Net Environmental - Economic Benefit Analysis Model

Abstract

ABSTRACT To be able to compare various response strategies for oil spill response a Net Environmental – Economic Benefit Analysis model (NEEBA) has been developed by TNO. This model consists of an oil behaviour module, a response module and an ecological effect module. In the oil behaviour module a quantitative division of the oil volume over the different compartments (air, water surface and water column) is determined on the basis of spreading, transport and weathering. This module determines also the fate of the remaining oil after one of the response options has been applied. With the ecological effect module the effects on organisms at the water surface, in the water column and on the sea floor are determined. In order to come up with one benefit score a simplified weighing method has been chosen to compare the effects on different species. The NEEBA score is therefore expressed in costs, using the costs of fish as basis. The “costs” of the other organisms in relation to fish are dependent on their place in the food chain. For each step in the food chain a factor ten has been applied. In other words 1 kg of birds equals 10 kg of fish and 100 kg of Zooplankton. To account for seasonal fluctuations the model can be adjusted by changing the densities of the different organisms over the year. The methodology, developed in MS excel, can be used by policy makers and decision takers to assist in choosing the most appropriate response option. The model interface consists of an input window, a default window with several variables and defaults and two output windows. In the input window parameters such as volume, density and viscosity of the oil but also meteorological and hydrological information can be filled in. In the default window parameters like the densities of the different organisms, weighing factors, costs, water type, etc, can be varied. The response option can be varied with respect to mobilization time, number of units deployed and capacity. The NEEBA model is a valuable tool to support decision-making and gives insight in the environmental effects related to a particular response option. The NEEBA model shows that there is a specific role for the different response options. Each option has a window of opportunity in which the use is most optimal. The tool can be used for preplanning as well as during actual spills. The model will be developed further to increase its value and realism