This could be of great use for applications such as surface vehicles with Global Navigation Satellite System (GNSS) to obtain high-quality bathymetry in shallow water or small autonomous underwater vehicles (AUVs) if simultaneous localization and mapping (SLAM) can be applied to correct the navigation estimate.

A System for Autonomous Seaweed Farm Inspection with an Underwater Robot.

This paper outlines challenges and opportunities in operating underwater robots (so-called AUVs) on a seaweed farm. The need is driven by an emerging aquaculture industry on the Swedish west coast where large-scale seaweed farms are being developed. In this paper, the operational challenges are described and key technologies in using autonomous systems as a core part of the operation are developed and demonstrated. The paper presents a system and methods for operating an AUV in the seaweed farm, including initial localization of the farm based on a prior estimate and dead-reckoning navigation, and the subsequent scanning of the entire farm. Critical data from sidescan sonars for algorithm development are collected from real environments at a test site in the ocean, and the results are demonstrated in a simulated seaweed farm setup.

Assessing the optimal location for Sipora wave energy power generator site placement from a geological perspective

One of the potential sources of renewable energy in the Mentawai region is ocean wave energy. The western Sumatra sea has a wave energy potential of up to 20 kW/m. The wave energy potential modeling conducted by the Marine Geological Institute (P3GL) ESDM revealed that western Mentawai waters are locations that produce annual average wave energy of around 20 kW/m. The geological survey of the seabed for power generating wave energy turbine sites using acoustic equipment including the Echosounder Odec, SBP Stratabox, and Star Fish Side Scan Sonar. The mapping of the seabed allows for the identification of undersea morphology, slopes, structural elements, and seafloor objects. Ocean depth sounding and bottom surface imaging are used in this research to determine the placement of the turbine site from the wave energy generator connection grid. The existence of underwater corals and fluvial plain units, continental shelf with shallow seabed and a gentle slope with an average depth of 30 meters was recognized as the most important factor in determining the site's location in this research. Based on the weighting and scoring results, optimal locations for potential power plant sites are in coastal areas located in offshore near Batu putih coast.

Informative Multiview Planning for Underwater Sensors

Many modern imaging sensors must obtain multiple looks or “views” of a target at different orientations to automatically classify it with high confidence. Therefore, when tasked with classifying many targets, a mobile sensor may need to travel a long distance to change its position and orientation relative to every target, resulting in costly and time-consuming operations. This article presents a novel and general approach, referred to as informative multiview planning (IMVP) that simultaneously determines the most informative sequence of views and the shortest path between them. The approach is demonstrated on an underwater multitarget classification problem in which a sidescan sonar installed on an unmanned underwater vehicle must classify all targets in minimum time. Simulation and experimental results show that IMVP can achieve the same, or better, classification performance in half the time of existing multiview path planning methods. Also, by determining the most informative views and the shortest path between them, IMVP significantly improves classification efficiency, classification confidence level, as well as performance robustness.

주파수 응답 함수를 적용한 소형 무인 잠수정 진동 특성에 관한 연구

This paper presents the study about the frequency response function of small unmanned underwater vehicle (UUV) based on the experiment in air condition. As the UUV has been widely used in scientific, military, and commercial areas, it is also important to gather the information in an underwater environment for autonomous operation. Only sonar systems that use sound waves can be used in underwater environments due to the strong attenuation of electromagnetic waves in them. Since the vibration of UUV is usually transferred through the inner space of UUV body, the transferred vibration can affect the performance of various sonar systems that equip the UUV such as side-scan sonar or forward-looking sonar. Therefore, it necessary to predict the effect of the transferred vibration of the UUV for high level autonomous operation. In this paper, an experimental study was carried out to analyze a vibration feature of a small real UUV in the air condition using frequency response function and the experimental results are presented.

PAVOT: FIRST DISCOVERED SUNKEN SHIP FROM 1ST WORLD WAR AT ISKENDERUN BAY

Iskenderun Bay was an important role in providing logistic support to the occupiying that invaded the Anatolian lands during the First World War. Five minesweepers of the allied powers had come to the İskenderun Bay in order to the clear the sea bad from torpedos. One of them, PAVOT which was bought by the French Navy in 1916, struck a mine and sank. Pavot's coordinates taken from the ship with side scan sonar and GPS are 36o 35, 982' N – 36o 07, 843' E (DMS 36o 35' 59'' N; 36o 07' 47'' E). Moreover, the angle with the Iskenderun Lighthouse is 289o. The distance to it is 1.41 nautical miles (2.46 km) the nearest point to the shore is 0.95 nautical miles (1.95 km). Diving to the sunken ship has been carried out by three instructor divers teaching at the Iskenderun Technical University (İSTE) Marine Vocational School Underwater Technologies Program. The ship named R/V İSTE1 belonging to İSTE was used during the divings. The divings have been performed with SCUBA equipments. The Pavot sunken ship was identified for the first time in the Iskenderun Bay with this study.

