Extensive use of geospatial technology allows the Blue Line Project to map and portray the potential future high tides with a high degree of accuracy and precision.  Geospatial technology behind the scenes includes an array of Geographic Information Systems (GIS), GPS and other satellite-based navigation, and use of aerial imagery and drone mapping (small Unmanned Aerial Systems, or sUAS).

 We acquired existing NOAA Light Detection and Ranging (LiDAR) digital elevation data from the NOAA Digital Coast and referenced this to the UTM earth coordinate system and NAVD88 vertical datum. Along with aerial photography, this allowed us to make a preliminary model of the current and future shorelines in 3D.

Then, we collected ultra-fine resolution aerial photos from ODU’s drone fleet with ~ 1inch resolution, overlaid hundreds of imagery in a sophisticated Structure from Motion (SfM) modeling algorithm, and generated a fine-scale 3D model of each site.  With the help of the NOAA National Geodetic Survey branch located based in Norfolk, we gathered accurate and precise topographic data to reference the 3D drone surface to the ground.

Drone mapping for each site was led by George McLeod, ODU’s Asst. Director for Geovisualization Computing and a certified FAA Drone Pilot. For each site, a predetermined flight plan and grid was flown at approximately 200ft altitude.  This allowed for overlap and high-accuracy orthoimagery and digital surface models. We used a DJI Mavic Pro 2 and its new Hasselblad camera system in conjunction with desktop and cloud-based photogrammetry software (Pix4D.) In conjunction with available LiDAR laser elevation data and prior aerial photography, these geospatial data provided an accurate foundation for mapping. See the examples from The Hague site in Norfolk below.

Orthomosaic and the corresponding initial resulting Digital Surface Model (DSM) for The Hague, Norfolk.   

Next, we adjusted everything in three dimensions together, so that water levels today in the river, at the NOAA Sewells Point tide gage, and future high tides could be delineated by flooding or contouring.  Finally, all the future shoreline delineations were assembled in a GIS, symbolized in a uniform and appropriate color and cartographic style, and published online as local “webmaps” for use in the field via SmartPhone, tablets, or other portable devices.

Mr. Chris Fox, a geography major, designed a mobile webmap app for the team to use in the field. The webmap allows users with smartphones and GPS (or tablet or other devices) to “follow the line” in the field. This method will be used with a mapping grade GPS receiver to guide the placement of flags, survey tape, and paint ahead of the King tide.

Preparatory mapping used aerial photography and digital Light Detection and Ranging (LiDAR), or airborne laser topographic mapping, to delineate initial potential high tide shorelines.

In addition to static maps of each future high tide shoreline, Kellie Burdick undertook an effort to animate the future high tides with a raster model of successive areal flooding.   The two animations below illustrate the “bath tub model” approach, which floods low-lying elevations to each successive increment of tidal flooding. While bath tub models are a simplistic flood representation in GIS, these two areas exhibit storm drains that can “backflow” from tides, filling up drains and onto streets via underground pipes that are not connected to the estuary over the surface. Notice this process in some of the animated maps.

For more info on geospatial technology, visit the ODU Geography program, or reach out directly to Dr. Tom Allen.