Summary of Working Paper No. 5-1994

I. 5.1: Content of Database, Planning and Risk Assessment.

By Sylvi Vefsnmo, SINTEF NHL, Trondheim, Norway.

The purpose of the 1993 INSROP Project I.5.1 "Content of database, planning and risk assessment" was to specify the requirements to the database, and to identify and evaluate the data sources. A feasibility study of local oil and ice drift models was also a part of the project in 1993/1994. The outcome of Project I.5.1 has been divided into three parts and is reported in WORKING PAPER NO. 5 (1994).

Part I of the report states the requirements to the physical environment database. The database shall provide essential supporting information on climatic variability and navigability which is needed for the assessment of the feasibility of opening the NSR to international shipping with an extended navigation season. The possible impacts from the planned activity along the NSR can be divided into two main categories. One is the impacts from the operational point of view, the other is the impacts from possible accidents. The operational and accident approach will principally be the same, even though the impact factors and the ecological components differ in valuation. For both the operational and the accidental scenarios, limitations in space and time are necessary. The temporal and spatial scenarios will depend on type of ship and convoys as well as the physical conditions.

In relation to natural conditions and ice navigation, INSROP GIS will serve as a tool to provide information within the following categories:

Base cartographic data

Infrastructure information

Planning of sailing (operational aspects)

Risk assessment (technical, personal)

Environmental impact assessment

In order to fulfil the requirements to the GIS system, the most important entities related to physical environment and navigability in ice are described in detail. The main limiting factors for transit sailing are the ice conditions and the water depth. Navigation in close ice is often accompanied by compaction, which is closely connected to the wind speed and direction and is relatively easy to predict from the weather forecasts. In fall the pressures are accompanied by adhesion to the ship's hull and in some narrow zones with a very rapid drift. In winter the success of the voyages will depend on the polynyas and the discontinuities in the drifting ice.

Part II of the report contains an overview of the mechanisms of drift and spread of oil under different surface conditions (open water, broken ice, level ice) and discusses various statistical and operational concepts for oil and ice drift. Pollution is the most serious environmental threat related to traffic along the NSR. In order to quantify the assessment of possible conflict between oil and vulnerable resources, oil drift data are needed to indicate the extent of the potential impacted area. The work recommends that existing statistical oil drift models should be modified in order to provide oil drift data for environmental impact assessments along the Northern Sea Route.

An operational oil spill model should produce forecast of the fate and behaviour of the oil spill. If the oil spill model is to be used for decision making related to oil spill combat and protection of sensitive resources, the model must provide details on spreading, weathering and partitioning of oil in different ice types. Sea ice processes and parameters significantly affect the fate and behaviour of spilled oil. In order to account for these effects, detailed information about the ice conditions is required, including areal fraction of different ice types, floe size distribution, ice thickness and velocity. To provide the operational oil drift model with necessary details of ice information, the report recommends a two-level concept for the ice drift model. This concept involves a mesoscale ice drift model (spatial resolution about 20 km) and a local ice drift model around the oil spill. The mesoscale model will produce general forecast for the ice conditions. The local ice drift model will only operate during special conditions, for instance an oil spill situation. Since the weathering processes of the oil depend strongly on the wave conditions, efforts should be made to include wave attenuation in the ice drift model.

Part III of the report contains an overview of the commonly available oil spill response systems with emphasis on cold waters. In principle the oil spill combat systems at sea can be divided into mechanical containment and recovery, chemical dispersants and in-situ burning. This part of the work also highlights the applicability and efficiency of these combat systems under various conditions (weathering state of the oil, sea state and wind). The efficiency of clean-up operations will be heavily dependent on access to combat equipment. The major conclusions are as follows:

No single response system can handle the variety of conditions normally encountered in oil spills in open waters.

Mechanical oil spill response is still the only true cleanup technique - the other modes serve to accelerate natural processes.

Dispersant application and burning techniques provide important backup capabilities.

In-situ burning may have an increased efficiency in broken ice compared to an open water spill due inter alia to reduced spreading of the oil (thicker oil film, etc.) and calmer sea state.