GdB has teamed with STARR II, as a survey subconsultant, through four fiscal years to perform Field Survey to obtain current “on the ground” data to support a RISK MAP Study in FEMA’s Region II which includes, Ontario, Orleans, Tompkins, Yates, Rensselaer, Saratoga, Seneca, Wayne, Chatauqua, Franklin, Genesee, Jefferson, St. Lawrence and Wyoming Counties. 

The detailed work was performed in support of riverine activities including hydrologic and hydraulic analysis of inland flooring sources (e.g. streams, rivers and lakes). The survey also included detailed locations of structures within the study limits such as bridges, culverts and dams. The survey data collected was then submitted to STARR II and was used to develop products to identify, assess and document flood risk. All work was performed using methodology approved by FEMA and laid out in their “Guidance for Flood Risk Analysis and Mapping” manuals. 

Field survey work included collecting cross section data, establishing benchmarks, performing structural measurements and gathering detailed measurement information on other flood control structure geometry. GdB staff also prepared detailed sketches and captured photographs of existing conditions for all scoped natural cross sections and flood control structures. 

As the scope of work involved natural features, there were certain areas of the project where Safety of the Field Crews became a huge factor. GdB field crews performing this work are equipped with a sUAS Drone to complete work on watersheds with an inaccessible ravine and channel bottom. At GdB, the safety of our employees is paramount, so in order to complete this task and provide the accuracy required by the client, we opted to use Small Unmanned Aircraft Systems (sUAS) flown by one of our FAA Part 107, Certified Remote Pilots to produce low altitude photogrammetry. 

In order to produce high quality survey grade topographic mapping and generate cross sectional data for our client, GdB first needed to set Aerial Targets and establish the Horizontal and Vertical location using traditional GPS techniques. Reflectorless shots were taken with a Total Station on prominent features in the ravine bottom and acted as check points when generating the 3D Point Cloud. This was all done while staying well away from the edge of the ravine and out of the creek bottom. Once Aerial Imagery was produced, it was processed together with the Aerial Target GPS locations and Total Station shots to produce a digital 3D point cloud for feature extraction. A high-resolution geo-referenced orthomosaic photo was also produced. From the data, cross sections were cut out of the point cloud and X,Y,Z data was gathered where the client had requested they be taken. From that data the rest of the process was the same and detailed sketches and photographs of existing conditions were created.