Analysis of Engineering and Geological Conditions of International Submarine Optical Fiber Cable Routing in the East China Sea Section

The East China Sea section of the Chinese international submarine optical fiber cable generally starts from the Shanghai coast, crosses the East China Sea shelf and continental slope to the east, and intersects with the international optical fiber cable system in Okinawa Trough. In this paper, the regional tectonic, seismic, and other environmental conditions of the East China Sea section of the international submarine optical cable are briefly described based on the previous data. Additionally, the geological engineering conditions of the international optical cable routing in the East China Sea area will be analyzed based on the field investigation data such as multibeam, side-scan sonar, shallow stratigraphic profile, sediment sampling, and cone penetration test (CPT). It is found that the main geological factors in the East China Sea shelf area are submarine scouring, sandwave, shallow gas, and hard seabed; in the land slope area are steep slope, submarine valley, rock, landslide, and shallow gas (pockmark); and in the Okinawa Trough area are gully, sea mound/seamount, rock, shallow gas, fault, and hard strata outcrop. This paper briefly analyzes the impact of each geological disaster factor on the submarine cable project and proposes solutions for providing essential information and some scientific basis for designing, constructing, operating, and maintaining international submarine optical fiber cables in the East China Sea area.

Underwater Macroplastic Detection Using Imaging Sonars

Plastic pollution in the ocean occurs mainly via riverine transport. In rivers, plastic is pervasive in sediments and in the water column. Monitoring of floating plastics in rivers is time consuming as it is usually collected using nets and classified by hand, or counted and classified visually. To make plastic detection in the water column more time- and cost-efficient, there is a need to explore remote sensing options. Here we present the results of two semi-controlled pilot tests in standing water using two imaging sonar technologies: an Adaptive Resolution Imaging Sonar (ARIS) sonar and a low-cost side-scan sonar (SSS). Additionally, the ARIS sonar was tested in flowing water at a sheltered shore channel behind a longitudinal training dam in the river Waal, Netherlands. Both technologies were able to detect 100% of the macroplastics tested in standing water. The ARIS sonar provided higher resolution images of the targets tested due to its high operation frequency detecting macroplastics down to a size of 1 cm2. The ARIS sonar detected macroplastics in the field, however, the detection decreased to 67% in flowing water. This sonar was limited to the 2D horizontal position of targets. The SSS is a low-cost option for monitoring of plastics and is integrated with CHIRP sonar technology that combines side and down imaging providing the 3D position of targets. For future monitoring, an ARIS sonar in motion or two ARIS sonars used simultaneously may provide the necessary 3D spatial information of plastic targets.

Simulation of an electro-hydraulic circuit for ALARS

In this paper, the authors present hydraulic and electro-hydraulic simulations of the circuits needed for ALARS (Automated Launch and Recovery System). In fact, the ALARS is used to launch the side-scan sonar into the sea. First hydraulic circuit has the following devices: tank, filter, fixed displacement pump, check valve, 4/3- way valve with two buttons, throttle valve, pressure relief valve and hand lever valve, tanks reservoir, filter and double acting cylinder (Cy 1-1). Afterwards, second hydraulic circuit has the following devices: pump unit, 4/2-way hand lever valve, throttle valve and two double acting cylinders (Cy 2-1 and Cy 2-2). Forward, the first electro-hydraulic circuit has the following devices: lamp, valve solenoid, pressure relief valve, double acting cylinder (Cy 3-1), throttle valve, 4/2-way solenoid valve, fixed displacement pump, valve displacement pump and tanks. Ultimately, the second electro-hydraulic circuit has the following devices: tank, pump unit, pressure relief valve, double acting cylinders (Cy 4-1 and Cy 4-2), relay, valve solenoid, and lamp.

The Status of Posidonia oceanica at Tremiti Islands Marine Protected Area (Adriatic Sea).

