İstanbul Boğazı'nda yakıt kirliliği, yayılım süreci ve müdahale esasları üzerine örnek senaryo çalışması

Abstract

Gerek gelişmiş gerekse gelişmekte olan ülke sanayilerinin en büyük hammaddesi konumunda olan petrolün arz ve talep kaynakları arasında ulaştırması yüksek oranda deniz yoluyla yapılmaktadır. Deniz ulaştırmasının bu denli yoğun kullanımı, kazalar sebebiyle petrolün denizel çevreyi felaket boyutunda kirletmesi sonucunu da beraberinde getirmiştir. Dünyanın en önemli suyollarından birisi olan İstanbul Boğazı'da tarihte benzer durumlara maruz kalmıştır. Elde edilen tecrübeler ve gelişen teknoloji, deniz kirliliği ile mücadelede daha etkin yöntemlerin üretilmesini de sağlamıştır. Bu çalışmanın amacı; İstanbul Boğazı'nda oluşabilecek bir deniz kirliliğine öncelikle elde mevcut imkan kabiliyetler ile müdahalenin etkinliğini ortaya koymak, daha sonra bu etkinliği artırmaya yönelik teknik ve taktik iyileştirmelerin neler olabileceğine yönelik tavsiyelerde bulunmaktır. Bu maksatla PISCES II (Potential Incident Simulation Control and Evaluation System) yakıt yayılım modellemesi ve karar destek sistemi kullanılmıştır. Öncelikle deniz üzerine dökülen yakıtın nasıl yayılacağı ortaya konmuş, bu kapsamda en önemli etken olan yüzey akıntı haritası İstanbul Boğazı için oluşturulmuştur. Diğer etkenler, rüzgar ve hava durumu ortalamalarını da sisteme entegre etmeyi müteakip, mevsimsel bazda yakıt yayılım modelleri oluşturulmuştur. Yayılımı modellenen bu kirliliklere kamu ve özel şirketlerin ellerinde mevcut vasıtalarla müdahale edildiğinde yakıtın nasıl kontrol edilebildiği belirlenmiş, bu durum vasıtalar modifiye edildiğinde ortaya çıkan kontrol biçimi ile karşılaştırılmıştır. Özellikle müdahalede kullanılan bariyerlerin yüksekliklerinin artırılmasının yakıtın kontrolünde radikal bir fayda sağladığı ortaya çıkmıştır. Çalışma neticesinde, İstanbul Boğazı'nda yakıt kirliliği ile mücadelede bariyerlerin nasıl bir taktikle kullanılması gerektiği, yüzer vasıtaların bu yöntemlerin içerisinde kullanılma biçimleri, ilk reaksiyon süresinin önemi karşılaştırmalı istatistiklerle ortaya konmuştur. İstanbul Boğazı'nın Kuzey ve orta kesimlerinde oluşabilecek bir kirlilikte, bariyerlerin yönlendirme maksatlı ve kademeli kullanımı ile yakıtın ters akıntılı koylara yönlendirilebileceği ve buralarda gerek toplayıcılar (skimmer) gerekse karadan emici pompalar vasıtasıyla toplanabileceği ulaşılan bir diğer sonuç olmuştur. Bu kapsamda, Kuzey kesimde Keçilik ve Anadolukavağı koyları, orta kesimde ise Paşabahçe koyu ve Kandilli Kuzeyi yakıtın yönlendirilebileceği alanlar olarak öne çıkmıştır. Güney kesimlerde oluşabilecek bir kirlilikte ise, yüksek süratli Güney yönlü yüzey akıntıları sebebiyle yakıtın çok kısa sürede Marmara Denizi'ne yayıldığı, Prens Adalarının yaklaşık 5 saat içerisinde kirliliğe maruz kaldığı tespit edilmiştir. Buna yönelik olarak, İstanbul Boğazı Güney kesiminde yüzer unsurlar ve mekanik vasıtalardan oluşacak etkin bir müdahale birliğinin varlığının gerekli olduğu, yapılacak maliyet etkinlik analizi neticesinde verilecek kararla, bu birliğin, özellikle arama kurtarma maksatlı Kınalıada'da konuşlandırılabileceği teklif edilmiştir. Yapılan bu çalışmada önerilen yaklaşımların, karar verici makamların benzer çalışmalarıyla geliştirilebileceği, deniz kirliliğine müdahaleye yönelik teknik imkanların iyileştirilebileceği, kirliliğe sebep olan yakıtın ihtiyaç halinde İstanbul Boğazı'nın hangi koylarına yönlendirilebileceğine karar verilebileceği, yüzer unsurlar ile müdahale vasıtalarının konuşlanma yerlerinin gözden geçirilmesine ve acil müdahale eylem planlarının oluşturulmasına/geliştirilmesine katkı sağlayabileceği değerlendirilmektedir.

