# Satellite-Derived Bathymetry for Selected Shallow Maltee Coastal Zones
## 5 Concluding Remarks  
The main aim of this study was to combine and integrate three separate bathymetric data collection techniques including sonar, lidar, and SDB to produce high resolution bathymetric maps of the Ghajn Tuffieha and Golden Bay region. Through the use of GEE, Sentinel-2 data, and in situ data, an empirical pre-processing workflow for estimating SDB  
Figure 8: SDB maps for the month of February 2021. Figure 7: SDB maps for the month of August 2020.  
was developed. The results obtained by four different machine learning techniques were also compared. Different depth accuracies were produced by each algorithm with K* and Random Forest delivering the most accurate depth values and LR having the least accurate depth values over the entire three-month study period. This study was possible due to the use of the PowerDolphin which provided in situ bathymetric data at very shallow depths. This instrument covers a wide range of applications due to its sonar technology, which gives quick feedback on the underwater dynamics, including the topographical distribution of the seabed and fish distribution. Thus, it can be used for both scientific research as well as a tool for professional fishermen. The PowerDolphin is a relatively cheap and time-effective tool to create bathymetric maps needed for coastal management, environmental impact assessments, and seasonal sediment monitoring. Furthermore, this equipment improves the results of shallow bathymetric surveys due to its practicality and high-resolution output. With these new advances in submarine topographic mapping, it has become possible to frequently update bathymetric maps, leading in turn to several advantages. Most importantly, due to the constant anthropogenic pressures experienced by coastal zones, the evolution of such regions can be mapped to help better understand the impacts exerted on these transitional zones by human activities such as dredging and coastal amrouring and to help predict future coastal morphodynamics as a way of mitigating the same putative impacts. Furthermore, accurate, up-to-date, high-resolution bathymetric information can also be crucial for navigation and Environment Impact Assessment (EIA) processes, specifically within nautical charts, benthic mapping, risk assessments, sea-level changes, tsunami modelling, and sediment transport. The integration of SDB data in coastal management presents several benefits to coastal geomorphologists and managers. The utilisation of satellite images enables extensive coverage and can be used to record bathymetric data over vast regions, resulting in a more time-efficient data acquisition approach when compared to in situ measurements. Once the technique has been calibrated for each site, the ability to estimate bathymetric data using SDB can lead to the generation of bathymetric maps with a temporal resolution determined by the satellite revisit time, usually a few days, depending on the satellite. This can provide more up-to-date data, compared to relying solely on in situ acquisitions, which are typically more costly and less frequent in time. Additionally, previous satellite imagery can be utilised to estimate bathymetry from past time periods. The extraction of bathymetry from satellite images acquired over time can be used to comprehend temporal changes in sedimentation patterns that shape the seafloor in coastal systems. This information is particularly valuable for research on coastal erosion and sedimentation and can result in morphodynamic models that provide managers with a tool capable of predicting the dynamic evolution of coastal sediment and make informed management decisions [52; 53; 54]. Conceptualisation, A.G.; methodology, A.G.; software, G.D. formal analysis, G.D.; writing--original draft preparation, G.D.; writing--review and editing, A.G., A.D., S.D. ; visualisation, L.G. ; supervision, A.G., S.D. ; project administration, S.D., L.G. ; funding acquisition, S.D. All authors have read and agreed to the published version of the manuscript.