Jackdaw Scar Irish Ford Hydrographic Survey

Metcalfe Civil Engineering
Eden Rivers Trust
The Environment Agency

case study intro

Scope of Project

Not every “topo” is a typical “topo”. The collective experience of our surveyors know this better than most. So when the Gridmark Survey team were asked to provide detailed topographical (topo) surveys of the riverbed and surrounding area at nine specific locations across a 2.5km length of the river Lyvennet, we knew we’d be getting wet and usually there is a surprise or two on a survey involving water.
Add to that the additional 3D laser scanning required at the key river crossings and the aerial survey we undertook to provide additional detail to support the terrestrial surveys and we were confident that our client would receive our usual, thorough results package, topped off with documentary photography for each structure and at each cross section on the survey site.
Our band of merry surveyors packed their waders along with base stations, a winged drone and 3D laser scanners and we looked forward to working on the river who’s source is thought to be close to Robin Hood’s grave.

Site & Technical Challenges

We were prepared for site access to be a little tricky so we arrived in one of our 4×4 vans but we did experience a few other challenges to deliver another successful survey project.
We initially intended to utilise one of our remote controlled boats which can carry a echo sounder but the river had an unaccommodating blend of shallow, fast moving and in some areas, overgrown stretches which meant that we had to put one of our favourite toys , or rather, technical pieces of equipment back in the van. But we used our trusty total station to take the required riverbed measurements.
Referencing the separate 3D laser scans and aerial drone survey point cloud to the topographical survey so that they all tied together at an appropriate level of accuracy is a challenge but our experienced team were up to it and this is something they relish.
We also planned on using a mobile phone signal to set up the VRS GPS receivers for accurate measurement but due to the location this proved impossible. Fortunately a local landowner who was a passionate member of the Eden Rivers Trust allowed us the use of one of his fields which was 0.5km away. We set up a GPS base station up a small hill along with a radio aerial to facilitate accurate GPS measurement across the full 2.5km site. We thank them once again for their hospitality.

Additional Points of Interest

We encountered several locals who were fascinated with the survey work we were carrying out and it was encouraging to see how many of them were so informed about the local wildlife, particularly the fish varieties including the Atlantic Salmon who are now nesting in the river due to the great work completed by the Rivers Trust which has added more bends to the river.
We also found an American Mink living on one of the riverbanks. We understand that this is a controversial creature but it was still enchanting to watch is going about it’s business in what we assumed was near it’s home. And we couldn’t help but think it was meant to be found by us when we checked on the species online as it’s scientific name is “Neovision Vision” – which seems apt for a team of geospatial surveyors don’t you think?

If you have topograhical survey requirements and believe that Gridmark Survey might be able to help you with your project please get in touch with one of our friendly team and we can discuss your survey requirements.

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