Trail Surveys Meets the Need for Accurate, Consolidated Data on Pongola Poort Dam (Jozini Dam) Survey

Trail Surveys’ handover of data collected from the Jozini Dam Survey Project showcases the strength of combining various Geomatics disciplines into a turn-key solution for our clients.

Most Geomatics companies limit their offering to only one or two survey disciplines which affect the cost effectiveness of the surveys, the survey project timeline, the integration of different survey data sets derived from different disciplines and in some cases the effective utilisation of all survey data by different engineering design teams. Trail Surveys, however combines eight different Geomatics disciplines as well as numerous survey technologies to provide clients with a holistic Geomatics solution.

The South African National Department of Water and Sanitation (DWS) appointed LTE Consulting for feasibility studies and design for modifications required to increase the spillway capacity of Jozini Dam, together with addressing various dam safety deficiencies.   LTE Consulting contracted Trail Surveys to provide fit-for-purpose accurate survey data on the dam wall and basin to facilitate the analyses and detail designs.

The Geomatics scope of work for this project comprised:

  • The establishment and fixing of a network of permanent survey controls within the area of interest;
  • Digital aerial photography and LiDAR survey of 45,169 Ha of the dam basin at 10cm GSD resolution with a LiDAR point density of 5 points per square meter;
  • Terrestrial laser scan survey of the isometric and downstream side of the Jozini Dam Wall structure measuring L430m x W260m x H800m;
  • Multi-Beam Echo Sounder (MBES) Bathymetric survey of the upstream (submerged) side of the Jozini Dam wall structure;
  • Single-beam Echo Sounder (SBES) bathymetric survey of Jozini Dam (13,368 Ha);
  • The compilation of an updated Cadastral key-plan of the dam basin (45,169 Ha), accurately reconstructed from surveyor general records;

The above scope of work effectively integrated four Geomatics disciplines, namely;

engineering -, remote sensing -, cadastral -, and hydrographic surveys. “Trail Surveys is one of very few companies on the African continent offering a full range of geomatics services,” says Jaco Wiesner, Business Development Manager & Engineering Surveyor at Trail Surveys. “This is because we have accumulated the skills, technology, experience and most importantly, the capacity to undertake and combine these services into a total solution, over the past 18 years since Trail Surveys’ inception in 2001.”

All the survey data deliverables were submitted to our client within 10 weeks from date of site handover, which in itself was quite a feat considering that we were challenged by almost two weeks of inclement weather conditions prohibiting the execution of our aerial and bathymetric surveysFollowing our field and office quality control on the surveys we could proudly boast a 90 to 95% level of confidence on all the respective surveys. This degree of accuracy gives our client peace of mind and helps to inform their analysis and detail designs moving forward,” says Jaco.

According to Jaco, what made this project unique was the merging of all the data sets to generate a continuous accurate terrain model for the entire dam basin, including the submerged portion of the Jozini Dam, as well as the 3D modelled dam wall. “In addition to the standard survey deliverables we were able to accurately determine the average annual sedimentation rate for Jozini Dam by comparing our survey data with the 1973 Bathymetric surveys of Jozini Dam.” Jaco explains.

With this being a first for data derived from several respective Geomatics disciplines being integrated into a single accurate, workable data set for DWS, Trail Surveys are both humble and proud to have contributed to the success of this project. “The majority of surveyors in South Africa simply do not have the capacity and ability to deliver these survey deliverables in a turn-key solution – which in essence exhibits one of Trail Survey’s greatest strengths,” Jaco concludes.