Focus Stories

Every month we will focus on a specific theme, featuring a selection of articles which have previously been published in Hydro International magazine. By including a mix of older and more recent articles, we will present a complete recap of the subject. Furthermore, we will be bringing you a bi-weekly round-up of ‘Focus Stories’ related to the theme through our newsletter (sign up here). The theme for April 2016 is Shallow Water.

An important area of work in hydrography is shallow water. This month, Hydro International collected papers focussing on shallow-water surveying. Interesting is that this field of work has multiple ways to collect the data: traditionally using a vessel but also techniques like Lidar, satellite bathymetry or hovercrafts (and smaller) are used.

Focus on: Shallow Water

Subsea Cable Route Surveying

Ninety-nine percent of international data is transmitted by around 265 subsea cable systems connecting the world. The total length of subsea cables exceeds 1.6 million kilometres, and they can be found as deep as 8,000m. The cables, which can cost hundreds of millions of dollars, must generally be run across flat surfaces of the ocean floor, taking... (read more)

Surveying Japanese Inland and Coastal Waters

In March 2015, Leica Geosystems conducted a series of demonstration surveys in Japan with the HawkEye III Airborne Topographic Bathymetric Lidar system. This demonstration was designed to prove the depth performance and general capabilities of the HawkEye III system in Japanese waters. It ambitiously targeted 13 geographically separated areas... (read more)

Mapping the Floor of Upper Loch Linnhe Using AUVs

Due to their particularly shallow and turbulent thermocline, conducting seafloor mapping in lochs, fjords and other estuaries always presents a unique challenge to the hydrographic surveyor. Surface vessels often struggle to obtain accurate measurements due to the highly variable impedance of an estuary’s mixing layer, which causes frequent a... (read more)

A Flooded Landscape Revealed

During the last week of a hydrographic survey of Lough Derg, Ireland’s third largest lake, the remnants of a preserved flooded landscape were unveiled beneath the surface with each passing swath. In early 2015, Geomara was commissioned by the utility company, Irish Water, to undertake a bathymetry and side-scan sonar survey of Lough Derg as p... (read more)

Imagery-derived Bathymetry and Seabed Classification Validated

Proteus FZC, EOMAP and DigitalGlobe have formed a partnership to bring satellite-derived bathymetry and seabed classification to the hydrographic community. A pilot conducted by UKHO in the Mediterranean confirms that the satellite-based process yields depth and seafloor information faster and more safely than traditional hydrographic survey method... (read more)

Riverbed Surveying

In order to meet the requirements of the European Water Framework Directive (EU-WFD), authorities face the problem of performing area-wide surveys of all kinds of inland waters repeatedly. Especially for mid-sized and small rivers, a traditional survey approach imposes almost insurmountable logistical efforts and costs. Employing the new airborne h... (read more)

Lidar Bathymetry on the Alaskan North Slope

In June 2014, the Bureau of Economic Geology, a research unit at the University of Texas at Austin, was contracted to conduct an airborne bathymetric Lidar survey on the Alaskan North Slope. The purpose of the project was to further determine, understand, and map the local landscape and thaw-lake attributes of an area west of the Dalton Highway and... (read more)

Radar-based Nearshore Hydrographic Monitoring

Shore-based marine radar techniques have recently proved to be an excellent tool for monitoring erosion and accretion in the dynamic nearshore area through repeated and automated large-area surveys. The ability to routinely survey intertidal areas has always been logistically challenging and expensive due to the limitations imposed by the tides, we... (read more)

General Description of XML File CUBE Parameters

Interferometric sonar acquire millions of soundings in a hydrographic survey. The processing of this data by a hydrographer without a reliable statistical algorithm like CUBE (Combined uncertainty and bathymetry estimator), to obtain a bathymetric map, would be practically impossible. CARIS HIPS software allows the use of the CUBE algorithm, invent... (read more)

Stop Using DGPS!

High-resolution multi-beam echo sounder (MBES) surveys should not be conducted where the uncertainty of the horizontal positioning system is larger than the nadir footprint of the MBES at the mean survey depth. In depths of 100 metres, the horizontal component of the nadir footprint of a 0.5 degree by 1.0 degree MBES, is an ellipse whose minor axis... (read more)

Very Shallow-water Bathymetry

The River Murray Operations Unit (RMOU) of the South Australian Water Corporation surveys very shallow waters, a type of surveying that has its own specific problems overcome by non-conventional solutions. This article was submitted by a surveyor from the above survey unit. I attended the Shallow Water Survey conference in Sydney in 2003 because th... (read more)

Hovercraft-based Munitions Detection System

Survey efforts in shallow water present a challenge; when coupled with protected species and critical habitat such as coral reefs, they can prove impossible. Tetra Tech, in conjunction with Neoteric Hovercraft, Inc., has developed an environmentally sensitive survey platform, which now allows for data collection in such areas. The TEMA-Lite (Towed... (read more)
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