Author: Charles Collins | Chief Surveyor, EGS Survey PtyThe Port of Darwin is Australia’s northern gateway of choice for trade due to its close proximity to key Asian markets and being the only multi-modal deep water port between Fremantle in Western Australia and Townsville in Queensland. In 2015 Darwin Port managed 2582 piloted vessels. This includes 65 cruise ships and cargo vessels carrying over 3,423,680 tonnes of goods.
EGS Survey Pty have undertaken the Darwin Port’s annual bathymetry monitoring program utilising their newly acquired Kongsberg dual head EM2040 multibeam echosounder. Vertical uncertainty of better than ±0.10m was achieved for this under-keel clearance survey.
The 0.7°x 0.7° dual head system allowed wider swath widths and greater productivity than previous surveys completed in the area with other single head systems. For example, in areas with less than 5m water depth swath widths of 40m+ were achieved whilst maintaining the uncertainty budget.
The dual swath capability allowed survey speeds of 10 knots and above whilst still ensuring along track data density. To verify data density was being achieved a 0.5m x 0.5m artificial target was positioned on the seabed and surveyed at 8-10 knots at various offsets. Due to the dual swath capability, up to 32 hits on the target were logged with each pass.
The attached images show sand wave formations in the Darwin Harbour approach and the wreck of the three masted schooner "Booya" lost during cyclone Tracy in 1974.