The transportation of oil, which is the biggest raw material of both the developed and developing country industries, between the supply and demand sources, is made by sea at a high rate. Such intensive use of maritime transport has brought along the result of oil pollution in the marine environment with a catastrophic extent due to accidents. In the Istanbul Strait, one of the most important waterways in the world, it was exposed to similar situations in history. For instance, in 1979 M/T Independenta and in 1994 M/T Nassia accidents had brought tens of loss of lives and environmental disaster. Experiences and developing technology have enabled more effective methods to be tackled with marine pollution. Besides the lack of effective response materials during previous oil spill calamities, today Turkey has got more effective capability. The purpose of this study; to reveal the effectiveness of the intervention to a marine pollution that may occur in the Istanbul Strait with the current available capabilities, and then to make recommendations on what technical and tactical improvements could be to increase this effectiveness. To serve the purpose of the study, PISCES II (Potential Incident Simulation Control and Evaluation System) oil spill modelling and decision support system were used. First of all surface current structure, which is the most important factor in this context, was created for the Istanbul Strait. Besides the using of PISCES current modelling feature, previous studies on surface current modelling for Istanbul Strait have been also taken into account. In addition to this, surface current data which is produced by Turkish Naval Forces Office of Navigation Hydrography and Oceanography and Republic of Turkey Ministry of Transport and Infrustructure Directorate of General of Coastal Safety has been also incorporated into the PISCES. After integrating other factors, wind and weather averages, into the system, oil spill models were created on a seasonal basis. Within 36 oil spill scenarios, it is determined how the oil can be controlled when these modelled pollutions are handled by the existing assets in the hands of public and private companies, and this situation is compared with the control mode that occurs when the assets are modified. The main idea for modifiying the assets is enhancing their capabilities. Within this frame, the maximum height of barriers has been updated from 1.6m. to 3m. and the capacity of skimmers has been raised to 200 m³/h from 50 m³/h. The fundemental tactic for northern and middle part of the Strait was using the coves for containment the spilled oil with the barriers which has been deployed in a cascade form. With diverting the oil to the coves it would be possible to collect with the skimmers. However; based on the output of the scenarios with 1.6m height of barriers, it has been observed that, barriers with this height were not able to control the oil and divert it to the coves. It has been identified that increasing the height of the barriers has a radical benefit in controlling the oil. As a result of the study, how to use the barriers in the response operation against oil pollution in the Istanbul Strait, the ways in which surface vessels are used in these operations and the importance of the first reaction time are demonstrated with comparative statistics. The excessive surface velocity of the Strait makes it necessary to intervene the oil on the sea surface as soon as possible. Depending on the increasing time, it becomes more difficult to collect the fuel, whose composition changes as a result of its interaction with the air. Time increases the toxicity of the sea area where the oil spreads and make the intervention impossible by sinking to the bottom of the sea and thus to paralyze the marine life. It takes at least 2-2.5 hours for intervention with 1000 meters barrier which is inflated by external compressors from a single point. It is considered that this period is unfavourable in waters with high current speed rate and narrow coastal areas such as the Istanbul Strait. It is of great importance for the barriers, which are the first and necessary condition of mechanical intervention to oil pollution at sea, to be prepared as independent of human intervention as possible, in order to shorten the duration of the intervention. In this context, it is considered that using the self inflatable barriers in Istanbul Strait will provide a great benefit since it will reduce the time to be ready for intervention to around 1 hour. Another result which has been reached at the end of this study is; in the pollution that may occur in the northern and middle parts of the Strait, barriers could be used in a cascade mode with diverting purpose to direct the oil to the bays, which has got reverse flow current, and the oil could be collected here either by skimmers or by suction pumps on land. In this context, Keçilik and Anadolukavağı bays in the northern part, Paşabahçe bay and north of Kandilli in the central part stand out as areas where oil can be diverted. In a pollution that may occur in the southern parts, it was determined that the oil spread to the Marmara Sea in a very short time due to the high-speed South-directional surface currents, and the Prince Islands were exposed to pollution in about 5 hours. Output of this result, altough it is possible to use the coves in the northern and middle part the Strait, for the southern part, it is mandatory to use surface vessels for deploying the barriers and skimmers in open waters. Based on current resources, 1 ERV (Emergency Response Vessel – Nene Hatun) and 1 ORV (Oil Recovery Vessel – Seyit Onbaşı) are the only main response vessels for big size of oil spills. It has been evaluated in the conclusion that, procurement of more ERV/ORV shoul be taken into account. In the light of oil spill modelling for southern part, it was proposed that the presence of an effective response unit consisting of surface vessels with mechanical assets in the southern part of the Istanbul Strait is required. And this unit could be deployed in Kınalıada, especially for search and rescue purposes, as a result of the cost-effectiveness analysis. Another result of the study was about integration of stakeholders on the foundation of decision making system. Witin this scope it has been advised that; decision makers for emergency situation in Turkey such as; Ministry of Environment and Urbanization, Ministry of Transport and Infrustructure, Directorate of General of Coastal Safety, Ministry of Interior Disaster and Emergency Management Presidecy etc. should be synchronized by way of any system such as YAKAMOS, OSCAR, PISCES etc. perpetually. Therefore, decision making system has to have real time information feeding from Turkish State Meteorological Service for weather data, Turkish Naval Forces Office of Navigation Hydrography and Oceanography and Republic of Turkey Ministry of Transport and Infrustructure Directorate of General of Coastal Safety for sea surface current flow. In this way, in cases such as marine pollution, where the response time is vital, via this decision support system, which is in effect 24/7, all stakeholders will be able to predict the location and type of intervention measures shortly after the event. The approaches proposed in this study can be developed through similar studies of decision makers and can be used for; improving technical capabilities, making decision to which bays of the Istanbul Strait could be used as a location for diverting the oil, deployment locations of response assets and contribution to the creation / development of their contingency plans.