Simple SummaryThe seagrass Posidonia oceanica is the most important marine phanerogam of the Mediterranean Sea due to its meadows’ complexity, persistence, and extension. These habitats provide a suite of ecosystem goods and services, being of primary importance in marine conservation. Despite their central role in the coastal ecology, P. oceanica meadows are undergoing overall deterioration and fragmentation in the basin mostly due to anthropogenic impacts at local to global scales. In the last decades, several management measures have been proposed aiming to improve the meadow health conditions, while the periodic monitoring of P. oceanica meadows allows for verifying their effectiveness. Here, we report the results of the monitoring of P. oceanica at Tremiti Islands Marine Protected Area (Adriatic Sea, Italy) carried out in 2003, 2015, and 2020. A general worsening was observed, particularly enhanced by direct anthropogenic impacts mostly related to anchoring practices, as well as by a certain level of sedimentation possibly deriving from coastal development. However, the identification of these impacts and the correct management of human activities to mitigate them produced positive results in a relatively short time span.Posidonia oceanica meadows are Mediterranean coastal habitats of great conservation importance. This study is focused on a meadow located at Tremiti Islands Marine Protected Area (Adriatic Sea, Italy), which was monitored in 2003, 2015, and 2020 to evaluate its health state over time in relation to coastal human activities, which have been highly affecting this MPA for the last 20 years. To assess any change in the physiognomy of the meadow, rhizome density, percentage coverage, and lower limit progressions and/or regression over time were evaluated by scuba diving, while the distribution and extension of the meadow were assessed through habitat mapping using a side-scan sonar. Moreover, phenological and lepidochronological analyses were performed on the collected rhizomes to assess the leaf area index (LAI, m2m−2) and the rhizome age (lepidochronological years). Our study showed a general deterioration of P. oceanica meadow from 2003 to 2020, with a significant reduction of its absolute and relative rhizome density and LAI at almost all sampling stations, absence of renovation of the meadow, and lower limit regression and overall worsening of the main conservation status indicators. However, appropriate management actions, such as the establishment of mooring buoy fields, supported the improvement of the P. oceanica status at the local scale with a significant increase in density and LAI and the presence of active stolonization processes, suggesting that mitigation actions can play a crucial role in the conservation of this habitat. On the contrary, local anthropogenic impacts, especially anchoring and coastal development, markedly affect the resilience of P. oceanica meadows to global stressors, such as climate change.

UXO Assessment on the Romanian Black Sea Coast

This paper aims to provide the reader with the results of the Unexploded Ordnance (UXO) survey of the defensive historical naval minefields launched by the Romanian and German Navies on the Romanian Black Sea coast, during the Second World War. This UXO survey was carried out between 2015-2018 by the Romanian Navy’s hydrographic ship “Commander Alexandru Cătuneanu” and Romanian Mine Warfare Data Center, using towed side-scan sonar technology and oceanographic observations. After explaining the materials and methodology, the results are presented and discussed: mosaics of the minefields, side-scan images of UXO contacts, side-scan images of the wrecks that were sunk in the minefields and some visible natural geological features of the seafloor. It was concluded that most of the objects discovered are sinkers, wreck debris or parts of chains, which does not represent a danger to navigation.

Rapid Assessment Survey Using Side Scan Sonar: International Obligations and Role of Hydrography in Ensuring Safety of Navigation – Case Study of the Aftermath of MV X- Press Pearl Incident

The International Maritime Organization (IMO) was established in 1948 as a specialized agency of the United Nations (UN). They provide international standards on the safety, security, and environmental performance of ships involved in international trade. International shipping is effective only if the regulations and standards are agreed upon, adopted and implemented on an international basis. IMO Instruments Implementation Code (III code) is one such attempt where it looks into states’ capacities of implementing obligations. Here, we present in what way the hydrographic rapid assessment survey support the above obligation of ensuring safety of navigation for ships visiting Colombo Port in the aftermath of MV X-Press Pearl accident in West coast of Sri Lanka. The comprehensive Side Scan Sonar (SSS) survey that was conducted over the area found some of the fallen containers and debris lying on the seabed. Due to the extent and the nature of the incident, and due to the ocean current dynamics, a larger area had to be investigated and a number of relevant agencies in the maritime field were involved. As a country, the responsible authorities have taken timely actions to disseminate the safety related information to the mariners and subsequent measures were taken to update the relevant nautical charts by conducting necessary systematic hydrographic surveys to fulfill the obligations of the International Convention for the Safety of Life at Sea ( SOLAS) of IMO.

Investigating the correspondence of acoustic amplitudes with penetrometer profiles in bottom sediments of a shallow coastal lake: Louisiana

