Recap of Shallow Survey 2018

  • By Chris Burnett

    Shallow Survey is a conference held every three years that enables key decision makers in the hydrographic industry to meet and talk about ground-breaking developments within the marine mapping sector. I attended the conference in St. John’s, Canada in October 2018 with Kyle Goodrich, TCarta’s President & Director of Products.

    The decision to host the conference in Canada was highly pertinent. The Canadian Hydrographic Service (CHS) has the complex task of accurately mapping the seafloor of the Canadian Arctic following receding ice as a result of global warming, as this article indicates: The Northwest Passage in 2017: This is the first in a series exploring the Arctic.

    Increasing maritime traffic in this region places a greater risk on CHS to ensure that accurate and up-to-date charts are available to the mariner to conduct activities safely and with confidence.

    Forty percent of the world’s coastline belongs to Canada and the north of Canada is either largely uncharted, or charted with insufficient accuracy and quality, and this lack of reliable information contributed to a vessel colliding with rocks towards the end of August 2018, at considerable cost of recovery: Grounded cruise ship rescue in Nunavut cost Canada's Armed Forces $513K

    The Shallow Survey conference has a regular discussion theme including traditional survey techniques such as multibeam and side scan sonar, however, the discussions have evolved in recent years to include Satellite Derived Bathymetry (SDB), Light Detection And Ranging (LiDAR) and remote sensing. While there are still no hydrographic standards in place for SDB, there is growing acceptance from the industry that SDB must now be taken seriously in order to cover the vast areas of uncharted waters and outdated survey data, observed many years ago using lead line surveys.

    Kyle Goodrich presented a paper during the conference to show how TCarta is using its’ National Science Foundation (NSF) grant to develop remote sensing approaches to assist the hydrographic industry. TCarta has developed a Stereo Photogrammetric Bathymetry (SPB) workflow to extract depth points using overlapping images, which is a different concept from the traditional SDB workflow. The SPB points can be utilised as calibration data in the absence of in situ data, which is ideal for the waters of the Canadian Arctic where there is little survey data available to quantify the vertical uncertainty of the SDB.

    TCarta produced 2 metre resolution SDB datasets for Cambridge Bay and Gjoa Haven that were compared to SPB and resulted in a vertical uncertainty of +/- 4.6% depth. This uncertainty means that at 10 metres depth the SDB is either 10.46 or 9.54 metres depth when compared with the SPB.  Coverage of the two locations was better than expected, resulting in maximum reliable depths of 18 metres.

    The key takeaway from the conference is that Satellite Derived Bathymetry has a major role to play in assisting Hydrographic Offices due to the ability:

    To cover large areas that cannot be covered efficiently using in situ methods

    To identify shallow water areas that are a risk to commercial and recreational sailing

    To provide rapid updates using newly collected imagery

    To utilise archive imagery to identify potential changes in the state of the seafloor

    Kyle’s paper was entitled “SDB has come of age.” The developments made over the past 5 to 10 years clearly show that while SDB still has a way to go to meet the accuracies of traditional survey methods, it must now be considered as a player at the table to address the challenges of cost, time, and safety where large areas of the globe remain inadequately charted. SDB has indeed come of age.

    Shallow Survey 2018

    Chris Burnett at Shallow Survey 2018 and the winner of the TCarta Bathyme-tie.

    Other recent articles by TCarta:

    A New Way to Explore Geospatial data

    Earth Observation Conference recap by Richard Flemmings