Case Studies

Tough Conditions, Precision Survey in Wales

Scroll

The Background

Date: February-April 2025

Client: Natural Resources Wales

This Natural Resources Wales commission was to provide an accurate topographic survey of the river channel system for the upper reaches of the Neath catchment including online and offline hydraulic structures, and bank and defence crest levels. The following rivers/channels Aber Nant, Addoldy River, Afon Mellte, Gelliceibryn Brook, Nant Clun Y Bont, Nant Gwrach, Nant Gwrelych, Nant Pergwm, Nant Y Gwyddyl, Neath Canal, River Neath, Trib01 & underpasses were included. Over 22,824m of river channel was surveyed over the duration of three months.

Process

The Challenge

Timing – Channel surveys undertaken in winter months typically involve high flow rates & river levels. Extensive forecasting & monitoring of river conditions was essential to ensure appropriate weather windows were targeted.
Technology – GNSS signal can historically be difficult to obtain in valleys. By using a combination of Trimble VRS & Base-Rover set ups, the survey teams were successful in accomplishing the full survey.
Scale – Over 22,824m of river channel was surveyed over the duration of several months. The project was completed using a range of survey teams, therefore continuous communication was essential in keeping the project on track.
Structural Complexity – The watercourses involved a variety of channels from dry ditches to canals to 30m wide rivers. As a result the structures involved ranged from footbridges to culverts to major highway bridges. Additionally flood walls, embankments, manholes, weir systems & gauging stations were all required to be surveyed in full.
Environment – The survey extent included areas of landslip, hostile sites, dense vegetation & complicated watercourses. All of these challenges had to be negotiated in coordination with the client.

Process

The Results

The survey was collected, processed & delivered to Environment Agency’s National Standard Technical Specification for Surveying Services (v5.01).
Over 800 cross sections were surveyed over a length of 22,824m, on 17 watercourses
Deliverables included cross section drawings, long section profiles, topographic drawings, XYZ exports, Flood Modeller Pro, HEC-RAS, TUFLOW, photography, manhole sheets, 360º GoPro photos, survey report & control.
The data was processed using our in-house GeoRiver® software to allow seamless integration & multiple exports to match the client specifications & requirements.

“This project was a comprehensive approach to capture the hydrological activity within the valley system. The deliverables will allow our client to accurately model the whole area of Glyn Neath & thereby enhance flood risk planning in the future.”