Marine Oil Spill Numerical Modeling And Risk Assessment For Guinean Conakry Waters

As the largest bay in Africa, the Gulf of Guinea is in West Africa, where oil resource is rich in the coastal, with more than ten countries and neighboring regions. It has become the one of the most important oil-producing areas in the world, the ascertained oil reserves are more than80billion barrels, accounting for about10%of the world's reserves. They mainly exported to Europe, North America and other western countries, as well as China, Japan, India, and other Asian countries. The water near Conakry, the capital of Guinea is the only way that the oil in Africa to North America and Europe is been shipped and there is a major risk of ships oil spill.This research uses numerical model that allows for qualitative and quantitative assessment of damage on marine environmental resources caused by spilled oil and appropriate responses. The research method is based on an important exploitation of library resources about oil spill and Guinean marine environment, also an analysis state-of-art of research and application of marine environment risks damage assessment techniques and methods; dissertation framework assessment environment resources damages resulting from marine oil spill by using numerical modeling, that focus on development and application of numerical assessment model from system and software. It has important theoretical significance and application value for developing the decision power of emergency command in Guinea and reducing ecological damage and economic loss as far as possible.The main research content and results in this paper are summarized as follows:1. The international research status and development trend of oil spill model and simulation system are comprehensive summarized. The recent statistics of mainly oil spill accidents in the world and African waters are analyzed that with the growth of oil production and traffic volume in African especially the Gulf of Guinea, the risk of significant platform and ship oil spill accident in the offshore area of Gulf of Guinea is existing while the Western African countries have not yet established oil spill emergency response system and the emergency power is very weak.2. The maritime simulation system of oil spill behavior is researched aiming at the hydrological and environmental characteristics of the waters in Conakry, Guinea, including Hydrodynamic Model on the basis of the characteristic of estuary wetland in coastal sea areas of Guinea; oil weathering model used for simulating the fate of oil spill such as evaporation, emulsion, dissolution, scatter and the qualitative change of density and viscosity according to the physical and chemical characteristics of crude oil in Africa. Oil drifting trajectory model is used for simulating the trajectory and diffusion dynamic of oil spillage in the marine environment based on the theory of oil particles and Random Walk Procedures. The dynamic of diffusion and distribution of concentration of soluble dispersive petroleum hydrocarbons underwater is calculated through the switching technique of "particle-concentration". The development systems are applying to simulate and verify the different oil spill cases occurred in Conakry, Guinea waters.3. Stochastic simulation statistic method is proposed to make the impact assessment for pollution risk of oil spill based on the feature of uncertainty of the occurrence time of oil spillage. The300different accident scenarios of oil spill accidents in the waters of Conakry, Guinea in recent3years is calculated by drifting trajectory simulation, each time is uncertain, randomly selected in any time from the past3years. The corresponding wind data is taking from nearly3years of hourly wind direction, historical monitoring data of wind speed, field data is obtained from the results of ocean dynamic simulation. Every accident simulation is calculated and recorded the data of drift last time and thickness of oil film in every gridding, the information of pollution probability that oil spill working on environment sensitive target and shoreline as well as the fastest effect time and oil film thickness distribution will got in the final statistics. Comparing with typical scenarios simulation method using assumed meteorological data, evaluation results are more reasonable and reliable that hazards risk that oil spill might cause on the sensitive resources around the environment can be evaluated more comprehensive.4. The stochastic simulation statistic method is used to analyse the hazards risk that oil spill in anchorage ground and channel might cause on the sensitive resources around the environment. We get that due to the direction of dominant wind is northwest and southwest, after the occurrence of ship oil spill accident in the channel, the pollution risk seems maximum relatively for the Island of Loos on the southeast of the channel and Conakry west bank on the southeast, the probability of pollution is20%and16%and fastest reach time is6h and8h respectively. It is necessary to strengthen the emergency prevention.5. On the basis of the analysis of existing emergency system of oil spill and current situation of emergency ability and existing problems, combining the above-mentioned evaluation result of the pollution risk of oil spill in Conakry waters, emergency precaution strategies and management measures to reduce the risk of the oil spill accident in Guinea are put forward pertinently.Oil spill models have been used and simulated to assess a possible environmental impact then developed an information system for a possible effective response on Conakry, Guinea waters in case the country is confronted by an oil spill situation. This research can be in good agreement with the investigating results that have been achieved and can help Guinean government, international organizations and shipping industry authorities to set up urgent, rigorous and coherent policies to protect marine environment and to manage oil exploitation and transport against an oil spill situation.