This study correlates side-scan sonar and CHIRP subbottom acoustic amplitudes with cone penetrometer data to expand the limited understanding of the geotechnical properties of sediments in coastal Louisiana's bays. Using cone penetrometer profiles is a methodology for characterizing the sediment properties of the water bottoms and shallow subsurface sediments of coastal water bodies. This study is the first in Louisiana to investigate the potential value of applying this methodology combined with both side-scan sonar images and CHIRP subbottom amplitude analysis to the sediment characteristics of coastal bay bottoms. Penetrometer results demonstrate the sediment-related variability in the shallow subsurface of Sister Lake, in south-central Louisiana, with the majority of tip resistance values under 98.0 kPa (1.0 kg/cm2), with peaks to approximately 686.5 kPa (7.0 kg/cm2). An amplitude analysis technique identified different reflectance regions within Sister Lake from the CHIRP subbottom profile data. Acoustic reflectance is related to sediment “hardness” or resistance. The side-scan sonar and CHIRP amplitude reflectivity results are compared to penetrometer data that quantifies geotechnical properties of surface and near-surface sediments. Insight into the relative hardness of the coastal lake bottom and shallow subsurface deposits is gained through this technique, useful for: (a) identifying areas of erosion (previously buried and consolidated sediments) versus recent deposition; (b) delineating hard bottom areas suitable for cultch plants for state oyster seed grounds; and (c) informing the parameterization, calibration, and validation of numerical models used for predicting the response of coastal systems to future environmental conditions and restoration efforts. Results indicate three distinct penetrometer, side-scan and CHIRP signatures that identify different water bottom and substrate areas within Sister Lake including: 1) clay to organic clay; 2) silt to sand; and 3) oyster cultch and scattered shell. Although amplitude levels of high-resolution acoustic data do not directly quantify the geotechnical properties of bottom sediments, results indicate a close relationship. The analysis procedures developed in this study can be applied in other dynamic aquatic coastal environments by “calibrating” the use of synoptic acoustic methods for large spatial-scale water bottom characterization.

A prior information‐based coverage path planner for underwater search and rescue using autonomous underwater vehicle (AUV) with side‐scan sonar

The coverage path planning (CPP) technique attracts growing interest in studies on underwater search and rescue (SAR) conducted with an autonomous underwater vehicle (AUV) equipped with a side-scan sonar (SSS). In SAR missions, prior information is crucial. Aiming at the underwater SAR mission with prior information, a new coverage path planner (SAR-A*) is proposed. The ultimate goal is to generate a feasible path for completely covering the task area and preferentially visiting more valuable cells with fewer turns. First, the whole task area is decomposed into hexagon cells as waypoints to be visited for complete coverage. Second, the probability of discovering the target is obtained according to the target presence probability and the SSS detection ability. Under the assumption of prior target information, the target presence probability is modelled as a two-dimension Gaussian distribution based on predicted target locations or trajectories. Then, an optimal next-waypoint selection process is formulated as a multi-objective decision-making problem and solved by the weighted metric method. Finally, simulation and experimental results demonstrate that the generated path can improve the cumulative probability of discovering the target with fewer turns.

Mapping of Seafloor and Delineating Coral Reefs of Southern Iraq/Northwest Arabian Gulf by Side Scan Sonar Technique

High-resolution Side Scan Sonar data, under-water observation (video and photograph) and bottom samples (rocks and sediments) were integrated to map the seafloor of the Palinurus shoal which is one of the submerged shoal site in the Iraqi territorial marine, Northwest region of the Arabian Gulf. The Side Scan Sonar field survey was carried out along with eight parallel profile extending in SE-NW direction, at a length of 2.8 km for each line. Four backscatter patterns were mapped within the study area. The pattern reflects various seafloor lithology. The average depth of sea bottom was determined at 7 - 10 m. Coral Reefs were mainly found at two parts of the shoal site in the formed assemblages and sporadic in central and northern parts of the site respectively. These coral take different shapes, sizes and colors. Also, they are live in some places and dead in others.

Sub-Bottom Profiler and Side Scan Sonar investigations, with the assistance of hydrochemical and isotopic analysis of Sawa Lake, Al-Muthana Governorate, Southern Iraq

A marine geophysical survey are including Sub Bottom Profilers and Side Scan Sonar integrating with under-water imagery, as well as hydrochemical and isotopic investigations have been carried out for Sawa Lake, one of the unique, shallow and closed water body in Iraq. The results showed that the depth of the Lake is shallow, ranged between 1 m in areas near the edges of the Lake and 2 m in the Lake center. The Recharge site has been detected exactly (this is a first recording (Nov. 2012)), as a hole. It has a longitudinal an axis of 50 m with NW-SE tren, which resembles the trending of the longitudinal axis of the Lake and Abu-Jir fault trending. The maximum width of this hole ranging from 23.0-29.5 m. The hole depth about 20 m, but may be greater then, because the emergence of a high proportion of noise in the geophysical sections. The Lake bottom is homogeneity and does not has any diacritical features. Also, the results showed discontinuous layers on either side of the hole due to the existance a number of caves under the bottom of the Lake extends into several meters with different dimensions and forms. Hydrochemical analysis of the water samples collected from different depths inside the hole by scientific diving with specefic equibments and the result showed that the water is NaCl type, with domination of Mg and Cl over Ca and SO4. The Stiff diagram, detected that very high TDS arising mainly from sodium and chloride, it is mostly typical marine water. Values of δ18O and δ2H in water samples of Sawa Lake, when plotted along the global meteoric water line shows that the three collected water samples from the lake, which have a similar isotopic composition, indicating that all of them are receiving water from the same flow zones, with diffuse recharge type. Also, the isotopic parameter showed that the Sawa lake water suffering from strong evaporation.