Land and Hydrographic Surveying

GMA Hydrology specializes in collecting survey data in and along rivers, estuaries, and reservoirs for a variety of purposes including geomorphic monitoring and assessment, hydraulic and habitat modeling, and restoration planning, design, and implementation.

GMA has developed unique capabilities for efficiently mapping long reaches of river systems using a variety of boat-based and land-based survey platforms. GMA has numerous watercraft that can be equipped with a variety of survey instruments depending on need. Our primary bathymetric survey method employs either a custom 8-channel Ross Laboratories portable sweep system or Norbit iWMBS multibeam system deployed from either a cataraft or jetboat platform. GMA uses Trimble R8 and R10 GPS units and Trimble and Leica total stations for land-based surveying.  GMA also has the capability of collecting site specific imagery and photogrammetric data using our small unmanned aircraft systems.

GMA integrates LiDAR, photogrametric, and other point cloud datasets to provide seamless high resolution Digital Terrain Models (DTM's).  All surveys include quality assurance and quality control ground survey check points that are used for accuracy assessment.  GMA believes in providing modelers and project designers what they need therefore synthesis products are delivered in a data package format that is well organized, documented, and accessible for rapid use.

In addition to terrain surveys GMA also conducts water surface elevation and water velocity surveys.

Services Include

  • Establishing survey control networks
  • Terrestrial surveys
  • Hydrographic surveys: channel topography, cross sections and profiles
  • Reservoir surveys
  • Construction surveys: base maps for design, stake-out, volumetrics, as-builts
  • Remote sensing mapping and interpretation
  • Integration with LiDAR and other point cloud data sets to produce seamless DEM’s
  • QAQC and certification of existing datasets
  • Water surface elevation surveys
  • Water velocity surveys