H-Sense': harbour sediment mapping using Chirp reflection surveys in Norway and Sweden

The EdgeTech (4-24 kHz -Fish) is used in the range of 4 to 16 kHz to map the most recent, usually contaminated, top layer in the harbour and estuaries of the low tidal harbours of Bergen, Norway and Gothenburg, Sweden. The principal objective is to relate distribution patterns of the sediments with natural and man-induced processes such as sediment supply, currents, waves. storms, and vessel movements. In February and March surveys were carried out which covered the harbour areas of Bergen and Gothenburg. Both surveys succeeded in not only mapping the top sediments but also in obtaining profiles at Bergen in water depths exceeding 300 m despite the signal return period exceeding the transmission periods. In the Gothenburg estuary reflectors were obtained from 40 m below seabed despite the high frequency range of the Chirp signal showing profiles infilled channels (see Figure 2). The initial results for the H-SENSE study (Harbours: Silting and Environmental Sedimentology European) are presented for two harbour basins in Bergen and Gothenburg respectively. The study is being carried out jointly between universities and institutes in Sweden. Norway, the UK. Netherlands and Latvia within the EC-Directorate General 6 (Transport) research programme.