International Journal of Coastal, Offshore and Environmental Engineering
Volume:3 Issue: 3, Summer 2018

The Caspian Sea level has experienced frequent fluctuations resulting in shoreline advance and retreat. Therefore, studying and predicting shoreline changes in the Caspian Sea are very important. The "Bruun Rule" was presented in order to predict shoreline variation due to sea level rise. In addition, to improve the predictions of the Bruun rule, added landward sediment transport to it, leading to more desirable results. In this research, the Bruun rule and its modified form, extended for landward transport, were investigated for the Caspian Sea level fall conditions. The modified equation in this study leads to the better results, which indicates that due to sea level fall and natural storms, there would be sediment deposition toward the shoreline. In terms of water level reduction, by applying the coefficient, the root mean squared error was obtained 3.447 meters for predicting shoreline changes in comparison to its natural changes. According to the results, the lowest difference in prediction is related to the Mahmudabad coast and the highest difference in prediction is related to the Dastak coast, which are equal to 0.059 and 4.849 meters, respectively. Based on this trend for forecasting shoreline changes by applying the coefficient and not having much difference in calculating the root mean square error based on the proposed equation of Rosati et al., it is possible to use the optimized equation in this study as a prediction of shoreline changes in terms of sea level fall; This coefficient has improved the forecasting trend of coastline changes in terms of water level reduction for each of the studied areas with direct deviations of D50 and HB in the equation, and the results obtained from forecasting shoreline variations show a lower difference for each area.

The nuclear disasters in Chernobyl and Fukushima have shown that such nuclear incidents are causing serious and undesirable long-term damage to the environment and the health of living beings, including humans. So that they should be taken very seriously. Considering the importance of the subject, in this paper, the simulation of the transmission and emission of cesium 137 nuclear abandoned from the contingency incident of Bushehr Power Plant in the Persian Gulf using the CROM (Código de cRiba para evaluaciÓn de iMpacto) code has been discussed. We assumed that the incident took place on July 1, 2018, and the most dangerous and an important nucleus of the abandoned is cesium 137. The simulation results show that the Cs-137 released from the incident is moved to the west and northwest of Persian Gulf and approach the head of the Persian Gulf after fifteen days. Then driven by the discharge of the Arvandrood River to the south coast and center of the Gulf moves forward and leads to the bottom. About two months later (late August) it will leave the Strait of Hormuz and will advance the Oman Sea and the Indian Ocean. Now, if this happens on January 1, after about 30 days, cesium 137 reaches the head of the Persian Gulf, and four months later (late March) will leave the Strait of Hormuz. The results of this study can be used under the same conditions in the nuclear emergency of Bushehr Power Plant.

Increasing problems due to supplying energy demand conveyed researchers to find a solution in renewable energy resources and consequently marine engineers drew attentions towards wave energy which has the merit of higher energy density than the other resources. Oscillating Water Column (OWC) is one of the most propitious devices for capturing wave energy. Researchers have studied the device under different wave height and period conditions and they investigated various geometric parameters such as front wall draft and the chamber length. However, the effects of wave spectrum type or shape has not been investigated deeply yet. Different wave spectra have been developed for different places around the world but the focus of this study is on the two well-known spectra called JONSWAP and Pierson-Moskowitz to see how the type of the spectrum can impact on inner chamber fluctuation, pressure variation and reflection response of an offshore OWC. To achieve this goal, a 1:15 scale model of an offshore OWC was constructed in National Iranian Marine Laboratory. The results show that inner chamber free surface spectrum is affected by the type of incident wave spectrum. In another word, energy content at peak frequency was approximately 50% higher when the incident wave spectrum is of JONSWAP type. However, energy corresponding to sloshing frequency and total energy content in the chamber were almost the same for both types of the spectra. Pressure spectra inside the chamber showed a similar trend as free surface elevation. Although there was a little difference in reflection response of an OWC influenced by the type of spectra, this discrepancy was more pronounced in high frequency waves.

Safety in marine operations primarily depends on forward-planning and people being aware of their surroundings and managing the presence of others in the same arena at the same time. Marine operations must contend with challenging environments and hazards that require greater domain awareness; especially when many operators from different organisations are working in the same area. Being aware of what is going on around you in a marine domain, is termed Marine Domain Awareness (MDA), which involves the perception and understanding of environmental factors, their meaning and effects, and foreseeing their likely status and impact in the near future.  This paper applies Situational Awareness (SA) concepts to the safety of marine operations and proposes a model for developing an information exchange system to enhance marine operational safety. The proposed model enhances MDA and can help in developing procedures and training programs to promote domain awareness.

More realistic simulation of hazards caused by Tropical Cyclones (TCs) requires knowledge of the mechanisms that formulate tropical cyclone. Here, sensitivity of an idealized framework has been tested to investigate role of two external parameters in vertical entropy flux. The first parameter controls the ratio of width of eyewall and downdraft regions to radius of maximum wind and the second parameter controls radial decay of wind velocity between two regions. This numerical model used conservation principles, assumed axi-symmetry and steadiness to model TC vortex, and let ventilation be occurred via the path-ways of downdrafts outside eyewall and eddy fluxes directly into eyewall. To test this framework, Tropical Cyclone Haiyan (TCH, formed over the Western part of Pacific Ocean on 3 November 2013) has been selected. Two kinds of datasets including Joint Typhoon Warning Centers (JTWC) Best Track data of Japan Meteorology Agency and Global Forecast System Analysis (GFS-ANL) data have been used. The model has been run for 60 different configurations, based on change of the two external parameters and size of two random do-mains. The sensitivity of the modeled convective entropy flux to the applied changes has been examined via two different aspects of investigation. In the first aspect, terms of the reference equation of convective entropy flux have been considered and their responses to the changes have been studies. While in the second aspect, values of the convective entropy flux at TCH peak activity time (PAT), before and after that have been inspected. Results, obtained from the first aspect, obviously indicate that the increase of the first external parameter increases the all terms of the referred equation, while increase of the second external parameter influenced the terms differently. Also enlarging the domains’ size does not impress the results similarly. Outcomes of the second aspect reveal that the implemented changes non-uniformly impact the values of the modeled convective entropy flux in the three considered times.

This paper examines the variation of wave characteristics and net Longshore Sediment Transport (LST) rates along the Ramin Harbor, southeast coast of Iran. Potential LST rates were determined based on three empirical relationships, namely, CERC, Kamphuis and Komar and using transformed hindcast offshore waves from 1985 to 2006. Detailed analysis of 22-year deep water wave information for the region indicates considerable seasonal variations for the wave conditions, with high energy monsoon waves being generated in Indian Ocean and Arabian Sea from southern direction during monsoon season. Moreover, the long period swell waves originated from Indian Ocean usually approach the coast from southeast to south. Further, the variable sea waves characterized by shorter-period, normally spreading from west to southwest, are superimposed on the basis swell during non-monsoon season. In order to assess the reliability and accuracy of the predicted magnitudes for LST rates, the achieved results were compared with the field data, with the Kamphuis equation being found to give acceptable estimation for the potential LST rate. Finally, through morphological analyze of the adjacent shorelines and coastal region, a reasonable agreement was established for the LST direction.