Volume and Rate Estimations of Sedimentation in Amirabad Port During Period 2018-2021

More than 70 percent of the Earth is covered by water, and water bodies are the main features in the globe. Hence, studies of water depth and bathymetry are of great importance. Hydrography is the most accurate method in bathymetry science to measure the seafloor surface and water depth for defense and security, development, and environmental purposes. Mainly, maritime transportation and safety rely on spatial information databases and accurate hydrography of the seafloor in ports and coastal areas as well as periodic sedimentation monitoring in ports and approaches channels. Regular sedimentation monitoring allows for sedimentation distribution mapping, precise maintenance dredging, and safe navigation in coastal zones. To determine spatial and temporal trends of sedimentation, periodic hydrography of coastal areas is in demand. Therefore, in the present study, sedimentation rates were estimated based on precise hydrographic datasets in the port basin and approaching channel of Amirabad port (one of the most important Iranian ports in the Caspian Sea) in the period 2018-2021. Using the Ceeducer Pro (a 200 kHz hydrographic survey system) in 10 separate hydrographic surveys (with 2 to 6 months intervals), the three dimensional (3D) datasets were acquired with accuracies of higher than 0.5 m. After data processing (based on different dates), the digital surface models of the seafloor were produced for every hydrographic surveying. Then, the sedimentation volumes were calculated and compared in pairs. To estimate the final volume of the sedimentation by considering the dredging operations in the study area, the amount of sedimentation transferred by the dredging processes was also calculated and added to the final volume of the sedimentation. The outcomes confirmed the average rates of annual and monthly sedimentation (m3 / m2) in the channel by 0.122m and 0.010m and in the basin by 0.160m and 0.013m, respectively. Generally, a homogeneous distribution in sedimentation was observed in the whole region. However, a pattern of the highest volume of sedimentation occurred in the entrance of the channel (in the north and northeast direction), in the south of the main basin, and the western and eastern parts of the basin. Moreover, the highest rates of sedimentation were predominantly observed in the warmer seasons in Amirabad port. According to the finding of this research, the maintenance dredging system was performed at a satisfying level, resulting in successful removal of sediment from the seabed in the study area. Besides, undertaking a maintenance dredging system at longer intervals (i.e., more than four months) might threaten the navigation safety of ships in the region. The results of this research will help private and government sectors for more accurate planning and optimal dredging of the region in the future. In addition, these datasets are reliable and accurate reference and source for the validation and evaluation of other common empirical and semi-empirical methods in estimating sedimentation rates in Amirabad port.