Environmental Management and Visual Mapping as Alternative Monitoring in Heterogeneous Areas

Abstract

Abstract Environmental Baseline Study (EBS) in Norway has been carried out as traditional sediment sampling at the planned production site for biological, chemical and physical analysis prior to production drilling according to regulation. The extent of such study should be related to the risk of impact from the planned operations. This baseline can then be used as a reference for future environmental monitoring. Equally important is the contribution to environmental impact assessments defining the measures to eliminate, limit or offsetting the adverse effects that the operation could generate. For the Victoria location, a traditional EBS based on sediment sampling was not considered beneficial due to both anticipated coarse sediment as well as presence of corals at the elevated ridge south west in the area. A comprehensive study including sediment analysis, visual mapping with ROV (Remotely Operated Vehicle), current measurements and interpretation of side scan sonar data and bathymetry data was therefore applied to meet the challenges at Victoria. The video lines covered more than 130 km of sea bed and the interpretation enabled categorisation of the seabed in soft bottom, rocks and reef building corals. Still photos and HD videos of the major corals structures were used to identify the dominant species and assess their health status (dead, poor, live). Results were transferred to a GIS to define the optimal position of anchoring corridors minimising interference with sensitive ecosystems. The combination of the different methods used in the EBS gives a thorough coverage of the area. The amount and quality of data gathered also beyond the location of the appraisal well location, allow a proper assessment of the sensitivity of the area at the field scale. Based on the experiences gained, it is recommended that future monitoring in areas comprising different habitats (soft bottom, rocky habitat etc.) apply different dedicated monitoring methods. For the visual monitoring a recommendation of approaches are: ‒Turbidity and current should be measured before and during drilling to document the dispersion of particles to secure the monitoring strategies.‒Establish photo stations and indicator species to be monitored based on the data from turbidity and current measurements.‒The use of a GIS based map system is highly recommended to handle the amount of data collected in an efficient and presentable way.‒Collected data from future surveys should be implemented in the already existing GIS based map system of the Victoria site to secure an up to date database.