Emre N. Otay

Modeling and analysis of vessel casualties resulting from tanker traffic through narrow waterways

This paper presents a stochastic model to examine ship casualties resulting from tanker traffic through narrow waterways. A state-space model is developed to represent the waterway and the location of vessels at a given time. The distribution of surface current at a given location of the waterway, depending on channel geometry, bottom topography, boundary conditions, and wind distribution, is determined. This is followed by determination of the distribution of the angular drift for a vessel traveling at a given location of a waterway. Lastly, the drift probabilities and random arrival of vessels are incorporated into a Markov chain model. Risk measures are obtained by analyzing the time-dependent and steady-state probabilities of the Markov chain. Results show that the expected number of casualties is proportional to the square of the tanker arrival rate. The methodology is presented on an experimental model of a hypothetical narrow waterway.

A Navigation Safety Support Model for the Strait of Istanbul

In this study, a real time maritime traffic support model is developed for safe navigation in the Strait of Istanbul, also known as the Bosporus. The present model simulates vessel trajectories corresponding to possible headings, using channel geometry, counter traffic, and surface currents as input. A new MATLAB code is developed for the simulation and the Marine GNC Toolbox (Fossen and Perez, 2004) is used for the vessel hydrodynamics and the auto-pilot model. After computing the trajectory tree of the vessel by forward-mapping its position distribution with respect to the initial position vector, the casualty probabilities of each trajectory are found. Within certain restrictions on vessel geometry, the proposed model predicts the safest possible intended course for the transit vessels based on the navigational parameters including position, speed, and course of the vessel. The model is tested for the Strait of Istanbul for validation. Without loss of generality, the model can be used for any narrow channel with a vessel traffic system providing the necessary input. 1. I N T R O D U C T I O N. In this study a real time dynamic navigation support model is developed for navigating vessels in narrow channels. The model is tested on the Strait of Istanbul (Bosporus) using the Strait geometry, counter traffic and the surface currents as the disturbances. The surface currents are treated as a random variable whose magnitude is normally distributed. The vessel trajectories are projected with respect to the discrete current magnitudes. By using a set of possible intended courses, probability distribution of current magnitudes and initial vessel positions, corresponding vessel trajectories are simulated. The grounding and collision probabilities are calculated for each trajectory. Finally, the trajectory with the lowest corresponding casualty probability is proposed as the safest for the navigating vessel. In the case of more than one safe manoeuvre, tie-breaker criteria are employed to select the best among the possible intended headings. After the model validation, some case studies are performed and the model successfully proposes a safe route in every case. Full Strait simulations are also

INFLUENCE OF NEARSHORE BERM ON BEACH NOURISHMENT

A study of alternatives including a shoreline evolution numerical modelization has been carried out in order to both diagnose the erosion problem at the beaches located between Cambrils Harbour and Pixerota delta (Tarragona, Spain) and select nourishment alternatives.

Maritime Traffic Analysis of the Strait of Istanbul based on AIS data

The Strait of Istanbul is one of the most congested and risky waterways in the world. Navigation patterns have been investigated using Automatic Indentification System (AIS) data collected over a long period. 1·5 billion AIS messages, gathered over a year from 309,000 moving vessels in the Strait were stored in a Structured Query Language (SQL) database. Grid-based analysis is used to track the time, number, position, type, dimension, heading, speed and course over ground of ships. Local traffic, whose effect on maritime risk has often been neglected, is found to dominate transit traffic by a ratio of eight to one. Vessel distributions indicate that the most common lengths of vessels are 100 m and 170 m. Draught analysis shows a net transfer of goods from north to south. Southbound vessels are more likely to exceed the enforced speed limit due to predominant currents. Courses indicate that the local traffic strongly affects navigation patterns, especially at sectors with sharp turns. All these results help to understand the navigation patterns of ships and give the necessary input to assist in predicting maritime risk.

Morphological evolution of the southwestern Black Sea coast of Turkey since the early 2000s: medium- vs. short-term changes

Coastal zones are in a state of continual flux worldwide, due in part to seasonal factors and in part to influences operating over longer periods of time. Discerning changes on different timescales remains a challenge. This study compares shoreline position and nearshore bathymetry over a time interval of 16 years in order to determine the extent of medium-term changes in comparison with short-term changes along the southwestern Black Sea coast of Turkey near Kilyos. For this purpose the results of surveys completed in 2001 and 2002 are compared with data collected in December 2015, September 2016, and March 2017 at the same location using a differential global positioning system (DGPS) in real-time kinematic (RTK) configuration combined with echo-sounder profiling. Average shoreline recession over the 16-year period (medium term) has been estimated at 3–4 cm/year as opposed to an average of 9.5 m in the 12-month period from June 2001 to June 2002 (short term). The medium-term nearshore sediment loss has been approx. 100–125 m3/m shoreline since the early 2000s. Over the same period a prominent offshore bar has moved seaward at a maximum rate of 1 m/year since 2002. Considering the large discrepancy in the shoreline recession rates recorded in the short and medium term, this aspect must be taken into account in any integrated coastal zone management strategy.